(error (format ...

(error (format ...

[Juanma Barranquero]

Is there any reason for uses like this one from simple.el:

  (error (format "No further undo information%s"
               (if (and transient-mark-mode mark-active)
                   " for region" "")))

instead of simply:

  (error "No further undo information%s"
         (if (and transient-mark-mode mark-active)
             " for region" ""))

-- 
                    /L/e/k/t/u

Re: (error (format ...

[David Kastrup]

Juanma Barranquero <lekktu@gmail.com> writes:

> Is there any reason for uses like this one from simple.el:
>
>   (error (format "No further undo information%s"
>                (if (and transient-mark-mode mark-active)
>                    " for region" "")))
>
> instead of simply:
>
>   (error "No further undo information%s"
>          (if (and transient-mark-mode mark-active)
>              " for region" ""))

I'd probably be tempted to use

    (error (concat "No further undo information"
                   (and transient-mark-mode mark-active
                        " for region")))

in this case.  It shares the disadvantage of the original version
(when compared to yours) of being more likely to lead to accidental
format string vulnerabilities if a user takes this as starting code
for something with a variable string.

It is perhaps more educational to preferable follow (error ... with a
constant string.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum

Re: (error (format ...

[Lennart Borgman]

David Kastrup wrote:

>It is perhaps more educational to preferable follow (error ... with a
>constant string.
>  
>
Yes, in all cases where format is implicitly or explicitly used.

Re: (error (format ...

[Juanma Barranquero]

> I'd probably be tempted to use
> 
>     (error (concat "No further undo information"
>                    (and transient-mark-mode mark-active
>                         " for region")))

Yes, in this case I think yours is better. But if the argument is a variable:

  (lambda (arg) (error (format "This is the error: %s" arg)))

would be preferable to

  (lambda (arg) (error "This is the error: %s" arg))

?
-- 
                    /L/e/k/t/u

Re: (error (format ...

[David Kastrup]

Juanma Barranquero <lekktu@gmail.com> writes:

>> I'd probably be tempted to use
>> 
>>     (error (concat "No further undo information"
>>                    (and transient-mark-mode mark-active
>>                         " for region")))
>
> Yes, in this case I think yours is better. But if the argument is a variable:
>
>   (lambda (arg) (error (format "This is the error: %s" arg)))
>
> would be preferable to
>
>   (lambda (arg) (error "This is the error: %s" arg))
>
> ?

Not at all.  The former is prone to bug out when "arg" contains "%"
somewhere.  The latter works fine in this case.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum