Shortcomings in Syntax Tree API - no common base class or interface for MethodDeclarationSyntax, FieldDeclarationSyntax etc. for important common properties

[gmamaladze]

Version Used:
Visual Studio 2015 Update 2

Shortcomings in Syntax Tree API:
While writing code for a code refactoring very often you need to perform similar checks or modifications on members containing actual code: methods, property accessors, indexer accessors etc. Most of them have common properties like Body, Modifiers, AttributeLists, ArgumentList.

There is no common base class or a common interface which would expose these common properties. That's why you end up with a lot of code duplication, with all consequences as shown in example below:

private static bool IsPrivate(MethodDeclarationSyntax method)
{
    return method.Modifiers.Any(IsPrivateModifier);
}

private static bool IsPrivate(FieldDeclarationSyntax field)
{
    return field.Modifiers.Any(IsPrivateModifier);
}

private static bool IsPrivate(PropertyDeclarationSyntax property)
{
    return property.Modifiers.Any(IsPrivateModifier);
}

private static bool IsPrivate(IndexerDeclarationSyntax indexer)
{
    return indexer.Modifiers.Any(IsPrivateModifier);
}

private static bool IsPrivateModifier(SyntaxToken modifier)
{
    return modifier.Kind() == SyntaxKind.PrivateKeyword;
}

Suggestion:

• One way would be to provide a common interface for all "method like" SyntaxNode-s.
• Another way is to provide adapter classes to adapt "method like" SyntaxNode-s to some interface which provides uniform and convenient access to properties like Modifiers, AttributeLists, Body, ArgumentList. This solution will have less implementation and runtime impact.

Related to: #9908

[ap0llo]

Should I give this issue a try or is there already someone working on this?

[CyrusNajmabadi]

These share MemberDeclarationSyntax which do expose things like Modifiers. Closing out.