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Closed 10 years ago.
I've recently purchased a Mac and use it primarily for C# development under VMWare Fusion. With all the nice Mac applications around I've started thinking about Xcode lurking just an install click away, and learning Objective-C.
The syntax between the two languages looks very different, presumably because Objective-C has its origins in C and C# has its origins in Java/C++. But different syntaxes can be learnt so that should be OK.
My main concern is working with the language and if it will help to produce well-structured, readable and elegant code. I really enjoy features such as LINQ and var in C# and wonder if there are equivalents or better/different features in Objective-C.
What language features will I miss developing with Objective-C? What features will I gain?
Edit: The framework comparisons are useful and interesting but a language comparison are what this question is really asking (partly my fault for originally tagging with .net). Presumably both Cocoa and .NET are very rich frameworks in their own right and both have their purpose, one targeting Mac OS X and the other Windows.
Thank you for the well thought out and reasonably balanced viewpoints so far!
No language is perfect for all tasks, and Objective-C is no exception, but there are some very specific niceties. Like using LINQ and var (for which I'm not aware of a direct replacement), some of these are strictly language-related, and others are framework-related.
(NOTE: Just as C# is tightly coupled with .NET, Objective-C is tightly coupled with Cocoa. Hence, some of my points may seem unrelated to Objective-C, but Objective-C without Cocoa is akin to C# without .NET / WPF / LINQ, running under Mono, etc. It's just not the way things are usually done.)
I won't pretend to fully elaborate the differences, pros, and cons, but here are some that jump to mind.
One of the best parts of Objective-C is the dynamic nature — rather than calling methods, you send messages, which the runtime routes dynamically. Combined (judiciously) with dynamic typing, this can make a lot of powerful patterns simpler or even trivial to implement.
As a strict superset of C, Objective-C trusts that you know what you're doing. Unlike the managed and/or typesafe approach of languages like C# and Java, Objective-C lets you do what you want and experience the consequences. Obviously this can be dangerous at times, but the fact that the language doesn't actively prevent you from doing most things is quite powerful. (EDIT: I should clarify that C# also has "unsafe" features and functionality, but they default behavior is managed code, which you have to explicitly opt out of. By comparison, Java only allows for typesafe code, and never exposes raw pointers in the way that C and others do.)
Categories (adding/modifying methods on a class without subclassing or having access to source) is an awesome double-edged sword. It can vastly simplify inheritance hierarchies and eliminate code, but if you do something strange, the results can sometimes be baffling.
Cocoa makes creating GUI apps much simpler in many ways, but you do have to wrap your head around the paradigm. MVC design is pervasive in Cocoa, and patterns such as delegates, notifications, and multi-threaded GUI apps are well-suited to Objective-C.
Cocoa bindings and key-value observing can eliminate tons of glue code, and the Cocoa frameworks leverage this extensively. Objective-C's dynamic dispatch works hand-in-hand with this, so the type of the object doesn't matter as long as it's key-value compliant.
You will likely miss generics and namespaces, and they have their benefits, but in the Objective-C mindset and paradigm, they would be niceties rather than necessities. (Generics are all about type safety and avoiding casting, but dynamic typing in Objective-C makes this essentially a non-issue. Namespaces would be nice if done well, but it's simple enough to avoid conflicts that the cost arguably outweighs the benefits, especially for legacy code.)
For concurrency, Blocks (a new language feature in Snow Leopard, and implemented in scores of Cocoa APIs) are extremely useful. A few lines (frequently coupled with Grand Central Dispatch, which is part of libsystem on 10.6) can eliminates significant boilerplate of callback functions, context, etc. (Blocks can also be used in C and C++, and could certainly be added to C#, which would be awesome.) NSOperationQueue is also a very convenient way to add concurrency to your own code, by dispatching either custom NSOperation subclasses or anonymous blocks which GCD automatically executes on one or more different threads for you.
I've been programming in C, C++ and C# now for over 20 years, first started in 1990. I have just decided to have a look at the iPhone development and Xcode and Objective-C. Oh my goodness... all the complaints about Microsoft I take back, I realise now how bad things code have been. Objective-C is over complex compared to what C# does. I have been spoilt with C# and now I appreciate all the hard work Microsoft have put in. Just reading Objective-C with method invokes is difficult to read. C# is elegant in this. That is just my opinion, I hoped that the Apple development language was a good as the Apple products, but dear me, they have a lot to learn from Microsoft. There is no question C#.NET application I can get an application up and running many times faster than XCode Objective-C. Apple should certainly take a leaf out of Microsoft's book here and then we'd have the perfect environment. :-)
No technical review here, but I just find Objective-C much less readable.
Given the example Cinder6 gave you:
C#
List<string> strings = new List<string>();
strings.Add("xyzzy"); // takes only strings
strings.Add(15); // compiler error
string x = strings[0]; // guaranteed to be a string
strings.RemoveAt(0); // or non-existant (yielding an exception)
Objective-C
NSMutableArray *strings = [NSMutableArray array];
[strings addObject:#"xyzzy"];
[strings addObject:#15];
NSString *x = strings[0];
[strings removeObjectAtIndex:0];
It looks awful. I even tried reading 2 books on it, they lost me early on,
and normally I don't get that with programming books / languages.
