Re: help create function alias

[Andreas Politz]

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