Create a new class on the fly

[Alex Martelli]

py_genetic <conor.robinson at gmail.com> wrote:

> Is this possible or is there a better way.  I need to create a new
> class during runtime to be used inside a function. The class
> definition and body are dependant on unknows vars at time of exec,
> thus my reasoning here.
> 
> class PosRecords(tables.IsDescription):
> 
> 
> class A(object):
>     self.__init__(self, args):

This makes 0 sense; maybe you should learn elementary Python syntax well
_before_ trying advanced stuff, no?

>          ........
>     def mkClass(self, args):
>           eval( "class B(object): ...") #definition on B is dependant
> on dynamic values in string
>           ......do stuff with class

Just use a class statement, and setattr on the resulting class object to
set stuff dynamically on it.  eval won't do what you want (it takes
expressions, not statements), and exec is an even worse way to go about
it.

E.g.:

class A(object):
  def mkClass(self, name, *k):
    class bah(object): pass
    bah.__name__ = name
    for n in k: setattr(bah, n, k[n])
    return bah


Alex