- _ _closure
-
In C++ Builder, a closure is like a pointer to a member function that
has been bound to a specific object. Given a closure, you can call it
the way you would call an ordinary function. To declare a closure
type or object, use _ _closure as a modifier for
the name of a function pointer:
typedef int (* _ _closure MemFunc)(int);
MemFunc func;
struct demo {
int sqr(int x) { return x * x; }
};
demo d;
func = d.sqr;
int n = func(10); // n = 100
- _ _declspec
-
The _ _declspec keyword takes an attribute in
parentheses and serves as a declaration specifier. Depending on the
attribute, it can be used to modify a function, object, or class. For
example, _ _declspec(noreturn) is a function
specifier that tells the compiler that the function does not return,
which permits additional optimization and error-checking (for
example, eliminating statements that follow a call to the
noreturn function):
void _ _declspec(noreturn) abort( );
Other attributes include:
- thread
-
A storage-class specifier that declares an object to be local to a
thread; that is, each runtime thread has a separate copy of the
object.
- dllexport
-
A function specifier that tells the linker to export the function
name from a dynamic-link library (DLL).
- uuid( string-literal)
-
Modifies a class declaration. It associates a universally unique
identifier (UUID) with the class, which is required for implementing
COM objects in Windows. A class's UUID can be
retrieved with the _ _uuidof operator.
- _ _int64
-
The _ _int64 type is a 64-bit integer type. In
current releases of C++ Builder and Kylix, long is
32 bits. A 64-bit integer literal is written with a suffix of
i64 (e.g., 10000000000000i64).
- _ _property
-
A property is a class member that is used like a data member, but it
can have the semantics of a member function. Properties are the
foundation for the RAD features of C++ Builder and Kylix. A property
is associated with a reader and writer, which can be data member
names or member function names:
class TControl {
private:
int height_;
void set_height(int h);
. . .
_ _published:
_ _property int height { read=height_, write=set_height };
};
TControl * ctl = new TControl;
ctl->height = 10; // Calls ctl->set_height(10)
int h = ctl->height; // Gets ctl->height_
- _ _published
-
The _ _published access
specifier label yields the same accessibility as the
public keyword, but it also directs the compiler
to store additional runtime type information (RTTI) for the published
declarations. The RAD features use the RTTI when the user designs an
application
- _ _thread
-
The _ _thread keyword is a synonym for _
_declspec(thread).
- _ _uuidof
-
The _ _uuidof operator takes an expression as an
operand and returns the UUID of the expression's
class. The class declares its UUID with _
_declspec(uuid( . . . )). A class can
implement the standard COM member function,
QueryInterface, with _ _uuidof:
class demo {
virtual HRESULT QueryInterface(const UUID& iid, void** obj)
{
if (iid == _ _uuidof(IUnknown)) {
*obj = reinterpret_cast<IUnknown*>(this);
static_cast<IUnknown*>(*obj)->AddRef( );
return S_OK;
}
return E_NOINTERFACE;
}
};
