Option to align multiple assignments

Often the following convention is used:

a   = 1
bb  = 2
ccc = 3

whilst this is against pep8, it seems like this would be a nice option to support for those people that are (forced??) to use this convention.

[kamahen]

“After 5 years, this is still an open issue…” – yapf is Open Source, and no doubt a contribution would be accepted.

[rwarren]

In case this does ever get worked on (even if by me), I’ll add some more notes…

It would be nice to go further and preserve alignment for more than just equals signs. Maybe an option along the lines of this:

PRESERVE_VERTICALLY_ALIGNED_SYMBOLS = true

When enabled, yapf could try and detect and preserve alignments such as this:

len1 = (foo                + 12) - somevar
len2 = (longer_var         + 19) - x
l3   = (an_even_longer_var + 19) - x
l3   = (yyy                +  4) - a_really_long_var_name_that_is_right_here

However, this could get confusing/complex if different symbols are used (+ vs -), or with commented lines (which I think should be ignored in a contiguous line block), or alternative object constructs…

len1 = (foo                + 12) - somevar
#len2 = (longer_var         + 19) - x
l3   = (an_even_longer_var + 19) - x
l3   = ((yyy + 9)          +  4) + a_really_long_var_name_that_is_right_here

My opinion on that example block is that it would still be be untouched with the alignment feature enabled. Reasons being: A) the commented line should be ignored from an alignment perspective (could be a pure comment); B) the the + and - could be recognized as symbols for alignment, and; C) the nested (yyy + 9) doesn’t have symbols that consistently align across the block so aren’t part of any alignment consideration.

Additional notes/ideas:

• There are many potential symbols/tokens to align on…
  • All operators for sure.
  • Most of the assignment delimiters, too. i.e. =, +=, |=, >>=, etc… but not delimiters used for literal definitions (all bracket forms, :, ., etc)
• line width changing such as converting (x+1) to (x + 1) would alter alignment, so any alignment detection (and any stashing of in-line alignment positions) would have to be determined in advance.
• Starting with simple alignment of = would be great, with possible expansion to aligning other tokens left as a future option/pipe-dream.
• # yapf: enable/disable works well enough for now