I am making a DLL of helper functions and I want to call them without calling the class they live in. For example:
namespace HelperFunctions
{
public static class Greetings
{
public static void greet()
{
Console.WriteLine("hello!");
}
}
How to I modify the above code so that I can do this:
using HelperFunctions;
namespace MyConsoleApp
{
class Program
{
static void Main()
{
greet();
}
}
}
Assumptions/Understandings:
I understand I can call Greetings.greet() but I dont want to.
I understand I will have to come up with unique names for my functions that won't clash with anything from the System namespace (or whatever other references I am using)
Presently, you can't.
When the next version of C# is released, you'll be able to write:
using HelperFunctions.Greetings;
and it will work.
Related
I want to call a static void function from another class, but it's said
The name [funcion name here] does not exist in the current context
Each class is in the same project, Framework 4.5.2
Its a public static void Function, in a public static class, don't see why it's not working.
The class where a function located, I want to call:
namespace Client.Modules
{
public static class Login
{
public static void Run()
{
// do something
}
}
}
The class where I want to call:
using Client.Modules;
namespace Client
{
public class Main
{
Login.Run(); // here
}
}
public class Main
{
Login.Run(); // here
}
That’s invalid: You can’t generally execute code outside methods. The only things that can go directly into classes are declarations. Put Login.Run() inside a method.
Question:
Is it possible to reference public static methods held within the CustomAction class, Votive generates for creating C# managed Custom Actions, from other libraries within the same solution?
I'm having trouble getting a reference to the class and method inside my C# library for the C# Custom Action when trying to create a test bed for the CA.
namespace TestInstaller.InstallCA
{
public class CustomActions
{
[CustomAction]
public static ActionResult InstallUIStart(Session session)
{
//Stuff
return Begin(<Constructed DataClass>);
}
public static ActionResult Begin(DataClass dc)
{
//Stuff I want to test
}
}
}
...
namespace TestInstaller.InstallerTest
{
static class Program
{
Static void Main()
{
//Stuff
//This line is not valid.
TestInstaller.InstallCA.CustomActions.Begin(<Constructed DataClass>);
}
}
}
Despite me adding a reference to InstallCA I cannot add a using statement for TestInstaller.InstallCA or InstallCA, and the compile time error only suggests adding a reference, which I have done.
Is this anything to do with Votive protecting its DLLs somehow?
I have a dll that I'm working with, it contains a class foo.Launch. I want to create another dll that subclasses Launch. The problem is that the class name must be identical. This is used as a plugin into another piece of software and the foo.Launch class is what it looks foe to launch the plugin.
I've tried:
namespace foo
{
public class Launch : global::foo.Launch
{
}
}
and
using otherfoo = foo;
namespace foo
{
public class Launch : otherfoo.Launch
{
}
}
I've also tried specifying an alias in the reference properties and using that alias in my code instead of global, that also didn't work.
Neither of those methods work. Is there a way I can specify the name of the dll to look in within the using statement?
You'll need to alias the original assembly and use an extern alias to reference the original assembly within the new one. Here's an example of the use of the alias.
extern alias LauncherOriginal;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace foo
{
public class Launcher : LauncherOriginal.foo.Launcher
{
...
}
}
Here's a walkthrough that explains how to implement that.
Also, you'd mentioned that you tried to use an alias before and encountered problems but you didn't say what they were, so if this won't work then please mention what went wrong.
as Chris said, you can use an alias on your original assembly.
If you can't you that, then you might be able to cheat by using a 3rd assembly
Assembly1.dll (your original)
namespace foo {
public class Launch {}
}
Assembly2.dll (dummy)
namespace othernamespace {
public abstract class Dummy: foo.Launch {}
}
Assembly3.dll (your plugin)
namespace foo{
public class Launch: othernamespace.Dummy{}
}
I'm not even proud of this!
Class name can be identical if it's defined in another namespace, but it boggles the mind why anybody would want to do that to themselves.
Maybe you need to use extern aliases.
For example:
//in file foolaunch.cs
using System;
namespace Foo
{
public class Launch
{
protected void Method1()
{
Console.WriteLine("Hello from Foo.Launch.Method1");
}
}
}
// csc /target:library /out:FooLaunch.dll foolaunch.cs
//now subclassing foo.Launch
//in file subfoolaunch.cs
namespace Foo
{
extern alias F1;
public class Launch : F1.Foo.Launch
{
public void Method3()
{
Method1();
}
}
}
// csc /target:library /r:F1=foolaunch.dll /out:SubFooLaunch.dll subfoolaunch.cs
// using
// in file program.cs
namespace ConsoleApplication
{
extern alias F2;
class Program
{
static void Main(string[] args)
{
var launch = new F2.Foo.Launch();
launch.Method3();
}
}
}
// csc /r:FooLaunch.dll /r:F2=SubFooLaunch.dll program.cs
In C/C++, I have a bunch of functions that I call from main(), and I want to rewrite this in C#. Can I have stand alone functions(methods) or do I have to put them in another class? I know I can have methods within the same class, but I want to have a file for each function/method.
