what does ByRef do? Topic is solved

[bigdeal]

hey im newbie and im a little starting to learn ahk, so I read it and still don't understand what it does, can someone explain me quick, thanks in advance btw

[A_AhkUser]

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MyFunc(__param) {
; ...
}
MyFunc(test)
MsgBox % test ; return blank not defined outside the scope of the function

;----------------------------------------

MyFunc(ByRef __param) {
__param := "blabla"
}
MyFunc(test)
MsgBox % test ; return blabla since the use of ByRef causes each parameter to become an alias for the variable passed in from the caller

EDIT*:

You can compare a byrefparameter to the 'outpuvar...' paramater of MouseGetPos command, for exemple:

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MouseGetPos, OutputVarX, OutputVarY, OutputVarWin, OutputVarControl
MsgBox % "the ID of the window under the mous is " . OutputVarWin

and:

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MouseGetPos(OutputVarX, OutputVarY, OutputVarWin, OutputVarControl)
MsgBox % "the ID of the window under the mous is " . OutputVarWin

MouseGetPos(ByRef OutputVarX: "", ByRef OutputVarY:="", ByRef OutputVarWin:="", ByRef OutputVarControl:="", Mode:="") {
	MouseGetPos, OutputVarX, OutputVarY, OutputVarWin, OutputVarControl, % Mode
}

do basically the same.

Hope this helps.

[bigdeal]

OOOOOOOOOOOO so it allows you to use that variable in the function, got it thanks alot man

[A_AhkUser]

OOOOOOOOOOOO so it allows you to use that variable in the function

Yes but note it is also the defnition of the global keywords:

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test := ""

MyFunc() {
global test ;  make test -- create outside the function -- accessible within the scope of the function -- where variable are all impicitly locals -- declaring it as global (see: https://autohotkey.com/docs/Functions.htm#Locals)
test := "bonjour"
}

MyFunc()
MsgBox % test ; returns bonjour

In fact, one of the main advantage of using ByRef is that it allows send back extra results since return can send back only one value.

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test := ""

MyFunc(ByRef __param) {
global test := "bonjour"
__param := 100*3
return 7
}

MsgBox % MyFunc(var) . "," .  test . "," . var ; returns 7,bonjour,300

See also documentation now you got it for other case where it is advantageous to use ByRef parameters.