I'm glad we have Mono for Mac OS, because if I'd had to rely on Apple
to give me a good development environment...
Manual memory management is something beginners to Objective-C seems to have most problem with, mostly because they think it is more complex than it is.
Objective-C and Cocoa by extension relies on conventions over enforcement; know and follow a very small set of rules and you get a lot for free by the dynamic run-time in return.
The not 100% true rule, but good enough for everyday is:
Every call to alloc should be matched with a release at the end of the current scope.
If the return value for your method has been obtained by alloc then it should be returned by return [value autorelease]; instead of being matched by a release.
Use properties, and there is no rule three.
The longer explanation follows.
Memory management is based on ownership; only the owner of an object instance should ever release the object, everybody else should always do nothing. This mean that in 95% of all code you treat Objective-C as if it was garbage collected.
So what about the other 5%? You have three methods to look out for, any object instance received from these method are owned by the current method scope:
alloc
Any method beginning with the word new, such as new or newService.
Any method containing the word copy, such as copy and mutableCopy.
The method have three possible options as of what to do with it's owned object instances before it exits:
Release it using release if it is no longer needed.
Give ownership to the a field (instance variable), or a global variable by simply assigning it.
Relinquish ownership but give someone else a chance to take ownership before the instance goes away by calling autorelease.
So when should you pro-actively take ownership by calling retain? Two cases:
When assigning fields in your initializers.
When manually implementing setter method.
Sure, if everything you saw in your life is Objective C, then its syntax looks like the only possible. We could call you a "programming virgin".
But since lots of code is written in C, C++, Java, JavaScript, Pascal and other languages, you'll see that ObjectiveC is different from all of them, but not in a good way. Did they have a reason for this? Let's see other popular languages:
C++ added a lot extras to C, but it changed the original syntax only as much as needed.
C# added a lot extras compared to C++ but it changed only things that were ugly in C++ (like removing the "::" from the interface).
Java changed a lot of things, but it kept the familiar syntax except in parts where the change was needed.
JavaScript is a completely dynamic language that can do many things ObjectiveC can't. Still, its creators didn't invent a new way of calling methods and passing parameters just to be different from the rest of the world.
Visual Basic can pass parameters out of order, just like ObjectiveC. You can name the parameters, but you can also pass them the regular way. Whatever you use, it's normal comma-delimited way that everyone understands. Comma is the usual delimiter, not just in programming languages, but in books, newspapers, and written language in general.
Object Pascal has a different syntax than C, but its syntax is actually EASIER to read for the programmer (maybe not to the computer, but who cares what computer thinks). So maybe they digressed, but at least their result is better.
Python has a different syntax, which is even easier to read (for humans) than Pascal. So when they changed it, making it different, at least they made it better for us programmers.
And then we have ObjectiveC. Adding some improvements to C, but inventing its own interface syntax, method calling, parameter passing and what not. I wonder why didn't they swap + and - so that plus subtracts two numbers. It would have been even cooler.
Steve Jobs screwed up by supporting ObjectiveC. Of course he can't support C#, which is better, but belongs to his worst competitor. So this is a political decision, not a practical one. Technology always suffers when tech decisions are made for political reasons. He should lead the company, which he does good, and leave programming matters to real experts.
I'm sure there would be even more apps for iPhone if he decided to write iOS and support libraries in any other language than ObjectiveC. To everyone except die-hard fans, virgin programmers and Steve Jobs, ObjectiveC looks ridiculous, ugly and repulsive.
One thing I love about objective-c is that the object system is based on messages, it lets you do really nice things you couldn't do in C# (at least not until they support the dynamic keyword!).
Another great thing about writing cocoa apps is Interface Builder, it's a lot nicer than the forms designer in Visual Studio.
The things about obj-c that annoy me (as a C# developer) are the fact that you have to manage your own memory (there's garbage collection, but that doesn't work on the iPhone) and that it can be very verbose because of the selector syntax and all the [ ].
As a programmer just getting started with Objective-C for iPhone, coming from C# 4.0, I'm missing lambda expressions, and in particular, Linq-to-XML. The lambda expressions are C#-specific, while the Linq-to-XML is really more of a .NET vs. Cocoa contrast. In a sample app I was writing, I had some XML in a string. I wanted to parse the elements of that XML into a collection of objects.
To accomplish this in Objective-C/Cocoa, I had to use the NSXmlParser class. This class relies on another object which implements the NSXMLParserDelegate protocol with methods that are called (read: messages sent) when an element open tag is read, when some data is read (usually inside the element), and when some element end tag is read. You have to keep track of the parsing status and state. And I honestly have no idea what happens if the XML is invalid. It's great for getting down to the details and optimize performance, but oh man, that's a whole lot of code.
By contrast, here's the code in C#:
using System.Linq.Xml;
XDocument doc = XDocument.Load(xmlString);
IEnumerable<MyCustomObject> objects = doc.Descendants().Select(
d => new MyCustomObject{ Name = d.Value});
And that's it, you've got a collection of custom objects drawn from XML. If you wanted to filter those elements by value, or only to those that contain a specific attribute, or if you just wanted the first 5, or to skip the first 1 and get the next 3, or just find out if any elements were returned... BAM, all right there in the same line of code.
