[Python-Dev] Re: opcode performance measurements

[Jeremy Hylton]

>>>>> "SP" == Samuele Pedroni <pedronis@bluewin.ch> writes:

  SP> Hi. Q about PEP 267 Does the PEP mechanims adress only
  SP> import a
  SP> use a.x

  SP> cases. How does it handle things like
  SP> import a.b
  SP> use a.b.x

You're a smart guy, can you tell me?  :-).  Seriously, I haven't
gotten that far.

import mod.sub
creates a binding for "mod" in the global namespace

The compiler can detect that the import statement is a package import
-- and mark "mod.sub" as a candidate for optimization.  A use of
"mod.sub.attr" in function should be treated just as "mod.attr".

The globals array (dict-list hybrid, technically) has the publicly
visible binding for "mod" but also has an internal binding for
"mod.sub" and "mod.sub.attr".  Every module or submodule attribute in
a function gets an internal slot in the globals.  The internal slot
gets initialized the first time it is used and then shared by all the
functions in the module.

So I think this case isn't special enough to need a special case.

Jeremy