Chapter 9 (functions) Flashcards
what can be used to check for global and local variables?
globals()
locals()
- These variables act as dictionaries that store the key (variable name) with its value (assigned data to the variable)
What is variable scope?
How accessible a variable is to sections of code:
- if a variable is local, it can only be accessed within the function, if it is global it can be accessed anywhere in the code
What are the 3 types of scope?
Built-in scope:
- can be accessed anywhere with no restrictions, they are the built-in names of python: str(), int(), etc.
Global scope:
- variables that have been declared outside of functions
Local scope:
- only accessible in a function
In what order are variables checked in a function?
- Local
- Global
- Built-in
What is namespace?
maps (like a dictionary) of names of objects in a given scope
What is scope resolution?
The process of searching namespace for a name,
- looking for a variable in the dictionary of names
How does python interpreter restrict variable scope?
assigning variables to a namespace
Can the same name be in multiple namespaces?
Yes
Will there be an error if I define a list as list() since it is already a built-in name?
No because it is going to be defined as a global or local variable which are read before the built-in names
Can immutable objects be edited inside a function?
no, the object will not be edited, instead a new object will be made in the local scope of the function with the values assigned to it instead of editing the global variable
Can mutable objects be edited inside a function?
Yes they can, for example a list or dictionary, however, only edited, not replaced.
- index overwriting is fine, but straight up changing the whole list all at once will not impact the list
what would be the output of:
def modify(list):
‘’’ docstring ‘’’
list[1] = 99
my_list = [1,2,3]
modify(my_list[:])
print(my_list)
[1,2,3] because the argument is actually a copy of my_list not the real list
When preassigning values to parameters, what must be true?
All parameters that have preassigned values must be in the correct order
Can you put the arguments in any order when calling a function?
Sometimes, only when the parameter is specified = a value
What is an arbitrary parameter?
When the number of parameters cannot be predicted, so the function excepts more than normal all stored in an arbitrary parameter
What are some examples of arbitrary parameters?
*args (arguments)
**kwargs (key word arguments, stores a dictionary)
What are some examples of arbitrary parameters?
*args (arguments)
**kwargs (key word arguments, stores a dictionary)
Can a function return more than one object?
no, however a tuple of multiple values can be returned
What does the follwing line do?
def f():
‘’’ docstring ‘’’
return val1,val2
val3, val4 = f()
val3 = val1
val4 = val2
val1 and val2 where returned in a tuple
MUST INCLUDE DOC STRING OR -2 POINTS
what does help(function) do?
Instead of running the function, it outputs the doc string
How do you define a function?
def function():
‘’’ docstring ‘’’
return value
How do you pass a create a function with a fixed value incase the variable is not passed?
def function(a, b=25):
How do you selectively run code depending on if the file is being run as a main program or an imported module?
if __name__ = ‘__main__’:
—-code for regular file
code if file was imported as a module
When returning a tuple from a function, how do you print an index from the tuple?
print(function(pass)[index])
When setting a default value in a function, what must be true in terms of order?
The default values must be declared last
What happens if there are two return statements in a function?
The first return statement that is encountered will end the function and return to the main code
