Pythonnet: Add support for DLR types

[filmor]

Using this it's possible to implement all required functionality in a separate DLR meta-class. I've already tried to do this in Python but sadly the .NET types (or their representation in Python-space) are not patchable.

[filmor]

Indeed I have now found a way around this, check out this gist: https://gist.github.com/filmor/58f5099f96570c64b1d3

The implementation of the member access is done by basically translating the code that the C# compiler produces when accessing dynamic properties to Python.

Note: Strictly speaking this does _not_ implement full support, as it only helps classes that derive from DynamicObject, not those that only implement IDynamicMetaObjectProvider.

[denfromufa]

@filmor what is the use case for exposing DLR types in python?

[filmor]

My particular use case is a configuration library that allows for constructs like:

string proxy = c.proxy.http;

where c is a dynamic object of which the members are implicitly created by reading from the config. It allows us to pass partial configuration around easily and reduces string-littering.

[denfromufa]

@filmor can this be used to access dynamic attributes of COM objects? if yes, can you provide minimal example?

[denfromufa]

@filmor here is my first attempt at using com objects from pythonnet:

https://gist.github.com/denfromufa/ec559b5af41060c5ac318f7f59d8b415#file-excel_interop_vsto-ipynb

[denfromufa]

@filmor how would you add support for IDynamicMetaObjectProvider?

[denfromufa]

This looks really powerful library:

https://github.com/ekonbenefits/dynamitey/wiki/UsageReallyLateBinding