[Dev-luatex] return value of filter callbacks

Manuel Pégourié-Gonnard mpg at elzevir.fr
Fri Nov 5 15:06:52 CET 2010


Le 05/11/2010 14:57, Taco Hoekwater a écrit :
> On 11/05/2010 02:56 PM, Manuel Pégourié-Gonnard wrote:
>> Le 05/11/2010 14:52, Taco Hoekwater a écrit :
>>> On 11/05/2010 02:46 PM, Manuel Pégourié-Gonnard wrote:
>>>> Le 05/11/2010 14:22, Taco Hoekwater a écrit :
>>>>> In all these cases the result of returning a boolean is the same:
>>>>>
>>>>>      false == callback has failed
>>>>>      true == callback has run ok, but nothing has been changed
>>>>>
>>>>> the latter case (true) is interesting because it allows a speed
>>>>> optimization that can be considerable. I could have sworn this was
>>>>> mentioned in the manual, but I cannot find it myself either.
>>>>
>>>> Ok, thanks for the clarification. Just to be sure: in case the function returns
>>>> false, and error will be issued, right?
>>>
>>> Eh ... no. You have to raise an error yourself, if you want that.
>>>
>> Hum, so what is the purpose of returning false rather than true, if no action is
>> taken based on this value?
> 
> Oh, now I see this was not clear. Action actually is taken:
> the whole node list starting at head is thrown away.

Ok, now it's perfectly clear.

Thanks again,
Manuel.


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