On 2/9/07, Josiah Carlson jcarlson@uci.edu wrote:
"Brett Cannon" brett@python.org wrote:
On 2/9/07, Ron Adam rrr@ronadam.com wrote:
Brett Cannon wrote:
On 2/8/07, Ron Adam rrr@ronadam.com wrote:
[SNIP]
If you remove the "__main__" name, then you will still need to have some attribute for python to determine the same thing.
Why? There is nothing saying we can't follow most other languages and just have a reserved function name that gets executed if the module is executed.
Yes, but this is where python is different from other languages. In a way, python's main *is* the whole module from the top to bottom. And so the '__main__' name is referring to the whole module and not just a function in it.
A more specific function would be needed to get the context right. Maybe __script__(), or __run__().
Or if you want to be consistent with class's, how about adding __call__() to modules? Then the main body of the module effectively works the same way as it does in a class. =)
Hey, I think that has some cool possibilities, it makes modules callable in general. So if I want to run a module's __call__(), AKA main() as you call it, after importing I would just do...
import module module()And it would just work. ;-)
I like this idea. Makes it very obvious. You just say "when a specific module is specified at the command line it is called. Could even have it take possibly sys.argv[1:] (which I think was supposed to turn into sys.args or sys.arg or something at some point).
What do other people think?
I don't like it. Much of my dislike comes from personal aesthetics, but then there is a logical disconnect. When an instance of a class is created, its __call__ method is not automatically called. By using the semantic of 'the __call__ function in the module namespace is automatically executed if the module is "run" from the command line', we are introducing a different instance creation semantic (an imported module is an instance of ModuleType).
But I don't see the leap of how specifying a module to execute on the command line is any different than doing ``Class()()`` for instantiation with an immediate call. It would still be a separate step.
I think we should just stick with what has been proposed for *years*, a __main__ function that is automatically executed after the module has been imported if its __name__ == '__main__'.
But that does not solve the problem Ron has been trying to deal with; setting __name__ to __main__ prevents the execution of a module that uses relative imports because the import machinery can then no longer infer what package the module is in.
-Brett