[SR-Dev] operators and variables

Jan Janak jan at ryngle.com
Fri Dec 12 16:41:46 CET 2008

On 11-12 22:01, Andrei Pelinescu-Onciul wrote:
> It would be better to have different operators for strings and for
> integers. Right now we have '+', '==' and '!=' that can be used both for
> strings and integers. The problem with this approach is that it makes
> some optimizations impossible, especially when combined with dynamic
> typed variables (avps or pvars). '+' is especially bad because one
> can tell what type ($v + x) has only at runtime.

  I would like to preserve the original behaviour for strings. They are used
  much more often than integers. If you need to change anything then, please,
  consider changing the behaviour of integer operators.

> I think having perl like operators would help a lot:
> - '.' for string concatenation (instead of reusing '+'), e.g.: 
>  $v= "foo" .  "bar"

  Yes, I like this one.

> - 'eq' instead of == for strings, e.g.: $v eq "bar" 
> - 'ne' instead of != for strings, e.g.: $v ne "bar"

  I don't like this. If there really is a need to have separate operators then
  use 'eq' and 'ne' for integers and keep == and != for strings. Test (see man
  test) has string and integer operators this way.

> We could support them right now in parallel with the old ones and 
>  obsolete +, ==  and != for strings in the future (but that means we
>  still cannot optimize '+' in all the cases) or switch right now
> (maybe with some old compat switch which will support old scripts
> style).
> The question is how much are they used right now. While I think '==' and
> '!=' are used quite often, I'm not sure about '+' for strings (and '+'
> is the most important anyway).

  I guess == and != are used most often with strings.

> Note: we can still support '==' and '!='  for condition tests not
> involving variables (e.g. method=="INVITE", uri=="sip:foo" a.s.o.).

  That would be inconsistent. if (method=="INVITE") would work, but
  if ($abc=="foo") would not work if strings operators are replaced with 'eq'
  and 'ne'.


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