idiom for constructor?

[Peter Dembinski]

Steven Bethard <steven.bethard at gmail.com> writes:

> Mac wrote:
>> Is there a nice Python idiom for constructors which would expedite
>> the following?
>> class Foo:
>>   def __init__(self, a,b,c,d,...):
>>     self.a = a
>>     self.b = b
>>     self.c = c
>>     self.d = d
>>     ...
>
> py> class Foo(object):
> ...     def __init__(self, a, b, c, d):
> ...         params = locals()
> ...         del params['self']
> ...         self.__dict__.update(params)
> ...
> py> vars(Foo(1, 2, 3, 4))
> {'a': 1, 'c': 3, 'b': 2, 'd': 4}
>
> Just make sure that "params = locals()" is the first line in
> __init__ method.  (Otherwise you might have other local variables
> slip in there.)

Or write it like this, using Python's dynamic code execution:

#v+

class A:
    def __init__(self, a, b, c, d):
        initial = {'a' : 1, 'b' : 2, 'c' : 3, 'd' : 4}

        for param in initial.keys():
            exec "self.%s = initial['%s']" % (param, param)

#v-

-- 
http://www.peter.dembinski.prv.pl