About a plugin framework!

[Simon Roses Femerling]

Dear pythonnians :)

Hopeful somebody can help me about implementing plugin support.

I'm working on a python/wxpython app that needs plugin support. My problem is:

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>
"""

class Test:
def Msg(self):
print "Hello"

---------------------------------

--- MyApp.py -----------

fp = open(f)
exec(fp) in globals()
str = __xml__
pxml = parsexml.ParseX ML()
pxml.BeginParse (str)
cn = pxml.GetClassna me()
mymod = cn() <-- Here is the error
mymod.Msg()

----------------------------------

The error is:

Traceback (most recent call last):
File "blackout.p y", 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.

Besides this anyone have suggestions for a better plugin framework ? Maybe using imp module to dynamically import
modules ?

Any examples ?

Thx for any help!

Sincerely

SRF

[Guyon Morée]

Re: About a plugin framework!

Hi,

change: cn = pxml.GetClassna me()
into: cn = globals()[pxml.GetClassna me()]


your line returns a string, the name of your class, which is not callable
the correct line looks up the name in your globals() dict and returns a
callable.


cheers,
guyon

=============== =============== =============== =============
"Simon Roses Femerling" <simonroses@gra nisla.com> wrote in message
news:mailman.69 3.1086683764.69 49.python-list@python.org ...
Dear pythonnians :)

Hopeful somebody can help me about implementing plugin support.

I'm working on a python/wxpython app that needs plugin support. My problem
is:

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>
"""

class Test:
def Msg(self):
print "Hello"

---------------------------------

--- MyApp.py -----------

fp = open(f)
exec(fp) in globals()
str = __xml__
pxml = parsexml.ParseX ML()
pxml.BeginParse (str)
cn = pxml.GetClassna me()
mymod = cn() <-- Here is the error
mymod.Msg()

----------------------------------

The error is:

Traceback (most recent call last):
File "blackout.p y", 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.

Besides this anyone have suggestions for a better plugin framework ? Maybe
using imp module to dynamically import
modules ?

Any examples ?

Thx for any help!

Sincerely

SRF

[Peter Otten]

Re: About a plugin framework!

Simon Roses Femerling wrote:
[color=blue]
> 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>
> """[/color]

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.

[color=blue]
> class Test:
> def Msg(self):
> print "Hello"
>
> ---------------------------------
>
> --- MyApp.py -----------
>
> fp = open(f)
> exec(fp) in globals()
> str = __xml__
> pxml = parsexml.ParseX ML()
> pxml.BeginParse (str)
> cn = pxml.GetClassna me()
> mymod = cn() <-- Here is the error[/color]

Which of the following would you expect to succed?
[color=blue][color=green][color=darkred]
>>> class Test: pass[/color][/color][/color]
....[color=blue][color=green][color=darkred]
>>> Test()[/color][/color][/color]
<__main__.Tes t instance at 0x40296acc>[color=blue][color=green][color=darkred]
>>> "Test"()[/color][/color][/color]
Traceback (most recent call last):
File "<stdin>", line 1, in ?
TypeError: 'str' object is not callable[color=blue][color=green][color=darkred]
>>> u"Test"()[/color][/color][/color]
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:
[color=blue][color=green][color=darkred]
>>> getattr(__main_ _, u"Test")()[/color][/color][/color]
<__main__.Tes t instance at 0x40296bcc>

[color=blue]
> mymod.Msg()
>
> ----------------------------------
>
> The error is:
>
> Traceback (most recent call last):
> File "blackout.p y", 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.[/color]

Why?
[color=blue]
> Besides this anyone have suggestions for a better plugin framework ? Maybe
> using imp module to dynamically import modules ?[/color]

If a plugin is in the python path, just do

plugin = __import__(plug inName)

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

[j_mckitrick]

Re: About a plugin framework!

> fp = open(f)[color=blue]
> exec(fp) in globals()
> str = xml[/color]

What do the second and third lines do here?

jonathon