Operator New Overload
Member operator to overload dynamic memory allocation process part provided by `Operator New Expression` when applying to a UDT (User Defined Type).
Syntax
`
Declare Operator New ( size As UInteger ) As Any Ptr
Declare Operator new[] ( size As UInteger ) As Any Ptr
`
Parameters
`size`
Number of bytes to allocate.
Return Value
A pointer of type Any Ptr to the start of the newly allocated memory.
Description
The member operator `New Overload` overloads the dynamic memory allocation process part provided by the `New Expression` operator when applying to a UDT (User Defined Type). So the user can define its own dynamic memory allocation process part.
But after that, the UDT instance construction process part provided by the `New Expression` operator is not modified.
`New[] Overload` operator is the (one-dimensional) array-version of the `New Overload` operator and overloads the dynamic memory allocation process provided by the `New[] Expression` operator when applying to a UDT (User Defined Type).
Memory allocated with `New Overload` operator must be freed by also defining a `Delete Overload` operator. Memory allocated with `New[] Overload` operator must be freed by also defining a `Delete[] Overload` operator, the array-version of `Delete Overload` operator. You cannot mix and match the different versions of the operators.
Member operators `New Overload`, and `New[] Overload` are always static, even if not explicitly declared (`Static` keyword is unnecessary but allowed). Thus, they do not have an implicit `This` instance argument passed to them (because instance not yet been constructed).
Example
Dynamic allocation displayer for UDT, by using the member operators "New([]) Overload" and "Delete([]) Overload" (very simple example, only for syntax usage):

- displaying of memory allocations: addresses, sizes,
- displaying of memory deallocations: addresses.

`
Type UDTdisplayer
'' user UDT fields:
Dim As Byte b(1 To 1024*1024)
'' display fields:
Public:
Declare Operator New (ByVal size As UInteger) As Any Ptr
Declare Operator Delete (ByVal buf As Any Ptr)
Declare Operator New[] (ByVal size As UInteger) As Any Ptr
Declare Operator Delete[] (ByVal buf As Any Ptr)
Private:
Declare Static Function allocation (ByRef N As String, ByVal size As UInteger) As Any Ptr
Declare Static Sub deallocation (ByRef D As String, ByVal p As Any Ptr)
End Type
Operator UDTdisplayer.New (ByVal size As UInteger) As Any Ptr
Return UDTdisplayer.allocation("New", size)
End Operator
Operator UDTdisplayer.Delete (ByVal buf As Any Ptr)
UDTdisplayer.deallocation("Delete", buf)
End Operator
Operator UDTdisplayer.New[] (ByVal size As UInteger) As Any Ptr
Return UDTdisplayer.allocation("New[]", size)
End Operator
Operator UDTdisplayer.Delete[] (ByVal buf As Any Ptr)
UDTdisplayer.deallocation("Delete[]", buf)
End Operator
Function UDTdisplayer.allocation (ByRef N As String, ByVal size As UInteger) As Any Ptr
Dim As Any Ptr p = Allocate(size)
Print "memory allocation for " & size & " bytes from '" & N & "' at address: " & p
Return p
End Function
Sub UDTdisplayer.deallocation (ByRef D As String, ByVal p As Any Ptr)
Print "memory deallocation from '" & D & "' at address " & p
Deallocate p
End Sub
Dim As UDTdisplayer Ptr pu1 = New UDTdisplayer
Dim As UDTdisplayer Ptr pu2 = New UDTdisplayer[3]
Delete pu1
Delete[] pu2
Sleep
`
Output example:

    memory allocation for 1048576 bytes from 'New' at address: 32677920
    memory allocation for 3145728 bytes from 'New[]' at address: 33775648
    memory deallocation from 'Delete' at address 32677920
    memory deallocation from 'Delete[]' at address 33775648

Aligned memory allocator:

- by using the member operators "New Overload" and "Delete Overload", any created User object is aligned to a multiple of "ALIGN" bytes (256 bytes in this example),
- the real pointer of the allocated memory is saved just above the User pointer, in the padding block.

