Re: About a plugin framework!
From: Peter Otten (__peter___at_web.de)
Date: 06/08/04
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Date: Tue, 08 Jun 2004 11:57:06 +0200
Simon Roses Femerling wrote:
> The way my app works is a python module (plugin) that contains (imbedded)
> XML defining the classname and some extra information and the app will be
> load the module using the classname:
>
> Example:
>
> ------ mymodule.py ----
>
> __xml__ ="""
> <data>
> <classname>Test</classname>
> </data>
> """
The xml stuff unnecessarily complicates things. Use a list with the names of
exposed classes
__all__ = ["Test"]
If there is only one I'd rather follow a naming convention, i. e. the class
name "Test" would be mandatory.
> class Test:
> def Msg(self):
> print "Hello"
>
> ---------------------------------
>
> --- MyApp.py -----------
>
> fp = open(f)
> exec(fp) in globals()
> str = __xml__
> pxml = parsexml.ParseXML()
> pxml.BeginParse(str)
> cn = pxml.GetClassname()
> mymod = cn() <-- Here is the error
Which of the following would you expect to succed?
>>> class Test: pass
...
>>> Test()
<__main__.Test instance at 0x40296acc>
>>> "Test"()
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: 'str' object is not callable
>>> u"Test"()
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: 'unicode' object is not callable
So the name is not enough - unicode or not. You have to get hold of the
class object, but that is no big deal:
>>> getattr(__main__, u"Test")()
<__main__.Test instance at 0x40296bcc>
> mymod.Msg()
>
> ----------------------------------
>
> The error is:
>
> Traceback (most recent call last):
> File "blackout.py", line 503, in onAttackMod
> mymod = cn()
> TypeError: 'unicode' object is not callable
>
> Any suggestions ? How can achieve this ?
> Each module (plugin) can have a different class name defined in the XML
> data.
Why?
> Besides this anyone have suggestions for a better plugin framework ? Maybe
> using imp module to dynamically import modules ?
If a plugin is in the python path, just do
plugin = __import__(pluginName)
and then retrieve the class
pluginClass = getattr(plugin, plugin.__all__[0])
Depending on whether you allow multiple plugins/classes at a time and how
you want to access them from your code you'd need registries (basically
python dictionaries) for plugin modules and clases.
Peter
- Next message: Zunbeltz Izaola: "Using ConfigParse"
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