[Python-Dev] redefining is

[François Pinard]

[Tim Peters]

>     buf is ''

There is question which traversed my mind recently.  While I would
never use `is' between ordinary strings, I might be tempted to use `is'
between explicitely interned strings, under the hypothesis that for
example:

    a = intern('a b')
    b = intern('a b')
    a is b

dependably prints `True'.  However, I remember a thread in this forum by
which strings might be un-interned on the fly -- but do not remember the
details; I presume it was for strings which the garbage collector may
not reach anymore.

There are a few real-life cases where speed considerations would invite
programmers to use `is' over `==' for strings, given they all get
interned to start with so the speed-up could be gleaned later.  The fact
that `is' exposes the implementation is quite welcome in such cases.

-- 
François Pinard   http://www.iro.umontreal.ca/~pinard