BRL.Hook: Functions Modinfo Source  

Hook functions

This module provides a generic way to hook into various BlitzMax commands, and to add support for hooks into your own code.

The following hook ids are currently used by BlitzMax modules:
Hook idDescriptionHook data
FlipHookA Max2D Flip is about to occurNull
EmitEventHookAn event has been emitted by a call to EmitEventAn event object
To hook into any of these functions, use AddHook with the specified hook id and your hook function.

To provide hook support for your own code, use AllocHookId to generate a valid integer hook id somewhere in your program's startup code. Then, when the section of code you would like to be 'hookable' is about to execute, simply call RunHooks with the previously generated hook id and your own custom 'data' object.

Functions

Function AddHook( id,func:Object( id,data:Object,context:Object ),context:Object=Null,priority=0 )
ReturnsA hook object that can be used with the RemoveHook command.
DescriptionAdd a hook function.
InformationAdd a hook function to be executed when RunHooks is called with the specified hook id.
Example
'This function will be automagically called every Flip
Function MyHook:Object( id,data:Object,context:Object )
	Global count
	
	count:+1
	If count Mod 10=0 Print "Flips="+count
	
End Function

'Add our hook to the system
AddHook FlipHook,MyHook

'Some simple graphics
Graphics 640,480,0

While Not KeyHit( KEY_ESCAPE )

	Cls
	DrawText MouseX()+","+MouseY(),0,0
	Flip

Wend

Function AllocHookId()
ReturnsAn integer hook id.
DescriptionAllocate a hook id.
InformationThe returned hook id can be used with AddHook, RunHooks and RemoveHook.

Function RemoveHook( id,func:Object( id,data:Object,context:Object ),context:Object=Null )
DescriptionRemove a hook function.
InformationRemoves the hook function specified by id, func and context.

Function RunHooks:Object( id,data:Object )
ReturnsThe data produced by the last hook function.
DescriptionRun hook functions.
InformationRunHooks runs all hook functions that have been added for the specified hook id.

The first hook function is called with the provided data object. The object returned by this function is then passed as the data parameter to the next hook function and so on. Therefore, hook functions should generally return the data parameter when finished.

Module Information

Version1.01
AuthorMark Sibly
LicenseBlitz Shared Source Code
CopyrightBlitz Research Ltd
ModserverBRL
History1.01 Release
HistoryAdded Context parameter to RemoveHook function