There are many open-source classes that make this processing a lot easier in Objective-C, so that does much of the heavy lifting. It's just not this built in.
*NOTE: I didn't actually compile the code above, it's just meant as an example to illustrate the relative lack of verbosity required by C#.
Probably most important difference is memory management. With C# you get garbage collection, by virtue of it being a CLR based language. With Objective-C you need to manage memory yourself.
If you're coming from a C# background (or any modern language for that matter), moving to a language without automatic memory management will be really painful, as you will spend a lot of your coding time on properly managing memory (and debugging as well).
Here's a pretty good article comparing the two languages:
http://www.coderetard.com/2008/03/16/c-vs-objective-c/
Other than the paradigm difference between the 2 languages, there's not a lot of difference. As much as I hate to say it, you can do the same kind of things (probably not as easily) with .NET and C# as you can with Objective-C and Cocoa. As of Leopard, Objective-C 2.0 has garbage collection, so you don't have to manage memory yourself unless you want to (code compatibility with older Macs and iPhone apps are 2 reasons to want to).
As far as structured, readable code is concerned, much of the burden there lies with the programmer, as with any other language. However, I find that the message passing paradigm lends itself well to readable code provided you name your functions/methods appropriately (again, just like any other language).
I'll be the first to admit that I'm not very familiar with C# or .NET. But the reasons Quinn listed above are quite a few reasons that I don't care to become so.
The method calls used in obj-c make for easily read code, in my opinion much more elegant than c# and obj-c is built on top of c so all c code should work fine in obj-c. The big seller for me though is that obj-c is an open standard so you can find compilers for any system.
Related
I'm working on my thesis about the impact of using exceptions on code complexity. It would be really great if I had a few thousand LOC that use good old error handling and exceptions for the same functionality. I don't even know where to start googling. Any C#, Java, C++, D project would suffice. My best guess is a project that switched to exceptions at a given version. Any help is appreciated.
Considering that in both Java and C# exception handling is essential for pretty much the complete base libraries, I doubt it.
Java is pretty much completely out of the loop because without out parameters you have to resort to extremely strange constructs (eg you either always return Object arrays or implement classes with a return value + the value that should be returned,..).
In c# you could theoretically get around using exceptions and using error codes if you ignore the base library, but I still doubt anyone would want to program that way. For both languages it's just integrated way too much into the core concept.
So your best bet of the named languages would be C++, but then C++ exceptions have a whole lot of problems compared to more modern implementations - really no fun to use them. You may look around for eg Python programs, I could imagine someone programming python without exceptions.
Anyways it's extremely unlikely (independent of language; although C++ is probably the only one where I could imagine it at all) to find a project that changed from error codes to exception handling - after all that'd be pretty much a complete rewrite..
I don't think you will find such projects, even if some project switched at some time, they will still be very much different, so you would compare apples and oranges anyway. Thesis is not supposed to be based on anecdotal information, questionable testing, and unwarranted conclusions.
You can approach this topic from two angles. One is to discuss theoretical implications of two approaches of error handling and illustrate that with three-liners. Another, is to conduct a controlled experiment writing probably short (~1000 lines) some real-life scenario test case and analyse it, followed by discussion whether it would or wouldn't scale on larger systems. And of course, if you have time (at least couple years) and money (at least couple million $) to hire a group of experienced developers and provide them with large-scale problems, you can gather some valuable statistics.
Not sure it fits, but:
GTK+, the C library, uses error codes whereas gtkmm, its C++ wrapper, wraps them in exceptions. (Example: GTK+ g_thread_create() vs gtkmm Glib::Thread::create()) Both are object-oriented.
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Closed 9 years ago.
I've been working with C# and more generally the .Net framework for a couple of years now. I often heard about the similarity between C# & the Java language and would like to learn more about the second one.
Have you got any specific advice to learn Java when coming from C# ?
Any common errors a C# programmer would do when starting Java ?
Any documentation showing the habits you can keep and the ones you must change (still in a C# to Java optic, so something a bit more specific then a C# vs Java comparison) ?
Well, while C# and Java are superficially alike there are a number of small differences that might bite you. Generally I think the opposite direction—going from Java to C#—is less problematic. This is mainly due to C# being a more complex language so you might find many simplifications from common Java patterns but the other way around might be a little painful.
Things to look out for (partial list, not guaranteed to be exhaustive):
Different ...
Naming conventions. In Java only type names start with a capital letter (i. e. PascalCase), everything else uses camelCase. Not very hard to adhere to, though.
Also interfaces generally don't start with I. On the other hand you have to implement them with a different keyword. Doesn't really help in the middle of the code, though.
