Setting function parameter as global variable

Question

I'm trying to simply make a parameter received by a function accesible for all other functions in a file, or be set as a global variable, and not have to pass it as an argument for all other functions. So far I've tried to set it as a global variable but apparently cannot have a parameter be also a global.

Here would be a simple example of what I would like:

def add(a,b, verbose):
    global verbose
    return a + b

result = add(2,3, False)
print(verbose)

In my case the called function is on another file, so cannot set verbose as a global beforehand. Any help would be appreciated!

@Mium what makes you think processes/threads are involved here? OP didn't mention either. — Daniel Roseman
– Daniel Roseman, Commented Jul 13, 2018 at 10:45

khelwood · Accepted Answer · 2018-07-13 10:48:45Z

3

If you want to assign to the global verbose variable inside your function, you can do this:

def add(a,b, verbose_value):
    global verbose
    verbose = verbose_value
    return a + b

result = add(2,3, False)
print(verbose)

answered Jul 13, 2018 at 10:48

khelwood

59.7k14 gold badges91 silver badges116 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

bruno desthuilliers Over a year ago

This only impact the current module's namespace, and is actually a very bad solution.

yatu Over a year ago

@brunodesthuilliers yes true, which is enough for my case however, as I will only be needing this variable in this module

bruno desthuilliers · Accepted Answer · 2018-07-13 11:00:44Z

1

First point, as a general rule, globals are evils - or, more exactly, mutating or worse rebinding globals from within a function should be avoided as much as possible.

Second point: in Python, 'global' really means 'module-level' - there's no 'process-level' globals (note that this is a designed choice, based on first point above)

Third point: for your general use case (application settings), the 'less evil' ways would be to have all your modules using a settings system so instead of "passing the param to a function that sets it as global so you don't need to pass it around", your modules just import the settings and read the param's value from there (cf django settings for an example).

The drawbacks are that 1/ only your own code can use those settings and 2/ it makes your code dependant on those settings (which can sometimes be a PITA).

And finally, given the "verbose" name, I assume you want to configure the verbosity level of your program's debugging / error outputs. The proper way to do that in a standard, portable and well decoupled way (which will fix both drawbacks above for this feature) is to use the stdlib's logging package. This package is designed to decouple logger's use (in the 'library' code, using logger.log(level, msg, ...) or one of it's shortcuts) from logging configuration (which is application/installation specific). It requires a bit of learning at first but from experience it's time well spent and actually very quickly saves time.

answered Jul 13, 2018 at 11:00

bruno desthuilliers

78.3k6 gold badges102 silver badges129 bronze badges

1 Comment

yatu Over a year ago

Thanks @bruno truth is I wanted really a simple solution to this. As you say the idea is to control the verbosity level of an already defined model which already has many prints in it. What I've finally gone for is to use the received verbose parameter, to define a function, "verboseprints" which prints its arguments or not depending on this verbose parameter, and set this function as global. Then just replace all prints by "verboseprints". Probably not a nice solution but a simple and practical one for thi case. Thanks for suggesting the logging package anyway.

Collectives™ on Stack Overflow

Setting function parameter as global variable

2 Answers 2

2 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related