class instance scope

[Ritesh Raj Sarraf]

Hi,

I have a class defined in a file called foo.py

In bar.py I've imported foo.py
In bar.py's main function, I instantiate the class as follows:

log = foo.log(x, y, z)

Now in main I'm able to use log.view(), log.error() et cetera.

But when I call the same method from some functions which are in
bar.py, it fails giving me the following error:

NameError: global name 'log' is not defined

1) I tried lookng into the docs but couldn't find anything on instance
scope.
2) How is such situation tackled ? Will I have to instantiate in every
function ?

Ritesh

[Steve Holden]

Re: class instance scope

Ritesh Raj Sarraf wrote:

Hi,
>
I have a class defined in a file called foo.py
>
In bar.py I've imported foo.py
In bar.py's main function, I instantiate the class as follows:
>
log = foo.log(x, y, z)
>
Now in main I'm able to use log.view(), log.error() et cetera.
>

Correct. Because, having instantiated the class and retained a reference
to the instance, the methods of the instance are available relative to
the name containing the reference.

But when I call the same method from some functions which are in
bar.py, it fails giving me the following error:
>
NameError: global name 'log' is not defined
>

Well, that's preumbaly because your

log = foo.log(x, y, z)

statement was inside a function, and so the name "foo" was created in
that function's local namespace rather than in the module's global
namespace.

1) I tried lookng into the docs but couldn't find anything on instance
scope.
2) How is such situation tackled ? Will I have to instantiate in every
function ?
>

The best thing to do would be to pass the instance in as an argument to
the functions that need to manipulate it.

regards
Steve
--
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[Ritesh Raj Sarraf]

Re: class instance scope


Steve Holden wrote:

Ritesh Raj Sarraf wrote:

But when I call the same method from some functions which are in
bar.py, it fails giving me the following error:

NameError: global name 'log' is not defined

Well, that's preumbaly because your
>
log = foo.log(x, y, z)
>
statement was inside a function, and so the name "foo" was created in
that function's local namespace rather than in the module's global
namespace.
>

So if I do the instantiation before calling main(), will it work.
Something like:

if __name__ == "__main__":
log = foo.log(x, y, z)
main()

In this case, will log be global ?
But still I get the same error.

1) I tried lookng into the docs but couldn't find anything on instance
scope.
2) How is such situation tackled ? Will I have to instantiate in every
function ?

The best thing to do would be to pass the instance in as an argument to
the functions that need to manipulate it.
>

But then how do os, sys, and other modules which are imported, become
accessible to all the functions ?

I'm a newbie, so please bear with me.

Ritesh

[Ritesh Raj Sarraf]

Re: class instance scope

log = foo.log(x, y, z)

Resulting line is:
log = foo.log(x, y, z)
global log

Making the instance "log" global makes it accessible to all the
functions.

Now I have only one question, Is this a correct way to do it ? Or are
there better way ?

Ritesh

[Jeethu Rao]

Re: class instance scope

You could possibly make the log class a singleton or a borg.

Jeethu Rao

Ritesh Raj Sarraf wrote:

>>log = foo.log(x, y, z)
>>>
>>>

>
Resulting line is:
log = foo.log(x, y, z)
global log
>
Making the instance "log" global makes it accessible to all the
functions.
>
Now I have only one question, Is this a correct way to do it ? Or are
there better way ?
>
Ritesh
>
>