Expression templates for arithmetic operations in python

[David Welch]

Hi,

I am new to python so I thought I would write a quick and simple 
vector/matrix multiplication class in c++ and use it in python.

Is it possible to overload the operators in python such a way that a 
tree of calculations is built which I can then pass to an evaluator 
written in c++ to calculate the tree with max efficiency.

My thought train is that the args are passed to c++ only once and so 
there is less overhead in unpacking them.

Is there are an existing implementation in python which does this?

What is the best way to implement this?

Thanks for your help.

David