Re: Improvements in psql hooks for variables

	Ashutosh Sharma wrote:

> postgres=# \echo :ENCODING
> UTF8
> postgres=# \set ENCODING xyz
> postgres=# \echo :ENCODING
> xyz
> 
> I think currently we are not even showing what are the different valid
> encoding names to the end users like we show it for other built-in
> variables
> VERBOSITY, ECHO etc. I mean if i run '\set VERBOSITY' followed by tab
> command it does show me the valid values for VERBOSITY but not for
> ENCODING.

Setting ENCODING has no effect, like DBNAME, USER, HOST and PORT.
In a way, it's a read-only variable that's here to inform the user,
not as a means to change the encoding (\encoding does that and
has proper support for tab completion)

What we could do as of this patch is emit an error when we try
to change ENCODING, with a hook returning false and
a proper error message hinting to \encoding.

I'm working on adding such messages to other variables.

Best regards,
-- 
Daniel Vérité
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