What does the easier to ask forgiveness than permission EAFP approach means?

254. From the glossary: Easier to ask for forgiveness than permission. This common Python coding style assumes the existence of valid keys or attributes and catches exceptions if the assumption proves false. This clean and fast style is characterized by the presence of many try and except statements.

Why EAFP in Python?

EAFP is a piece of gem advice in the Python community which may not be familiar to programmers of other communities. Quickly, EAFP or ‘Easier to Ask for Forgiveness than Permission’ means holding an optimistic view for the code you are working on, and if an exception is thrown catch it and deal with it later.

Is better to Ask for Forgiveness than for Permission Python?

One idiomatic practice in Python that often surprises people coming from programming languages where exceptions are considered, well, exceptional, is EAFP: “it’s easier to ask for forgiveness than permission”.

What is idiomatic Python?

Idiomatic Python is what you write when the only thing you’re struggling with is the right way to solve your problem, and you’re not struggling with the programming language or some weird library error or a nasty data retrieval issue or something else extraneous to your real problem.

Who said it’s better to ask for forgiveness than permission?

Admiral Grace Hopper
What Admiral Grace Hopper really meant when she said, “It’s easier to ask forgiveness than it is to get permission”

What does EAFP mean?

WHO said it is easier to get forgiveness than permission?

Benedict. It was Benedict who observed more than 1400 years ago that “It is easier to beg forgiveness than to seek permission.”

What is the pythonic way?

Pythonic means code that doesn’t just get the syntax right but that follows the conventions of the Python community and uses the language in the way it is intended to be used.

What is idiomatic code?

An idiomatic way of writing some code is when you write it in a very specific way because of language-specific idioms that other languages don’t have. For example, in C++, exploiting the RAII idiom leads to ways of writing C++ code managing resources that are idiomatic.

Is it really easier to ask for forgiveness than permission?

The next generation growing up with the computers will change that. It’s easier to ask forgiveness than it is to get permission. Variant: If it’s a good idea, go ahead and do it. It is much easier to apologize than it is to get permission.

Should I ask for forgiveness or permission?

Proverb. It is better to act decisively and apologize for it later than to seek approval to act and risk delay, objections, etc.

What is the difference between EAFP and LBYL?

Quickly, EAFP means that you should just do what you expect to work and if an exception might be thrown from the operation then catch it and deal with that fact. What people are traditionally used to is LBYL: “look before you leap”.

Is it wise to use EAFP in Python?

In Python, it seems the accepted style is EAFP, and it seems to work well with the language. My question is this: I had never even heard of using EAFP as the primary data validation construct, coming from a Java and C++ background. Is EAFP something that is wise to use in Java? Or is there too much overhead from exceptions?

Is there a mismatch between LBYL and eaftp?

The later, using EAFTP, results in correct handling, by definition. There is no scope for a behavioural mismatch, because the code that needs the requirement is the code that asserts that requirement. Using LBYL means taking internal logic and copying them into every call-site.

Why do you check for key before using LBYL?

In LBYL you would check for the key first before using it: This prevents a KeyError exception from being raised which seems logical. But what this code confers to the user is that the exceptional case is that the dictionary has the key, not that the key may be absent which may not be true.