bug#4869: 23.1.50; weak documentation of prefer-coding-system

[Lennart Borgman]

On Fri, Nov 6, 2009 at 2:47 AM, Juri Linkov <juri@jurta.org> wrote:
>> The function prefer-coding-system does not explain if the CODING-SYSTEM
>> argument must be a symbol or a string (or either).
>>
>> Without seeing a code example, a user might try using a quoted string:
>>
>>    (prefer-coding-system "utf-8")
>>
>> In which case, the error message is very confusing (this makes it sound
>> as though utf-8 is not supported):
>>
>>    error: Invalid coding system `utf-8'
>>
>> At a minimum, the documentation should be made more explicit, and I
>> would strongly suggest adding a code example:
>>
>>    (prefer-coding-system 'utf-8)
>
> Why not allow both?  Some MULE functions allow a symbol and a string.

Because it is at least a rudimentary type check? ;-)