interactive and &optional arguments

interactive and &optional arguments

[Thorsten Jolitz]

Hi List, 

sometimes I want a function with &optional args to be interactive, and I
wonder if there is a way to, as default action, interactively call the
function via M-x without args, except the user does something special -
e.g. C-u M-x - and only then ask the user for input?

That is

 ,-----------------------------------------
 | (defun foo (&optional arg1 arg2 arg3)
 |     (interactive "???")
 |     ...)
 | 
 | M-x foo         ; call foo without args
 | C-u M-x foo     ; ask the user for input
 `-----------------------------------------

or something similar?

-- 
cheers,
Thorsten

Re: interactive and &optional arguments

[Stefan Monnier]

> sometimes I want a function with &optional args to be interactive, and I
> wonder if there is a way to, as default action, interactively call the
> function via M-x without args, except the user does something special -
> e.g. C-u M-x - and only then ask the user for input?

Just use a (interactive <spec>) where <spec> is not a string but some
Elisp expression that computes the arguments you want to provide to
the function.


        Stefan

Re: interactive and &optional arguments

[Thorsten Jolitz]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

>> sometimes I want a function with &optional args to be interactive, and I
>> wonder if there is a way to, as default action, interactively call the
>> function via M-x without args, except the user does something special -
>> e.g. C-u M-x - and only then ask the user for input?
>
> Just use a (interactive <spec>) where <spec> is not a string but some
> Elisp expression that computes the arguments you want to provide to
> the function.

I see, thanks, its even described in the manual, but somehow I couldn't
relate the dense paragraph to my problem without some external hint.

-- 
cheers,
Thorsten