Is there a wildcard expansion option for .net apps?

Question

I've used the setargv.obj linking for Expanding Wildcard Arguments in the past for a number of C and C++ apps, but I can't find any similar mention for .net applications.

Is there a standard way to have your app's command line parameters automatically wildcard expanded? (i.e. expand *.doc from one entry in args parameter to all that match that wildcard).

P.S. I've hacked something together with Directory.GetFiles() for my current little project, but it does not cover wildcards with paths (yet), and it would be nice to do it without custom code.

Update: here is my rough hack, for illustration. It needs to split the parameters for path and name for the GetFiles, but this is the general idea. Linking setargv.obj into a C or C++ app would basically do all the wildcard expansion, leaving the user to only iterate over the argv array.

static void Main(string[] args)
{
    foreach (String argString in args)
    {
        // Split into path and wildcard
        int lastBackslashPos = argString.LastIndexOf('\\') + 1;
        path = argString.Substring(0, lastBackslashPos);
        filenameOnly = argString.Substring(lastBackslashPos, 
                                   argString.Length - lastBackslashPos);

        String[] fileList = System.IO.Directory.GetFiles(path, filenameOnly);
        foreach (String fileName in fileList)
        {
            //do things for each file
        }
    }
}

Answer 1

I'm not sure exactly what you're after... but if I get where you're going with the Directory.GetFiles() "hack" you mentioned, then something like this might work:

var Dirs = Directory.GetDirectories(@"C:\Windows", "sys*", 
SearchOption.TopDirectoryOnly).ToList();
var Files = new List<String>();
Dirs.ForEach(dirName => Files.AddRange(Directory.GetFiles(dirName, "*.sys", SearchOption.AllDirectories)));

The wildcard option on the GetDirectories call will allow you to grab all the directories contained in the Windows folder [directly] that match the pattern "sys*".

You can then iterate over those folders grabbing all the files that match the pattern "*.sys".

Is that the kind of thing you're looking for? To automatically expand the args, you'd have to extract the wildcards in some kind of meaningful manner and apply them to that model...

For instance:

RunMyApp "C:\Windows\Sys*\ *.sys"

You'd pull out the string C:\Windows - probably with a regular expression, find the lowest level directory that doesn't contain a wildcard and apply it to the GetDirectories method, attaching the wildcarded string as the search parameter.

Then if your end of string (in this case *.sys) as the search pattern for Directory.GetFiles.

If you wanted to get more complicated and do something like:

C:\Windows\*\Sys*\*.sys

You would use the SearchOptions to set this behaviour:

Directory.GetDirectories(@"C:\Windows", "sys*", SearchOptions.AllDirectories)

This would grab all directories that matched the sys* wildcard in the Windows directory and all directories below it.

If you wanted to get much more complicated than that, then I'm not sure how you would do that... for instance, say you wanted folders that are contained by folders directly inside the Windows directory - I have no idea how you would go about something like that I'm afraid...I don't imagine exporting the entire tree structure to XML and using XPath to do it would be so efficient - the XPath would be fabulously simple for parsing out using wildcards - but converting to XML wouldn't be so efficient...

Answer 2

Your code looks like exactly how you're supposed to do it.

Answer 3

Here us my rough hack. I'd love for it to be recursive. And having experienced the shortcoming of Windows wildcards I might decide to use regular expressions rather than letting GetFiles() do it for me.

using System.IO;

public static string[] ExpandFilePaths(string[] args)
{
    var fileList = new List<string>();

    foreach (var arg in args)
    {
        var substitutedArg = System.Environment.ExpandEnvironmentVariables(arg);

        var dirPart = Path.GetDirectoryName(substitutedArg);
        if (dirPart.Length == 0)
            dirPart = ".";

        var filePart = Path.GetFileName(substitutedArg);

        foreach (var filepath in Directory.GetFiles(dirPart, filePart))
            fileList.Add(filepath);
    }

    return fileList.ToArray();
}