>>> On Tue, 2010-03-02 at 08:01 -0500, lloyd konneker wrote:
> I agree with Joao S. O. Bueno and disagree with David Bowers.
Well, I'm glad you don't disagree with me, but who is that?
> Its better to make plugins meet the normal expectations of Python
> programmers (you can import any Python file to use pieces of it) than to
> add new conventions and directories for shared Python plugin code.
> Simpler is better?
The normal expectations of Python programmers are that the main loop
will be guarded.
This is exactly the thing that allows you to import otherwise
without it, no guarantees can be made that the code you are importing
will not interfere with global state in a way which causes your plugin
to crash. You can depend on a specific version of a plugin which has
known behaviour; In that case you prevent the user from upgrading that
plugin, and you rely on knowledge of the internals of that plugin,
which is very likely to get you into trouble if you ever need to
The same principle applies to python scripts that are unguarded:
importing them will, at the least, have significant side effects.
Often they are entirely incapable of being cooperative.
Hence, it's not practical to import a plugin module unless it
specifically indicates that it is fit to be imported (by guarding the
> Often, authors don't plan their code will be useful to others. It's
> just serendipity. If authors don't plan to share code and put it in
> these new directories, it thwarts serendipitous reuse and
> It is inconsistent for a duplicate call to register() to be harmless
> with a warning while a duplicate call to main() is fatal.
Currently, the latter is serving the function of preventing the
previously mentioned possibility of side effects of importing a plugin
in this way.
If there is another way of preventing that problem, then we could look
at removing that aspect of main() calls.
Otherwise, we absolutely must not.
> Also, new conventions and directories does not solve my wish to call
> pydoc on plugins (which is not very important. I hope to download a
> prototype Inspect plugin to gimp registry soon.) But it illustrates
> that you can't always anticipate what people will want to do.
I wanted to do that too.
Just because you want to do something, doesn't mean it's wise to do so.
Calling pydoc on unguarded python modules is just as unpredictable as
importing unguarded python modules. Why? Because the way it gets the
documentation is by first importing the module in question.
Furthermore, all GIMP plugins' dependency on the 'gimp' (and/or
gimpfu, etc..) modules mean that even if they are in the module search
path, pydoc's attempt at importing them will fail (because the gimp
and gimpfu,etc.. modules are only available to Python scripts that are
being run by GIMP).Changing the mechanics of main() would not effect
If you don't believe that, it's easy to check; set PYTHON_PATH to your
plugins directory (full, absolute path like
/home/llkk/.gimp-2.7/plugins), start Python, and try to import one of
those plugins as a module.
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