Undef variable

Testing if a Variable Is Defined
Credit: Hamish Lawson

Problem
You want to take different courses of action based on whether a variable is defined.

Solution
In Python, all variables are expected to be defined before use. The None object is a value you often assign to signify that you have no real value for a variable, as in:

try: x
except NameError: x = None
Then it’s easy to test whether a variable is bound to None:

if x is None:
    some_fallback_operation(  )
else:
    some_operation(x)

Source: oreilly.com

Similar codes

1 vote172 views1 answer
Pass a list to a function in python
Python
0 vote169 views1 answer
Get timestamp with pyrhon
Python
34 votes174 views4 answers
Save thing in pickle python
Python
0 vote158 views1 answer
No module named 'fastai'
Python
0 vote181 views1 answer
Python requests pass auth token
Python
8 votes211 views3 answers
Your account has reached its concurrent builds limit
Python
4 votes207 views5 answers
Min max python
Python
1 vote153 views1 answer
Euclidean division in python
Python
0 vote146 views1 answer
Django show image in admin page
Python
1 vote180 views1 answer
Ascending discending
Python