Re: C-x &

[Michael Albinus <michael.albinus@gmx.de>]

Drew Adams <drew.adams@oracle.com> writes:

>> I haven't said that `C-x &' is any kind of command, at least in my last
>> email.
>
> Right. You didn't. But some others did. And it wasn't obvious (to me)
> that you didn't mean to say that `C-x &' is a "prefix command". If you
> meant only that `universal-sync-argument' is a prefix command then, as
> I said, that's OK by me. (The doc should then define "prefix
> command".)
>
>> Again, I haven't said that `C-x &' is a command, in my last email.
>> 
>> Let's agree the obvious: `universal-async-argument' is a command, by
>> default bound to the key sequences `C-x &' and `M-x  u n i v e r s a l -
>> a s y n c - a r g u m e n t RET.'
>
> Agreed.
>
> (Although I wouldn't say that the command is bound to `M-x...'. That
> sequence of keys invokes `u-a-a', but the command is not bound to
> it. We just don't say that kind of thing in Emacs. The key sequences
> bound to a command are well defined, and they don't include `M-x'
> followed by keys spelling out the command name. Similarly, the command
> is not bound to `M-x uni-a-arg TAB RET' etc.)
>
>> The only raison d'être of `universal-async-argument' is to read another
>> key sequence, which invokes the command bound to that key sequence. This
>> means, the command `universal-async-argument' always precedes another
>> command, which I call a prefix in my understanding. 
>
> Agreed. (Although the command that is preceded by `u-a-a' is, if
> anything, a suffix of it, not a prefix. I suspect you just misspoke in
> the last phrase.)
>
>> Therefore, I've proposed to call `universal-async-argument' a
>> "prefix command".
>
> OK by me (where "it" is the command, not `C-x &'). "Prefix command"
> then needs to be described/defined/explained in the manual.

OMG: we are in violent agreement :-)

>> The Emacs manual distinguishes between commands and the key (sequence) a
>> command is bound to. But it explicitely says, that both could be used
>> equal:
>> 
>> --8<---------------cut here---------------start------------->8---
>>    In this manual, we will often speak of keys like ‘C-n’ as commands,
>> even though strictly speaking the key is bound to a command.
>> --8<---------------cut here---------------end--------------->8---
>> 
>> See (info "(emacs) Commands")
>
> Yeah. I was afraid someone might quote that passage. ;-) 

That's because of *you* - you have forced me to consult the manual about.

> I don't have a problem with that text, because its purpose is to state
> that we sometimes speak that way even though it is not really
> correct. It's not defining a key sequence as the command that it's
> bound to - quite the opposite. It both (1) points out that a key
> sequence is not the same thing as the command that it's bound to and
> (2) mentions that sometimes we gloss over that difference, for brevity
> and when the context makes the meaning clear.
>
>> So it would be also allowed to speak about the key sequence `C-x &' as a
>> command, but I don't insist on this if it makes you feel bad.
>
> It would be allowed to say "command `C-x &'", yes, for brevity. That's
> a far cry from defining a new term "prefix command" and applying it to
> `C-x &'. (Especially since there is also a notion of prefix key, which
> is something quite different.)
>
> In sum, I don't have a problem with calling `universal-async-argument'
> a "prefix command", if that term is defined in the manual.

Agreed.

Best regards, Michael.