Is 't' positive?

Is 't' positive?

[Leo]

Quite a few commands require positive arguments such as ido-mode.

,----
| (ido-mode &optional arg)
| 
| Toggle ido speed-ups on or off.
| With arg, turn ido speed-up on if arg is positive, off otherwise.
`----

However, it seems legal to use 't' and they will behave like it is
positive. So the question, is 't' positive? Is it safe to use 't' in
this kind of functions?

Thanks,
-- 
Leo <sdl.web AT gmail.com>                         (GPG Key: 9283AA3F)

Re: Is 't' positive?

[Johan Bockgård]

Leo <sdl.web@gmail.com> writes:

> However, it seems legal to use 't' and they will behave like it is
> positive. So the question, is 't' positive? Is it safe to use 't' in
> this kind of functions?

(info "(elisp)Minor Mode Conventions")

     [...]
     The command should accept one optional argument. If the argument
     is `nil', it should toggle the mode (turn it on if it is off, and
     off if it is on). It should turn the mode on if the argument is a
     positive integer, the symbol `t', or a list whose CAR is one of
     those. It should turn the mode off if the argument is a negative
     integer or zero, the symbol `-', or a list whose CAR is a
     negative integer or zero. The meaning of other arguments is not
     specified.

-- 
Johan Bockgård

Re: Is 't' positive?

[Pascal Bourguignon]

Leo <sdl.web@gmail.com> writes:

> Quite a few commands require positive arguments such as ido-mode.
>
> ,----
> | (ido-mode &optional arg)
> | 
> | Toggle ido speed-ups on or off.
> | With arg, turn ido speed-up on if arg is positive, off otherwise.
> `----
>
> However, it seems legal to use 't' and they will behave like it is
> positive. So the question, is 't' positive? Is it safe to use 't' in
> this kind of functions?

Depends on the function.  t may have a different meaning than 1, and
nil than 0...

-- 
__Pascal Bourguignon__
http://www.informatimago.com
http://pjb.ogamita.org

Re: Is 't' positive?

[Leo]

----- Johan Bockgård (2007-04-12) wrote:-----

> Leo <sdl.web@gmail.com> writes:
>
>> However, it seems legal to use 't' and they will behave like it is
>> positive. So the question, is 't' positive? Is it safe to use 't' in
>> this kind of functions?
>
> (info "(elisp)Minor Mode Conventions")
>
>      [...]
>      The command should accept one optional argument. If the argument
>      is `nil', it should toggle the mode (turn it on if it is off, and
>      off if it is on). It should turn the mode on if the argument is a
>      positive integer, the symbol `t', or a list whose CAR is one of
>      those. It should turn the mode off if the argument is a negative
>      integer or zero, the symbol `-', or a list whose CAR is a
>      negative integer or zero. The meaning of other arguments is not
>      specified.

Thanks.

-- 
Leo <sdl.web AT gmail.com>                         (GPG Key: 9283AA3F)