Develop Reference

How can I provide a tab completion list, with the values generated on powershell startup?

So I have a cmdlet written in c#: Get-LivingCharacter. I want users to use this like Get-LivingCharacter -Name "Bran", but I would like to allow for the list of available characters to change. Maybe today, "Bran" is a valid name to pass in for Get-LivingCharacter, but maybe in the future it will not be. Things happen.
For convenience I want to allow tab-completion of this field. However, I can't seem to get that to work for non-const data sets. Dynamic fields don't even auto-complete the field name, nevermind the value, and I don't know a way to implement this for a non-dynamic field. Conceptually, I could generate a .ps1 file on startup given the current data set, and then load that ps1 as the module, but this feels a bit like killing a pup with a greatsword - lots of overkill. Is there a better option?

I had already implemented a similar function to the DynamicParam helper function, as reference in the comments. However, tab completion wasn't working. I was writing a minimal reproduction example, when...my tab completion worked.
It turns out, it reproducibly works/breaks based on the inclusion of a WriteDebug statement:
[Cmdlet("Get", "LivingCharacter")]
public class GetLivingCharacter : Cmdlet, IDynamicParameters
{
protected override void ProcessRecord()
{
}
public object GetDynamicParameters()
{
WriteDebug("Getting names"); // Tab completion won't work with this here - comment it out and it works.
^^^^^^^^^^
var chars = new List<String>() { "Bran", "Arya" };
var dict = new RuntimeDefinedParameterDictionary();
var attributes = new Collection<Attribute>
{
new ParameterAttribute
{
HelpMessage = "Enter a valid open name",
Mandatory = true
},
new ValidateSetAttribute(chars.ToArray()),
};
dict.Add("Name", new RuntimeDefinedParameter("Name", typeof(string), attributes));
return dict;
}
}
After some digging, the WriteDebug statement is throwing (which I assume is because it can't output while I'm typing). It then recreates the GetLivingCharacter class after I've finished the command to validate. It took a while to find since, because of the issue, I can't write the error to the console, so I had to append to a temp file instead.

Keeping track of user customization's c#

Good evening; I have an application that has a drop down list; This drop down list is meant to be a list of commonly visited websites which can be altered by the user.
My question is how can I store these values in such a manor that would allow the users to change it.
Example; I as the user, decide i want google to be my first website, and youtube to be my second.
I have considered making a "settings" file however is it practical to put 20+ websites into a settings file and then load them at startup? Or a local database, but this may be overkill for the simple need.
Please point me in the right direction.

Given you have already excluded database (probably for right reasons.. as it may be over kill for a small app), I'd recommend writing the data to a local file.. but not plain text..
But preferably serialized either as XML or JSON.
This approach has at least two benefits -
More complex data can be stored in future.. example - while order can be implicit, it can be made explicit.. or additional data like last time the url was used etc..
Structured data is easier to validate against random corruption.. If it was a plain text file.. It will be much harder to ensure its integrity.

The best would be to use the power of Serializer and Deserializer in c#, which will let you work with the file in an Object Oriented. At the same time you don't need to worry about storing into files etc... etc...
Here is the sample code I quickly wrote for you.
using System;
using System.IO;
using System.Collections;
using System.Xml.Serialization;
namespace ConsoleApplication3
{
public class UrlSerializer
{
private static void Write(string filename)
{
URLCollection urls = new URLCollection();
urls.Add(new Url { Address = "http://www.google.com", Order = 1 });
urls.Add(new Url { Address = "http://www.yahoo.com", Order = 2 });
XmlSerializer x = new XmlSerializer(typeof(URLCollection));
TextWriter writer = new StreamWriter(filename);
x.Serialize(writer, urls);
}
private static URLCollection Read(string filename)
{
var x = new XmlSerializer(typeof(URLCollection));
TextReader reader = new StreamReader(filename);
var urls = (URLCollection)x.Deserialize(reader);
return urls;
}
}
public class URLCollection : ICollection
{
public string CollectionName;
private ArrayList _urls = new ArrayList();
public Url this[int index]
{
get { return (Url)_urls[index]; }
}
public void CopyTo(Array a, int index)
{
_urls.CopyTo(a, index);
}
public int Count
{
get { return _urls.Count; }
}
public object SyncRoot
{
get { return this; }
}
public bool IsSynchronized
{
get { return false; }
}
public IEnumerator GetEnumerator()
{
return _urls.GetEnumerator();
}
public void Add(Url url)
{
if (url == null) throw new ArgumentNullException("url");
_urls.Add(url);
}
}
}

