with statement support

[Alejandro Martinez]

One of the major statement-level shortcomings of lambda-py is the lack of support for the with statement (the other being the lack of support for metaclass programming), I plan to give it a try in the following days, the steps would be as follows:

    1) add PyWith(context, target, body) to surface language and get-structured-python

    2) add LexWith(context, target, body) to lexical language taking care of target variables

    3) desugar LexWith according to http://www.python.org/dev/peps/pep-0343/

    4) add support for the context manager protocol to file objects

Any comments or suggestions are welcomed.

Alejandro.

[Alejandro Martinez]

This is finished, I will take a look at metaclasses now.