c# - Can I use Roslyn for compile time code rewriting?

Question

For example I have

class Foo: INotifyPropertyChanged {
    public event PropertyChangedEventHandler PropertyChanged;
    public int Bar {get;set;}
}

Can I get the Foo class AST and rewrite Bar, in compile time, to

    public string Bar
    {
        get { return this.bar; }

        set 
        {
            if (value != this.bar)
            {
                this.phoneNumberValue = value;
                PropertyChanged(this, new PropertyChangedEventArgs("Bar"));
            }
        }
    }

.

Answer 1

Compile time re-writing isn't directly supported by Roslyn today, but syntactic and semantic transformations definitely are. In fact, take a look at the "ImplementNotifyPropertyChanged" sample included in the CTP to see something of what you want to do. The sample is implemented as a design time transformation in and IDE feature, but you can extract the logic and make it into something like a pre-build task that rewrites files before compilation.