You clearly need some sort of persistence, for which there are a few options:
Local database
- As you have noted, total overkill. You are just storing a list, not relational data
Simple text file
- Pretty easy, but maybe not the most "professional" way. Using XML serialization to this file would allow for complex data types.
Settings file
- Are these preferences really settings? If they are, then this makes sense.
The Registry - This is great for settings you don't want your users to ever manually mess with. Probably not the best option for a significant amount of data though
I would go with number 2. It doesn't sound like you need any fancy encoding or security, so just store everything in a text file. *.ini files tend to meet this description, but you can use any extension you want. A settings file doesn't seem like the right place for this scenario.

How to read data from multiple (multi language) resource files?

I am trying the multi language features in an application. I have created the resource files GlobalTexts.en-EN.resx GlobalTexts.fr-FR.resx and a class that sets the culture and returns the texts like (I will not go in all the details, just show the structure):
public class Multilanguage
{
...
_res_man_global = new ResourceManager("GlobalResources.Resources.GlobalTexts", System.Reflection.Assembly.GetExecutingAssembly());
...
public virtual string GetText(string _key)
{
return = _res_man_global.GetString(_key, _culture);
}
}
...
Multilanguage _translations = new Multilanguage();
...
someText = _translations.GetText(_someKey);
...
This works just fine.
Now, I would like to use this application in another solution that basically extends it (more windows etc.) which also has resource files ExtendedTexts.en-En.resx ExtendedTexts.fr-FR.resx and a new class like:
public class ExtendedMultilanguage : Multilanguage
{
...
_res_man_local = new ResourceManager("ExtendedResources.Resources.ExtendedTexts", System.Reflection.Assembly.GetExecutingAssembly());
...
public override string GetText(string _key)
{
string _result;
try
{
_result = _res_man_local.GetString(_key, _culture);
}
catch (Exception ex)
{
_result = base.GetText(_key);
}
}
...
ExtendedMultilanguage _translations = new Multilanguage();
...
someText = _translations.GetText(_someKey);
...
the idea being that if the key is not found in ExtendedTexts the method will call the base class which is looking into GlobalTexts. I did this in order to use the call GetText(wantedKey) everywhere in the code without having to care about the location of the resource (I do not want to include the translations from the extensions in the GlobalTexts files); it is juts the used class that is different from project to project.
The problem I am facing is that the try/catch is very slow when exceptions raise- I wait seconds for one window to populate. I tested with direct call and works much faster, but then I need to care all the time where the resource is located...
The question is: is there an alternative way of doing this (having resources spread in various files and have only one method that gives the desired resource without throwing an error)?

In the end I took a workaround solution and loaded all the content of the resource files in dictionaries. This way I can use ContainsKey and see if the key exists or not.

C# String Property and string literal concatenation issue

I am a bit new at C# and I have run into a string concatenation issue. I am hoping someone might be able to give me a hint and help me resolve this. I have searched Google extensively and have spent more than a week on this so any help/advice would be greatly appreciated.
I have created a custom PathEditor for a string property. The property basically allows the user to key in a file to use in the app. If the file typed in is correct, it shows in the property cell as it should. What I am trying to do is output to the property cell an error message if the file typed in does not exist - I check this in my file validator. Here is the string literal issue.
If I use:
return inputFile+"Error_";
this works OK and I get the outpur file123.txtError_ in the property grid cell.
If I use:
return "Error_"+inputFile;
I get only the inputFile without the literal "Error_". Sot he property grid cell shows file123.txt in the property grid cell.
I have checked and inputFile is a string type. Any ideas as to why this is happening?
Also, is there any way to change to font, and/or, color of the message output? I tried to change the background of the property grid cell and I understand that this is not possible to do.
Thank you.
Z
More of the code:
[
Description("Enter or select the wave file. If no extension, or a non .wav extension, is specified, the default extension .wav will be added to the filename."),
GridCategory("Sound"),
Gui.Design.DisplayName ("Input Sound"),
PathEditor.OfdParamsAttribute("Wave files (*.wav)|*.wav", "Select Audio File"),
Editor(typeof(PathEditor), typeof(System.Drawing.Design.UITypeEditor))
]
public string InputWavefile
{
get { return System.IO.Path.GetFileName(inputtWavefile); }
set
{
if (value != inputWavefile) // inputWavefile has been changed
{
// validate the input stringg
_inputWavefile = FileValidation.ValidateFile(value);
// assign validated value
inputWavefile = _inputWavefile;
}
}
}

My guess is that you've got a funky character at the start of inputFile which is confusing things - try looking at it in the debugger using inputFile.ToCharArray() to get an array of characters.
The string concatenation itself should be fine - it's how the value is being interpreted which is the problem, I suspect...

