Pseudocode

Overview

Examples

Simple Interface Declarations

Derived Interfaces

Interface Templates

Grammar

Overview

The macro based Interface Definition Language (IDL) can be more difficult to read than ordinary C++ class definitions. Therefore, we occassionally describe interfaces using pseudocode which is closer to C++ class definitions.

Examples

Example I: Simple interface declarations.

An interface which is not a template and which does not derive from any other interface can be written as follows:

interface IPoint {
    long x() const;
    long y() const;
    void x(long);
    void y(long);
};

Note that overloading is permitted, and that member functions may be declared const. They may not be templates, however, nor may they be declared static, virtual or volatile:^[1]

interface IBad {
    template<typename T>
    void foo(const T&);  // Error
    virtual void foo();  // Error
    void foo() volatile; // Error
};

Example II: Derived interfaces.

Interfaces may be declared to derived from other interfaces, just as classes may be declared to derived from other classes:

interface ICircle : IPoint {
    long diameter() const;
    void diameter(long);
}

Multiple inheritance is allowed. The order in which base interfaces are specified is significant. See BOOST_IDL_EXTENDS.

Example III: Interface templates.

Interfaces may be templates:

template<typename T>
interface IStack {
    bool empty() const;
    void push(const T&);
    void pop();
    T& top();
    const T& top() const;
};

Grammar

Coming soon.

^[1]Support for volatile member functions is possible but would require twice as many macros for declaring functions.

Revised 13 Jan, 2005

© Copyright Jonathan Turkanis, 2005. Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)

Sha'arei Tefila, an Orthodox Shul (Synagogue) in Salt Lake City, Utah Chabad Lubavitch of Utah