Michael said:
Hi,
I think my problem deals with class casting and inheritance.
I want to deal with various Audio Formats, reading into memory for
modification, working with it (done by different classes), and writing the
result to disk afterwards.
Therefore I have created some classes, e.g. WaveFileIO and AiffFileIO and
MP3FileIO and AuFileIO for the In/Out operations.
They all are inherited from the AudioFileIO class, because they all share
common methods like readSamples, writeSamples, readHeader, writeHeader.
Only the implementation is sometimes different.
Now, I want to use them in a let's say generic way:
[1]
while(there is data)
{
IN.readSamples(); // using the classes mentioned above
DelayEffect.work(); // modify the memory buffer(sample data)
OUT.writeSamples(); // using the classes mentioned above
}
But due to different audio formats, the type of the IN and OUT variable
depends on the desired audio format the user specifies.
I do not want to code every time many IF-THEN-ELSE statements for checking
the desired format and for using the proper variable.
What, exactly, do you mean "the type of the IN and OUT variable depends on
the desired audio format the user specifies." Why isn't the IN and OUT
variables members of the audio formats themselves? Why aren't they just
functions? Why do they depend on the type of the desired audio format?
Where do IN and OUT get their data to work on?
It sounds like you just need polymorphism, but it could also be that you
need RTTI. I don't understand what you are trying to do in your code
snippet. You don't specify what type IN and OUT can be nor why you need
them.
I'm sure there's many ways to do what you want, but I don't understand what
it is you're trying to do.
Isn't it possible to check the audio format of the incoming audio material
at first and then casting the IN and OUT variable to the proper type of
audio class?
Like:
IF the incoming file is a WAV, then IN = Type of WaveFileIO
ELSE IF incoming file is a AIF, then IN = Type of AiffFileIO
Using RTTI you can check the type of a polymorphic variable. But is this
what you are really needing to do? I'm just not sure.
In case you are, though, it would something like this:
if ( typeid( MyVar ) == typeid( MyClass ) )
so, for instance, if your polymorphic variable was stored in the variable
format it would be:
if ( typeid( Format ) == typeid( WaveFileIO ) )
although it might be a differernt if Format is a pointer. I *think* this
syntax is what you need (not positive)
if ( typeid( Format ) == typeid( WaveFileIO* ) )
// then using the code fragment [1], and other code fragments like [1]
Ciao, Michael