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Opened 18 months ago

#3938 new Feature Request

ByRef inside the same scope

Reported by: mars(autoit.de) Owned by:
Milestone: Component: AutoIt
Version: Severity: None
Keywords: ByRef Cc:

Description

; Feature Request:
; -------------------------------
; ByRef inside the same scope
; -------------------------------

; The Code below is just "one" example that I encountered lately.
; The description of the problem/request is inside the comments.
; The Code is only there to show the problem, it will not run.


; Example:
; You have a Geometry consisting of Vertices, Indices, Colors, etc.
Func Geometry()
	Local $aVertex[3] = [0, 1, 2] ; xyz coordinates
	Local $aVertices = [$aVertex1, $aVertex2, ...]
	Local $aTriangle[3] = [0, 1, 2] ; Indices of 3 vertices inside $aVertices
	Local $aIndices = [$aTriangle1, $aTriangle2, ...]
	Local $aRGB = [0.5, 0.6, 0.7] ; RGB Color
	Local $aColors = [$aRGB1, $aRGB2, ...] ; One Color for every Triangle
	Local $aGeo = [$aVertices, $aIndices, $aColors]
	Return $aGeo
EndFunc

Func ProjectOnSphere(ByRef $aGeo)
	; To do anything without copying, you will need to wrap things inside a function:
	__ProjectOnSphere($aGeo[0])
EndFunc

Func __ProjectOnSphere(ByRef $aVertices)
	; To do anything without copying, you will need to wrap things inside a function again:
	For $i = 0 To UBound($aVertices) - 1 Step 1
		VertexNormalize($aVertices[$i])
	Next
EndFunc

Func VertexNormalize(ByRef $aVertex) ; 3rd layer of functioncalls
	Local $l = $aVertex[0]^2 + $aVertex[1]^2 + $aVertex[2]^2
	$aVertex[0] /= $l
	$aVertex[1] /= $l
	$aVertex[2] /= $l
EndFunc

; The problems now are:
; - The arrays can be expensive to copy (10 vertices? ok, 1000 vertices -> not ok) so you MUST use functions to access byref functionality
; - What if you have a "Group of Geometries" (an Array of "Geometry") -> you will need more and more layers of wrapping then because you cannot access anything directly
; - The Overhead is always a tradeoff between copying something (this may be good for vertices because they are only of type Array[3]) and using another layer of functions
; - There is code duplication or many function parameters (to pass down previous calculated stuff that is needed in the lower levels) this way.

; ----------------------------------------------------------------
; Suggestion: ByRef inside the same scope.
; ----------------------------------------------------------------
; - Makes functions that are only used for their ByRef obsolete
; - Improves readability
; - Improves performance (the code has less overhead, so it will propably be faster)
; - Greatly improves the comfort when dealing with nested arrays
; ----------------------------------------------------------------

; Example usage (with the above example):
Func ProjectOnSphere(ByRef $aGeo) ; -> You can pass the Geometry directly -> Minus 1 Layer of calls
	Local ByRef $aVertices = $aGeo[0] ; Syntax suggestion 1: "Local ByRef $var1 = $var2", another variation would be "Local $var1 = ByRef $var2"
	Local ByRef $aVertex              ; Syntax suggestion 2: "Local ByRef $var1" -> works like a function ByRef Parameter.
	Local $l ; normal local var
	For $i = 0 To UBound($aVertices) - 1 Step 1
		$aVertex = $aVertices[$i] ; You can access the internals directly -> Minus 1 Layer of calls
		$l = $aVertex[0]^2 + $aVertex[1]^2 + $aVertex[2]^2
		$aVertex[0] /= $l
		$aVertex[1] /= $l
		$aVertex[2] /= $l ; $aGeo is updated automatically without any copying or any additional function calls.
	Next
EndFunc

; I know that the parentheses symtax can be used to access nested arrays, but it only works for "read" access.
Global $a[3], $b = [$a, $a, $a]
($b[0])[0] = 1 ; this does not work
ConsoleWrite(($b[0])[0] & @CRLF) ; this works
; enabling write access here would propably also help a lot, but adding ByRef is far superior


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