#31
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Quote:
In order for it to work, you need to figure out the structure of the range object in your example and reserve a buffer with sufficient bytes, for Mem_Copy to dump into. You need to create a 4 byte buffer just like in the scalar routine to receive the bytes you transfer. |
#32
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Slow "comparison/replace" script
Try this instead...
Code:
Option Explicit Public lng_VarPtr As Long Public lng_ObjPtr As Long #If Win64 Then Public Const PTR_LENGTH As Long = 8 #Else Public Const PTR_LENGTH As Long = 4 #End If Public Declare PtrSafe Sub Mem_Copy Lib "kernel32" Alias "RtlMoveMemory" ( _ ByRef Destination As Any, _ ByRef Source As Any, _ ByVal Length As Long) ' Platform-independent method to return the full zero-padded ' hexadecimal representation of a pointer value Function HexPtr(ByVal Ptr As LongPtr) As String HexPtr = Hex$(Ptr) HexPtr = String$((PTR_LENGTH * 2) - Len(HexPtr), "0") & HexPtr End Function Public Function Mem_ReadHex(ByVal Ptr As LongPtr, ByVal Length As Long) As String Dim bBuffer() As Byte, strBytes() As String, i As Long, ub As Long, b As Byte ub = Length - 1 ReDim bBuffer(ub) ReDim strBytes(ub) Mem_Copy bBuffer(0), ByVal Ptr, Length For i = 0 To ub b = bBuffer(i) strBytes(i) = IIf(b < 16, "0", "") & Hex$(b) Next Mem_ReadHex = Join(strBytes, "") End Function Sub pionterToSomething(name As String, lng_Ptr As Long, Length As Long) Debug.Print name & " : 0x"; HexPtr(lng_Ptr); _ " : 0x"; Mem_ReadHex(lng_Ptr, Length) End Sub Sub ExampleForScalar() Dim lngValue As Long lngValue = &HAAAAAAAA lng_VarPtr = VarPtr(lngValue) pionterToSomething "lngValue", lng_VarPtr, 4 End Sub Sub ExampleForObject() Dim objRange As Object Set objRange = ActiveCell lng_ObjPtr = ObjPtr(objRange) pionterToSomething "objRange", lng_ObjPtr, 4 'Set objRange = Nothing End Sub Sub ObjectIsGone() Debug.Print ExampleForObject pionterToSomething "objRange", lng_ObjPtr, 4 End Sub Sub ValueIsGone2() Debug.Print ExampleForScalar pionterToSomething "lngValue", lng_VarPtr, 4 End Sub Last edited by CoolBlue; 06-20-2014 at 03:00 PM. |
#33
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Slow "comparison/replace" script
Maybe this will do it for you...
Create a Custom Class Code:
'Class2 Option Explicit Public i As Long Public j As Long Public k As Long Code:
Const clsBytes As Long = 32 * 4 '/////////////////////////////////// '/////////////////////////////////// Sub ExampleForClass() Dim objCls As Class2 Dim str As String Set objCls = New Class2 objCls.i = &HAAAAAA objCls.j = &HABABAB objCls.k = &HBCBCBC lng_ObjPtr = ObjPtr(objCls) str = PionterToSomething("objCls", lng_ObjPtr, clsBytes) Debug.Print str 'Set objCls = Nothing End Sub '/////////////////////////////////// '/////////////////////////////////// Sub classIsGone() Debug.Print ExampleForClass DoEvents printPionterToSomething "objCls", lng_ObjPtr, clsBytes End Sub No difference. Last edited by CoolBlue; 06-20-2014 at 02:57 PM. |
#34
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Hi CoolBlue
Quote:
Now I gave some more thoughts to the function ObjectFromPointer(). That's because, what do I gain by copying the contents assigned to a pointer? Sure if still pointing to the same object (as in the example with objRange) I can ask if "Nothing" or use a property of the initial object to identify it. But in case the pointer is already assigned something else it will give me a hard time to keep the macro out of trouble. Therefore I wonder if it would make sense to read always a fix parameter of length for example 32 and just compare the results. If they show a difference, it will tell that something else got assigned to the pointer, and that's good enough. Just to avoid missunderstanding: I didn't say, that the reference count doesn't work at all. It's just as Bob put it "there might be circumstances when it doesn't". In the moment we do with simple structures because it's about figuring out a way to keep track on ongoing things within memory. Therefore I'm expecting reference count doing allright and would be dissapointed if failing (though creating a new instance of an object was said in former times might be already to much for automatic deallocation, the same as for not handled errors). |
