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Thread: UDT-improvement

  1. #1
    thinBasic MVPs ReneMiner's Avatar
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    UDT-improvement

    Udt - improvement

    Just thoughts...:

    The UDTs in tB already have properties and functions.
    Quite good so far.

    What will be next?

    We know from other languages events on GUI-controls (buttons, textboxes etc.) as "_click()", "_gotFocus()".
    Did you know that the UDTs in thinbasic already have EVENTS ?

    Currently there's ._create() and ._destroy() only - but it shows a direction.
    The difference is, event-functions-names in let's say visual basic are composed of the variables name and the event name, not separated by a dot but just like "Button1_Click()".
    How good thinbasic supports already:
    Dim vN  As String ' holds variables name
    Dim eN As String ' holds events name
    
     Call_IfExists "" & vN & eN {(parameters)}
    

    ...
    maybe no PC currently but always a head full of ideas

  2. #2
    thinBasic MVPs ReneMiner's Avatar
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    ...next thought:

    What does the above mean?

    If a variable of some user-defined-type >>UDT<< shall have user-defined-events the variable of our UDT needs a name. Quite simple to provide, just add a Name$-property and if more than one object with this name shall be possible suggest to add an Index-property too.
    Do not get confused: the objects variable-name is not equal to the objects name.
    Check this:

    Type tButton
      Name$ As String
      Index As Long
    End Type
    Dim Buttonvar(123) As tButton
    
    Buttonvar(1).Name$ = "myButton"
    
    The variables name is "Buttonvar", the actual buttons name stored in Buttonvar(1) is "myButton", the variables Index is 1 while the Index of the stored object still remains 0 - not assigned.

    Think...

    to be continued
    maybe no PC currently but always a head full of ideas

  3. #3
    thinBasic MVPs ReneMiner's Avatar
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    ...are you following?

    No matter if the objects in an array are GUI-controls as buttons, textboxes etc. or soldiers, cannons and tanks in the players army or whatever... you will want to store their data in some array.
    Hmm - an array? How can objects of different types be stored in an array you will ask, arrays consist of variables or UDTs that are all the same type.
    You're right. Even if for example all GUI-controls have the same basic properties as position, size, visibility, name and index they all differ somehow. A textbox might have scrollbars and accept keyboard-input while a button only can be clicked. How can we store completely different sized items in an array so it's possible to process them one after the other?
    The solution is simple: store only the pointers of all the objects in the array!

    This will make another property necessary where we can store the information of what type the object at this pointer is.

    [Bold]Type$ As String[/bold]

    Because this is very basic and important information we should find it at the beginning of every items UDT-structure.
    At the beginning: allows us without further calculation to read out the type-name at the pointer that is stored in the above described array.

    So what we have?

    Type tBasicObject
      Type$ As String
      Name$ As String
      Index As Long
    End Type
    
    This is the basic information that all objects will share. Any user-defined-object can be an extension of this basic type

    ...more later
    maybe no PC currently but always a head full of ideas

  4. #4
    thinBasic MVPs ReneMiner's Avatar
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    The next step is to think about should this tBObject (t for Type, B for Base/Basic) be part of core-engine, a Module or just an #Include-File?I guess as #Include should serve as long as there's no hard-coded but only user-defined-events. Also some additional common properties as "Bit-flags, Visible, Enabled, Position (2d or 3d), width, height, (depth)..." can simply be added by the user to his desired kind of base-type.Only be aware to keep Type$,Name$ and Index as the first 3 properties.
    Last edited by ReneMiner; 05-03-2018 at 09:46.
    maybe no PC currently but always a head full of ideas

  5. #5
    thinBasic MVPs ReneMiner's Avatar
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    Now let's order this in a simple example:Assumed our objects are just geometric shapes as triangles, rectangles and circles drawn in 2d.What will all of these have in common?
    Type tBasicShape  ' information of type and identity  Type$ as String  Name$ as String  Index as Long   ' ability to enable and disable events ' like clicking or dragging Enabled as Boolean ' visibility - (if not visible it's not ' necessary to process this object)  Visible as Boolean    ' an individual color  Red as Byte  Green as Byte  Blue as Byte    ' a location where this object will appear  ' we might calculate it somehow so it should  ' be more precise than Integer or Single  PosX as Double  PosY as Double  ' that should be enough properties for the meantime  End Type
    
    For the position we will always use the center of the object and calculate all other points/corners/radius or whatever our object defines in relation to the centers position. Now let's setup the types for 3 kinds of objects:
    Type tShapeRectangle Extends tBasicShape  ' it has 4 corners   CornerX(4) as Double  CornerY(4) as Double ' and it gets drawn it's own way:  Function DrawIt()      '  UseColor (Me.Red, Me.Green, Me.Blue  ' now here we calculate the 4 positions of   ' the corners and draw a rectangular shape  End FunctionEnd TypeType tShapeTriangle Extends tBasicShape  ' has 3 corners  CornerX(3) as Double  CornerY(3) as Double  Function DrawIt()   UseColor (Me.Red, Me.Green, Me.Blue)  ' calculate the corners position and draw    End FunctionEnd TypeType tShapeCircle Extends tBasicShape  Radius As Double  Function DrawIt()  ' guess...  End FunctionEnd Type
    
    ...
    maybe no PC currently but always a head full of ideas

  6. #6
    thinBasic MVPs ReneMiner's Avatar
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    Him, strange, I cannot edit the post above to bring the code in readable lines...

