Re: IF (NOT) EXISTS in psql-completion

Hello,

At Tue, 28 Feb 2017 10:39:01 -0500, Stephen Frost <sfrost(at)snowman(dot)net> wrote in <20170228153901(dot)GH9812(at)tamriel(dot)snowman(dot)net>
> * David Fetter (david(at)fetter(dot)org) wrote:
> > On Mon, Feb 27, 2017 at 11:53:17PM -0500, Stephen Frost wrote:
> > > * Kyotaro HORIGUCHI (horiguchi(dot)kyotaro(at)lab(dot)ntt(dot)co(dot)jp) wrote:
> > > > I suppose it is for suggesting what kind of word should come
> > > > there, or avoiding silence for a tab. Or for symmetry with other
> > > > types of manipulation, like DROP. Another possibility is creating
> > > > multiple objects with similar names, say CREATE TABLE employee_x1,
> > > > CREATE TABLE employee_x2. Just trying to complete existing
> > > > *schema* is one more another possible objective.
> > >
> > > I don't buy any of these arguments either. I *really* don't want us
> > > going down some road where we try to make sure that hitting 'tab'
> > > never fails...

These suggestions exist before this patch. Whether to remove them
would be another discussion. I was going to add some but finally
I believe I have added no such things in this patchset.

> > Wouldn't that just be a correct, grammar-aware implementation of tab
> > completion? Why wouldn't you want that?
>
> No, it wouldn't, it would mean we have to provide something for cases
> where it doesn't make sense to try and provide an answer, as being
> discussed here for CREATE TABLE.
>
> We can't provide an answer based on tab-completion to what you want to
> call your new table.

The difference seems to be that what we take this feature to
be. If we see it as just a fast-path of entering a word where we
know what words should come, silence is not a problem. If we see
it as safety-wheels to guide users to the right way to go,
silence would be bad. A silence during word completion suggests
something wrong in the preceding words to me so it is a bit
annoying.

As an analogous operation, mkdir on bash suggests existing
directories. We can suggest existing tables for CREATE TABLE with
the same basis.

Another possible way to go would be showing a 'suggestion' not a
list of possibilities. If readline allows such operation, I
imagine the following. But this is a quite diferrent discussion.

=# CREATE TABLE <tab>
<<a table name to create>>
=# CREATE TABLE table1 <tab>

regards,

--
Kyotaro Horiguchi
NTT Open Source Software Center