Copy and Paste Driven Development

This post isn't a rant about copy and pasting code you don't understand into your projects.

I was recently convinced by a college that declaring variables in javascript should be done like this:

var foo = '123';
var bar = '789';
var baz = '000';

Instead of the more often recommended version that I've been religiously using up until now:

var foo = '123',
    bar = '789',
    baz = '000';

Why?

Let's look at commenting out lines (perhaps temporarily):

as you can see it's much easier to do this in the explict multiple var version because you don't have to care about where the line you're commenting out, copying, pasting or reordering is.

Your linter might shout at you about too many var statements but since your minifier will end up producing code without multiple var statements I think it's OK to turn off that particular warning.

Python: trailing commas in tuples

The whole conversation came about because I was expressing my preference for always leaving a trailing comma on a python tuple. Not because it's easier to copy and paste but because there's a nasty gotcha in Python's syntax which means that if you remove all but the last element of a tuple definition then it'll no longer be a tuple unless you leave a trailing comma.

t1 = (
    'a', 
    'b', 
    'c'
)
# t1 is a tuple

t2 = (
   # 'a', 
    'b', 
    'c'
)
# t2 is a tuple

t3 = (
   # 'a', 
   # 'b', 
    'c'
)
# t3 is a string... WAT?

t4 = (
  #  'a', 
  #  'b', 
    'c',
)
# t4 is a tuple

SQL: prefix comma

For all the same reasons everybody knows that SQL pros always use prefix commas.

SELECT   id
        ,foo 
        ,bar 
        ,baz
FROM
        foobarbazes;

instead of

SELECT  id,
        foo, 
        bar, 
        baz
FROM
        foobarbazes;