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 vote108 views1 answer
How to create a fixed size empty array in python
Python
0 vote93 views1 answer
Numpy symmetrize array
Python
0 vote56 views1 answer
Finetune vision model huggingface pytorch github
Python
2 votes124 views2 answers
Print labels on confusion_matrix
Python
0 vote100 views2 answers
Compute the variance of this RDD’s elements
Python
7 votes105 views3 answers
Determine if number is prime python
Python
0 vote91 views1 answer
Get type name python
Python
0 vote97 views1 answer
How to have framer read json timestamps
Python
0 vote106 views3 answers
Python convert dat file to csv
Python
0 vote101 views1 answer
Get height of image in pygame
Python