I'm guessing your filename looks something like this, C:\Folder\FileName.txt when you start out.
In your FileValidation.ValidateFile() method you
return "Error_" + InputFileName;
it now looks like this: Error_C:\Folder\FileName.txt.
So, when you run the line below,
get { return System.IO.Path.GetFileName( _inputWavefile ); }
it strips off the path and returns the filename only, FileName.txt.
Even when the filename is not valid, you are still running System.IO.Path.GetFileName() on it.

Assuming this is a PropertyGrid in winforms app. Then it's neither a string concatenation issue, nor PropertyGrid issue, as could be proven by the following snippet. So you need to look elsewhere in your code:
public partial class Form1 : Form {
PropertyGrid pg;
public Form1() {
pg = new PropertyGrid();
pg.Dock = DockStyle.Fill;
this.Controls.Add(pg);
var inputFile = "some fileName.txt";
var obj = new Obj();
obj.One = "Error_" + inputFile;
obj.Two = inputFile + "Error_";
pg.SelectedObject = obj;
}
}
class Obj {
public string One { get; set; }
public string Two { get; set; }
}

C# Backing Up And Restoring Clipboard

I have a program that uses clipboard but I want to restore the clipboard to its former state after I am done with it.
This is my code :
IDataObject temp = Clipboard.GetDataObject();
//Some stuff that change Cliboard here
Clipboard.SetText("Hello");
//Some stuff that change Cliboard here
Clipboard.SetDataObject(temp);
But it if I copy a text, and run this code, I get nothing on notepad.
NOTE : I can't use Clipboard.Contains because I want to preserve the Clipboard EXACLY how it was before, even if the user copied a file.

I cannot confirm whether this will work, but I see no reason why you shouldn't be able to back up the data using the longer approach of actually reading the data and restoring it afterwards.
Read here: http://msdn.microsoft.com/en-us/library/system.windows.forms.idataobject.aspx
You would do something like (pseudo-code)
//Backup
var lBackup = new Dictionary<string, object>();
var lDataObject = Clipboard.GetDataObject();
var lFormats = lDataObject.GetFormats(false);
foreach(var lFormat in lFormats)
{
lBackup.Add(lFormat, lDataObject.GetData(lFormat, false));
}
//Set test data
Clipboard.SetText("asd");
//Would be interesting to check the contents of lDataObject here
//Restore data
foreach(var lFormat in lFormats)
{
lDataObject.SetData(lBackup[lFormat]);
}
//This might be unnecessary
Clipboard.SetDataObject(lDataObject);

Is your application exiting after resetting the clipboard?
Assuming it is a Win Form app. (not sure how it works in wpf though)
You could use one of the other overloaded version of Clipboard.SetDataObject
public static void SetDataObject(object data, bool copy)
which preserves the data even after your app exits.
ex: in your case after removing the text content you could call Clipboard.SetDataObject(iDataObject, true);
EDIT:2
I Could source step through Clipboard.cs .NET Frameword 4 / VS 2010.
Download the .NET Framework 4 from here http://referencesource.microsoft.com/netframework.aspx.
Follow the below steps and if it asks for the source (Clipboard.cs) it would be in the Source sub-dir of the installation dir.
EDIT:1
Not sure why the same code doesn't work.
Cannot be a security/permission issue as the code doesn't throw an exception as you say.
There is another approach - source stepping into Framework code - Clipboard.cs
Based on the VS version and .NET framework it may vary ( I couldn't get the source stepping work for .NET 4 as the info is that the symbols with source support haven't yet been released). I'm trying my luck by downloading it manually from here (.NET Version 4)
If you are running VS 2008 and older version of .NET then the below steps should work for you.
More details are here. For .NET Framework 4 - here

