I currently have code like this:
cache = 1
def foo():
global cache
# many
# lines
# of code
cache = 2
However, this may lead to hard-to-find-bugs in the future, because the reader may not notice that global cache appears somewhere above cache = 2. Alternatively, a contributor may mistakenly add def bar(): cache = 2 and forget to add the global cache.
How can I avoid this pitfall?
class Cache:
myvar = 1
def foo():
Cache.myvar = 2
This way, Cache.myvar is practically a "global". It's possible to read/write to it from anywhere.
I prefer this over the dictionary alternative, because it allows for auto-complete of the variable names.
cache = 1
def foo():
return 2
cache = foo()
or
d = {'cache': 1}
def foo(x):
x['cache'] = 2
foo(d)
"the reader may unintentionally think that the global variable has been updated" isn't much of a pitfall. You have to expect that people reading your code know how Python works. If you want to make it extra clear, use a comment. That's what they're for.
Using global variable is not a good programming practice. Pass the variable as an argument: make function returns something and use it in another function. Function can be assignment to variable that's how Python works.
