Question

When indenting long if conditions, you usually do something like this (actually, PyDev indents like that):

if (collResv.repeatability is None or
    collResv.somethingElse):
    collResv.rejected = True
    collResv.rejectCompletely()

However, this puts the block started by the if statement on the same indentation level as the last part of the if condition which makes it very ugly/hard to read in my opinion as you don’t immediately see where the block starts.

Some other styles I thought about:

if (collResv.repeatability is None or
        collResv.somethingElse):
    collResv.rejected = True
    collResv.rejectCompletely()

This looks pretty inconsistent as the second line is indented much more than the first line but it’s readable.

if (collResv.repeatability is None or
  collResv.somethingElse):
    collResv.rejected = True
    collResv.rejectCompletely()

This is also more readable than the first example, but the indentation is not a multiple of 4 anymore and besides that it looks wrong as the second line has less indentation than the beginning of the condition in the first line.

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So, my main question is: Is there a suggested indentation style for cases like that which do not require overly-long lines (i.e. a single-line condition)?
If not, what do you prefer for cases like that?

Answer 1

This is an indirect answer–not answering the style question directly, but it’s the practical answer in general, so it’s worth mentioning.

I find it extremely rare to need to write multi-line conditionals. There are two factors to this:

• Don’t wrap code at 80 columns. PEP-8’s advice on this subject is ancient and harmful; we’re well past the days of 80×25 terminals and editors that can’t sensibly handle wrapping. 100 columns is fine, and 120 is usually acceptable, too.
• If conditions become so long that they still need to wrap, it’s usually reasonable to move some of the logic out of the conditional and into a separate expression. This also tends to help readability.

Grepping through my recent projects, around 12kloc, there’s only one conditional long enough that it needed to be wrapped; the issue simply very rarely arises. If you do need to do this, then as nosklo says, indent it separately–as you noticed, indenting it to the same level as the block beneath it is confusing and hard to read.