Why does Python have a pass statement?

Regarding the passstatements in Python, it seems to be very simple, only four letters, and even beginners without any programming experience can quickly grasp its usage.

The introduction of the official document is very simple, the following three examples can let us quickly understand how to use it:

Why does Python have a pass statement?

pass is a null operation. When the interpreter executes it, it skips without doing anything except checking whether the syntax is legal.

There are two reason why does Python have a pass statement?

As a space placeholder

I think of it as a concise and concise way of commenting, which is tantamount to saying that the first reserve a place here, and then come back and add the specific code implementation.

For example, in a multi-layer if-elif-else structure, we can write the judgment condition first, then write pass in the corresponding block, and then gradually improve it later.

As a space placeholder, the pass is mainly convenient for us to conceive a partial code structure and has a certain auxiliary reminder function.

Therefore, from the perspective of space placeholders, pass is not a necessary design element in a programming language.

For grammatical completeness

For the usage of the previous item, the position of the pass in the code is theoretically unlimited.

However, when we use pass most often, it is basically on the line below the colon, and there is only this statement in the indented code block at this level.

Python uses the pass statement to support purely no-op code blocks (empty functions, empty classes, empty loop control blocks, etc.). With it, it can additionally express a placeholder semantics.

Leave a Comment