EAFP principle (Easier to Ask for Forgiveness than it is to get Permission)
The EAFP is a common principle/coding style used by the python community.
It is a style in which the attributes or keys are assumed to be present and if the assumption is false, it is catched and handled in an exception. try/except play a great role in this style. This is opposed to LBYL style(Look Before You Leap) where the programmer needs to carefully evaluate the conditions before doing something.
Example:
(LBYL style):
from os import path
if path.isfile('hello.txt'):
data = open('hello.txt')
else:
print('file does not exist')
(EAFP style):
try:
data = open('hello.txt')
except FileNotFoundError:
print('file does not exist')
Advantages
- Cleaner code
- Code is faster when running in the happy path. This is because the conditional checks are avoided before doing someting.
- A try/except block is extremely efficient if no exceptions are raised. how fast are exceptions
Also to be noted: While most of the times the EAFP style might be the way to go, Sometimes it is not.
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