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pythonclassobjectdeap

In python DEAP package, why a function can be called from a module which dose not have such function?

I have just started to use the DEAP package in python. Following the tutorial, I can't understand this statement:

toolbox.register("cross",tools.cxTwoPoint)

I understand that tools.cxTwoPoint is to call the cxTwoPoint function. However, I checked the source code, the cxTwoPoint function is not within tools module, and it is a defined function within crossover.py. Also, I didn't find any statement in tools.py which may relate to crossover.py or cxTwoPoint.

Can someone help me? Many many thanks!!!

Solution

  • The tools.py is used for benchmarking the algorithm. As we can seen from __init__.py, there is a statement from .crossover import * which means import all of the functions in the crossover module where located same directory as __init__.py. This gives you a easy way to access these functions in other files. And __init__.py are required to make Python trent the directories as containing packages as answered in:What is __init__.py for?.