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RE: [External] : Re: master 101f3cf5b9: Add support for user edits to VC
From: |
Drew Adams |
Subject: |
RE: [External] : Re: master 101f3cf5b9: Add support for user edits to VC command arguments |
Date: |
Thu, 22 Sep 2022 22:21:16 +0000 |
> I thought that in Lisp we often call boolean values predicates too,
I do. But I think it's become verboten for Emacs.
> even though that violates the usage of 'predicate' in mathematics.
No, it doesn't, actually. A programming "variable"
can be likened to a nullary function. That we also
have another kind of nullary function doesn't change
this.
(And a predicate "in mathematics" is not necessarily
a function at all. There are several (related) uses
of the term.)
> Is there some other convention for booleans like this one?
I don't think I've seen one adopted by Emacs. But
someone will correct me...
There is the `-flag' suffix convention for user
options (not other variables), which Stefan mentioned.
RMS promotes that. I use it, but I may be the only
one who does. I think it's helpful to have a separate
such suffix for options, even if that one is a bit long.
The argument Stefan makes against any such convention
is reasonable. It's definitely the case that a var
often starts out as Boolean and later allows for more
values. Renaming isn't such a big deal for user code.
But it's a pain for vanilla Emacs code (i.e., a big
user base).
This is a real consideration, no doubt. But hey, this
is Lisp - schema-flexible, etc. And we have aliasing.
Que demande le peuple ?
That worry/argument, BTW, doesn't apply to local vars,
e.g., let-bound vars and function parameters. I often
use suffix `-p' in those contexts. It's a very short
suffix, and it makes the code/intention clearer, IMHO.
Re: master 101f3cf5b9: Add support for user edits to VC command arguments, Sean Whitton, 2022/09/22