c++ - 将代码块优化为循环

Question

我对 C++ 和编译语言非常陌生，总的来说，我有很强的解释背景，所以我试图了解在编译时无法访问某些内容的限制。

目前我有一大段代码，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;

此方法中的代码重复了 48 次，这不是一个好的做法。我如何在 PHP 中实现此目的的示例，解释性语言看起来像这样

$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到一个整洁的循环中，我只是找不到那里的资源来解释给我。

Answer 1

假设 BinaryData 是 JUCE 生成的资源文件，以下算法应与您的 PHP 版本相同。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(糟糕的)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);

以下代码是由预处理阶段生成的:

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该与您当前的解决方案等效，但一般来说，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。