Question

While the C# spec does include a pre-processor and basic directives (#define, #if, etc), the language does not have the same flexible pre-processor found in languages such as C/C++. I believe the lack of such a flexible pre-processor was a design decision made by Anders Hejlsberg (although, unfortunately, I can’t find reference to this now). From experience, this is certainly a good decision, as there were some really terrible un-maintainable macros created back when I was doing a lot of C/C++.

That said, there are a number of scenarios where I could find a slightly more flexible pre-processor to be useful. Code such as the following could be improved by some simple pre-processor directives:

public string MyProperty {   get { return _myProperty; }   set   {     if (value != _myProperty)     {       _myProperty = value;       NotifyPropertyChanged('MyProperty');       // This line above could be improved by replacing the literal string with       // a pre-processor directive like '#Property', which could be translated       // to the string value 'MyProperty' This new notify call would be as follows:       // NotifyPropertyChanged(#Property);     }   } } 

Would it be a good idea to write a pre-processor to handle extremely simple cases like this? Steve McConnell wrote in Code Complete (p208):

Write your own preprocessor If a language doesn’t include a preprocessor, it’s fairly easy to write one…

I am torn. It was a design decision to leave such a flexible pre-processor out of C#. However, an author I highly respect mentions it may be ok in some circumstances.

Should I build a C# pre-processor? Is there one available that does the simple things I want to do?

Answer 1

Consider taking a look at an aspect-oriented solution like PostSharp, which injects code after the fact based on custom attributes. It’s the opposite of a precompiler but can give you the sort of functionality you’re looking for (PropertyChanged notifications etc).