Re: PL/pgSQL 'i = i + 1' Syntax

Douglas McNaught wrote:
> Mark Dilger <pgsql@markdilger.com> writes:
> 
> 
>>Tom Lane wrote:
>>
>>>No it isn't.  The plpgsql scanner treats := and = as *the same token*.
>>>They can be interchanged freely.  This has nothing to do with the case
>>>of modifying a loop variable in particular.
>>
>>I disagree.  If the scanner treated them the same, then
>>
>>  if i := 1 then ...
>>
>>would work, but it doesn't.  The := is rejected in a conditional.  Try the
>>following code if you don't believe me:
> 
> 
> That's because (AIUI) all expressions to be evaluated are handed off
> to the SQL parser (why re-implement all that logic and have subtle and
> annoying differences?)  plpgsql only handles the statements, loops, etc.
> So it doesn't care about the difference but SQL does...

Ok, ten out of ten for technical accuracy; the error occurs at a lower level.
But that really doesn't matter, does it?  If the syntax results in an error,
then the argument that '=' and ':=' are interchangeable is wrong.

As a coder, if you notice that using ':=' within a conditional fails, wouldn't
you think that implied that ':=' is for assignment and '=' is for comparison?

mark