[Python-Dev] PEP 0008 confusion - here it is, but don't use it?

[Skip Montanaro]

>From Raymond's checkin:

    Programming Recommendations
  
    - Code should be written in a way that does not disadvantage other
      implementations of Python (PyPy, Jython, IronPython, Pyrex, Psyco, and
      such).  For example, do not rely on CPython's efficient implementation
      of in-place string concatenation for statements in the form a+=b or
      a=a+b.  Those statements run more slowly in Jython.  In performance
      sensitive parts of the library, the ''.join() form should be used
      instead.  This will assure that concatenation occurs in linear time
      across various implementations.

I'm a bit confused.  Why bother to speed up s+=t if we aren't supposed to
use it?

Skip