#35
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Slow "comparison/replace" script
Quote:
Code:
Mem_Copy oTemp, lPtr, 4 Code:
Mem_Copy ObjPtr(oTemp), lPtr, 4 For sure, this will corrupt the structure of oTemp. Then when you do Code:
Set ObjectFromPointer = oTemp But I'm interested that you say you said you can calculate the required bytes... How do you do that? I've been searching for an explanation of the byte structure that VBA uses for storing it's various types: do you have that? Quote:
But anyway, it seems like very start of that structure is always set to zeros when the variable is erased by VBA's memory management. So you can always see that the object has been erased. This is the best indication I've seen so far to show the life cycle of the variable. Here are a few sample runs... Code:
objCls : 0x18E11A58 : 0x04C0031500000000741AE1181C753904047539040000000000000000ECEC831A0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC00F4E9101500000000000000009C0601005FB4AF2E060100802300E7719425E771 objCls : 0x18E11A58 : 0x0000000000000000741AE11800000000000000000000000000000000ECEC831A0100000000000000000000006E1C000000000000AAAAAA00ABABAB00BCBCBC00F4E9101500000000000000009C0601005FB4AF2E060100800D00530041004100 objCls : 0x18E11A58 : 0x04C0031500000000741AE1181C753904047539040000000000000000ECEC831A0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC00F4E9101500000000000000009C0601005FB4AF2E060100802300E7719425E771 objCls : 0x18E11A58 : 0x0000000000000000741AE11800000000000000000000000000000000ECEC831A0100000000000000000000006E1C000000000000AAAAAA00ABABAB00BCBCBC00F4E9101500000000000000009C0601005FB4AF2E060100802300E7719425E771 objCls : 0x18E11A58 : 0x04C0031500000000741AE1181C753904047539040000000000000000ECEC831A0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC00F4E9101500000000000000009C0601005FB4AF2E060100804400E7719425E771 objCls : 0x18E11A58 : 0x0000000000000000741AE11800000000000000000000000000000000ECEC831A0100000000000000000000006E1C000000000000AAAAAA00ABABAB00BCBCBC00F4E9101500000000000000009C0601005FB4AF2E060100801800E7719425E771 Code:
objCls : 0x18E11950 : 0xEC2C0915000000006C19E118648948044C8948040000000000000000ECEC831A0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC000000000004E9101500000000000000003EB4AF2EE50000880000000000000000 after exit... objCls : 0x18E11950 : 0x00000000000000006C19E11800000000000000000000000000000000ECEC831A0100000000000000000000006E1C000000000000AAAAAA00ABABAB00BCBCBC000000000004E9101500000000000000003EB4AF2EE50000880000000000000000 objCls : 0x18E11950 : 0xEC2C0915000000006C19E118648948044C8948040000000000000000ECEC831A0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC000000000004E9101500000000000000003EB4AF2EE50000880000000000000000 Set to Nothing... objCls : 0x18E11950 : 0x00000000000000006C19E11800000000000000000000000000000000ECEC831A0100000000000000000000006E1C000000000000AAAAAA00ABABAB00BCBCBC000000000004E9101500000000000000003EB4AF2EE50000880000000000000000 after exit... objCls : 0x18E11950 : 0x00000000000000006C19E11800000000000000000000000000000000ECEC831A0100000000000000000000006E1C000000000000AAAAAA00ABABAB00BCBCBC000000000004E9101500000000000000003EB4AF2EE50000880000000000000000 Quote:
|
#36
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Here are the results for a circular list compared to a single object...
