Hi,

thanks for your answer, and your questions. Very good draw. I printed it in my office ^^

First i'd like to precise that, as in title, aim is not to gurantee quality but minimal quality. I think it's really two different things.

About metrics, my ideas was about following (for the moment):

Basical Python Rules respect: PEP8 & PEP20 respect
Docstring/documentation respect: PEP257 respect
Code readability: percentage of commentary line and percentage of blank line
Code maintainability / complexity: the facility to re-read code if old code, or to understand code for an external developer. If not comprehensive, for example, i use McCabe in my work
Code coverage: by unit tests

From your question on objective metrics, i don't think that reliable metrics exists. We can only verify that minimal quality can be reached. As you say, it's a subjective apprehension, but in my mind, this "PEP" could be a guideline to improve development for some developers.