[Baypiggies] padding variable assignments, why is it bad?

[Kalb, Jon]

Imagine that I'm trying to do research in the source code repository on how, when, and who modified "last_access." I see that a change was made to the the last line in your example, but after wasting some of my time investigating it, I discover that the only reason the line was touched was because a new member with a long name was added and that caused this line to be touched to change its white space.

Treating lines of code independently has important advantages when "diff"ing and tracing changes throw source code repositories.

From: Wai Yip Tung <tungwaiyip at yahoo.com<mailto:tungwaiyip at yahoo.com>>
Date: Friday, August 10, 2012 12:01 PM
To: "baypiggies at python.org<mailto:baypiggies at python.org>" <baypiggies at python.org<mailto:baypiggies at python.org>>
Subject: Re: [Baypiggies] padding variable assignments, why is it bad?

Imagine your have some code like this

row.name = encode(src.get('name'), 'xmlref')
row.description = encode(src.get('description'), 'xmlref')
row.enabled = encode(src.get('enabled'), 'xmlref')
row.last_access = encode(src.get('last_access'), 'xmlref')

This looks a mumbo jumbo lines of code.

However by aligning them into columns, the pattern become immediately obvious.

row.name        = encode(src.get('name'),        'xmlref')
row.description = encode(src.get('description'), 'xmlref')
row.enabled     = encode(src.get('enabled'),     'xmlref')
row.last_access = encode(src.get('last_access'), 'xmlref')

It is clear that the code is applying similar operation on 4 items. It is a lot easier to tell which of the 4 elements and if you should include more or less into the list. It is a huge visualization improvement. PEP-8's suggestion on this is not a good one in my opinion.

The down side is it takes some effort to keep it neat and tidy. Of course I have editor macro that does that. I think every decent text editor should have some function to help people to align things.

Wai Yip




[cid:part1.06070707.07080708 at yahoo.com]
Aleksandr Miroslav<mailto:alexmiroslav at gmail.com>
Friday, August 10, 2012 10:19 AM
(Reading this email requires a monospaced font.)

I do this a lot in my code:

foo = 1
foo_bar = 2
foo_bar_quux = 3

but pep8, which I started using recently, considers this wrong, so I
have to rewrite to the more common form:

foo = 1
foo_bar = 2
foo_bar_quux = 3

which I think sacrifices readability. Perhaps this is the n00b in me
talking, but why is this considered bad?
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