initialising a class by name

[Steven D'Aprano]

On Wed, 14 Jan 2009 13:19:23 +0530, Krishnakant wrote:

> On Tue, 2009-01-13 at 21:51 -0800, Chris Rebert wrote:
>> Assuming all the classes are in the same module as the main program:
>> 
>> instance = vars()[class_name](args, to, init)
>> 
> The classes are not in the same module. Every glade window is coupled
> with one py file (module) containing one class that has the events for
> the glade file. Inshort, there is one class in one module and they are
> all seperate.


Just import the classes you need, and dispatch on them.

import spammodule, hammodule
dispatch_table = {
    "Spam": spammodule.Spamclass, "Ham": hammodule.Hamclass}

# later

obj = dispatch_table[ user_input ]()





>> Assuming the classes are all in the same module "mod", which is
>> separate from the main program:
>> 
>> instance = getattr(mod, class_name)(args, to, init)
>> 
> Can you explain the difference between getattr and var()?


They are completely different things. At an interactive prompt, type:

help(getattr)

help(var)

and read what they say.



-- 
Steven