CODEWITHSUNDEEP
c++struct
ph4nt0m
ph4nt0m

Reputation: 968

What is the best way to define a struct which is only needed by a certain class?

Given the following simplified class which contains a vector of MyStruct objects, where should I define MyStruct assuming that it's only being used inside of Foo and should not be seen or used from outside?

class Foo
{
  std::vector<MyStruct> array;
};

Two possibilities I've come across are putting the definition of MyStruct right inside of Foo or using an anonymous namespace.

Upvotes: 0

Views: 120

Answers (3)

James Kanze
James Kanze

Reputation: 153919

In this case, you have to define it in Foo, since it has to be completely defined before you use it to instantiate std::vector. Otherwise, it depends; I'd tend to define it in a private namespace: an unnamed namespace in the implementation file if all of the functions are in a single source file, otherwise in a private, implementation header file in a private namespace (e.g. FooPrivate) if they aren't.

Upvotes: 1

utnapistim
utnapistim

Reputation: 27365

If array is in any way a public part of Foo interface, declare MyStruct like this:

class Foo
{
public:
    struct MyStruct { /* stuff */ };
    /* ... */
};

Otherwise: declare it in the private section of Foo.

Upvotes: 1

Aswin Murugesh
Aswin Murugesh

Reputation: 11070

If you do not want it to be used outside Foo, then the best way is to declare it in the private section of Foo

class Foo
{
    struct My_Struct;
}

Upvotes: 0

Related Questions