AsClip() problems

[kassandro]

In a forthcoming filter I have severe problems with the AsClip() function. Firstly one cannot specify a default value AsClip(defaultclip), where defaultclip is a PClip lvalue.
Secondly AsClip() does not work with named variables, i.e. I would like to use it as follows: myfilter(clip1, secondclip=clip2). If secondclip is not specified, then the filter should take clip1 as default value. There is no way to implement this kind functionality. I simply cannot understand, why AsClip() is designed so differently from AsBool, AsInt, AsString etc.. This deficiency simply forces me to disable an important feature of my filter.

[WarpEnterprises]

Did you try to let the variables unasserted and test the array members with IsClip()?

[sh0dan]

Use IsDefined() before getting the clip as PClip. This will allow you to skip the AsClip() if it is an optional parameter.

Something like this:

PClip c1 = args[0].AsClip()
PClip c2 = args[1].IsDefined() ? args[1].AsClip() : c1;

[kassandro]

In a much simplified form the situation was as follows:

DLL initialisation:
env->AddFunction("myfilter", "c[secondclip]c", creat_myfilter, 0);

in the function "creat_myfilter" I had the following lines:
PClip clip1 = args[0].AsClip();
PClip clip2 = arg2[1].AsClip(clip1);

These lines were rejected by the compiler, because AsClip() unlike AsInt() dosen't accept any argument. But, sh0dan, your suggestion doesn't work either, because the compiler rejects args[1].IsDefined() and "IsDefined" can't be found anywhere in avisynth.h.

[kassandro]

Ok, instead of IsDefined() you have to take Defined().
It now works! Thank you!
Nevertheless, to have a uniform design, AsClip() should accept a argument.