Class library :-)
While obvious, this has been the thing I spent most time on when learning a language. When dealing with a known paradigm the syntax differences are quickly sorted out, but getting to know the standard library / class library / framework takes some time in some cases :-)
Patterns. Well, not quite, it's still the same stuff. But C# supports some patterns at the language level, while you still have to implement them yourself in Java. No events, but the Observer pattern (very prevalent in Swing—whenever you see a Listener, you know what to do :-))
Exception handling. Java has so-called checked exceptions which means that an exception must either be caught or declared upwards. Usually this means that you have
catch (SomeException ex) {
ex.printStackTrace();
}
pretty often in your code1 :-)
Types. While .NET has normal objects and value types, they both are objects and support methods, properties, &c. Java has a dichotomy of primitive types, such as int, float, char, &c. and classes such as String. Doesn't matter much since they implemented auto-boxing, but sometimes it's still annoying to wrap int in Integer.
Polymorphism: All Java methods are virtual by default whereas c# methods are not.
Minor syntactic differences.
foreach (a in b) → for (a : b)
Different access keywords. Things like internal and protected internal don't exist. But unqualified members are visible to other classes in the same package (sort of internal, but then again not quite).
String comparison isn't done with == in Java. You have to use .equals(). While in C# == on strings is value equality, in Java == is always reference equality.
No ...
Properties. In Java this is generally done with the Foo getFoo()/void setFoo(Foo foo) pattern which C# generates silently behind your back when using properties but you have to do it explicitly in Java. Generally, to keep the language itself simpler many things in Java are just conventions. Still, most of the time you're better off adhering to them :-)
Operator overloading. Deemed a hazard to the righteous programmer they weren't implemented for fear of abuse. Don't need them too often anyway, not even in C#, but sometimes they are nice and then you're missing something.
Indexers. You always have to access list items through myList.get(5) instead of the array-like syntax myList[5]. Just a mild inconvenience, though.
LINQ (though there exist implementations2 but it's not as nicely integrated), or lambda functions3 (no delegates anyway, but anonymous classes), extension methods, or partial classes (yes, that's a painful one when dealing with Swing, unless you're very disciplined), and a few more things.
Multidimensional arrays. You can use jagged arrays (arrays of arrays), buttrue multidimensionality isn't there.
Generics are compile-time only, at runtime only Objects remain. Also wildcards in generics can be hard to resolve sometimes when the compiler complains about all of the four ? in your generics having different types. (Though to be fair: That was a case where I would have needed type information at runtime anyway so I reverted back to Objects).
General advice: Grab a friend with Java experience and let him glance over your code. While he probably can't tell you everything you should take care of when you directly ask him that question, he can spot strange things in code just fine and notify you of that. This has greatly helped me learning Java (although I learned Java first and then C#, so it might be different).
1 Yes, I know many catch blocks look different, but still, this is probably the archetypical one and not even that rare.
2 Quaere, JaQue, JaQu, Querydsl
3 There's lambdaj, though. Thanks for pointing that out, Esko.
I honestly think the biggest hurdle for many C# developers trying to learn Java is learning a new IDE. Visual Studio is great, and when you're coding in C# for a long period of time, you get used to it. When having to move over to Eclipse or Netbeans, you suddenly feel lost. How do I set a breakpoint? Where's the immediate window? How do I create a windows app? etc etc... I know this sounds crazy, but I'm telling you, people get very attached to their IDE's and have a tough time getting used to new ones...
Languages themselves are pretty similar, sans few keywords and Java lacking some features C# programmers got used to (properties, using, reified (non-type-erased) generics).
The main problem here is knowledge of frameworks, of which there are thousands for Java.
The main language is fine. Getting to know the libraries will be one thing which takes time. If you're doing web-applications, there is a LOT to learn... equivalent technologies to WCF and ASP.net.
You don't say what kind of area you work in... desktop, server, or web-server?
Biggest difference between C# and Java : In Java, all methods are virtual. Hence the reason why tools such as NUnit and such came from the Java world.
To be honest, if you're a competent C# programmer I don't believe there's much you do need to know apart from packaging and deployment of applications.
Here's a good link http://en.wikipedia.org/wiki/Comparison_of_Java_and_C_Sharp
The biggest thing you need to learn is how to Greenspun C#'s functional style features in Java. For example, you can expect to make a lot of interfaces with only one method to get around Java's lack of lambda functions and delegates.
I honestly recommend Java in a Nutshell. Most Java/any_other_lang introduction books are for totally novice readers explaining the concept of a loop for pages and recursion for a chapter... You can start writing Java programs within two days with this book. Of course it will take you a long time to understand what is going on under the hood and how to use all the available framework. But once the language itself is mastered, it is easy to get along even with google only resources.
Although, this is the other way around, I found the following link to be quite useful for comparing Java and C#.
C# From a Java Developer's Perspective
I made a transition from Java to C# and back to Java again. I think syntactically they are very similar and most of the trouble I had was learning the .NET APIs and learning how to use them effectively. Many times I was using 'syntactic sugar', writing my code as if it was in Java and then translating it to C#. I spent a lot of time on Microsoft's website reading and learning about the APIs which was a huge help.
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For someone who’s been happily programming in C# for quite some time now and planning to learn a new language I find the Python community more closely knit than many others.
Personally dynamic typing puts me off, but I am fascinated by the way the Python community rallies around it. There are a lot of other things I expect I would miss in Python (LINQ, expression trees, etc.)
