source: code/branches/gui/src/tolua/MANUAL @ 2989

This tolua++ is modified with support for exception handling, and more will
likely come over time.

So to avoid forgetting how it works and what's new, all added features will
be documented in full in this file:

***********************
* Exception handling: *
***********************
A new function modifier 'tolua_throws' has been added. It goes the same place
as 'tolua_outside' etc. - so before the function name and return type.

Two "types" of exceptions are supported internally, but they can be customized
by making the tolua++ binary execute a Lua script before parsing with the '-L'
command line option.
Look in '../LuaScriptModule/package/exceptions.lua' to see the format. It's
fairly simple and gives you alot of control.

You always have 'std::exception' and 'any' (which means ...) available.

This first example would be valid in a .pkg file for tolua++, and would ensure
that any exceptions based on 'std::exception' thrown by the real C++ function
would result in return value of 'nil' in Lua:

        tolua_throws|std::exception,nil| void I_Throw:StdException();

Inside the pipes the exception name follow by return values (or actions) are
listed. The syntax is like so:

        tolua_throws|<exceptionName>[,<ret1>[,<ret2> ... [, <retN>]]]|[<exceptionName>...|]

The return values can by any of the following:
* nil
* message (the exception message, or 'Unknown' if not possible.
* true
* false
* error (can only be used alone, will contain the exception is possible)

In case no return values are specified, it will default to: 'nil, message'.

Example 1: 
----------
Returns 'nil, false' for all exceptions:

        tolua_throws|any,nil,false|

Example 2:
----------
Returns 'nil, message' if a 'std::exception' is thrown:

        tolua_throws|std::exception,nil,message|

Example 3:
----------
If a CEGUI::Exception is thrown, return 'nil, message'.
If any other kind of exception is thrown abort (error).

        tolua_throws|CEGUI::Exception|any,error|