PEP308 Late Entry

[Stephen Horne]

I've been putting off making my vote because I wasn't fully happy with
any option. I finally came up with a new choice - it's late, I know,
but here is my late attempt to drum up support.

The syntax would have variants such as...

  select        : (c1       : r1; c2       : r2; r3)
  select s      : (v1       : r1; v2       : r2; r3)
  select sa, sb : (v1a, v1b : r1; v2a, v2b : r2; r3)

's' stands for 'switch expression'.
'c' for condition.
'r' for result.
'v' for switch-value.

Switch values could even support special syntaxes such as relative
operator prefixes ('<', '>' etc) or perhaps a '..' or 'to' notation
for ranges - though the non-switch first form might be clearer.

Advantages are...

1.  It handles 'elif' simply and succinctly.

2.  It supports the switch/case functionality as a simple extension,
    but unlike the earlier proposal does not have to be split over
    multiple lines unless clarity genuinely demands it.

3.  The use of punctuation keeps it succinct while the initial keyword
    makes it clear what is happening (easy to look up in documentation
    etc).

4.  The initial ':' and the use of ':' and ';' in the parentheses
    makes it clear that this is not a function, for those who see
    function-call notation as implying no shortcircuiting.

-- 
steve at ninereeds dot fsnet dot co dot uk