Eachin is not by reference?

[DiffrenzyKeymaster]

I find it confusing that Eachin seems to work on a copy of my collection and not looping through it as I expect it to, like it does im monkey-x and c#

Is this intended behaviour, and where do I read about it?

Example:

Monkey

Local points:= New Vec2f[2] points[0].x=10 points[0].y=10 points[1].x=20 points[1].y=20 Local off:= New Vec2f(7,6) ' this one works 'For Local i:Int = 0 Until points.Length ' points[i] +=off 'next For Local p:=Eachin points p +=off next For Local p:=Eachin points Print "Result : " + p.x + " , " + p.y next

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Local points:= New Vec2f[2]   points[0].x=10 points[0].y=10 points[1].x=20 points[1].y=20   Local off:= New Vec2f(7,6)         ' this one works 'For Local i:Int = 0 Until points.Length ' points[i] +=off 'next For Local p:=Eachin points p +=off next For Local p:=Eachin points Print "Result : " + p.x + " , " + p.y next

[codifiesParticipant]

looks like you’re changing a local variable p not items in points…

see the Icontainer “interface” documentation, it shows you the code eachin gets converted into.

[DiffrenzyKeymaster]

looks like you’re changing a local variable p not items in points…

Yes, that’s what going on. However this Monkey-x code treats the p as a reference:

Monkey

Strict Class Vec2f Field x:Float Field y:Float Method New(x:Float,y:Float) Self.x = x Self.y = y End Method End Class Function Main:int() Local points:Vec2f[2] points[0] = New Vec2f points[1] = New Vec2f points[0].x=10 points[0].y=10 points[1].x=20 points[1].y=20 Local off:= New Vec2f(7,6) ' this one works 'For Local i:Int = 0 Until points.Length ' points[i] +=off 'next For Local p:=Eachin points p.x += off.x p.y += off.y next For Local p:=Eachin points Print "Result : " + p.x + " , " + p.y Next Return 0 End Function

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Strict   Class Vec2f Field x:Float Field y:Float Method New(x:Float,y:Float) Self.x = x Self.y = y End Method End Class     Function Main:int()     Local points:Vec2f[2] points[0] = New Vec2f points[1] = New Vec2f points[0].x=10 points[0].y=10 points[1].x=20 points[1].y=20 Local off:= New Vec2f(7,6)         ' this one works 'For Local i:Int = 0 Until points.Length ' points[i] +=off 'next For Local p:=Eachin points p.x += off.x p.y += off.y next For Local p:=Eachin points Print "Result : " + p.x + " , " + p.y Next Return 0 End Function

 

[nerobotParticipant]

The difference (not your nickname:) ) is: in mx2 vec2f is a struct but it is a class in mx1. struct is copied when assign it to var.

If you define vector as a class in mx2 it will be changed by the way you shown above.

[DiffrenzyKeymaster]

Thanks nerobot. That makes sense, and explains the behaviour.

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