Re: psql - add ability to test whether a variable exists

On Sat, Aug 26, 2017 at 2:09 PM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>
wrote:

>
>
> 2017-08-26 19:55 GMT+02:00 Fabien COELHO <coelho(at)cri(dot)ensmp(dot)fr>:
>
>>
>> Any colon prefixed syntax can be made to work because it is enough for
>>> the lexer to detect and handle... so
>>>
>>> :{defined varname}
>>>
>>> may be an option, although I do not like the space much because it adds
>>> some fuzzyness in the lexer which has to process it. It is probably doable,
>>> though. I like having a "?" because there is a question. Other
>>> suggestions somehow in line with your proposal could be
>>> :{?varname}
>>> :{varname?}
>>> what do you think?
>>>
>>
>> Here is a version with the :{?varname} syntax.
>
>
> It looks much better for me.
>
> Regards
>
> Pavel
>

+1. Glad to have this feature. Any of the proposed syntaxes look good to
me, with a slight preference for {?var}.