[Ffmpeg-devel] [PATCH] Wildcard and catalog image sequences

[Michel Bardiaux]

Michael Niedermayer wrote:
> Hi
> 
[snip]
>>>>> +int filename_catalog_test(const char *filename)
>>>>> +{
>>>>> +    if(!filename)
>>>>> +        return (-1);
>>>>> +    else if(filename[0]=='@')
>>>>> +        return 0;
>>>>> +    else
>>>>> +        return (-1);
>>> versus
>>>
>>>> return filename && filename[0]=='@';
>>> i cant see how the later is more obfuscated, additionally
>> I dont mean all one-liners are obfuscated, only that they quickly become 
>> so. Esp. since the correct one is
>>
>> return (filename && filename[0]=='@')?0:-1; // justified below.
>>
>> Still reasonable, but the one about wildcards is even bigger. If one has 
>> to code for multiple levels of conditions, nested ?: become quite 
>> unreadable. So there is a limit to one-liners, and where it is is a 
>> matter of taste, isnt it?
> 
> sure but my suggestion wouldnt need the ?: and without that the one liner
> really seems to be the better solution

But your suggestion doesnt conform to the API! (And IIRC *your* API, 
arent you the prime author of img2.c?) Of course, the awkwardness of the 
one-liner can be considered a reason to *change* the API as you suggest 
below.

> 
> 
>> You dont dispute that the object code size is likely to be the same?
> 
> it will likely be similar yes
> 
> 
>>> 1. is the NULL check really needed at all?
>> I dont know: there was one in the original filename_number_test() so I 
>> put one too. Keeping maximum symmetry between all 3 kinds of sequences 
>> seemed a good strategy for implementation.
> 
> yes, and factoring that check out and putting it before the decission which
> of the 3 functions is called also seems like its a good idea

But it cant be factored out of filename_number_test because that is 
called for output sequences too. And actually *every* call to one of the 
probes would have to have a test for !filename before. The end result 
would probably be *more* lines of code.

> 
> 
>>> 2. in C 0 is false not 0 is true, using 0 as true is broken as logical 
>>> and/or
>>>   will no longer have their intuitive meaning, do you disagree here?
>> Not at all. I knew you want patches to be as little intrusive as 
>> possible, so I tried not to change anything to numbered sequences, which 
>> are known to work. Hence I had to conform to the API defined by 
>> get_frame_filename and filename_number_test, which is on the lines of 
>> UNIX-style syscalls. Maybe this has to be changed, but shouldnt that be 
>> a different patch?
> 
> of course it should be a seperate patch :)

I wonder what your reaction would have been to a patch just to change 
*that* (filename_number_test returning 0/1 instead of -1/0) coming out 
of the blue... Do you really want one?

> 
> [...]


-- 
Michel Bardiaux
R&D Director
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