How to code dynamically created methods?

kj socyl at 987jk.com.invalid
Wed Jun 20 15:55:09 CEST 2007


Nevermind, I found the problem...

Thanks,

kj

In <f5bb99$2jr$1 at reader2.panix.com> kj <socyl at 987jk.com.invalid> writes:



>I've tried a bazillion ways to code dynamically generated methods,
>to no avail.

>The following snippet is a very simplified (and artificial) demo
>of the problem I'm running into, featuring my latest attempt at
>this.  The idea here is to use __getattr__ to trap any attempt to
>invoke a nonexistent method, have it return a generic handler called
>_auto which creates the new method dynamically, invokes it, and
>"installs" it in the class, so that subsequent calls to the same
>method go directly to the newly created method, instead of to
>__getattr__.  It is this last step, the "installation" of the new
>method, that is giving me problems.


>class A( object ):
>    def __getattr__( self, name ):
>        self._auto_name = name
>        return self._auto

>    def hello( self, name ):
>        print "hi! my name is %s" % name
>        
>    def _auto( self, *args ):
>        name = self._auto_name
>        def m( self, *args ): self.hello( name )
>        m( self, *args )

>        m = classmethod( m )
>        setattr( A, name, m )

>x = A()
>x.foo()  # ok
>x.foo()  # bombs


>>>> reload(test) hi! my name is foo Traceback (most recent call
>last):
>  File "<stdin>", line 1, in ? File "test.py", line 19, in ?
>    x.foo() File "test.py", line 12, in m
>    self.hello( name ) TypeError: unbound method hello() must be
>called with A instance as first argument (got str instance instead)
>>>>

>I'm sure that the problem is with my naive attempt to add a method
>to class A dynamically (in the last two lines of the definition of
>_auto).  What's the right way to do this?

>Thanks!

>kj

>-- 
>NOTE: In my address everything before the first period is backwards;
>and the last period, and everything after it, should be discarded.
-- 
NOTE: In my address everything before the first period is backwards;
and the last period, and everything after it, should be discarded.



More information about the Python-list mailing list