Re: psql - add special variable to reflect the last query status

Hello Pavel,

>> We can introduce macro SetVariableBool(vars, varname, bool) instead
>>
>>  SetVariable(pset.vars, "ERROR", "FALSE");
>
> I checked source code, and it requires little bit more harder refactoring
> because now we have SetVariableBool - what is unhappy name, because it
> initialize variable to ON value. It is question what is better name?

The boolean values (on/off 1/0 true/false...) accepted for pg settings is 
probably convenient but also somehow fuzzy.

From a programming point of view, I like booleans to have either true or 
false values, and nothing else.

I agree that the existing "SetVariableBool" function is a misnommer, it 
should be "SetVariableOn" given what it does, and it is not what we need.

Here is a v4 which attempts to extend & reuse the function. People might 
be surprised that TRUE is used where ON was used before, so I'm not sure.

> I found more interesting issue - the code of  SetResultVariables is
> partially redundant with AcceptResult - maybe the switch there can be
> shared.

I agree that there is some common structure, but ISTM that the 
AcceptResult function is called in a variety of situation where variables 
are not to be set (eg "internal" queries, not user provided queries), so I 
thought it best to keep the two apart.

-- 
Fabien.