Global var access in imported modules?

[RgeeK]

I have a main module doStuff.py and another module utility.py. At the
start of doStuff.py I call

import utility.py

Then I also proceed to initiallize some global variables

sName = ""

Then I create a class, some methods etc. In one of the methods I assign
a value to my variable sName. Then I call a function from within
my utility.py file:

utility.makeOne(stuff)


Within my utility.py file, I define the makeOne function. But I want to
use that same global variable "sName" In utility.py I have tried to
indicate that I'm using the global "sName" through the statement:

global sName

But when I go to use the variable it still gives me an error:

NameError: global name 'sName' is not defined

I thought perhaps I need to indicate 'globality' in my main module, so
before I initiallized sName in doStuff.py I added:

global sName

But it doesn't help me. I had this issue before and resolved it by
declaring the variable global in the sub-module utility.py, but then I
needed to reference it in my main module with a prefix:

utility.sName = ""

It's more verbose,and defining globals in a submodule seems backward.
But also, what if I need to access "sName" in another imported module,
say "otherstuff.py"? I would do my "import otherstuff" call in my main
module, but would I have to put an "import utility" into the
otherstuff.py file?

Is there some way I can define globals in my main module, and have them
accessible in all my imported submodule?

As you can see I'm a little unsure about the global handling in a
multi-module environment. Any suggestions appreciated. I've read
http://docs.python.org/ref/naming.html but it hasn't enlightened me on
this one.

 

[Fredrik Lundh]

I have a main module doStuff.py and another module utility.py. At the
start of doStuff.py I call

import utility.py

that tries to import a module named "py" from the package "utility".

Then I also proceed to initiallize some global variables

sName = ""

Within my utility.py file, I define the makeOne function. But I want to
use that same global variable "sName" In utility.py I have tried to
indicate that I'm using the global "sName" through the statement:

global sName

the "global" directive in Python is used *inside* a function or method
to indicate that a given name is not local.

Python doesn't have "program-wide global" variables; if you need that,
create a support module and import that module everywhere you need to
access those variables:

# file: globalvars.py
sName = ""

# file: myprogram.py
import globalvars
print globalvars.sName

etc.

</F>

 

[Rgg]

that tries to import a module named "py" from the package "utility".

oops - that was just a typo in my post - I meant of course "import utility"

Python doesn't have "program-wide global" variables; if you need that,
create a support module and import that module everywhere you need to
access those variables:

# file: globalvars.py
sName = ""

# file: myprogram.py
import globalvars
print globalvars.sName

etc.

</F>

That's news - thanks, I didn't realize that there just wasn't the
concept of program-wide globals. The support module idea sounds like a
path forward.

-R.

 

[RgeeK]

> that tries to import a module named "py" from the package "utility".

oops - that was just a typo in my post - I meant of course "import utility"

>
> Python doesn't have "program-wide global" variables; if you need that,
> create a support module and import that module everywhere you need to
> access those variables:
>
> # file: globalvars.py
> sName = ""
>
> # file: myprogram.py
> import globalvars
> print globalvars.sName
>
> etc.
>
> </F>
>

That's news - thanks, I didn't realize that there just wasn't the
concept of program-wide globals. The support module idea sounds like a
path forward.

-R.

 

[RgeeK]

I hope not... import utility no .py
Python does not have global variables. Names belong within a module
(or within functions defined within the module).

The global statement is only used within functions (def blocks) to
indicate that "writes" to the specified name are to modify the MODULE
level version of the name, otherwise a write modifies a function local
version of the name (you don't need global for read-only access of
names, the search for names first looks inside the function, then out to
the module)

If you really need "globals" the common solution is to create a
module such as "myglobals", define all the shared names within that
module, and import that module where ever you need access to one of the
names. And yes, you will need to qualify all those names with the module
name (though you can do things like:

import myglobals as mg

and then use

mg.somename

instead of

myglobals.somename)

Thanks for the reply. Good to see that approach has broad support
I'll do that. I like the idea of a nice short alias for the import to
keep the qualifications brief.

Ross.