Re: help create function alias

[Adam <nospam@example.com>]

Andreas Politz wrote:

> Adam <nospam@example.com> writes:
> 
>> Pascal J. Bourguignon wrote:
>>
>>> Adam <nospam@example.com> writes:
>>> 
>>>>> Marc Mientki wrote:
>>>> [ ... ]
>>>>
>>>> Here's the (insert-date) function.  Which I now find doesn't
>>>> work when called from the changed (id) example below.
>>>>
>>>> M-x id  returns "Wrong type argument: stringp, nil"
>>>> Strange, as I never used M-x insert-date  with any prefix-argument.
>>>> Indeed am not sure how I'd do that (to use its options).
>>>>
>>>> (defun insert-date (prefix)
>>>>     "Insert the current date. With prefix-argument, use ISO format.
>>>>     With
>>>>    two prefix arguments, write out the day and month name."
>>>>     (interactive "P")
>>>>     (let ((format (cond
>>>>                    ((not prefix) "%A, %d %B %Y")
>>>>                    ((equal prefix '(4)) "%Y-%m-%d")
>>>>                    ((equal prefix '(16)) "%A, %d. %B %Y")))
>>>>           (system-time-locale "de_DE"))
>>>>       (insert (format-time-string format))))
>>> 
>>> (defalias 'id 'insert-date)
>>> 
>>> M-x id RET     --> Monday, 20 September 2010
>>> C-y M-x id RET --> 2010-09-20
>>
>> Thanks. I saw alias somewhere recently, but couldn't
>> er.. didn't find it in a search looking for it simply
>> by name.
>>
>> Out of interest, how does one use the (insert-date) function
>> above with a prefix ?
>>
>> e.g.  C-u 4 M-x insert-date   returns an error, and
>> evaluating (insert-date 4) is not right.
> 
> keys  |  resulting arg
> C-u 4 => 4
> C-u   => (4)
> 
> Since (equal 4 '(4)) is false and the cond has no default case, format
> is nil and format-time-string reports an error for it.
> 
> -ap

OK. But I still don't get it. How do I work 
those 2 non-nil options ?  

Or how do I work them from two custom defuns, 
say M-x id4   M-x id16  ?