Like this works:
using System.IO;
using System;
class Program
{
static void Main()
{
House balls = new House();
balls.said();
}
}
public class House
{
public void said()
{
Console.Write("fatty");
Console.ReadLine();
}
}
But then I have to create an instance of House and call said(), when in C I can just call said().
For reference, I want to add the using static addition of C# 6 here.
You can now use methods of a static class without having to type the name of that class over-and-over again. An example matching the question would be:
House.cs
public static class House
{
public static void Said()
{
Console.Write("fatty");
Console.ReadLine();
}
}
Program.cs
using static House;
class Program
{
static void Main()
{
Said();
}
}
No. Make them static and put them in a static utility class if they indeed don't fit within any of your existing classes.
If using C# 9 it is now kinda possible, thanks to the top-level statements feature.
In your executable project, the following syntax is now allowed:
using SomeNamespace;
// The following statements are seemingly defined without even a method,
// but will be placed inside a "Main" static method in a "$Program" static class
SayHello();
var classFromSomeNamespace = new SomeClass(); // from SomeNamespace
classFromSomeNamespace.SomeMethod();
// This function is seemingly defined without a class,
// but on compile time it will end up inside a "$Program" static class
void SayHello()
{
Console.WriteLine("Hello!");
}
// Here the "traditional" syntax may start
namespace SomeNamespace
{
public class SomeClass
{
public void SomeMethod()
{
Console.WriteLine("SomeMethod called");
}
}
}
It should be noted, that the above syntax is valid only for a single file in a project, and the compiler actually still wraps this all inside a $Program static class with static methods. This feature was introduced specifically to avoid boilerplate code for the program entry point, and make it possible to easily write "scripts" in C#, while retaining the full .NET capabilities.
There is no concept of standalone functions in C#. Everything is an object.
You can create static methods on some utility class, and call those without creating an instance of a class eg
class Program
{
static void Main()
{
House.said();
}
}
public class House
{
public static void said()
{
Console.Write("fatty");
Console.ReadLine();
}
}
You have to put them in a class, but the class can be static as others mentioned. If you REALLY want to have a separate file for each method, you can mark the class as partial to get the following:
Program.cs
----------
class Program
{
static void Main()
{
House.said();
House.saidAgain();
}
}
House-said.cs
-------------
public static partial class House
{
public static void said()
{
Console.Write("fatty");
Console.ReadLine();
}
}
House-saidAgain.cs
------------------
public static partial class House
{
public static void saidAgain()
{
Console.Write("fattyAgain");
Console.ReadLine();
}
}
I wouldn't recommend separating each one out, however. Partial classes are mostly used so that designer-generated code won't overwrite any custom code in the same class. Otherwise you can easily end up with hundreds of files and no easy way to move from one method to another. If you think you need a partial class because the number of methods is getting unmaintainable, then you probably need to separate the logic into another class instead.
Although the concept of stand-alone functions exists in .NET, C# doesn't allow you to specify such functions. You need to stick them inside a static Utils class or similar.
If you declare your method as static (that is: public static void said()) then you can just call it with House.said(), which is as close as you'll get in C#.
You could add all your methods to the Program class, but this would quickly become an unmaintainable mess, commonly referred to as the God Class or Ball of Mud anti-pattern.
Maintaining a single file for each function would similarly become a huge mess. The questions "Where do I put my methods" and "What classes should I create" are answered by Design Patterns. Classes aggregate behavior (functions) and should do one thing (Single Reponsibility.)
I currently have a function that looks like this:
public void AnimateLayoutTransform(object ControlToAnimate)
{
//Does some stuff
}
I use this function in a lot of different projects, so I want it to be very reusable. So for now I have it in a .cs file, enclosed in a namespace and a class:
namespace LayoutTransformAnimation
{
public class LayoutAnims
{
public void AnimateLayoutTransform(object ControlToAnimate)
{
//Do stuff
}
}
}
The problem with this is that to use this one function in a given project, I have to do something like
new LayoutTransformAnimation.LayoutAnims().AnimateLayoutTransform(mygrid);
Which just seems like a lot of work to reuse a single function. Is there any way to, at the very least, use the function without creating a new instance of the class? Similar to how we can Double.Parse() without creating a new double?
One option is to make it a normal static method. An alternative - if you're using C# 3.0 or higher - is to make it an extension method:
public static class AnimationExtensions
{
public static void AnimateLayoutTransform(this object controlToAnimate)
{
// Code
}
}
Then you can just write:
mygrid.AnimateLayoutTransform();
Can you specify the type of the control to animate any more precisely than "Object"? That would be nicer... for example, can you only really animate instances of UIElement? Maybe not... but if you can be more specific, it would be a good idea.
You could make it into a static method.
MSDN Example
I find it useful to have a static util class with static methods in them which can be used within the project namespace.
public static class YourUtilsClass
{
public static Void YourMethod()
{
//do your stuff
}
}
You can call it like so: YourUtilsClass.YourMethod()
namespace LayoutTransformAnimation
{
public class LayoutAnims
{
public static void AnimateLayoutTransform(object ControlToAnimate)
{
//Do stuff
}
}
}
LayoutTransformAnimation.LayoutAnims.AnimateLayoutTransform(something);