Menu
I have a class in C++/CLI that I'd like to give a property. I want to declare the property in a header file and then implement that property in a .cpp file.
Here's the header:
public ref class Dude
{
static property Dude^ instance
{
Dude^ get();
}
}
If I declare the header file and don't put anything in the cpp, i get the following error:
1>Dude.obj : error LNK2020: unresolved token (06000001) Test.Dude::get_instance
From this I concluded that I should implement the property as
static Lock myInstanceLock;
Dude^ Dude::get_instance()
{
if(myInstance == nullptr)
{
myInstanceLock.lock();
if(myInstance == nullptr)
{
myInstance = gcnew Dude();
}
myInstanceLock.unlock();
}
return myInstance;
}
However, when I compile this code, I get a bunch of errors. The first error (The others are a result of the first one) is:
1>.\Dude.cpp(13) : error C2039: 'get_instance' : is not a member of 'Test::Dude'
Can anyone shed some light on this issue?
262
To write a forward declaration for a function, we use a function declaration statement (also called a function prototype). The function declaration consists of the function header (the function's return type, name, and parameter types), terminated with a semicolon. The function body is not included in the declaration.
Forward Declaration refers to the beforehand declaration of the syntax or signature of an identifier, variable, function, class, etc. prior to its usage (done later in the program). Example: // Forward Declaration of the sum() void sum(int, int); // Usage of the sum void sum(int a, int b) { // Body }
In C++, classes and structs can be forward-declared like this: class MyClass; struct MyStruct; In C++, classes can be forward-declared if you only need to use the pointer-to-that-class type (since all object pointers are the same size, and this is what the compiler cares about).
A forward declaration is much faster to parse than a whole header file that itself may include even more header files. Also, if you change something in the header file for class B, everything including that header will have to be recompiled.
Change the implementation to:
Dude^ Dude::instance::get()
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