What are the good things about Python that developers love? Stuff that’ll excite me more than C#.
For me its the flexibility and elegance, but there are a handful of things I wish could be pulled in from other languages though (better threading, more robust expressions).
In typical I can write a little bit of code in python and do a lot more than the same amount of lines in many other languages. Also, in python code form is of utmost importance and the syntax lends its self to highly readable, clean looking code. That of course helps out with maintenance.
I love having a command line interpreter that I can quickly prototype an algorithm in rather than having to start up a new project, code, compile, test, repeat. Not to mention the fact I can use it to help me automate my server maintenance as well (I double as a SA for my company).
The last thing that comes to mind immediately is the vast amounts of libraries. There are a lot of things already solved out there, the built-in library has a lot to offer, and the third party ones are many times very good (not always though).
Being able to type in some code and get the result back immediately.
(Disclaimer: I use both C# and Python regularly, and I think both have their good and bad points.)
I'm primarily .NET developer and using Python for me personal projects.
What are the good things about python that developers love?
I can say for myself - Python is like a breath of fresh air.
1) It's simple to learn, took about a week for me in the evenings. I'm saying about Python + Django. Python syntax is quite simple.
2) It's simple to use. No troubles installing Python + Django on Windows at all.
3) It can be run on Windows and UNIX.
4) I need it for web, so I get cheaper hosting than ASP.NET.
5) All the advantages of Python language over C#. Like tuples - so useful!
The only thing I don't like is that my favorite IDE Visual Studio doesn't support it (I know about IronPython, don't you worry).
I'm a very heavy user of both C# and Python; I've built very complicated applications in both languages, and I've also embedded Python scripting in my major C# application. I'm not using either to do much in the way of web work right now, but other than that I feel like I'm pretty qualified to answer the question.
The things about Python that excite me, in particular:
The deep integration of generators into the language. This was the first thing that made me realize that I needed to take a long, serious look at Python. My appreciation for this has deepened considerably since I've become conversant with the itertools module, which looks like a nifty set of tools but is in fact a new way of life.
The coupling of dynamic typing and the fact that everything's an object makes pretty sophisticated techniques extremely simple to implement. It's so easy to replace logic with tables in Python (e.g. o = class_map[k]() instead of if k='foo': o = Foo()) that it becomes a basic technique. It's so normal in Python to write methods that take methods as parameters that you don't raise an eyebrow when you see d = defaultdict(list).
zip, and the methods that are designed with it in mind. It takes a while before you can intuitively grasp what dict(zip(k, v)) and d.update(zip(k, v)) are doing, but it's a paradigm-shifting moment when you get there. An entire universe of uninteresting and potentially error-laden code eliminated, just by using one function. Then you start designing functions and classes with the expectation that they'll be used in conjunction with zip, and suddenly your code gets simpler and easier. (Protip: Or itertools.izip. Or itertools.izip_longest.)
Speaking of dictionaries, the way that they're deeply integrated into the language. Understanding what a line of code like self.__dict__.update(**kwargs) does is another one of those paradigm-shifting moments.
List comprehensions and generator expressions, of course.
Inexpensive exceptions.
An interactive intepreter.
Function decorators.
IronPython, which is so much simpler to use than we have any right to expect.
And that's without even getting into the remarkable array of functionality in the standard modules, or the ridiculous bounty of third-party tools like BeautifulSoup or SQL Alchemy or Pylons.
One of the most direct benefits that I've gotten from getting deeply into Python is that it has greatly improved my C# code. I could generally understand code that had a variable of type Dictionary<string, Action<Foo>> in it, but it didn't seem natural to write it. (I use static dictionaries to replace hard-coded logic far more frequently today than I did a year ago.) I have no difficulty understanding what LINQ is doing now, or how IEnumerable<T> and return yield work.
So what don't I like about Python?
Dynamic typing really limits what you can do with static code analysis. Not only isn't there a tool like Resharper for Python, in a language where it's possible to write getattr(x, y)() there really can't be.
It has a bunch of inelegant conventions. How I would love to be able to go back in time and try to talk GVR out of the idea that lambda expressions should be introduced with the word lambda - it's pretty damning that something as fundamental as lambda expressions should be more concise in C# than they are in Python. The leading and trailing double-underscore convention is horrible, and the fact that people mutely acquiesce to it is testimony to Dostoevsky's observation that man is the animal who can get used to anything. And don't get me started on the fact that a module with the name of StringIO was allowed to get out the door.
Some of the features that make Python work on multiple platforms also make it kind of baffling. It's easy to use import, but it's really not easy to understand what the hell it's actually doing. (Where is it looking? What does __init__.py do? Etc.)
The amazingly rich library of standard modules is so amazingly rich that it's hard to know what's in it. It's often easier to write a function than it is to find out whether or not there's something in the standard library that does the same thing - I'm looking at you, itertools.chain.