    Nevertheless, continue:

    We have a base type and a few that Extends it. All extensions "know" what type they are of, have Names and Indexes.
    Now we have to think about to collect the pointers of all the object into an array. That will allow to loop and cycle through all our objects, no matter if it's a circle, triangle or rectangle. A layover of the basic-type at the pointer that is stored in the array will inform us about Type, Name and Index already and if we use Dim-Like-syntax it is very easy to call the specific functions and access the properties of the actual type. Only keep in mind if you
     
    Function drawAllObjects()
      ' this is not a Type-Funtion of tBasicType nor of its extensions!
    
      Long i
    
      Dim basicObject  as tBObject At 0
    For i = 1 to Ubound (myPtrs)
      SetAt(basicObject, myPtrs (i))
      ' now call tBasicType-function:
      If basicObject.DrawToCanvas Then Nop
    
    Why like this?
    Inside the function DrawToCanvas we will use dynamic type-declaration of the actual extending type. To make sure it works correctly we have to request the functions result even if we don't need to use it...
    So far.
    Function tBObject.DrawToCanvas()
    ' create layover of the extension at same pointer:
    Local myObject  Like Me.Type$ At Varptr(Me)
    ' now we call drawing function of the actual object
    
    myObject.DrawToCanvas()
    
    '...
    
    OK so far. I hope you understand until here

    Assume we also have functions that check if the mousepointer is currently pointing one of our objects and if left mousebutton goes down we will call:

    Call_IfExists "" & basicObject.Name$ & "_click" (basicObject. Index)
    If we have a rectangle that's Name$ property holds "myRect" then we should have a
    Sub myRect_click(Byval Index As Long)
    ' Index will receive the passed content of tObjectRectangle.Index
    
    End Sub
    
    Hmm...
    How we store the different objects?

    At Heap of course!
    If we would make one array of circles, one for triangles and another one for the rectangles, what you think - will their pointers still be valid after we redim to add or remove one object?
    Surely not. So we have to store every object at heap-memory and save the pointers in some DWord-Array. Pointers will never be negative numbers and there's an arsenal of array-functions contained in thinbasic that are ready to work with pointer-arrays (check help for thincore's Array-Functions that contain parameters as "DWord" and "Ptr")

    Mandatory all objects must be fixed size, means no udt-property must have dynamic arrays. Also for properties that shall contain string-data I would recommend to use DWord's instead and store the desired data at heap.

    ...

    So far, difficult to type all this on a mobile phone, with my next post I will come to the first of my improvement-ideas
    maybe no PC currently but always a head full of ideas

  7. #7
    thinBasic author ErosOlmi's Avatar
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    Quote Originally Posted by ReneMiner View Post
    Him, strange, I cannot edit the post above to bring the code in readable lines...
    http://www.thinbasic.com/community/s...in-forum-rules
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  8. #8
    thinBasic MVPs ReneMiner's Avatar
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    Thanks Eros for reminding me - and everything else

    Now my first idea: we have several objects of different type, some of them have similar properties that others don't have, for example a .Width or .Text-property and those properties shall behave similar so I don't like to repeat writing the same code over and over again I would usually create an UDT (example tWidth) give it some desired functions (like .Enlarge(...) or .Reduce(...) ) and then I create the other UDT and give it a property
    Width As tWidth

    Actually the width is one numeric variable like "Long" only, so if .Width becomes a sub element of another UDT and has functions i have to give the Type tWidth a property lWidth to store the value.
    Type tWidth
      lWidth As Long
      Function Enlarge(Byval howMuch As Long) As Long
      '...
      End Function
    '...
    End Type
    
    Type tButton Extends tBObject
      Width As tWidth
      '...
    End Type
    
    If I want the width of a button I have to use

    myButton.Width.lWidth

    Is there a way that

    myButton.Width can just access the very first/only property of tWidth?
    Can it be that the first property of an UDT|Union is it's default-property?
    Last edited by ReneMiner; 13-03-2018 at 03:09.
    maybe no PC currently but always a head full of ideas

  9. #9
    thinBasic MVPs ReneMiner's Avatar
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    Perhaps like
    Type tType
      Public
      Default
      defaultProperty As Long
      '...
    End Type
    Dim x As tType
    
    Every time if just "x" is used it means to use "x.defaultProperty".
    The default property must be public of course
    maybe no PC currently but always a head full of ideas

  10. #10
    thinBasic MVPs ReneMiner's Avatar
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    Hmm, no reply yet...

    But another question into that direction:
    Could "Heap" be a built-in functional UDT (or module)?
    I mean somewhat like

    Alias DWord As Heap

    where the DWord stores the pointer and we can just use it like
    Dim x(123)As Heap
    X(1).Allocate (nBytes)
     ' equal to currently
    X(1) = Heap_Allocate (nBytes)
    
    but also we could treat X(123) like a DWord-Array at the same time?
    All Heap-functions should be available using dot-notation to a variable declared as heap but actually the array should be treated/stored likewise DWord....

    ???
    maybe no PC currently but always a head full of ideas

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