Class decorator with class methods

Question

I have written a class decorator that monkey-patches a class overwriting the init and adding a method persist (). So far everything OK.

Now I need to add a class method (static method) to the decorated class. What do I have to change in my code to make staticMethod() a static method of the decorated class?

This is my code:

#! /usr/bin/env python
# -*- coding: utf-8 -*-

class Persistent (object):
    def __init__ (self, table = None, rmap = None):
        self.table = table
        self.rmap = rmap

    def __call__ (self, cls):
        cls.table = self.table
        cls.rmap = self.rmap
        oinit = cls.__init__
        def finit (self, *args, **kwargs):
            print "wrapped ctor"
            oinit (self, *args, **kwargs)
        def persist (self):
            print "insert into %s" % self.table
            pairs = []
            for k, v in self.rmap.items (): pairs.append ( (v, getattr (self, k) ) )
            print "(%s)" % ", ".join (zip (*pairs) [0] )
            print "values (%s)" % ", ".join (zip (*pairs) [1] )
        def staticMethod (): print "I am static"
        cls.staticMethod = staticMethod
        cls.__init__ = finit
        cls.persist = persist
        return cls

@Persistent (table = "tblPerson", rmap = {"name": "colname", "age": "colage"} )
class Test (object):
    def __init__ (self, name, age):
        self.name = name
        self.age = age

a = Test ('John Doe', '23')
a.persist ()
Test.staticMethod ()

And the output is:

wrapped ctor
insert into tblPerson
(colage, colname)
values (23, John Doe)
Traceback (most recent call last):
  File "./w2.py", line 39, in <module>
    Test.staticMethod ()
TypeError: unbound method staticMethod() must be called with Test instance as first argument (got nothing instead)

GWW · Accepted Answer · 2011-06-01 02:47:18Z

3

    @staticmethod
    def staticMethod (): print "I am static"

or

    def staticMethod (): print "I am static"
    cls.staticMethod = staticmethod(staticMethod)

answered Jun 1, 2011 at 2:47

GWW

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2 Comments

Hyperboreus Over a year ago

Thank you. Sometimes it is so simple.

GWW Over a year ago

Python has strange syntax sometimes.

Julien Grenier · Accepted Answer · 2011-06-01 02:52:20Z

1

use the @staticmethod decorator.

@staticmethod
def staticMethod() : ...

answered Jun 1, 2011 at 2:52

Julien Grenier

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