Your question is kind of like a plumber asking why carpenters are always going on and on about hammers. After all the plumber doesn't have a hammer and has never missed it. Python (even IronPython) and C# target different types of developers and different types of programs. I am very comfortable in Python and enjoy the freedom to focus on the business rules without being distracted by the syntax requirements of the language. On the other hand I have written some fairly substantial code in C# and would be very concerned about the lack of type safety had I taken on the same task in Python. This is not to say that Python is a "toy" language. You can (and people have) write a complete medium or large application in Python. You have the freedom of dynamic typing, but you also have the responsibility to keep it all straight (frameworks help here). Similarly you can write a small application in C#, but you will bring along some overhead you do not likely need.
So if the problem is a nail use a hammer, if the problem is a screw use a screw driver. In other words spend some time to learn Python, get to know it's streangths (text processing, quick coding cycles, simple clean code, etc) and then when you are looking at tackling a new problem ask whether you would be better off in Python or C#. One thing is certain. So long as C# is the only programming language you know, it is the only one you will ever use.
Pat O
My language of choice is C#, and I didn't quite see the point for me to learn Python so far. This talk from PDC09 really piqued my interest: the guy demonstrates how you can use IronPython (or IronRuby) to make a C# app scriptable (in his demo, drop a Python script in a text box, and it works with/extends your C# code). I found this really fascinating: I don't even know where I would start to do something similar in C#, and this made me at least appreciate that it brings something different to the table, which could really enrich what I can develop!
I'm an asymmetrical user of both languages, in a sense that I use C# mostly professionally and Python for all my "fun" projects (not that work is never fun, but... you know...)
This difference of context may skew my perspective, including my opinion that they are two distinct types (pun intended) of languages for, generally, distinct purposes.
This said, it may not be a coincidence that Python is, at this point in time, [one of?] the languages of choice for all kinds of cutting edge, somewhat scholarly, technology/science oriented projects. (And BTW, this "scholarly" keyword here doesNOT imply, that Python is a university toy, plenty of "serious" applications in plenty of domains/industry are proof to the contrary). This may be due to several factors:
(I don't develop most points, readily well expressed in other responses)
the openness and quasi universal availability of Python (unlike C# !)
the lightweight / ease of use / low learning curve
the extensive, high quality, "standard" library and the extensiver (and occasionally bum quality, but on the whole available, open-sourced, etc.) additional library.
the wide array of open source projects in Python language
the relative ease to bind with C/C++ for reusing legacy code, but also for placing performance-critical portions of a project
the generally higher level of abstraction of may constructs of the language
the multi-paradigms (imperative, object oriented and functional)
the availability of practitioners in so many domain of science and technology
and, yes, the
"herd mentality effect" mentioned in a remark, possibly in a [self?] deriding way. The fact that a language attracts a broad, "closely knit" community, makes it attractive too, beyond the superficial ("look cool" and such) traits of herd mentality. Put in broader context, sometimes the best technology/language to use is not measured on the its intrinsic merits but on the overall "picture", including the user community.
I like all stuff with [] and {}. Selectors like this [-1:1]. Possibility to write less code, but more something meaningfull, that gives to write Models and other declarative things very DRY.
Like any programming language, it is just a tool in the box or a brush by which you may paint your creation. Any creative endeavour requires that the artist loves the tools he uses; otherwise, the outcome suffers. Some people like Python for the same reason others love Perl. Incidentally, I have found that most Python lovers loathe Perl's flexible and expressive syntax. As a Perl lover, I don't hate Python, but consider it to be overly structured and restrictive.
If you ask me, all of these throngs of people who seem to love Python were silently suffering under the tool choices before Python came into being. Some suffered under Perl, others under something else. In other words, I believe that when Python came along, it found a large group of silent sufferers longing for a tool like Python.
I can't program in Python because I can't "think" in Python. I can "think" in Perl, therefore, it is the tool I prefer. The silently suffering mass of, now, Python users seem to have found some long lost salvation. Now if they could only keep their evangelism to themselves :).
If you are familiar with the .NET CLR and prefer a statically-typed language, but you like Python's lightweight syntax, then perhaps Boo is the language for you.
Don't get me wrong, I am and will always be a devoted fan of C#.
But sometimes there are things I can't do in C#. lthough C# keeps reducing those gaps, Python is still the language I go to to fill them.
It's dynamic, flexible, powerful, and clean. Lovely language. Whenever I need to script or build dynamic or functional (as in functional programming) software, I go Python.
For me Python is the most elegant language I've used. The syntax is minimalist (significantly less punctuation than most) and intentionally modeled after the psuedo-code conventions which are ubiquitously used by programmer to outline their intentions.
Python's if __name__ == '__main__': suite encourages re-use and test driven development.
For example, the night before last I hacked together to run thousands of ssh jobs (with about 100 concurrently) and gather up all the results (output, error messages, exit values) ... and record the time take on each. It also handles timeouts (An ssh command can stall indefinitely on connection to a thrashing system --- it's connection timeouts and retry options don't apply after the socket connection is made, not matter if the authentication stalls). This only takes a few dozen lines of Python and it's really is easiest to create it as a class (defined above the __main__ suite) and do my command line parsing in a simple wrapper down inside __main__. That's sufficient to do the job at hand (I ran the script on 25,000 hosts the next day, in about two hours). It I can now use this code in other scripts as easily as:
from sshwrap import SSHJobMan
cmd = '/etc/init.d/foo restart'
targets = queryDB(some_criteria)
job = SSHJobMan(cmd, targets)
job.start()
while not job.done():
completed = job.poll()
# ...
# Deal with incremental disposition of of completed jobs
for each in sorted(job.results):
# ...
# Summarize results
... and so on.
