I think this is basically a problem of trying to use a C library as a C++ library. What are you trying to do? If you just want to create a vector of PmStream, I think you can set the vector length at creation time or after creating it. You don't need to construct it incrementally/iteratively by calling push_back() n times.

If you want to open streams and add them to the list, then do something like:

PmStream *s;
if (Pm_OpenOutput(&s, ...) == pmNoError) {
    v.push_back(s);
}

In C++, you might expect that if you delete a vector, the components of the vector will be properly deallocated, but since the components here are just pointers, you'll have to explicitly call Pm_Close() on each vector element before deleting the vector.

This could be handled by "smart pointers" similar to C++ strings, but I think that's overkill for a simple problem (unless someone wants to fully wrap PortMidi as a C++ class, similar to the Java API).

-Roger

Hi,

 

I have a std:vector of PmStream* but I can’t figure out a way to create the stream objects on-the-fly.  Here’s my code:

 

Int streamcount = some_value;

int i;

std::vector < PmStream*> v;

 

for (i = 0; i < streamcount; i++)

{

// VS2010 reports error C2469: 'new' : cannot allocate 'void' objects with the following line

PmStream* s = new PmStream();

v.push_back(s);

}

 

Can anybody see where I’m going wrong, please?  My research on the net would seem to indicate that using “new” to create instances of a void (abstract) class isn’t allowed, but I can’t find a work-around.

 

Best wishes.

 

Tim Burgess

Raised Bar Ltd

Phone:  +44 (0)1827 719822

 

Don't forget to vote for improved access to music and music technology at

 

http://www.raisedbar.net/petition.htm

 

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