问题
I need some help in Nested classes. This has sprung from a question I asked here
Essentially I have a class 'myPlugin'. This class is the bulk of my program and includes the 'processReplacing' function.
Within processReplacing I need to filter the signal using DSP, currently I am using 11 filters and that has led to 11 filters (and all buffers) being hard coded into processReplacing.
However, now I have decided to create a filter class, so I can create a new instance for each filter, call as necessary and improve my code efficiency.
So far I have had little success. But now I am using nested classes which, if I can get to work, should mean all else should follow suit.
Class definitions in the header are:
class myPlugin : public AudioEffectX
{
public: myPlugin (audioMasterCallback audioMaster); ~myPlugin ();
// Processing
virtual void processReplacing (float** inputs, float** outputs, VstInt32 sampleFrames);
virtual void processDoubleReplacing (double** inputs, double** outputs, VstInt32 sampleFrames);
virtual void midiOutNoteOn (int iKey, int iVel);
virtual void midiOutNoteOff (int iKey, int iVel);
// Program
virtual void setProgramName (char* name);
virtual void getProgramName (char* name);
// Parameters
virtual void setParameter (VstInt32 index, float value);
virtual float getParameter (VstInt32 index);
virtual void getParameterLabel (VstInt32 index, char* label);
virtual void getParameterDisplay (VstInt32 index, char* text);
virtual void getParameterName (VstInt32 index, char* text);
virtual bool getEffectName (char* name);
virtual bool getVendorString (char* text);
virtual bool getProductString (char* text);
virtual VstInt32 getVendorVersion ();
virtual VstInt32 canDo (char* text);
class aFilterL
{
friend class myPlugin;
public:
aFilterL ();
~aFilterL ();
float fOut1_l;
float filterOut1_l;
float Out_1_l;
float Out_2_l;
float* buffer_Out_1_l;
float* buffer_Out_2_l;
virtual float aFilterMethodL (float a0, float a1, float a2, float b1, float b2, float inputL, float prevInput1L, float prevInput2L)
{
Out_1_l = buffer_Out_1_l[0];
Out_2_l = buffer_Out_2_l[0];
filterOut1_l = (a0 * inputL) + (a1 * prevInput1L) + (a2 * prevInput2L) - (b1 * Out_1_l) - (b2 * Out_2_l) + 1.0E-25;
fOut1_l = filterOut1_l;
buffer_Out_2_l[0] = buffer_Out_1_l[0];
buffer_Out_1_l[0] = fOut1_l;
return fOut1_l;
}
};
class aFilterR
{
friend class myPlugin;
public:
aFilterR ();
~aFilterR ();
float fOut1_r;
float filterOut1_r;
float Out_1_r;
float Out_2_r;
float* buffer_Out_1_r;
float* buffer_Out_2_r;
virtual float aFilterMethodR (float a0, float a1, float a2, float b1, float b2, float inputR, float prevInput1R, float prevInput2R)
{
Out_1_r = buffer_Out_1_r[0];
Out_2_r = buffer_Out_2_r[0];
filterOut1_r = (a0 * inputR) + (a1 * prevInput1R) + (a2 * prevInput2R) - (b1 * Out_1_r) - (b2 * Out_2_r) + 1.0E-25;
fOut1_r = filterOut1_r;
buffer_Out_2_r[0] = buffer_Out_1_r[0];
buffer_Out_1_r[0] = fOut1_r;
return fOut1_r;
}
};
};#endif
My issue then is that I can't initialize the filter class correctly. The constructor for 'myPlugin' looks like this (Please bear in mind that this is a very simplified version of the actual constructor)
myPlugin::myPlugin (audioMasterCallback audioMaster)
: AudioEffectX (audioMaster, 1, 1) // 1 program, 1 parameter only {
setNumInputs (2); // stereo in
setNumOutputs (2); // stereo out
setUniqueID ('Gain'); // identify
canProcessReplacing (); // supports replacing output
canDoubleReplacing (); // supports double precision processing
myPlugin *my_aFilter1L = new aFilterL();
myPlugin *my_aFilter1R = new aFilterR();
}
myPlugin::~myPlugin ()
{ }
When I then try and use my_aFilter1L etc in processReplacing it throws the error:"error C2065: 'my_aFilter1L' : undeclared identifier" and "error C2227: left of '->aFilterMethodL' must point to class/struct/union/generic type"
I have tried initializing values stored in the filter classes within the myPlugin constructor. I have tried creating the filter constructor i.e. myPlugin::aFilter1L() OR aFilter1L::aFilter1L() but these have caused more errors.
