Menu
I am trying to access a local function variable outside the function in Python. So, for example,
bye = '' def hi(): global bye something something bye = 5 sigh = 10 hi() print bye The above works fine as it should. Since I want to find out if I can access bye outside hi() without using global bye, I tried:
def hi(): something something bye = 5 sigh = 10 return hi() x = hi() print x.bye The above gives AttributeError: 'NoneType' object has no attribute 'bye'.
Then, I tried:
def hi(): something something bye = 5 sigh = 10 return bye hi() x = hi() print x.bye This time it doesn't give even an error.
So, is there a way to access a local function variable (bye) outside its function (hi()) without using globals and without printing out variable sigh as well? (Question was edited to include sigh after @hcwhsa 's comment below.
319
To access a variable outside a function in JavaScript make your variable accessible from outside the function. First, declare it outside the function, then use it inside the function. You can't access variables declared inside a function from outside a function.
If you want to assign a value to a name defined outside the function, then you have to tell Python that the name is not local, but it is global. We do this using the global statement. It is impossible to assign a value to a variable defined outside a function without the global statement.
The variables that are defined inside the methods can be accessed within that method only by simply using the variable name. Example – var_name. If you want to use that variable outside the method or class, you have to declared that variable as a global.
variables declared inside a function can only be accessed inside that function. think of each function as a box and the lid can only be opened from inside: the function can grab what's outside or put something out, but you can't reach in its box.
You could do something along these lines (which worked in both Python v2.7.17 and v3.8.1 when I tested it/them):
def hi(): # other code... hi.bye = 42 # Create function attribute. sigh = 10 hi() print(hi.bye) # -> 42 Functions are objects in Python and can have arbitrary attributes assigned to them.
If you're going to be doing this kind of thing often, you could implement something more generic by creating a function decorator that adds a this argument to each call to the decorated function.
This additional argument will give functions a way to reference themselves without needing to explicitly embed (hardcode) their name into the rest of the definition and is similar to the instance argument that class methods automatically receive as their first argument which is usually named self — I picked something different to avoid confusion, but like the self argument, it can be named whatever you wish.
Here's an example of that approach:
def add_this_arg(func): def wrapped(*args, **kwargs): return func(wrapped, *args, **kwargs) return wrapped @add_this_arg def hi(this, that): # other code... this.bye = 2 * that # Create function attribute. sigh = 10 hi(21) print(hi.bye) # -> 42 This doesn't work for class methods. Just use the instance argument, named self by convention, that's already passed to methods instead of the method's name. You can reference class-level attributes through type(self). See Function's attributes when in a class.
174
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