So my script can be used for simple jobs ... and it can be imported as a module for more specialized work that couldn't be described on my wrapper's command line. (For example I could start up "consumer" subprocesses for handling other work on each host where the job was successful while spitting out service tickets or automated reboot requests for all hosts reporting timeouts or failures, etc).
For modules which have no standalone usage I can use the __main__ suite to contain unit-tests. Thus every module can contain its own tests ... which, in fact, can be integrated into the "doc strings" using the doctest module from the standard libraries. (Which, incidentally, means that properly formatted examples in the documentary comments can be kept in sync with the implementation ... since they are parts of the unit-test suite).
The main thing I like about Python is its very concise, readable syntax. Though using indentation as a block delimiter can seem strange at first, once you begin to code a lot in the language I find it begins to make sense. Though the core language is quite simple, its more advanced features, e.g. list comprehension, decorators and generators, are rather useful too.
In addition, the Python standard library is just fantastic; its documentation is very well written, and it contains a lot of very useful packages. I also find that there are plenty of good bindings for C libraries, such as PyGTK, Webkit and Qt, to name but a few.
One caveat is that Python, like most dynamic languages, is quite slow in comparison with compiled, statically-typed languages. However, you can easily extend it with C, allowing you to write code requiring better performance in C and the rest in Python.
It's a great language overall, and (for me at least) makes coding more productive and enjoyable.
I am a C++ programmer moving into C#. I worked with the language for a month now and understand many concepts.
What are some surprises I may get while moving from C++ to C#? I was warned about destructors not being executed as I intended. Recently I tried to do something with generics that would use T as the base class. That didn't work. I also had another problem but I'll chalk that up to inexperience in C#. I was also surprised that my app was eating RAM, then I figured out I needed to use .dispose in one function. (I thought it would clean up like a smart pointer)
What else may surprise me?
Please no language bashing. I doubt anyone will but just in case...
Fortunately, Microsoft have some of that info here: C# for C++ Developers.
The struct vs class differences is another biggie for C++ origins.
I think you've covered the main one. You should read up on garbage collection, understand why there are no destructors as such, figure out the IDisposable pattern (which kind of replaces destructors). I'd say that was the big one.
The only other thing I would say is to warn you the C# and the .Net Base Class Library are pretty big, to get the most out of it there is a lot to learn... Once you have covered the basics of garbage collection and the type system you'll want to look at LINQ, and you should take the time to explore the relevnt libraries / frameworks for your area (e.g. WPF, WCF, ASP.Net etc). But it's all good. I moved from C++ to C# and would never go back, I find it way more productive (I'm not bashing C++, I do still dable:-) )
Well, the languages are completely different as I'm sure you've realized if you've worked with C# for any time. You don't have a powerful macro or templating (I realize there are generics in C#) in C# as you do in C++. As far as memory, remember you aren't in a tightly controlled environment anymore. Expect to see a lot of memory usage in Task Manager and similar tools, this is normal. There are better, more fine-grained performance counters to see true memory usage. Also, you probably don't need to call dispose as much as you might think (by the way, check out "using" blocks if you haven't already).
Another clear one is the default constructor, in C# this does not create a new Foo object:
Foo myFoo;
You can't have anything like a "void pointer" unless you just think of that as being like having a reference of type object. As well, you need to think of Properties as syntactic sugar for methods and not public members as they look in C++ syntax.
Make sure you understand "out" and "ref" parameters.
Obviously this not a large list, just a few "pointers" (no pun intended).
This is a rather big topic. A few thoughts:
C# is garbage collected. Doesn't mean you can stop paying attention about resource allocation, but in general you don't have to worry nearly as much about the most common resource: memory.
In C# Everything is an object. There are no "primitive" datatypes, even an int is an object.
C# has generics, not templates. Templates are far richer and more complex than C#'s similarly syntaxed generics, but generics still provide nearly all of the practical utility of templates, without many of the headaches.
C# has interfaces and single inheritance. Where you might look to multiple inheritance in C++, instead look to using interfaces or a different design pattern (e.g. strategy).
C# has delegates instead of function pointers. A delegate is basically just a typed function pointer. The use of delegates and delegate-relatives (lambda expressions, events, predicates, etc.) is very powerful and worth putting significant effort into studying.
C# supports yield return. This is very fundamental to the C# way of doing things. The most common form of iterating over some set is to use foreach. It's worth understanding how IEnumerable and iterators work.
I've made pretty much the same change some months ago (before that I've made a change to Java - but I didn't really spend much time programming Java).
Here are some of the biggest traps I've come across:
Attribute vs. Variable vs. Setter
One of the biggest traps I was stepping into was knowing if you have to change an attribute or set a variable or use a setter to set some aspect of a class.
IList vs. List vs. other collections
Know the difference between IList, List and all the other collections (IMO you can't really do much with an IList).