`
Const ALIGN = 256
Type UDT
Dim As Byte a(0 To 10 * 1024 * 1024 - 1) '' 10 megabyte fixed array
Declare Operator New (ByVal size As UInteger) As Any Ptr
Declare Operator Delete (ByVal buffer As Any Ptr)
Declare Constructor ()
Declare Destructor ()
End Type
Operator UDT.New (ByVal size As UInteger) As Any Ptr
Print " Overloaded New operator, with parameter size = &h" & Hex(size)
Dim pOrig As Any Ptr = CAllocate(ALIGN-1 + SizeOf(UDT Ptr) + size)
Dim pMin As Any Ptr = pOrig + SizeOf(UDT Ptr)
Dim p As Any Ptr = pMin + ALIGN-1 - (CUInt(pMin + ALIGN-1) Mod ALIGN)
Cast(Any Ptr Ptr, p)[-1] = pOrig
Operator = p
Print " real pointer = &h" & Hex(pOrig), "return pointer = &h" & Hex(p)
End Operator
Operator UDT.Delete (ByVal buffer As Any Ptr)
Print " Overloaded Delete operator, with parameter buffer = &h" & Hex(buffer)
Dim pOrig As Any Ptr = Cast(Any Ptr Ptr, buffer)[-1]
Deallocate(pOrig)
Print " real pointer = &h" & Hex(pOrig)
End Operator
Constructor UDT ()
Print " Constructor, @This = &h" & Hex(@This)
End Constructor
Destructor UDT ()
Print " Destructor, @This = &h" & Hex(@This)
End Destructor
Print "'Dim As UDT Ptr p = New UDT'"
Dim As UDT Ptr p = New UDT
Print " p = &h" & Hex(p)
Print "'Delete p'"
Delete p
Sleep
`
Output example:

    'Dim As UDT Ptr p = New UDT'
      Overloaded New operator, with parameter size = &hA00000
      real pointer = &h420020   return pointer = &h420100
      Constructor, @This = &h420100
      p = &h420100
    'Delete p'
      Destructor, @This = &h420100
      Overloaded Delete operator, with parameter buffer = &h420100
      real pointer = &h420020

Dynamic allocation manager for UDT, by using the member operators "New[] Overload" and "Delete[] Overload":

- monitoring of memory allocations/deallocations: addresses, sizes and total memory used,
- detection of abnormal deallocation requests,
- detection of a failed allocation (Allocate() returning null pointer),
- detection of total allocated memory size exceeding a threshold,
- the last two detection cases induces an automatic memory freeing before forcing the program to end.

