debugging DLR

Question

DLR looks like a way to implement macroses in applications. But how would those macroses be debugged?
Is there a debugging API for dynamic languages?

Answer 1

We are working on in-process debugging similar to how VBA debugging works in Office. It's not 100% finished yet and therefore not part of the VS 2010 release. However IronPython already uses it to enable lightweight debugging. You can learn more at http://devhawk.net/2009/07/08/MicrosoftScriptingDebugging.aspx and http://devhawk.net/2009/10/06/Lightweight+Debugging+For+Hybrid+CIronPython+Apps.aspx.

You can also compile an Expression Tree to IL with debug information and use traditional PDB based VS debugger. Use Expression.DebugInfo node to add sequence point and source file information to the tree, create a TypeBuilder and a MethodBuilder via Reflection.Emit (see an example at http://msdn.microsoft.com/en-us/library/bs22fky4.aspx) and finally LambdaExpression.CompileToMethod (http://msdn.microsoft.com/en-us/library/dd728258(VS.100).aspx) to emit the IL into the MethodBuilder. You can then place breakpoints to the source files referred to by DebugInfo nodes and step thru the code using VS debugger.

Answer 2

Very interesting.

How do you compile Expression Tree to IL?