Re: \if, \elseif, \else, \endif (was Re: PSQL commands: \quit_if, \quit_unless)

>
> ISTM that it's important that eventually ParseVariableBool()
> and \if agree on what evaluates to true and false (and the
> more straightforward way to achieve that is by \if calling
> directly ParseVariableBool), but that it's not productive that we
> discuss /if issues relatively to the behavior of ParseVariableBool()
> in HEAD at the moment, as it's likely to change.
>

I'd like to keep in sync with ParseVariableBoolean(), but

Also, Fabien has made a good case for invalid parsed values being an
ON_ERROR_STOP-able error, and not defaulted to either true or false.

This might be asking a lot, but could we make a "strict" mode for
ParseVariableBool() that returns a success boolean, and have the existing
ParseVariableBool() signature call that new function, and issue the
"assuming " warning if the strict function failed?