This cannot be done. You cannot backup/restore the clipboard without causing unintended consequences.
Please see my post on a similar question. My answer is the one that starts with "It's folly to try to do this".
How do I backup and restore the system clipboard in C#?
Furthermore, I suspect that your motivation for wanting to backup/restore the clipboard is because you want to use it as a crutch to move data, without the user's knowledge or consent. Please read:
http://www.clipboardextender.com/developing-clipboard-aware-programs-for-windows/common-general-clipboard-mistakes
and
http://www.flounder.com/badprogram.htm#clipboard
Lastly, please read and understand this quote:
“Programs should not transfer data into our out of the clipboard without an explicit instruction from the user.” — Charles Petzold, Programming Windows 3.1, Microsoft Press, 1992

I tested the pseudocode from Lukas and found out doesn't work always, this works in all my tests:
// Backup clipboard
lBackup = new Dictionary<string, object>();
lDataObject = Clipboard.GetDataObject();
lFormats = lDataObject.GetFormats(false);
foreach (var lFormat in lFormats)
{
lBackup.Add(lFormat, lDataObject.GetData(lFormat, false));
}
//Set test data
Clipboard.SetText("asd");
//Restore clipboard
lDataObject = new DataObject();
foreach (var lFormat in lFormats)
{
lDataObject.SetData(lFormat, lBackup[lFormat]);
}
//This might be unnecessary
Clipboard.SetDataObject(lDataObject);

I have had success with this.
...to a certain degree.
Where I am currently falling down is trying to copy and restore Bitmaps of varying size.
I can successfully copy and restore a Bitmap of smallish size.
I then tried to do the same for (as the fore-warning Chris Thornton suggested) a gargantuan Excel worksheet with both thousands of cell data, as well as two sets of data on a graph, lying on the same worksheet.
I have found that the data copies and restores without problem. Where it falls down in this instance is allowing the 2-set graph with the worksheet copy.
If any of you have had a problem in copying and restoring Bitmaps, let me suggest what worked for me: when attempting to restore the Clipboard, iterate through the list of formats in reverse order and set each data object that way. (i.e. It seems that a Clipboard must be set in reverse order that it was copied in)
Regarding the case of the gargantuan Excel worksheet and accompanying graph, I also hit another stumbling block: I could not successfully copy the data object whose format was "Meta Data File". That could be the reason why Copy/Restore doesn't work in this case.
I got this far about two weeks ago, and tabled it for more pressing issues.
I wanted to put this out there to let anyone else trying to do the same that it seems like it can be done. (anything can be done in computer science. anything.)

I compiled this code and it seems to work for me. I am persisting via converting to and from json. (Note. It will not do steams so adapt if you need it to)
using Newtonsoft.Json;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
namespace Clipboard
{
class Program
{
static void Main(string[] args)
{
Execute(() =>
{
var backup = Backup();
System.Windows.Forms.Clipboard.SetText("text"); //just to change clipboard
Restore(backup);
});
}
private static void Execute(Action action)
{
var thread = new Thread(() => action());
thread.SetApartmentState(ApartmentState.STA);
thread.Start();
thread.Join();
}
private static List<ClipboardItem> Backup()
{
var backup = new List<ClipboardItem>();
var data = System.Windows.Forms.Clipboard.GetDataObject();
System.Windows.Forms.Clipboard.SetDataObject(data, copy: true); //This seems to be needed to be able to serialize data later.
data = System.Windows.Forms.Clipboard.GetDataObject();
var formats = data.GetFormats(false).ToList();
formats.ForEach(f =>
{
if (data.GetData(f, false) != null && !(data.GetData(f, false) is Stream))
{
backup.Add(new ClipboardItem()
{
Format = f,
ObjectType = data.GetData(f, false).GetType(),
ObjectJson = JsonConvert.SerializeObject(data.GetData(f, false))
});
}
});
return backup;
}
private static void Restore(List<ClipboardItem> backup)
{
var data = new System.Windows.Forms.DataObject();
backup.ForEach(item =>
{
data.SetData(item.Format, JsonConvert.DeserializeObject(item.ObjectJson, item.ObjectType));
});
System.Windows.Forms.Clipboard.SetDataObject(data, copy: true);
}
}
public class ClipboardItem
{
public string Format { get; set; }
public Type ObjectType { get; set; }
public string ObjectJson { get; set; }
}
}