XPCOM

Welcome to the XPCOM page. This area is intended to be a central clearinghouse for information related to XPCOM. Currently, XPCOM documentation is spread all over mozilla.org. Hopefully, it will migrate (or we'll link to it from) here.

Topics of Interest

The Future

• XPCOM Plans
• nsCOMPtr Plans

General

• Roadmap for XPCOM, XPConnect, XPTCall, and XPIDL describes how they all fit together
• Modularization Techniques describes XPCOM and how to use it.
• Rules we break lists and comments on xpcom rules being broken in our codebase
• XPCOM Brown Bag 1 (August 17 1999) [NEW]
• nsString Proposal proposes a string class for XPCOM.
• mozIRegistry describes the "registry" interface and how you can use it to dynamically bind to interface implementations
• Generic Factories reference document for Generic Factories.
• A Reference Implementation of QueryInterface shows one good way to implement QueryInterface().
• nsISupport Proxies describes how to use thread-crossing XPCOM proxies.
• XPCOM code FAQ has common questions from people implementing XPCOM components
• XP Event Loop describes the XP Event Loop.
• Porting XPCOM talks about what is required to port XPCOM to another platform.

Smart Pointers and Ownership

• Some COM Ownership Guidelines gives a brief set of guidelines to help you build a supportable ownership model.
• nsCOMPtr User Manual describes a `smart-pointer' class for XPCOM. Check out The nsCOMPtr Home Page for more documentation.
• nsIWeakReference User Manual describes one implementation of a safe, non-dangling, non-owning pointer you can use with XPCOM.

XPIDL, XPConnect, and friends

• 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

See Also

• Essential COM by Don Box hardcopy book that explains the rationale behind COM's design
• The nsCOMPtr Home Page.
• C++ portability guide general guidelines for writing portable code