[pythonvis] More on ... Re: Re: Indentation of code
- From: "Richard Dinger" <rrdinger@xxxxxxxxxx>
- To: <pythonvis@xxxxxxxxxxxxx>
- Date: Sat, 10 May 2014 07:56:22 -0700
Sorry, I forgot some of our members are new to programming. I will try to
explain below about indentation in Python.
A program is organized into a hierarchy of statements. I think help files are
the closest example of a hierarchical organization that non programmers have
encountered. So first, take a look at how help files are organized.
When you first open a help file, you are at level 0 and are shown a list of
topics and books. You can arrow up and down through the list at level 0. If
you press right arrow on Book A that book opens and displays a sublist of one
or more topics and books that are part of Book A. This sublist is indented to
level 1. The sublist is indented to indicate that it is part of Book A. The
structure can continue to as many levels as needed.
Programs are organized in a somewhat similar manner. A Python program is a
sequence of statements that instruct the computer on how to solve some problem.
Some Python statements are like topics and do not enclose other statements.
And some are like books that do enclose other statements.
Here is a very simple code fragment:
if x < 0:
print ‘x is negative’
In the above code, x is a variable that contains some value. The if statement
tests to see if x is less than zero. If it is true a message is printed.
Since the print statement is enclosed by the if statement, the print is
indented two spaces.
Adding another if inside the first adds another indentation level:
if x < 0:
if y < 0:
print ‘x and y negative’
Indentation must be consistent within a given file. The most common
indentation standards are two spaces or four spaces per level. I prefer two
because it does not use up page width as fast. If you are using a Braille
display, you may want to use a single space for similar reasons.
JAWS can be configured to announce the level every time it changes and will
speak ‘left edge’, ‘tab1’, ‘tab2’ and so forth. JAWS can alternatively play a
note or other indications. EdSharp can be set to speak change in indentation
‘in 1’, ‘out 1’. Both are silent if there is no change in indentation.
Richard
From: Charles Rivard
Sent: Thursday, May 08, 2014 10:05 AM
To: pythonvis@xxxxxxxxxxxxx
Subject: [pythonvis] Re: Indentation of code
Are there different levels on indentation? If so, wouldn't the program run
differently when different lengths of indentation is used? Or are you speaking
only of representation for reading purposes rather than for actual code
writing? Thanks.
---
Be positive! When it comes to being defeated, if you think you're finished,
you! really! are! finished!
----- Original Message -----
From: Richard Dinger
To: pythonvis@xxxxxxxxxxxxx
Sent: Wednesday, May 07, 2014 9:41 PM
Subject: [pythonvis] Indentation of code
A close relative to Sharon’s code format issue is how many spaces to use in
code examples. This may be controversial.
Although four spaces is the most common indentation, I suggest two spaces per
indentation level will work better especially for email. Two and four spaces
are both common standards, but four spaces eats too much page territory.
Richard
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