The principle is to manage a dynamic list of successful allocations, but not yet freed, containing the allocated addresses with their requested sizes:
`
Type UDTmanager
'' user UDT fields:
Dim As Byte b(1 To 1024*1024)
'' manager fields:
Public:
Declare Operator New[] (ByVal size As UInteger) As Any Ptr
Declare Operator Delete[] (ByVal buf As Any Ptr)
Static As UInteger maxmemory
Private:
Static As Any Ptr address()
Static As UInteger bytes()
Static upbound As UInteger
Declare Static Function printLine (ByRef text As String, ByVal index As UInteger, ByVal sign As Integer) As UInteger
Declare Static Sub endProgram ()
End Type
Dim As UInteger UDTmanager.maxmemory = 3 * 1024 * 1024 * 1024
ReDim UDTmanager.address(0)
ReDim UDTmanager.bytes(0)
Dim UDTmanager.upbound As UInteger = 0
Function UDTmanager.printLine (ByRef text As String, ByVal index As UInteger, ByVal sign As Integer) As UInteger
Dim As UInteger total = 0
For I As UInteger = 1 To UDTmanager.upbound
If I <> index OrElse Sgn(sign) > 0 Then
total += UDTmanager.bytes(I)
End If
Next I
Print text, "&h" & Hex(UDTmanager.address(index), SizeOf(Any Ptr) * 2),
If sign <> 0 Then
Print Using " +####.## MB"; Sgn(sign) * Cast(Integer, UDTmanager.bytes(index) / 1024) / 1024;
Else
Print Using "( ####.## MB)"; UDTmanager.bytes(index) / 1024 / 1024;
End If
Print,
Print Using "###.## GB"; total / 1024 / 1024 / 1024
Return total
End Function
Sub UDTmanager.endProgram ()
Do While UDTmanager.upbound > 0
Deallocate UDTmanager.address(UDTmanager.upbound)
UDTmanager.printLine("memory deallocation forced", UDTmanager.upbound, -1)
UDTmanager.upbound -= 1
ReDim Preserve UDTmanager.address(UDTmanager.upbound)
ReDim Preserve UDTmanager.bytes(UDTmanager.upbound)
Loop
Print "end program forced"
Print
Sleep
End
End Sub
Operator UDTmanager.New[] (ByVal size As UInteger) As Any Ptr
Dim As Any Ptr p = Allocate(size)
If p > 0 Then
UDTmanager.upbound += 1
ReDim Preserve UDTmanager.address(UDTmanager.upbound)
ReDim Preserve UDTmanager.bytes(UDTmanager.upbound)
UDTmanager.address(UDTmanager.upbound) = p
UDTmanager.bytes(UDTmanager.upbound) = size
If UDTmanager.printLine("memory allocation", UDTmanager.upbound, +1) > UDTmanager.maxmemory Then
UDTmanager.address(0) = p
UDTmanager.bytes(0) = size
Print
UDTmanager.printLine("memory allocation exceeded", 0, 0)
UDTmanager.endProgram()
End If
Return p
Else
UDTmanager.address(0) = p
UDTmanager.bytes(0) = size
Print
UDTmanager.printLine("memory allocation failed", 0, 0)
UDTmanager.endProgram()
End If
End Operator
Operator UDTmanager.Delete[] (ByVal buf As Any Ptr)
Dim As UInteger found = 0
For I As UInteger = 1 To UDTmanager.upbound
If UDTmanager.address(I) = buf Then
Deallocate buf
UDTmanager.printLine("memory deallocation", I, -1)
For J As UInteger = I + 1 To UDTmanager.upbound
UDTmanager.address(J - 1) = UDTmanager.address(J)
UDTmanager.bytes(J - 1) = UDTmanager.bytes(J)
Next J
UDTmanager.upbound -= 1
ReDim Preserve UDTmanager.address(UDTmanager.upbound)
ReDim Preserve UDTmanager.bytes(UDTmanager.upbound)
found = 1
Exit For
End If
Next I
If found = 0 Then
UDTmanager.address(0) = buf
UDTmanager.bytes(0) = 0
UDTmanager.printLine("deallocation not matching", 0, 0)
End If
End Operator
Print "Message",, "Address" & Space(SizeOf(Any Ptr)), "Size", "Total"
Print
Randomize
Dim As UDTmanager Ptr pu1 = New UDTmanager[CUInt(Rnd() * 256 + 1)]
Dim As UDTmanager Ptr pu2 = New UDTmanager[CUInt(Rnd() * 256 + 1)]
Dim As UDTmanager Ptr pu3 = Cast(UDTmanager Ptr, 1)
Delete[] pu2
Delete[] pu3
Delete[] pu2
Delete[] pu1
Do
Dim As UDTmanager Ptr pu = New UDTmanager[CUInt(Rnd() * 512 + 1)]
Loop
`
Output for fbc 32-bit (maximum dynamic data < 2 GB).
Here, program is stopped because of memory allocation failed:

    Message                     Address       Size          Total

    memory allocation           &h020E0020       +99.00 MB    0.10 GB
    memory allocation           &h083F3020        +3.00 MB    0.10 GB
    memory deallocation         &h083F3020        -3.00 MB    0.10 GB
    deallocation not matching   &h00000001    (    0.00 MB)   0.10 GB
    deallocation not matching   &h083F3020    (    0.00 MB)   0.10 GB
    memory deallocation         &h020E0020       -99.00 MB    0.00 GB
    memory allocation           &h020ED020      +103.00 MB    0.10 GB
    memory allocation           &h087F2020      +106.00 MB    0.20 GB
    memory allocation           &h0F20D020      +230.00 MB    0.43 GB
    memory allocation           &h1D812020      +137.00 MB    0.56 GB
    memory allocation           &h2612C020      +377.00 MB    0.93 GB
    memory allocation           &h3DA30020      +275.00 MB    1.20 GB
    memory allocation           &h4ED40020      +220.00 MB    1.41 GB
    memory allocation           &h5C958020      +229.00 MB    1.64 GB

