Simon Fell > Its just code > sample code

Thursday, August 17, 2006

The MSDN library is littered with sample code, most of it annoys the hell out me because it doesn't say what the expected outcome is from running the code, and sometimes the samples are downright misleading, take this one from CodeTypeReferenceCollection

// Creates an empty CodeTypeReferenceCollection.
CodeTypeReferenceCollection collection = new CodeTypeReferenceCollection();

// Adds a collection of CodeTypeReference objects to the collection.
CodeTypeReferenceCollection referencesCollection = new CodeTypeReferenceCollection();
referencesCollection.Add( new CodeTypeReference(typeof(bool)) );
referencesCollection.Add( new CodeTypeReference(typeof(bool)) );
collection.AddRange( referencesCollection );

// Tests for the presence of a CodeTypeReference in the 
// collection, and retrieves its index if it is found.
CodeTypeReference testReference = new CodeTypeReference(typeof(bool));
int itemIndex = -1;
if( collection.Contains( testReference ) )
    itemIndex = collection.IndexOf( testReference );

No where does it mention what value itemIndex might have when you run this. I saw this and took it to mean that the CodeTypeReference's would get compared by value rather than reference, and so find the bool CodeTypeReference even though its a different instance, but no, running the code reveals that CodeTypeReference doesn't seem to override Equals or ==, and so the collection.Contains call returns false. grrrhhh. (this makes finding out if a particular type is in the Collection something of a PIA if you didn't construct and populate the collection yourself.)