c++ - 将代码块优化为循环

Question

我对 C++ 和一般的编译语言还很陌生，我有很强的解释背景，所以我试图解决在编译时无法访问某些东西的限制。

目前我有一大块代码，如下所示:

//New note, note36

MemoryInputStream* input36 = new MemoryInputStream(BinaryData::C1hard1_wav, BinaryData::C1hard1_wavSize, false);
auto reader36 = audioFormatManager.createReaderFor(input36);

BigInteger note36;
note36.setRange(36, 1, true);

addSound(new SamplerSound("note36", *reader36, note36, 36, 0.001, 0.01, 26.0));

delete input36;
delete reader36;

//New note, note37

MemoryInputStream* input37 = new MemoryInputStream(BinaryData::Csharp1hard1_wav, BinaryData::Csharp1hard1_wavSize, false);
auto reader37 = audioFormatManager.createReaderFor(input37);

BigInteger note37;
note37.setRange(37, 1, true);

addSound(new SamplerSound("note37", *reader37, note37, 37, 0.001, 0.01, 26.0));

delete input37;
delete reader37;

这段代码在这个方法中重复了 48 次，这不是好的做法。我将如何在 PHP 中实现此目的的示例，一种解释型语言看起来像这样

$noteMap = array(36 => "C1", 37 => "Csharp1");

foreach($noteMap as $midiNumber => $note)
{
    $name = $note . "hard1_wav";
    $size = $note . "hard1_wavSize";

    $input = new MemoryInputStream(BinaryData::$name, BinaryData::$size, false);
    $reader = audioFormatManager->createReaderFor($input);

    //I know this bit is bad PHP, no bigintegers in PHP but I can't think of a way to replicate it for arguments sake
    $note = 0;
    $note->setRange($midiNumber, 1, true);

    addSound(new SamplerSound("note".$midiNumber, $reader36, $note, $midiNumber, 0.001, 0.01, 26.0));
}

这更易于管理和重用。我所做的更改不需要在整个文件中仔细重复，并且可以快速进行更改。我知道将变量作为函数名传递不是在编译语言中完成的事情，但即使考虑到这一点，也必须有一种方法将我的大代码块包装成一个整洁的循环我只是找不到那里的资源解释对我来说。

Answer 1

假设 BinaryData 是 JUCE 生成的资源文件，以下算法应该等同于您的 PHP 版本。这不使用动态变量名称，而是使用应出现在 JUCE generated code 中的 BinaryData::getNamedResource 函数.

std::map<int, std::string> note_map{{36, "C1"}, {37, "Csharp1"}};
for ( const auto& note : note_map ) {
    BigInteger midi_bit;
    midi_bit.setBit(note.first);

    int size;
    std::string note_resource = note.second + "hard1_wav";
    auto data = BinaryData::getNamedResource(note_resource.c_str(), size);

    auto input = new MemoryInputStream(data, size, false);
    auto reader = audioFormatManager->createReaderFor(input);

    auto note_name = "note" + std::to_string(note.first);
    addSound(new SamplerSound(note_name.c_str(), *reader, midi_bit,
                              note.first, 0.001, 0.01, 26.0));
}

另一个(不好的)解决方案是使用 C 预处理器生成如下代码:

#define note(num, name)                                                                                               \
    MemoryInputStream* input##num = new MemoryInputStream(BinaryData::name##_wav, BinaryData::name##_wavSize, false); \
    auto reader##num = audioFormatManager.createReaderFor(input##num);                                                \
    BigInteger note##num;                                                                                             \
    note##num.setBit(num);                                                                                            \
    addSound(new SamplerSound("note" #num, *reader##num, note##num, num, 0.001, 0.01, 26.0));                         \
    delete input##num;                                                                                                \
    delete reader##num
note(36, C1);
note(37, Csharp1);

预处理阶段生成如下代码:

MemoryInputStream* input36 = new MemoryInputStream(BinaryData::C1_wav, BinaryData::C1_wavSize, false); auto reader36 = audioFormatManager.createReaderFor(input36); BigInteger note36; note36.setBit(36); addSound(new SamplerSound("note" "36", *reader36, note36, 36, 0.001, 0.01, 26.0)); delete input36; delete reader36;
MemoryInputStream* input37 = new MemoryInputStream(BinaryData::Csharp1_wav, BinaryData::Csharp1_wavSize, false); auto reader37 = audioFormatManager.createReaderFor(input37); BigInteger note37; note37.setBit(37); addSound(new SamplerSound("note" "37", *reader37, note37, 37, 0.001, 0.01, 26.0)); delete input37; delete reader37;

预处理器解决方案的代码应与您当前的解决方案等效，但通常以这种方式使用宏生成大量变量并不是很好的做法。上面的运行时解决方案应该优于使用预处理器。