From: Daniel Shahaf <d.s@daniel.shahaf.name>
To: zsh-workers@zsh.org
Subject: Re: [PATCH] declarednull: rename DECLARED to NULL
Date: Thu, 7 Jan 2021 15:48:18 +0000 [thread overview]
Message-ID: <20210107154818.GB25249@tarpaulin.shahaf.local2> (raw)
In-Reply-To: <CAH+w=7a5xzztvJ9hRB-2-LyzyZFx74Pfy5z8cJu01=hOh_AHQw@mail.gmail.com>
Bart Schaefer wrote on Wed, Jan 06, 2021 at 09:33:49 -0800:
> On Wed, Jan 6, 2021 at 8:02 AM Daniel Shahaf <d.s@daniel.shahaf.name> wrote:
> >
> > Bart Schaefer wrote on Mon, 04 Jan 2021 21:57 +00:00:
> > > So the "bits that need to be named" are:
> > > 1) the bit representing "remember that this was declared but no value
> > > was assigned"
> > > 2) the combination of that with PM_UNSET that represents "functionally
> > > behaves like NULL"
> >
> > To be clear, (2) would generally be used as testing whether _either_
> > PM_UNSET or the bit from #1 is set, right?
>
> Most often it's used for changing the value of both bits at once, not
> testing. The bits are almost always tested independently.
*nod*
> > How about, for #1, PM_BEEN_ASSIGNED or PM_INITIALIZED?
>
> The latter was already rejected. Both of these arguably describe the
> opposite of the actual state, that is, PM_HAS_NOT_BEEN_ASSIGNED would
> be more accurate ... but Felipe has essentially argued that after
> "unset foo" the variable still has not been assigned, so why clear a
> bit with that name?
After «unset», PM_UNSET would be set, and I don't immediately see why bit #1
should be tested at all if if PM_UNSET is set. If the «unset» is followed by
an assignment and/or (re-)declaration, the value of bit #1 can then be set
properly, and PM_UNSET cleared. Makes sense?
> PM_DECLARED_BUT_NEITHER_ASSIGNED_NOR_UNSET is just too verbose, and
> shortening it to just the first word got us into this discussion in
> the first place.
>
> > As to the combination, my first inclination would have been to leave it
> > unnamed so that it's obvious PM_UNSET is being inspected, but if the
> > combination merits being named, then perhaps PM_HAS_VALUE(pm).
>
> The reason for doing it the way I did is because (I presumed) most
> cases would never examine bit #1 because they are already examining
> PM_UNSET by itself.
>
> PM_HAS_VALUE(pm) is actually also backwards. It would usually be
> PM_HAS_NO_VALUE(pm). But there's actually exactly one such test.
So long as we don't have «!PM_HAS_NO_VALUE(pm)» ☺
next prev parent reply other threads:[~2021-01-07 15:48 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-28 22:13 Felipe Contreras
2021-01-03 1:18 ` Bart Schaefer
2021-01-03 2:38 ` Felipe Contreras
2021-01-03 18:26 ` Bart Schaefer
2021-01-04 6:17 ` Daniel Shahaf
2021-01-04 21:57 ` Bart Schaefer
2021-01-06 16:02 ` Daniel Shahaf
2021-01-06 17:33 ` Bart Schaefer
2021-01-07 15:48 ` Daniel Shahaf [this message]
2021-01-07 22:29 ` Bart Schaefer
2021-03-27 19:24 ` Lawrence Velázquez
2021-03-27 20:42 ` Bart Schaefer
2021-03-29 0:44 ` Oliver Kiddle
2021-04-10 18:56 ` Bart Schaefer
2021-04-10 21:58 ` Oliver Kiddle
2021-04-10 22:35 ` Bart Schaefer
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