instantiate a class with a variable

[John]

Hi, is it possible to instantiate a class with a variable.

example

class foo:
def method(self):
pass

x='foo'

Can I use variable x value to create an instance of my class?

Thanks, John

[Ben Finney]

Re: instantiate a class with a variable

"John" <johnwadeunderw ood@yahoo.com> writes:[color=blue]
> class foo:
> def method(self):
> pass
>
> x='foo'
>
> Can I use variable x value to create an instance of my class?[/color]

You seem to be asking "is it possible to call an object whose name is
stored in a string".

The answer is yes::
[color=blue][color=green][color=darkred]
>>> class Foo:[/color][/color][/color]
... pass
...[color=blue][color=green][color=darkred]
>>> foo_name = 'foo'
>>> foo_class = locals().get(fo o_name)
>>> bar = foo_class()
>>> bar[/color][/color][/color]
<__main__.Foo instance at 0x401e468c>

Or, more succinctly but rather harder to follow::
[color=blue][color=green][color=darkred]
>>> class Foo:[/color][/color][/color]
... pass
...[color=blue][color=green][color=darkred]
>>> foo_name = 'foo'
>>> bar = locals().get(fo o_name)()
>>> bar[/color][/color][/color]
<__main__.Foo instance at 0x401e46ec>

--
\ "I went to the cinema, it said 'Adults: $5.00, Children $2.50'. |
`\ So I said 'Give me two boys and a girl.'" -- Steven Wright |
_o__) |
Ben Finney

[Cameron Laird]

Re: instantiate a class with a variable

In article <mailman.3742.1 143505181.27775 .python-list@python.org >,
Ben Finney <bignose+hate s-spam@benfinney. id.au> wrote:[color=blue]
>"John" <johnwadeunderw ood@yahoo.com> writes:[color=green]
>> class foo:
>> def method(self):
>> pass
>>
>> x='foo'
>>
>> Can I use variable x value to create an instance of my class?[/color]
>
>You seem to be asking "is it possible to call an object whose name is
>stored in a string".
>
>The answer is yes::
>[color=green][color=darkred]
> >>> class Foo:[/color][/color]
> ... pass
> ...[color=green][color=darkred]
> >>> foo_name = 'foo'
> >>> foo_class = locals().get(fo o_name)
> >>> bar = foo_class()
> >>> bar[/color][/color]
> <__main__.Foo instance at 0x401e468c>
>
>Or, more succinctly but rather harder to follow::
>[color=green][color=darkred]
> >>> class Foo:[/color][/color]
> ... pass
> ...[color=green][color=darkred]
> >>> foo_name = 'foo'
> >>> bar = locals().get(fo o_name)()
> >>> bar[/color][/color]
> <__main__.Foo instance at 0x401e46ec>[/color]

[Ben Finney]

Re: instantiate a class with a variable

Ben Finney <bignose+hate s-spam@benfinney. id.au> writes:
[color=blue][color=green][color=darkred]
> >>> class Foo:[/color][/color]
> ... pass
> ...[color=green][color=darkred]
> >>> foo_name = 'foo'[/color][/color][/color]

Dang. As Cameron Laird points out, this should be
[color=blue][color=green][color=darkred]
>>> foo_name = 'Foo'[/color][/color][/color]

each time.

Moral of the story: if the example already works, and then you cut and
paste into the message compose window, and then notice that it could
be clearer and edit it some more...

.... always test the example code you're *actually* presenting, after
all edits.

--
\ "You know what would make a good story? Something about a clown |
`\ who makes people happy, but inside he's real sad. Also, he has |
_o__) severe diarrhea." -- Jack Handey |
Ben Finney

[bruno at modulix]

Re: instantiate a class with a variable

John wrote:[color=blue]
> Hi, is it possible to instantiate a class with a variable.
>
> example
>
> class foo:
> def method(self):
> pass
>
> x='foo'
>
> Can I use variable x value to create an instance of my class?[/color]

You got examples using string 'foo', now if all you need is to store or
pass around the class, just use it as any other object (yes, classes
*are* objects):

class Foo(object): pass

x = Foo

f = x()
assert type(f) is Foo


--
bruno desthuilliers
python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
p in 'onurb@xiludom. gro'.split('@')])"

[John]

Re: instantiate a class with a variable

Thanks for the help, this was exactly what I needed. Working Great
bruno at modulix wrote:[color=blue]
> John wrote:[color=green]
> > Hi, is it possible to instantiate a class with a variable.
> >
> > example
> >
> > class foo:
> > def method(self):
> > pass
> >
> > x='foo'
> >
> > Can I use variable x value to create an instance of my class?[/color]
>
> You got examples using string 'foo', now if all you need is to store or
> pass around the class, just use it as any other object (yes, classes
> *are* objects):
>
> class Foo(object): pass
>
> x = Foo
>
> f = x()
> assert type(f) is Foo
>
>
> --
> bruno desthuilliers
> python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
> p in 'onurb@xiludom. gro'.split('@')])"[/color]