Referencing New (Constructor)

[Matthew SmithParticipant]

I’m wanting to essentially overload New but rather than having to duplicate code, I’d like to pass onto another New like such:

Monkey

Class Sprite Field Blend:=BlendMode.Alpha Field Color:= New Color( 1,1,1,1 ) Field Images:Image[] Field Enabled:=True Field Frame:=0.0 Field Rotation:=0.0 Field Scale:=New Vec2f( 2,2 ) Field Position:=New Vec2f Method New(image:Image,x:Int,y:Int) Self.New(New Image[](image),x,y) End Method New(images:Image[],x:Int,y:Int) ' Set Self.Images=images Self.Position.X=x Self.Position.Y=y ' Set image properties For Local i:=0 Until Self.Images.Length Self.Images[i].Handle=New Vec2f( .5,.5 ) Next ' Store Sprites.Push(Self) End Method Update() End Method Render(canvas:Canvas) canvas.BlendMode=Self.Blend canvas.Color=Self.Color canvas.DrawImage( Self.Images[Self.Frame],Self.Position,-Self.Rotation,Self.Scale ) End End

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Class Sprite Field Blend:=BlendMode.Alpha Field Color:= New Color( 1,1,1,1 ) Field Images:Image[] Field Enabled:=True Field Frame:=0.0 Field Rotation:=0.0 Field Scale:=New Vec2f( 2,2 ) Field Position:=New Vec2f Method New(image:Image,x:Int,y:Int) Self.New(New Image[](image),x,y) End Method New(images:Image[],x:Int,y:Int) ' Set Self.Images=images Self.Position.X=x Self.Position.Y=y   ' Set image properties For Local i:=0 Until Self.Images.Length Self.Images[i].Handle=New Vec2f( .5,.5 ) Next ' Store Sprites.Push(Self) End Method Update() End Method Render(canvas:Canvas) canvas.BlendMode=Self.Blend canvas.Color=Self.Color canvas.DrawImage( Self.Images[Self.Frame],Self.Position,-Self.Rotation,Self.Scale ) End End

As you can see the first New is calling the second New.  Currently I’m getting the following:

Monkey

MX2CC V0.010 ***** Building app 'D:/Dev/Monkey/Game/Game.monkey2' ***** Parsing... Semanting... Translating... Caught signal:Memory access violation Done.

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MX2CC V0.010   ***** Building app 'D:/Dev/Monkey/Game/Game.monkey2' *****   Parsing... Semanting... Translating... Caught signal:Memory access violation Done.

Been quite a while since I did any Blitz/Monkey coding so a bit rough in remembering this stuff! Too much C# nowadays. Thanks Playniax for the example.

[therevillsParticipant]

In Java you can do something like this(pun!) with ctor chaining:

Monkey

[crayon-5cba14959a447619835852 inline="true" ]class Sprite { public Sprite(float x, float y) { this(x, y, 3); } public Sprite(float x, float y, int lives) { } }

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[crayon-5cba14959a447619835852 inline="true" ]class Sprite {   public Sprite(float x, float y)   {     this(x, y, 3);   }   public Sprite(float x, float y, int lives)   {   } }

[/crayon]

With Monkey I think you need to create a common method or function:

Monkey

[crayon-5cba14959a44c811032891 inline="true" ]Class Player Extends Sprite Field lives:Int Method New(x:Float, y:Float) Init(x, y, 3) End Method New(x:Float, y:Float, lives:Int) Init(x, y, lives) End Method Init(x:Float, y:Float, lives:Int) Self.x = x Self.y = y Self.lives = lives End End

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[crayon-5cba14959a44c811032891 inline="true" ]Class Player Extends Sprite Field lives:Int Method New(x:Float, y:Float) Init(x, y, 3) End Method New(x:Float, y:Float, lives:Int) Init(x, y, lives) End Method Init(x:Float, y:Float, lives:Int) Self.x = x Self.y = y Self.lives = lives End End

[/crayon]

It would be nice to have ctor chaining.

[Matthew SmithParticipant]

@therevills

Thanks for your response – yeah would be a nice to have! But no probs.

C# has a similar option using both this (Self) and base (Super):

Monkey

class Sprite { public Sprite(float x, float y) : this(x, y, 3) { } public Sprite(float x, float y, int lives) { } }

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class Sprite {   public Sprite(float x, float y) : this(x, y, 3)   {   }   public Sprite(float x, float y, int lives)   {   } }

[Mark SiblyKeymaster]

Unfortunately, you’ll currently have to use the ‘Init’ approach for this particular code.

The problem is that you can’t currently have ‘complex’ parameter expressions when you chain new’s together (ie: the ‘New Image[]( image )’ ) – mainly because you can’t in C++, and mx2 New currently maps directly to c++ ctors. Which seemed like a good idea at the time but has proven to have some serious limitations.

I do plan to eventually fix this though, hopefully soon!

[Matthew SmithParticipant]

Ok – thanks Mark!

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