Single Object Code:
No Cleanup, No Error SingleObject set... objCls : 0x18DECA08 : 0x64C67D1C0000000024CADE18EC577803D45778030000000000000000ECECAE1B0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC00000000002489C3180000000000000000FD3D013B6500008C0000000028000000 after exit... objCls : 0x18DECA08 : 0x000000000000000024CADE1800000000000000000000000000000000ECECAE1B0100000000000000000000006E1C000000000000AAAAAA00ABABAB00BCBCBC00000000002489C3180000000000000000FD3D013B6500008C0000000028000000 With Cleanup, No Error SingleObject set... objCls : 0x18DECA08 : 0x64C67D1C0000000024CADE18EC577803D45778030000000000000000ECECAE1B0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC00000000002489C3180000000000000000FD3D013B6500008C0000000028000000 Set to Nothing... objCls : 0x18DECA08 : 0x000000000000000024CADE1800000000000000000000000000000000ECECAE1B0100000000000000000000006E1C000000000000AAAAAA00ABABAB00BCBCBC00000000002489C3180000000000000000FD3D013B6500008C0000000028000000 after exit... objCls : 0x18DECA08 : 0x000000000000000024CADE1800000000000000000000000000000000ECECAE1B0100000000000000000000006E1C000000000000AAAAAA00ABABAB00BCBCBC00000000002489C3180000000000000000FD3D013B6500008C0000000028000000 With Cleanup, Error after setting the pointer SingleObject set... objCls : 0x18DECA08 : 0x64C67D1C0000000024CADE18EC577803D45778030000000000000000ECECAE1B0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC00000000002489C3180000000000000000FD3D013B6500008C0000000028000000 Set to Nothing... objCls : 0x18DECA08 : 0x000000000000000024CADE1800000000000000000000000000000000ECECAE1B0100000000000000000000006E1C000000000000AAAAAA00ABABAB00BCBCBC00000000002489C3180000000000000000FD3D013B6500008C0000000028000000 After Error, Before End Sub after error... objCls : 0x18DECA08 : 0x8841BF182AA30000712CBB1BDC25BB1BC6D3B71B10000400F88656080000000000000000000000000000000006000000100000005029881C000000005F005F005300520050005F000000000000000000FD3D013B6500008C0000000028000000 No Cleanup, Error after setting the pointer SingleObject set... objCls : 0x18DECA08 : 0x64C67D1C0000000024CADE18B45778039C5778030000000000000000ECECAE1B0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC00000000002489C3180000000000000000FD3D013B6500008C0000000028000000 After Error, Before End Sub after error... objCls : 0x18DECA08 : 0x8841BF182AA30000712CBB1BDC25BB1BC6D3B71B1000040030865608000000000000000000000000000000000600000010000000D82B881C000000005F005F005300520050005F000000000000000000FD3D013B6500008C0000000028000000 Code:
No Cleanup, No Error circularList set... objCls : 0x18DECA08 : 0x64C67D1C0000000024CADE18EC577803D45778030000000000000000ECECAE1B0200000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC00C8CC82182489C3180000000000000000FD3D013B6500008C0000000028000000 after exit... objCls : 0x18DECA08 : 0x64C67D1C0000000024CADE18EC577803D45778030000000000000000ECECAE1B0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC00C8CC82182489C3180000000000000000FD3D013B6500008C0000000028000000 With Cleanup, No Error circularList set... objCls : 0x0DA0DC70 : 0x64C67D1CC8CC82188CDCA00D245878030C5878030000000000000000ECECAE1B0200000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC0000A9B70D2489C31800000000000000005E55B53900000088E073AF1B08179D0D Set to Nothing... objCls : 0x0DA0DC70 : 0x64C67D1CC8CC82188CDCA00D245878030C5878030000000000000000ECECAE1B0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC0000A9B70D2489C31800000000000000005E55B53900000088E073AF1B08179D0D after exit... objCls : 0x0DA0DC70 : 0x64C67D1CC8CC82188CDCA00D245878030C5878030000000000000000ECECAE1B0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC0000A9B70D2489C31800000000000000005E55B53900000088E073AF1B08179D0D With Cleanup, Error after setting the pointer circularList set... objCls : 0x1882CDD0 : 0x64C67D1C00A9B70DECCD8218945878037C5878030000000000000000ECECAE1B0200000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC0078CD82182489C318000000000000000042AC103B000000804400FA171A000000 Set to Nothing... objCls : 0x1882CDD0 : 0x64C67D1C00A9B70DECCD8218945878037C5878030000000000000000ECECAE1B0100000000000000000000000F10000000000000AAAAAA00ABABAB00BCBCBC0078CD82182489C318000000000000000042AC103B000000804400FA171A000000 After Error, Before End Sub after error... objCls : 0x1882CDD0 : 0x0D00E7719425E7717825E7715825E7714825E771000000006890851868908518000000000000000078908518000000000900000000000000000000000000000001000000DCCD821800000000FA050E0042AC103B000000802E00E7719425E771 The detector works... You have to scroll across a bit but you can see that the object is not released when there is a circular reference. Its not released by VBA or by the set to nothing. |
#37
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I should have said: I can imagine you can calculate the required bytes
