Understanding "help" command description syntax - explanation needed

[Ivan Evstegneev]

Firtst of all thanks for reply.

>>brackets [] means that the argument is optional.

That's what I'm talking about (asking actually), where do you know it from? 
I mean, if there are some resources, which explain all these syntax abbreviations? The general concept.


Like this one(just for example):
class bytearray([source[, encoding[, errors]]]) --- What does it mean? 
Is that  I can use it in optional way? 
Like: class bytearray(source) or class bytearray(encoding) ?
or just write down all three of them? 
In which format do I do so? 

Sincerely,

Ivan.

 




-----Original Message-----
From: Jean-Michel Pichavant [mailto:jeanmichel at sequans.com] 
Sent: Wednesday, November 5, 2014 13:55
To: Ivan Evstegneev
Cc: python-list at python.org
Subject: Re: Understanding "help" command description syntax - explanation needed

---- Original Message -----
> From: "Ivan Evstegneev" <webmailgroups at gmail.com>
> To: python-list at python.org
> Sent: Wednesday, 5 November, 2014 12:00:16 PM
> Subject: Understanding "help" command description syntax - explanation 
> needed So here is the question itself:
> 
> If I use the help command to check the “range” command I get this
> info:
> 
> 
> 
> range(stop) -> range object
> 
> range(start, stop[, step]) -> range object

With python 2.7, when I type help(range), I get

"""
Help on built-in function range in module __builtin__:

range(...)
    range([start,] stop[, step]) -> list of integers
    
    Return a list containing an arithmetic progression of integers.
    range(i, j) returns [i, i+1, i+2, ..., j-1]; start (!) defaults to 0.
    When step is given, it specifies the increment (or decrement).
    For example, range(4) returns [0, 1, 2, 3].  The end point is omitted!
    These are exactly the valid indices for a list of 4 elements.
"""

range([start,] stop[, step]) tells you how to call the range function, there's a start, stop and step argument.
The purpose of these arguments are given by the longer description.

brackets [] means that the argument is optional.

Though there's nothing wrong with googling the function for help, I'm doing it all the time.
Actually, the python documentation is a better place to get help on a particular function, just make sure you hit the correct version, for either python 2 or 3:

https://docs.python.org/2/library/functions.html#range

I'm using python's help function only when working offline.

JM



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