\if defined varname \if sql boolean expression to send to server \if compare value operator value
I'm still thinking:-)
Independently of the my aethetical complaint against having a pretty unusual keyword prefix syntax, how would you envision a \set assignment variant? Would \if have a different expression syntax somehow?
Any further thoughts?
My current opinion:
- I'm fine if \set stays as it is, i.e. no expression.
- I agree that some client-side expressions are needed, along the semantics suggested by Tom, i.e. definition and comparisons.
- I'm really against the prefix syntax suggested by Tom
I wish I could have an explanation about why the :?varname (or some other variant) syntax I suggested has a "namespace" issue.
The advantage that I see is that although it is obviously ugly, it is ugly in the continuity of the various :["'?]varname syntaxes already offered and it allows to get rid of "defined varname" which does not look like SQL. A second advantage is that with the "defined" proposal
I don't think so this argument is valid - \if doesn't look like SQL too.
\if defined var1 and defined var2 or defined var3 and sqlrt() >= ..
Would probably never work work, as it cannot be embedded in another expression, while it would work with
\if :?var1 and :?var2 or :?var3 and ...
I don't see any reason why first should not work and second should to work
Moreover, I would like the condition syntax to be basically SQL & psql variables, without explicit prefixes, with a transparent decision whether it is evaluated client side or server side.
As client-side expressions are pretty simple, ISTM that some regex could be used for this purpose, eg for integer and boolean comparisons:
So that one could just write the expressions without having to tell where it is executed, eg
\if :VERSION_NUM < 110000
Would lead to
\if 100000 < 110000
Caught by the first regex, and evaluated with a few lines of code.
I have a different opinion - the condition expression should not be SQL necessary. This language is oriented on client side operations. What is benefit from server side expression?