    memory allocation failed    &h00000000    (  142.00 MB)   1.64 GB
    memory deallocation forced  &h5C958020      -229.00 MB    1.41 GB
    memory deallocation forced  &h4ED40020      -220.00 MB    1.20 GB
    memory deallocation forced  &h3DA30020      -275.00 MB    0.93 GB
    memory deallocation forced  &h2612C020      -377.00 MB    0.56 GB
    memory deallocation forced  &h1D812020      -137.00 MB    0.43 GB
    memory deallocation forced  &h0F20D020      -230.00 MB    0.20 GB
    memory deallocation forced  &h087F2020      -106.00 MB    0.10 GB
    memory deallocation forced  &h020ED020      -103.00 MB    0.00 GB
    end program forced

Output for fbc 64-bit (maximum dynamic data < virtual memory).
Here, program is stopped because of total allocated memory size > 3 GB (adjustable threshold):

    Message                     Address                     Size          Total

    memory allocation           &h0000000001EA5040            +105.00 MB    0.10 GB
    memory allocation           &h00000000087BC040             +93.00 MB    0.19 GB
    memory deallocation         &h00000000087BC040             -93.00 MB    0.10 GB
    deallocation not matching   &h0000000000000001          (    0.00 MB)   0.10 GB
    deallocation not matching   &h00000000087BC040          (    0.00 MB)   0.10 GB
    memory deallocation         &h0000000001EA5040            -105.00 MB    0.00 GB
    memory allocation           &h0000000001EA1040            +155.00 MB    0.15 GB
    memory allocation           &h000000000B9BF040            +165.00 MB    0.31 GB
    memory allocation           &h0000000015ED8040            +382.00 MB    0.69 GB
    memory allocation           &h000000002DCE7040            +458.00 MB    1.13 GB
    memory allocation           &h000000004A6FB040            +255.00 MB    1.38 GB
    memory allocation           &h000000005A607040             +96.00 MB    1.48 GB
    memory allocation           &h000000006061B040            +426.00 MB    1.89 GB
    memory allocation           &h000000007FFF9040            +221.00 MB    2.11 GB
    memory allocation           &h000000008DD03040            +119.00 MB    2.22 GB
    memory allocation           &h0000000095413040            +147.00 MB    2.37 GB
    memory allocation           &h000000009E727040            +217.00 MB    2.58 GB
    memory allocation           &h00000000AC03C040            +334.00 MB    2.91 GB
    memory allocation           &h00000000C0E4B040            +280.00 MB    3.18 GB

    memory allocation exceeded  &h00000000C0E4B040          (  280.00 MB)   3.18 GB
    memory deallocation forced  &h00000000C0E4B040            -280.00 MB    2.91 GB
    memory deallocation forced  &h00000000AC03C040            -334.00 MB    2.58 GB
    memory deallocation forced  &h000000009E727040            -217.00 MB    2.37 GB
    memory deallocation forced  &h0000000095413040            -147.00 MB    2.22 GB
    memory deallocation forced  &h000000008DD03040            -119.00 MB    2.11 GB
    memory deallocation forced  &h000000007FFF9040            -221.00 MB    1.89 GB
    memory deallocation forced  &h000000006061B040            -426.00 MB    1.48 GB
    memory deallocation forced  &h000000005A607040             -96.00 MB    1.38 GB
    memory deallocation forced  &h000000004A6FB040            -255.00 MB    1.13 GB
    memory deallocation forced  &h000000002DCE7040            -458.00 MB    0.69 GB
    memory deallocation forced  &h0000000015ED8040            -382.00 MB    0.31 GB
    memory deallocation forced  &h000000000B9BF040            -165.00 MB    0.15 GB
    memory deallocation forced  &h0000000001EA1040            -155.00 MB    0.00 GB
    end program forced

Dialect Differences

- Only available in the -lang fb dialect.

Differences from QB

- New to FreeBASIC

See also

- `New Expression`
- `Delete Overload`
- `Allocate`