Generics do have their own pitfalls
And if you plan to use a lot of generics, maybe reading this helps you avoiding some of my errors:
Check if a class is derived from a generic class
But in general I'd say that the change went pretty painlessly.
Differences in the object model. For example value and reference types are separate by definition, not by how they are instantiated. This has some surprises, e.g.
myWinForm.Size.Width = 100;
will not change the width, you need to create a new Size instance and assign it.
Some things that I have not seen mentioned that are not available in C++ and may be a bit surprising are attributes and reflection
Attributes as such do not give you full fledged AOP. However, they do allow you to solve a bunch of problems in a way that is very different to how you would solve them in C++.
Unmanaged languages notwithstanding, is F# really better than C# for implementing math? And if that's the case, why?
I think most of the important points were already mentioned by someone else:
F# lets you solve problems in a way mathematicians think about them
Thanks to higher-order functions, you can use simpler concepts to solve difficult problems
Everything is immutable by default, which makes the program easier to understand (and also easier to parallelize)
It is definitely true that you can use some of the F# concepts in C# 3.0, but there are limitations. You cannot use any recursive computations (because C# doesn't have tail-recursion) and this is how you write primitive computations in functional/mathematical way. Also, writing complex higher order functions (that take other functions as arguments) in C# is difficult, because you have to write types explicitly (while in F#, types are inferred, but also automatically generalized, so you don't have to explicitly make a function generic).
Also, I think the following point from Marc Gravell isn't a valid objection:
From a maintenance angle, I'm of the view that suitably named properties etc are easier to use (over full life-cycle) than tuples and head/tail lists, but that might just be me.
This is of course true. However, the great thing about F# is that you can start writing the program using tuples & head/tail lists and later in the development process turn it into a program that uses .NET IEnumerables and types with properties (and that's how I believe typical F# programmer works*). Tuples etc. and F# interactive development tools give you a great way to quickly prototype solutions (and when doing something mathematical, this is essential because most of the development is just experimenting when you're looking for the best solution). Once you have the prototype, you can use simple source code transformations to wrap the code inisde an F# type (which can also be used from C# as an ordinary class). F# also gives you a lot of ways to optimize the code later in terms of performance.
This gives you the benefits of easy to use langauges (e.g. Python), which many people use for prototyping phase. However, you don't have to rewrite the whole program later once you're done with prototyping using an efficient language (e.g. C++ or perhaps C#), because F# is both "easy to use" and "efficient" and you can fluently switch between these two styles.
(*) I also use this style in my functional programming book.
F# has many enormous benefits over C# in the context of mathematical programs:
F# interactive sessions let you run code on-the-fly to obtain results immediately and even visualize them, without having to build and execute a complete application.
F# supports some features that can provide massive performance improvements in the context of mathematics. Most notably, the combination of inline and higher-order functions allow mathematical code to be elegantly factored without adversely affecting performance. C# cannot express this.
F# supports some features that make it possible to implement mathematical concepts far more naturally than can be obtained in C#. For example, tail calls make it much easier to implement recurrence relations simply and reliably. C# cannot express this either.
Mathematical problems often require the use of more sophisticated data structures and algorithms. Expressing complicated solutions is vastly easier with F# compared to C#.
If you would like a case study, I converted an implementation of QR decomposition over System.Double from 2kLOC of C#. The F# was only 100 lines of code, runs over 10× faster and is generalized over the type of number so it works not only on float32, float and System.Numerics.Complex but can even be applied to symbolic matrices to obtain symbolic results!
FWIW, I write books on this subject as well as commercial software.
F# supports units of measure, which can be very useful for math work.
I'm from a maths background, and have looked at F#, but I still prefer C# for most purposes. There are a couple of things that F# makes easier, but in general I still prefer C# by a large margin.
Some of the touted F# benefits (immutability, higher-order functions, etc) can still be done in C# (using delegates etc for the latter). This is even more apparent when using C# 3.0 with lambda support, which makes it very easy and expressive to declare functional code.
From a maintenance angle, I'm of the view that suitably named properties etc are easier to use (over full life-cycle) than tuples and head/tail lists, but that might just be me.
One of the areas where C# lets itself down for maths is in generics and their support for operators. So I spend some time addressing this ;-p My results are available in MiscUtil, with overview here.
This post looks like it might be relevant: http://fsharpnews.blogspot.com/2007/05/ffts-again.html
Also: C# / F# Performance comparison
The biggest advantage for pure math is what PerpetualCoder said, F# looks more like a math problem so it's going to be easier for a mathematician to write. It reminded me a lot of MATLAB when I looked at it.
I am not sure if its better or worse but there is certainly a difference in the approach. Static languages over specify how a problem will be solved. Functional languages like F# or Haskell do not do that and are more tailored at how a mathematician would solve a particular problem. Then you have books like this that tout python to be good at it. If you are talking from a performance point of view nothing can beat C. If you are talking from libraries I believe Functional Langauges (F# and the likes), Fortan (yes its not dead yet), Python have excellent libraries for math.
One of the great advantages of functional languages is the fact they they can run on multi-processor or multi-core systems, in parallel without requiring you to change any code.
That means you can speed up your algorithms by simply adding cores.