That is if you've got a simple object and some insight on how objects are stored in memory. But forget about this remark, I hope we don't have to go down this road all the way. The crash with Mem_Copy oTemp, lPtr, 4 when checking afterwards is still some secret to me. (though I might have an idea where it comes from, but I might be wrong so I will put this aside for the moment, furthermore it's not important in the moment). Of course I tried your example with the Class (ever since I trip over your "pionterToSomething" - I should have corrected it but I didn't). What I did change, was "name as string" to "strname as string" - you know why! And, yes, I'm familiar as to the results showing. But let's few our new "tool" - we still facing at least two problems: 1. An ordinary object requires only 4 bytes in memory. If I'm not mistaken, every set object to an object that already exists (without using the keyword "New") only is a number in the range of "As Long". But see the example it makes it clear: Code:
Private Const coBytes As Long = 4 Sub PointsToAnotherObject() Dim objwks As Worksheet Debug.Print Debug.Print ObjPtr(Sheet1) pionterToSomething "Sheet1 ", ObjPtr(Sheet1), coBytes Set objwks = Sheet1 Debug.Print ObjPtr(objwks) pionterToSomething "objwks ", ObjPtr(objwks), coBytes End Sub 2. If memory is freed, we might find "cleared to zero", but there might be something else assigned to the pointer. Up to now it only occured when testing with pointers to a Long-variable, but I think it always can happen. Therefore we better compare - keeping in mind point 1 Just got the message of your new post, I will have a look at it now. But I anyway wanted to say, circular reference in classes - I don't know if you can free memory at all - without closing excel. |
#38
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The SingleObject example:
In the error-cases the pointer is assigned to something else. By the look of it, I tend to say the error-window is stored there since you twice got the same hex-code - is this possible?. Concerning the Circular List, well I don't know what macro is behind. But for the error it's again an error-window? |
#39
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Quote:
But anyway, the Byte Comb link you provided helps a little on that. Quote:
Well, its only a theory and I think it crashes before the line Code:
Set ObjectFromPointer = oTemp I also learned since that the first two options below will crash excel... Code:
Sub crashMem_Copy() Dim lptr As LongPtr ' Mem_Copy lptr, ByVal 0, 4 'crashes excel ' Mem_Copy lptr, ByVal lptr, 4 'crashes excel Mem_Copy lptr, lptr, 4 'is fine End Sub Quote:
Quote:
Code:
Sub getReference() #If Win64 Then Const PTR_LENGTH As Long = 8 #Else Const PTR_LENGTH As Long = 4 #End If Const coBytes As Long = 4 Dim objwks As Worksheet, lptr As LongPtr, objName As String, objwksPtr As LongPtr Debug.Print ' Sheet1 Object reference and first coBytes bytes lptr = objPtr(Sheets(1)): objName = "Sheet1 " Debug.Print PointerToSomething(objName, lptr, coBytes) & vbTab & "using objPtr" ' Using objPtr, can't diferentiate because the reference is resolved before reporting Set objwks = Sheets(1) lptr = objPtr(objwks): objName = "objwks " Debug.Print PointerToSomething(objName, lptr, coBytes) & vbTab & "using objPtr" ' Using varPtr, can diferentiate. ' The local Worksheet Object is treated as a reference, not an Object: the reference is not resolved lptr = VarPtr(objwks): objName = "objwks " Debug.Print PointerToSomething(objName, lptr, coBytes) & vbTab & "using varPtr" ' The contents of the local variable (objwks) is the address of the global object but byte-reversed (little endian) ' Load the reference into a LongPtr type and read back the byte-corrected (big endian) value of the reference Mem_Copy objwksPtr, ByVal VarPtr(objwks), PTR_LENGTH Debug.Print objName & vbTab & "points to: " & "0x" & HexPtr(objwksPtr) ' Can also do this passing objwks as ByRef (default) Mem_Copy objwksPtr, objwks, PTR_LENGTH Debug.Print objName & vbTab & "points to: " & "0x" & HexPtr(objwksPtr) ' Or like this... Mem_Copy ByVal VarPtr(objwksPtr), objwks, PTR_LENGTH Debug.Print objName & vbTab & "points to: " & "0x" & HexPtr(objwksPtr) End Sub Code:
Sheet1 : Address: 0x18240578 : Contents: 0xC0EA4C18 using objPtr objwks : Address: 0x18240578 : Contents: 0xC0EA4C18 using objPtr objwks : Address: 0x002AEF90 : Contents: 0x78052418 using varPtr objwks points to: 0x18240578 objwks points to: 0x18240578 objwks points to: 0x18240578 And here you can see how the local variable's value is zero when its set to nothing... Code:
Sub getReference2() #If Win64 Then Const PTR_LENGTH As Long = 8 #Else Const PTR_LENGTH As Long = 4 #End If Const coBytes As Long = 4 Dim objwks As Worksheet, lptr As LongPtr, objName As String, objwksPtr As LongPtr Debug.Print ' Sheet1 Object reference and first coBytes bytes lptr = objPtr(Sheets(1)): objName = "Sheet1 " Debug.Print PointerToSomething(objName, lptr, coBytes) & vbTab & "using objPtr" ' Using varPtr, can see the local variable is set to nothing. ' The local Worksheet Object is treated as a reference, not an Object: the reference is not resolved lptr = VarPtr(objwks): objName = "objwks " Debug.Print PointerToSomething(objName, lptr, coBytes) & vbTab & "using varPtr, set to Nothing" ' Using objPtr, can't diferentiate because the reference is resolved before reporting Set objwks = Sheets(1) lptr = objPtr(objwks): objName = "objwks " Debug.Print PointerToSomething(objName, lptr, coBytes) & vbTab & "using objPtr" ' Using varPtr, can diferentiate. ' The local Worksheet Object is treated as a reference, not an Object: the reference is not resolved lptr = VarPtr(objwks): objName = "objwks " Debug.Print PointerToSomething(objName, lptr, coBytes) & vbTab & "using varPtr" ' The contents of the local variable (objwks) is the address of the global object but byte-reversed (little endian) ' Load the reference into a LongPtr type and read back the byte-corrected (big endian) value of the reference Mem_Copy objwksPtr, ByVal VarPtr(objwks), PTR_LENGTH Debug.Print objName & vbTab & "points to: " & "0x" & HexPtr(objwksPtr) End Sub Code:
Sheet1 : Address: 0x18240578 : Contents: 0xC0EA4C18 using objPtr objwks : Address: 0x002AEF90 : Contents: 0x00000000 using varPtr, set to Nothing objwks : Address: 0x18240578 : Contents: 0xC0EA4C18 using objPtr objwks : Address: 0x002AEF90 : Contents: 0x78052418 using varPtr objwks points to: 0x18240578 Quote:
In summary, I cant see any reason to set local objects to nothing at the end of a sub. Even if there is an error and the sub doesn't complete normally, or if there are structures that fool the reference counting, everything is still cleaned up in the former and the set to nothing does nothing extra in the latter. I learned a lot from this exercise and added some nice routines to my library, so this has been most interesting! For anyone who wants to run the above routines, here is a .bas file with everything you need... well its .txt but just need to change it to .bas and you can import into a module. Last edited by CoolBlue; 06-22-2014 at 08:38 AM. Reason: added .bas attachment; added outputs from debug window |
#40
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Sorry for the delay, but i kept thinking and thinking ...
Point1: Post #35 I basically share your opinion about the application crash on the attempt to Mem_copy something what doesn't match a 4 Bytes Code. By accident I choose first a range-object (and experienced the crashes), afterwards I changed to a worksheet-object (avoiding crashes I didn't any mem-copy to an object or a variant). I was just looking at the numbers of ObjPtr which are always the same whether you obtain them directly from the object ObjPtr(Sheet1) or from the variable ObjPtr(objwks) Therefore I wondered, why did excel crash, because even with the variable gone I ask at the end of the Copy of ObjPtr(Range("A1")), and since the Range still exists and hasn't changed, what's the problem to copy it? It took me a long time to figure out there is a difference between Range and Worksheet: Whereas Worksheet keeps his pointer throughout the application, this isn't the case with Range. A Range changes its pointer, furthermore the variable (objRange) set to the Range is assigned another pointer. I said the choice was by accident but actually I'm glad about the choice because otherwise it would have led in a complete different direction... Point2: I regret the lack of knowlegde about the architecture of objects and what they look like in memory. I really do, probably it would make things a lot easier knowing about this things. Point3: Quote:
But Yes, I agree, at least for the moment let's depend on the change. Point4: According to Point 4, I agree, memory is freed whether or not the variable is set to Nothing (at least valid for the macros I tried up to now). A surprise to me: Classes are destroyed without explicity destroying them. But I don't agree on this Quote:
Attached the file including 4 tests - as well the CircRef - with some kind of summary. |
#41
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Quote:
I'm surprised that the crashMem_Copy routine in my previous post crashes excel because the destination pointer is fine. Why crash when the source pointer is set to zero? Its only a read... Any thoughts? Quote:
But your link was very helpful, I've seen the byte comb site before but it was good to be reminded of it, it informed my thinking on this. Quote:
Quote:
Its quite simple really, all object life cycle is managed by reference counting: when the reference count goes to zero, the object is scheduled for deletion. There are no no exceptions. I guess this will be a background process that is run when VBARuntime has free time and it will just scan the reference count field in the object table and "Erase" those with zero reference. The ERASE method will not delete the object from the object table, but it will release any memory used by the object's structure. Quote:
The full quote on this is: Quote:
I am saying that setting to nothing does nothing extra in these cases. Im saying it makes no difference. The problem will still be there. I am arguing against using set to nothing remember? As you can see in your example, the result after run-time is the same if you have Code:
Set objcls1 = Nothing Code:
'Set objcls1 = Nothing So, the two points I was trying to argue against are:
And thanks for the attachment... your documentation style is much nicer than mine, I will study it and improve my ways! |
#42
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Quote:
And I remember very well that you argue against - therefore we are here But I enjoy. That way I learn quite a lot about memory, which really is due in regard that obviously MS has improved on the subject. Yeah, the VarPtr of an object - honestly I don't know if it makes sense. I tried to figure out whether the Mem_ReadHex of VarPtr points to the ObjPtr by converting the HexToDec, but was disapointed by the result. Even worse HexToDec comes up with negative figures, so what shall we make of this? Maybe Val("&H"&...) isn't the right tool? Quote:
Documentation is a selfish thing - I know after several days I will end up with x files not knowing anymore what I intended to achieve, just testing, playing, ... But one thing is sure, the time I used formatting the immediate window, I rather would have spent for another output. But for the moment it's ok. Me as well, I spent a lot of time searching the web for information about "memory" and related words, but google misunderstands what I'm looking for, and mostly comes up with things I'm not interested in. |
#43
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Quote:
And yes, I agree, its a good idea to set objects to nothing earlier if you don't need them anymore... but if you are already at the end of the sub then... yep, we agree on that. Quote:
Quote:
The memory image is in a format called little endian. Intel-based systems store bytes little end first so the least significant byte is on the left. You have to flip the bytes to see the true hex value... If you look at the last section of getReference2() in my previous post you will see how that I move the contents of the local pointer (the address of Sheet1) into another LongPtr type called objwksPtr. I can then print out the hex value of that pointer and VBA will interpret it correctly. Code:
01 Sheet1 : Address: 0x1D6DA618 : Contents: 0xC0EA4C18 using objPtr 02 objwks : Address: 0x002AEF90 : Contents: 0x00000000 using varPtr, set to Nothing 03 objwks : Address: 0x1D6DA618 : Contents: 0xC0EA4C18 using objPtr 04 objwks : Address: 0x002AEF90 : Contents: 0x18A66D1D using varPtr 05 objwks points to: 0x1D6DA618 Line 04 is from this... ' Using varPtr, can diferentiate. ' The local Worksheet Object is treated as a reference, not an Object: the reference is not resolved lptr = VarPtr(objwks): objName = "objwks " Debug.Print PointerToSomething(objName, lptr, coBytes) & vbTab & "using varPtr" It produces this image of the contents of the objwks reference 0x18A66D1D Line 05 is from this ' The contents of the local variable (objwks) is the address of the global object but byte-reversed (little endian) ' Load the reference into a LongPtr type and read back the byte-corrected (big endian) value of the reference Mem_Copy objwksPtr, ByVal VarPtr(objwks), PTR_LENGTH Debug.Print objName & vbTab & "points to: " & "0x" & HexPtr(objwksPtr) It produces this image of the contents of the objwks reference 0x1D6DA618 And this is the correct address of the Sheet1 Object But in fact they are the same number but in different formats... 1D6DA618 18A66D1D Ive also attached a couple of pics to try to make it clear... |
#44
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I am attaching a better version for handling the endian-ness...
This version is actually endian-agnostic: I let VBA figure it out and we always get the correct answer. The routine is called Mem_ReadHex_Words. It also allows for 4, 8 or 16 bit words which are required by some data structures. I use the idea of loading the memory image, one word at a time, into a LongPtr Type and then convert the LongPtr to hex. All the underlying byte swapping is taken care of by VBA automatically. |
#45
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Quote:
I will have a look at your files later on, is to say in the evening, still got some other work to do ... |
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