On 11/05/2013 01:29, Bruce Leban wrote:
I got bit by this quite recently, leaving out a comma in a long list of strings and I only found the bug by accident.
This being python "ideas" I'll throw one out.
Add another prefix character to strings:
a = [m'abc' 'def'] # equivalent to ['abcdef']
A string with an m prefix is continued on one or more following lines. A string must have an m prefix to be continued (but this change would have to be phased in). A conversion tool need merely recognize the string continuations and insert m's. I chose the m character for multi-line but the character choice is available for bikeshedding. The m prefix can be combined with u and/or r but not with triple-quotes. The following are not allowed:
b = ['abc' # syntax error (m is required for continuation) 'def')
c = [m'abc'] # syntax error (when m is used, continuation lines must be present)
d = [m'abc' m'def'] # syntax error (m only allowed for first string)
The reason to prohibit cases c and d guard against comma errors with these forms. Consider these cases with missing or extra commas.
e = [m'abc', # extra comma causes syntax error 'def']
f = [m'abc' # missing comma causes syntax error m'def', 'ghi']
Yes, I know this doesn't guard against all comma errors. You could protect against more with prefix and suffix (e.g., an m at the end of the last string) but I'm skeptical it's worth it.
Conversion to this could be done in three stages:
(1) accept m's (case a), deprecate missing m's (case b), error for misused m's (case c-f) (2) warn on missing m's (case b) (3) error on missing m's (case b)
It wouldn't help with: f = [m'abc' 'def' 'ghi'] vs: f = [m'abc' 'def', 'ghi'] I think I'd go more for a triple-quoted string with a prefix for dedenting and removing newlines: f = [m''' abc def ghi '''] where f == ['abcdefghi'].