You are currently viewing a snapshot of www.mozilla.org taken on April 21, 2008. Most of this content is highly out of date (some pages haven't been updated since the project began in 1998) and exists for historical purposes only. If there are any pages on this archive site that you think should be added back to www.mozilla.org, please file a bug.

XPCOM

Welcome to the XPCOM page. This area is intended to be a central clearinghouse for information related to XPCOM.

General

Creating XPCOM Components written by Doug Turner and Ian Oeschger that introduces XPCOM and illustrates how to create XPCOM components for Gecko-based applications.
An introduction to XPCOM on IBM's website by Rick Parrish.
Presentation: Introduction To XPCOM, Alec Flett (Feb 4, 2002)
Presentation: The XPCOM Library, Alec Flett (Feb 11, 2002)
Standalone XPCOM : Document on building xpcom standalone.
Information on the built-in support for detecting memory leaks.

Rules and guidelines for writing new code

IDL Interface Rules - Guidelines for writing interfaces. Requirements for freezing.
Rules we break lists and comments on xpcom rules being broken in our codebase

Smart Pointers and Ownership

Some COM Ownership Guidelines gives a brief set of guidelines to help you build a supportable ownership model.
Using nsCOMPtr describes a 'smart-pointer' class for XPCOM.
The nsCOMPtr homepage. has even more on nsCOMPtr
nsIWeakReference User Manual describes one implementation of a safe, non-dangling, non-owning pointer you can use with XPCOM.

Manuals and Guides

Strings - The mozilla string guide
Hashtables - The mozilla hashtable guide
Arrays - The mozilla array guide
Generic Factories - don't write factory code yourself
A Reference Implementation of QueryInterface shows one good way to implement QueryInterface().
nsISupport Proxies describes how to use thread-crossing XPCOM proxies.
General Overview of nsIClassInfo infrastructure
Use the Console Service to log script errors and other user-visible messages.

Technotes

Statement on binary compatibility of XPCOM interfaces across compiler versions.

XPIDL, XPConnect and friends

Roadmap for XPCOM, XPConnect, XPTCall, and XPIDL describes how they all fit together
XPConnect describes how XPCOM based classes can be accessed through JavaScript.
XPIDL is the XP Interface Description Language used to specify XPCOM interface classes
- XPIDL syntax
- XPIDL Author's guide
xptcall is a library that supports invoking methods on arbitrary xpcom objects and implementing classes whose objects can impersonate an xpcom interface
- porting status lists the currently supported platforms. There are currently many platforms that we need help on.
- porting guide describes the assembly code that is needed to implement xptcall
Type Library Format describe the type libraries (.xpt files) that are binary representations of XPCOM interfaces
- Tools for Typelibs - xpt_dump dumps the information in a typelib to the screen and xpt_link merges typelib files

Soon to be removed

Modularization Techniques describes XPCOM and how to use it.

Mozilla