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mikep
Joined: 24 Sep 2005
Posts: 765
Location: Austin, TX
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Posted: 19 February 2006, 23:48 PM Post subject: Suggested Enhancement: VB Structures |
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It would seem that there is enough support in both the compiler and the runtime to add ZBasic language support for Visual Basic like structures.
Under the covers it could be implemented by the compiler using an array of bytes with temporary variable aliases for each data element. This means that there may be some restrictions such as they are fixed in size, can only be passed ByRef to routines and cannot contain strings. The compiler needs to generate the alias variables for each place a variable is declared that uses a structure type including parmaters. But this does not result in any additional memory usage.
Perhaps Don has already thought of this idea but has not yet implemented it in the compiler. The advantage of course is that the VM does not need to be changed. Here is some example code of how it might be used: | Code: | Public Structure MotorControl
Public Speed as Integer
Public Turn as Integer
Public Brake as Boolean
End Structure
Public Sub Main()
Dim control as MotorControl
Do
Call SenseInputs()
control.Speed = 5
control.Turn = 2
control.Brake = false
Call DriveMotor(control)
Loop
End Sub
Public DriveMotor(ByRef c as MotorControl)
End Sub |
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dkinzer
Site Admin
Joined: 03 Sep 2005
Posts: 2493
Location: Portland, OR
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Posted: 20 February 2006, 1:39 AM Post subject: |
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| Quote: | | It would seem that there is enough support in both the compiler and the runtime to add ZBasic language support for Visual Basic like structures. |
That is on the list and some of the supporting infrastructure already exists in the compiler internals. The address of the structure members resolves to the address of the parent structure plus a fixed offset. The most significant work yet to be done is with the type checking system.
Structures could be passed by value in the same way that String variables are. Internally, a reference is passed but the structure is read-only in the called routine and neither it nor any of its members can be passed by reference to other routines. |
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victorf
Joined: 01 Jan 2006
Posts: 342
Location: Schenectady, New York
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Posted: 20 February 2006, 2:21 AM Post subject: |
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I agree with mikep about the need for Structures in ZBasic. I was suprised and somewhat mystified to find that the language did not have them. When programming in VB and Delphi I am contantly using Structures/Records. I am happy to hear that they are "on the list". 
Vic |
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stevech
Joined: 23 Feb 2006
Posts: 656
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Posted: 23 February 2006, 20:44 PM Post subject: |
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| yeah, lack of structures is kind of like going without shoes - slower going. |
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