in use

class MyClass( object ):
    def __init__( self, a, b, c="somec", d="somed" ):
        self.a = a
        self._b = b
        self.__c = c
        self.__d__ = d

    def get_c(self):
        return self.__c

    def getD(self):
        return self.__d__

class MyReprdClass( MyClass, ReprFromInit ):
    pass

>>> mc = MyClass( 1, 2 )
>>> mrc = MyReprdClass(3,4)
>>> 
>>> mc
<repr_from_init.MyClass object at 0x1070e8510>
>>> mrc
repr_from_init.MyReprdClass(a=3, b=4, c='somec', d='somed')
>>> 
>>> mrc2 = MyReprdClass(3,4, c="another", d="yet more")
>>> mrc2
repr_from_init.MyReprdClass(a=3, b=4, c='another', d='yet more')
>>> 

ReprFromInit Mixin

import inspect
class ReprFromInit( object ):
    def __repr__( self ):
         args = inspect.getargspec( self.__class__.__init__ ).args
         path = "{modulename}.{classname}".format( modulename=self.__class__.__module__, classname=self.__class__.__name__ )
         argstrs = []
         for arg in args[1:]: # skip self
             for argname in [ arg, "_"+arg, '' ]:
                 if hasattr( self, argname ):
                     break
             if argname:
                 a = getattr( self, argname )
                 val = a 
             else:
                 # might have a getter
                 if hasattr( self, "get_"+arg ):
                     val = eval( "self.get_{arg}()".format(arg=arg) )
                 elif hasattr( self, "get" + arg[0].upper() + arg[1:] ):
                     val = eval( "self.get{arg}()".format(arg=arg[0].upper() + arg[1:]) )
                 else:
                     val = "ERROR"#: cant find value for "+ arg+ "to create the repr" )
             argstrs.append( "{k}={v}".format( k=arg, v=repr(val) ) )
         argstr = ", ".join( argstrs )
         constructor_call_str = "{p}({a})".format( p=path, a=argstr )
         return constructor_call_str