Private class name abbreviation techniques?

c++, c-preprocessor, class, private, typedef

Solution

The class name is already a namespace, so there's no reason to give the impl such a long name:

class LongDescriptiveClassName
{
public:
    // Stuff...

private:
    struct Impl;

    // shared_ptr is also an option if that's
    // the semantics you want.    
    std::unique_ptr<Impl> Data;
};

// and off in the implementation, we have...
struct LongDescriptiveClassName::Impl
{
    void PrivateMethod1();
    void PrivateMethod2();
    // and so on...
};

void LongDescriptiveClassName::Impl::PrivateMethod1()
{
    // Stuff...
}

It works just fine.

Incidentally, your code is not an example of the pimpl idiom. The "p" in "pimpl" means "pointer", and this is important. A reference means that the object does not own its implementation.

It's not necessarily wrong; there are sometimes good reasons to wrap a reference in a class, but it's not the pimpl idiom.

Problem

My class uses the PImpl idiom and looks something like this: ``` // In LongDescriptiveClassName.hpp class LongDescriptiveClassName { public: // Stuff... private: struct LongDescriptiveClassNameData; LongDescriptiveClassNameData &Data; }; ``` In the .cpp file, I declare/define the private struct: ``` // In LongDescriptiveClassName.cpp struct LongDescriptiveClassName::LongDescriptiveClassNameData { void PrivateMethod1(); void PrivateMethod2(); // and so on... }; void LongDescriptiveClassName::LongDescriptiveClassNameData::PrivateMethod1() { // Stuff... } void LongDescriptiveClassName::LongDescriptiveClassNameData::PrivateMethod2() { // Stuff... } ``` This is painful for me to read. Is there a way that I can abbreviate the names leading up to the private methods? My understanding is that I can't `typedef` it in the .cpp file because the PImpl struct is private. Would it be an evil to use `#define`? ``` #define ShortName LongDescriptiveClassName::LongDescriptiveClassNameData struct ShortName { // ... }; void ShortName::PrivateMethod1() // ... ``` This .cpp file is the only source file that would need to abbreviate it, and then only for method definitions. What do you recommend?

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