Question

Take this non-compiling code for instance:

public string GetPath(string basefolder, string[] extraFolders) {     string version = Versioner.GetBuildAndDotNetVersions();     string callingModule = StackCrawler.GetCallingModuleName();     return AppendFolders(basefolder, version, callingModule, extraFolders); } private string AppendFolders(params string[] folders) {     string outstring = folders[0];     for (int i = 1; i < folders.Length; i++)     {         string fixedPath = folders[i][0] == '\\' ? folders[i].Substring(1) : folders[i];         Path.Combine(outstring, fixedPath);     }     return outstring; } 

This example is a somewhat simplified version of testing code I am using. Please, I am only interested in solutions having directly to do with the param keyword. I know how lists and other similar things work.

Is there a way to ‘explode’ the extraFolders array so that it’s contents can be passed into AppendFolders along with other parameters?

Answer 1

One option is to make the params parameter an object[]:

static string appendFolders(params object[] folders)  { return (string) folders.Aggregate('',(output, f) =>                         Path.Combine( (string)output                                     ,(f is string[])                                        ? appendFolders((object[])f)                                       : ((string)f).TrimStart('\\')));  } 

If you want something more strongly-typed, another option is to create a custom union type with implicit conversion operators:

  static string appendFolders(params StringOrArray[] folders)      { return folders.SelectMany(x=>x.AsEnumerable())                      .Aggregate('',                        (output, f)=>Path.Combine(output,f.TrimStart('\\')));      }     class StringOrArray      { string[] array;         public IEnumerable<string> AsEnumerable()         { return soa.array;}         public static implicit operator StringOrArray(string   s)            { return new StringOrArray{array=new[]{s}};}         public static implicit operator StringOrArray(string[] s)           { return new StringOrArray{array=s};}      } 

In either case, this will compile:

appendFolders('base', 'v1', 'module', new[]{'debug','bin'});