Re: more than one prefix argument

[Tim Cross <theophilusx@gmail.com>]

On Wed, Jul 27, 2011 at 7:37 PM, Andreas Röhler
<andreas.roehler@online.de> wrote:
> Am 27.07.2011 11:25, schrieb Tim Cross:
> [ ... ]
>>
>> While P and p are similar, I'm not sure they are as similar as you
>> imply. Consider a very simple example. You have a function and you
>> want it to use a prefix arg and you want the raw form because you want
>> to distinguish between no prefix arg and C-u 1 or M-1. You then define
>> a second function, but this time, you want it to default to 1 if no
>> prefix arg or whatever the value is if one is provided, then the 'p'
>> numeric version is what you want. In each case, the P and p support
>> what you need
>
> yes, but one of them would be sufficient.
>
> OTOH we have not a handy code for branching.
>
> Do you know case, "p" receiving M- numeric arg must fail, so C-u NUMBER
> through "P" is needed?
>
>
>  without you having to do additional code. Yes, you could
>>
>> solve this with just the P version, but then you would have to do more
>> code to handle the common case of just wanting to process the prefix
>> arg as a number.
>>
>> This additional code
>
> Don't suggest additional code but a better use of "P" - no parallel
> implementations. Having "P" as a branch-flag not affected by "p"
>

Sorry, just not quite following your argument.

If we were to get rid of one, it would have to be the numeric version
(i.e. p) rather than P as sometimes you need to be able to distinguish
between nil and 1. Essentially, we would need the raw form. This means
that whenever you need to process the prefix argument as a number you
will need to test and convert it to distinguish nil and extract the
value from the list - this would be additional code ini your function.

I don't understand what you mean by having a handy code for branching.
Can you give an example of how this code would work and how a command
using this code would be called?

tim