Not quite sure what I can do. I have worked with classes/functions before, but never nested classes so a bit lost. I've seen lots of threads online and every answer doesn't quite apply; or I have tried the solutions I found and they haven't worked.
回答1:
you have to add them to an instance of your effect, like so (copy to your editor and search for LOOK HERE):
class myPlugin : public AudioEffectX {
public:
myPlugin (audioMasterCallback audioMaster);
~myPlugin ();
// Processing
virtual void processReplacing (float** inputs, float** outputs, VstInt32 sampleFrames);
virtual void processDoubleReplacing (double** inputs, double** outputs, VstInt32 sampleFrames);
virtual void midiOutNoteOn (int iKey, int iVel);
virtual void midiOutNoteOff (int iKey, int iVel);
// Program
virtual void setProgramName (char* name);
virtual void getProgramName (char* name);
// Parameters
virtual void setParameter (VstInt32 index, float value);
virtual float getParameter (VstInt32 index);
virtual void getParameterLabel (VstInt32 index, char* label);
virtual void getParameterDisplay (VstInt32 index, char* text);
virtual void getParameterName (VstInt32 index, char* text);
virtual bool getEffectName (char* name);
virtual bool getVendorString (char* text);
virtual bool getProductString (char* text);
virtual VstInt32 getVendorVersion ();
virtual VstInt32 canDo (char* text);
class aFilterL
{
friend class myPlugin;
public:
aFilterL ();
~aFilterL ();
float fOut1_l;
float filterOut1_l;
float Out_1_l;
float Out_2_l;
float* buffer_Out_1_l;
float* buffer_Out_2_l;
virtual float aFilterMethodL (float a0, float a1, float a2, float b1, float b2, float inputL, float prevInput1L, float prevInput2L)
{
Out_1_l = buffer_Out_1_l[0];
Out_2_l = buffer_Out_2_l[0];
filterOut1_l = (a0 * inputL) + (a1 * prevInput1L) + (a2 * prevInput2L) - (b1 * Out_1_l) - (b2 * Out_2_l) + 1.0E-25;
fOut1_l = filterOut1_l;
buffer_Out_2_l[0] = buffer_Out_1_l[0];
buffer_Out_1_l[0] = fOut1_l;
return fOut1_l;
}
};
class aFilterR
{
friend class myPlugin;
public:
aFilterR ();
~aFilterR ();
float fOut1_r;
float filterOut1_r;
float Out_1_r;
float Out_2_r;
float* buffer_Out_1_r;
float* buffer_Out_2_r;
virtual float aFilterMethodR (float a0, float a1, float a2, float b1, float b2, float inputR, float prevInput1R, float prevInput2R)
{
Out_1_r = buffer_Out_1_r[0];
Out_2_r = buffer_Out_2_r[0];
filterOut1_r = (a0 * inputR) + (a1 * prevInput1R) + (a2 * prevInput2R) - (b1 * Out_1_r) - (b2 * Out_2_r) + 1.0E-25;
fOut1_r = filterOut1_r;
buffer_Out_2_r[0] = buffer_Out_1_r[0];
buffer_Out_1_r[0] = fOut1_r;
return fOut1_r;
}
};
/* LOOK HERE */
private:
aFilterL filterL;
aFilterR filterR;
};
myPlugin::myPlugin (audioMasterCallback audioMaster) : AudioEffectX (audioMaster, 1, 1), filterL(), /* LOOK HERE */ filterR() /* LOOK HERE */ {
setNumInputs (2); // stereo in
setNumOutputs (2); // stereo out
setUniqueID ('Gain'); // identify
canProcessReplacing (); // supports replacing output
canDoubleReplacing (); // supports double precision processing
/* LOOK HERE */
//myPlugin *my_aFilter1L = new aFilterL();
//myPlugin *my_aFilter1R = new aFilterR();
}
the nested class is only a declaration (sort of like a namespace, but you have a few additional options regarding visibility). declaring a class in this scope does not automatically add filters to the effect, you'll still have to declare them exactly as any static or instance variable of the class.
来源：https://stackoverflow.com/questions/4885161/vst-c-nested-classes-construction-and-inclusion