Topic on Manual talk:Coding conventions

the width allowed for the left column constantly has to be increased as more items are added

which items are added? new columns added? what is "width allowed for the left column"? i think it is tab size. then, if you make longer strings in any column, not only left column, then tab size has to be increased, or, more tabs has to be used between columns, and, if there are elements of much different size, different count of tabs need to be used between columns.

The point is, you shouldn't have to change spacing in ten lines just because you replaced a name on one line. It makes for more confusing diffs. So we prefer

[
    'foo' => 0,
    'foobar' => 1,
]

over

[
    'foo'    => 0,
    'foobar' => 1,
]

(except for Puppet, apparently).