Python Syntax Format

Question

Since I am new to programming, I just want to understand the format the built-in functions is represented in the documentations. This is the one from python

bytearray ([source[, encoding[,errors]]])

Why all the square brackets are terminated at the end? The brackets are nested. There is comma immediately after the square bracket too. Does it mean it takes only 3 arguments? Is the below same as the above one?

bytearray ([source],[encoding],[errors])

I am not understanding the format it represents.

Answer 1

Brackets means something is optional. For instance foo[bar]qux could be either fooqux or foobarqux. You could treat it like a regular expression foo(bar)?qux in your head if that helps.

Thus bytearray ([source[, encoding[,errors]]]) could be any one of

• bytearray(source, encoding, errors)
• bytearray(source, encoding)
• bytearray(source)
• bytearray()

This also shows that you need to open the brackets before the comma, and close them all at once. With your suggested bytearray([source], [encoding], [errors]), the options would be:

• bytearray(source, encoding, errors)
• bytearray(source, , )
• bytearray(, , errors)
• bytearray(, , )
• etc. (There are eight possibilities in total, I'm not going to type them all out.)