Moin,
On Wed, February 6, 2019 8:10 pm, Michael Paquier wrote:
> On Wed, Feb 06, 2019 at 03:41:20PM +0100, Daniel Gustafsson wrote:
>> Correct. One could argue that the regex is still suboptimal since
>> “COMMENT ON
>> DATABASE postgres IS ;” will be matched as well, but there I think the
>> tradeoff
>> for readability wins.
>
> Okay, that looks like an improvement anyway, so committed after going
> over the tests for similar problems, and there was one for CREATE
> DATABASE and DROP ROLE. It is possible to have a regex which tells as
> at least one non-whitespace character, but from what I can see these
> don't really improve the readability.
Sorry for being late to the party, but it just occured to me that while
".+" is definitely an improvement over ".*", it isn't foolproof either,
as it also matches ";".
Thus:
regexp => qr/^COMMENT ON DATABASE postgres IS .+;/m,
matches things like:
'COMMENT ON DATABASE postgres IS ;;'
'COMMENT ON DATABASE postgres IS ;'
'COMMENT ON DATABASE postgres IS --;'
etc.
I'm not sure it is really necessary to deal with these cases, but one
possibility would be to pre-compute regexps:
$QR_COMMENT = qr/[^ ;]+/;
$QR_IDENTIFIER = qr/[^ ;]+/; # etc
or whataver is the thing that should actually be matched here and use them
like so:
regexp => qr/^COMMENT ON DATABASE postgres IS $QR_COMMENT;/m,
That way it is easily changable and quite readable.
Oh, one more question. Shouldn't these regexps that start with "^" also
end with "$"? Or can there be output like:
'COMMENT ON DATABASE postgres IS $QR_IDENTIFIER; SELECT 1;'
?
Best regards,
Tels
