LinkPad is a free utility that is available at http://www.LinqPad.net
I use the DirectlyLookupModuleEnumerator class for my SDMS application (blogged HERE and HERE) so when I stumbled across the following my first reaction was 
followed by 
--- the pit-bull side of me said "you have to understand what this is doing".
Enter stage left - LINQPAD!!! I emulated the above LINQ Query, step-by-step, so that I could see what the query was doing. You'll see I pretty much evolve the same lines (in below image) to see what is returned. I was particularly interested in what line 185 was doing above.
For your convenience (COPY / PASTE)
/*000*/ string searchFolder = @"C:\Windows\System", fileFilter="*.DLL";
/*001*/ Directory.GetFiles(searchFolder, fileFilter).Dump("All files in folder");
/*002*/
/*003*/ string[] filter = {"avi","ole"}; // files we want to filter (include)
/*005*/ // Get all files in the debug folder
/*006*/ Directory.GetFiles(searchFolder, fileFilter)
/*007*/ // Each file in our filter will be processed against fileName
/*008*/ .Where(filterName => filter // Note: Where clause expects bool result
/*009*/ .FirstOrDefault(fileName => filterName.ToLower().Contains(fileName))!=null).Dump("Files to be processed");
/*006a*/ Directory.GetFiles(searchFolder, fileFilter)
/*007a*/ // Each file in our filter will be processed against fileName
/*008a*/ .Where(filterName => filter // Note: Where clause expects bool result
/*009a*/ .FirstOrDefault(fileName => filterName.ToLower().Contains(fileName))!=null)
/*010a*/ .SelectMany( file => file.Split('\\')
).Dump("SelectMany results without .Where() clause");
/*006b*/ Directory.GetFiles(searchFolder, fileFilter)
/*007b*/ // Each file in our filter will be processed against fileName
/*008b*/ .Where(filterName => filter // Note: Where clause expects bool result
/*009b*/ .FirstOrDefault(fileName => filterName.ToLower().Contains(fileName))!=null)
/*010b*/ .SelectMany( file => file.Split('\\').Where(segment=> segment.Contains(".DLL"))
).Dump("SelectMany results with .Where() clause to only pull .DLL entries");
/*999*/
/*999*/ (filter.FirstOrDefault(listname => listname.Contains("ole")) )
/*999*/ .Dump("Line 009 returns string if found without {!= null} which will crash .Where() clause");
/*999*/ (filter.FirstOrDefault(listname => listname.Contains("ole"))!=null)
/*999*/ .Dump("Line 009 returns bool with {!= null} which is what .Where() clause is expecting");
/*999*/
Tags:
compositewpf,
moduleloader,
linqpad,
linq
Categories:
CompositeWPF