[Python-Dev] peps 329, 266, 267 (original) (raw)

Phillip J. Eby pje at telecommunity.com
Wed Apr 21 16:54:34 EDT 2004

At 04:39 PM 4/21/04 -0400, Jewett, Jim J wrote:

>> If this is really only about globals and builtins, >> then you can just initialize each module's dictionary >> with a copy of builtins. (Or cache them in the module >> dict on the first lookup, since you know where it >> would have gone.)

Phillip J. Eby: > Interesting thought. The same process that currently > loads the builtins member could instead update the > namespace directly. > There's only one problem with this idea, and it's a big > one: 'import *' would now include all the builtins, > causing one module's builtins (or changes thereto) to > propagate to other modules. Why is this bad?

Because some modules are examined by software, and only the expected names belong there. For example, I believe if you run 'pydoc' on such a module, it will proceed to document all the builtins.

The reason to import * is that you intend to use the module's members as if they were your own. If the other module actually has modified a builtin, you'll need to do the same, or the imported members won't work quite right.

shudder I'm glad the language really doesn't work in the way you just described. :) No, just because one module shadows a builtin, doesn't mean you have to follow suit.

> ... declare that the any builtin used in a module > that's known to be a builtin, is allowed to be > optimized to the meaning of that builtin.

> In effect, 'builtins' should be considered an > implementation detail, not part of the language, Many builtins (None, True, KeyError) are effectively keywords, and I would agree. Others, like debug, are really used for intermodule communication, because there isn't any other truly global namespace. (Perhaps there should be a conventional place to look, such as a settings module?)

debug is also a builtin, in the sense of being optimizable by the compiler, so I don't see any reason to look at it differently. In fact, isn't debug already treated as a constant by the compilers?

Python 2.2.2 (#37, Oct 14 2002, 17:02:34) [MSC 32 bit (Intel)] on win32 Type "copyright", "credits" or "license" for more information. IDLE 0.8 -- press F1 for help

debug 1 debug=0 SyntaxError: can not assign to debug (<pyshell#1>, line 1)

Yep, I guess so.

More information about the Python-Dev mailing list