How to fix: Audio Processor &p provides no initializer for:

General JUCE discussion
1

I asked this question in audio plugins but I haven’t received any responses so I am posting it here.
Hi I am a beginner to JUCE and C++ in general and I am following the Audio Programmers Guide for making a sampler, and I am getting one final error that I can not figure out. It says: Audio Processor &p provides no initializer for:
Any help would be appreciated!
Here is the code I have:
PluginEditor.cpp

InstrumentLibraryOneAudioProcessorEditor::InstrumentLibraryOneAudioProcessorEditor (InstrumentLibraryOneAudioProcessor& p)
    : AudioProcessorEditor (&p), audioProcessor (p)
{
    // Make sure that before the constructor has finished, you've set the
    // editor's size to whatever you need it to be.
  
    
    addAndMakeVisible(samplerButton);  
    samplerButton.onClick = [&]() {processor.loadFile(); };
    setSize(800, 500);
}

pluginEditor.h:

private:
    InstrumentLibraryOneAudioProcessor& audioProcessor;
    juce::TextButton samplerButton{ "Sampler" };

    InstrumentLibraryOneAudioProcessor& processor;
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (InstrumentLibraryOneAudioProcessorEditor)

pluginprocessor.cpp

InstrumentLibraryOneAudioProcessor::InstrumentLibraryOneAudioProcessor()
#ifndef JucePlugin_PreferredChannelConfigurations
     : AudioProcessor (BusesProperties()
                     #if ! JucePlugin_IsMidiEffect
                      #if ! JucePlugin_IsSynth
                       .withInput  ("Input",  juce::AudioChannelSet::stereo(), true)
                      #endif
                       .withOutput ("Output", juce::AudioChannelSet::stereo(), true)
                     #endif
                       )
#endif
{
    for (int i = 0; i < numVoices; i++)
    {
        formatManager.registerBasicFormats();

        mSampler.addVoice(new SamplerVoice());
    }
}

InstrumentLibraryOneAudioProcessor::~InstrumentLibraryOneAudioProcessor()
{
    formatReader = nullptr;
}


void InstrumentLibraryOneAudioProcessor::loadFile()
{
    FileChooser chooser{ "Select Audio File" };

    if (chooser.browseForFileToOpen())
    {
        auto file = chooser.getResult();
        formatReader = formatManager.createReaderFor(file);
    }
    BigInteger range;
    range.setRange(0, 128, true);

    mSampler.addSound(new SamplerSound("Sample", *formatReader, range, 60, 0.1, 0.1, 10));
}

pluginprocessor.h

private:
    Synthesiser mSampler;
    const int numVoices{ 6 };
    AudioFormatManager formatManager;
    AudioFormatReader* formatReader{ nullptr };
    
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (InstrumentLibraryOneAudioProcessor)

I did not include the whole code, only the sections I changed.

2

Why the two InstrumentLibraryOneAudioProcessor references?

    InstrumentLibraryOneAudioProcessor& audioProcessor;
    InstrumentLibraryOneAudioProcessor& processor;

This surely can’t be what you intend?

The second one is not initialized in the initializer list of the constructor, that’s the compiler’s complaint. References must always be initialized.

3

Where and what would I add to in order to initialize the second one? I have never heard of what an initializer list is or how to add to one.

4

Well, you can better drop the second one, “processor” - I bet you are not using it in the rest of your code. If your are, replace it with audioProcessor.

An initializer list is a recommended way to initialize variables / objects that you have declared in your class (in the header file). Simple variables do not need to be initialized there, but at least references must be assigned there; I prefer to initialize objects there as well.

Look at the first line in your code:

    : AudioProcessorEditor (&p), audioProcessor (p)

what follows after the colon “:” is an initializer list.

Anything you haven’t heard of before, be it about C++, JUCE, DSP, Google it! Or ask here :wink:
C++ is a pretty difficult language, you need to have regular doses of new lessons, otherwise you will never improve your skills.

Success!

2 Likes
5

Thank you it is working now!

6

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