OLE and Widestring
lazarus / 34-Windows

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dseligo · 2020-11-21 16:06

I have a question regarding OLE and Widestring type.

I am creating OLE object, then calling some method with parameters,
something like that:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i var ole:
OleVariant;    sParameter:String;...sParameter:='test_string';ole :=
CreateOLEObject('...ole object...');ole.SomeFunction(sParameter); 
And this doesn't work well.

If instead of variable I use literal string then it works fine:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
ole.SomeFunction('test_string');
I made it working by declaring widestring variable and use it like
this:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i wsParameter
:Widestring;...wsParameter:=sParameter;...ole.Somefunction(wsParameter
); 
My question is: Is there a simpler way to use "String" type variable
to call OLE method? I tried casting, without luck:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
ole.Somefunction(WideString(sParameter));
And here (https://wiki.freepascal.org/Widestring) it says that correct
way is to use UTF8ToUTF16 function from LazUTF8, I tried like that and
it doesn't work either (I get SIGSEGV exception):
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
ole.Somefunction(UTF8ToUTF16(sParameter));
I have this string variable declared elsewhere, and I use it in
multiple places in program so I don't want to declare it as a
Widestring in a first place - I need to convert it before calling OLE
method.

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PascalDragon · 2020-11-21 20:20

Turns out that most of the problems you have (likely) seen where due
to a buggy implementation of the parameter dispatching. I have now
fixed this in trunk (revisions 47516-47519). If you'd please check
whether it works correctly there it would be great and I'd merge that
back to 3.2.1 then (so that it will be in the upcoming 3.2.2).

As a workaround (in 3.2.0 and older) you should indeed best use
WideString variables.

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dseligo · 2020-11-23 10:41

Thanks for help. It is somewhat better but it isn't solved yet.

I enabled DEBUG_COMDISPATCH in ComObj.pas. This is test program I
used:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
proba;uses ComObj, Variants; { $define ws} var ole: OleVariant;   
sPar1,sPar2,sPar3,sPar4,sPar5,sPar6,sPar7:{$ifdef
ws}WideString{$else}String{$endif}; begin  sPar1:='FISKAL 4'; 
sPar2:='98765432109';  sPar3:='19.11.2020 09:09:32';  sPar4:='100'; 
sPar5:='P1';  sPar6:='333';  sPar7:='99.99';   ole := CreateOLEObject(
'Raverus.FiskalizacijaDEV.COM.CentralniInformacijskiSustav');  WriteLn
(ole.ZastitniKodIzracun(sPar1,sPar2,sPar3,sPar4,sPar5,sPar6,sPar7)); 
VarClear(ole);end.
This is the output when parameters are WideString:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
ComObjDispatchInvoke calledComObjDispatchInvoke: @CallDesc = $0044004C
CallDesc^.ArgCount = 7SearchIDs: Searching 1 IDsSearchIDs: Original
name: ZastitniKodIzracun Len: 18SearchIDs: Translated name:
ZastitniKodIzracunSearchIDs: GetIDsOfNames result = 00000000SearchIDs:
ID[0] = 1610743821DispatchInvoke: Got 7 arguments   NamedArgs =
0DispatchInvoke: Params = 0145FF1CDispatchInvoke: Got ref argument
with type = 8 Value = 99.99DispatchInvoke: Params =
0145FF20DispatchInvoke: Got ref argument with type = 8 Value =
333DispatchInvoke: Params = 0145FF24DispatchInvoke: Got ref argument
with type = 8 Value = P1DispatchInvoke: Params =
0145FF28DispatchInvoke: Got ref argument with type = 8 Value =
100DispatchInvoke: Params = 0145FF2CDispatchInvoke: Got ref argument
with type = 8 Value = 19.11.2020 09:09:32DispatchInvoke: Params =
0145FF30DispatchInvoke: Got ref argument with type = 8 Value =
98765432109DispatchInvoke: Params = 0145FF34DispatchInvoke: Got ref
argument with type = 8 Value = FISKAL 4DispatchInvoke: MethodID:
1610743821 InvokeKind: 3f9990122fd1b5fb0abe6bd43b54f94b6
And this is output when parameters are declared as String:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
ComObjDispatchInvoke calledComObjDispatchInvoke: @CallDesc = $0044004C
CallDesc^.ArgCount = 7SearchIDs: Searching 1 IDsSearchIDs: Original
name: ZastitniKodIzracun Len: 18SearchIDs: Translated name:
ZastitniKodIzracunSearchIDs: GetIDsOfNames result = 00000000SearchIDs:
ID[0] = 1610743821DispatchInvoke: Got 7 arguments   NamedArgs =
0DispatchInvoke: Params = 0145FF1CDispatchInvoke: Got argument with
type 8 Value = 100DispatchInvoke: Params = 0145FF20DispatchInvoke: Got
argument with type 8 Value = 100DispatchInvoke: Params =
0145FF24DispatchInvoke: Got argument with type 8 Value =
100DispatchInvoke: Params = 0145FF28DispatchInvoke: Got argument with
type 8 Value = 100DispatchInvoke: Params = 0145FF2CDispatchInvoke: Got
argument with type 8 Value = ZastitniKodIzracunDispatchInvoke: Params
= 0145FF30DispatchInvoke: Got argument with type 8 Value = FISKAL
4DispatchInvoke: Params = 0145FF34DispatchInvoke: Got argument with
type 8 Value = FISKAL 4DispatchInvoke: MethodID: 1610743821
InvokeKind: 3561d46a69e250b902276864552986b40
I couldn't find where "CallDesc" and "Params" are initially set, and I
suspect the problem is there.
One more thing. At the beginning of the procedure ComObjDispatchInvoke
3rd parameter was still '19.11.2020 09:09:32', but after call to the
SearchIDs procedure it was changed to 'ZastitniKodIzracun'.

I can give you needed dll's if you are willing to further debug this
problem.

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PascalDragon · 2020-11-23 22:01

Quote from: dseligo on November 23, 2020, 11:41:53 amThanks for help.
It is somewhat better but it isn't solved yet.

I enabled DEBUG_COMDISPATCH in ComObj.pas. This is test program I
used:
Add {$mode objfpc}{$H+} at the top. By default FPC uses String =
ShortString and those indeed don't work. (I've tested your code and I
can reproduce your findings only with ShortStrings)

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dseligo · 2020-11-24 01:40

You are right, that was the problem.

These are results with those compiler directives:
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
ComObjDispatchInvoke calledComObjDispatchInvoke: @CallDesc = $0044004C
CallDesc^.ArgCount = 7SearchIDs: Searching 1 IDsSearchIDs: Original
name: ZastitniKodIzracun Len: 18SearchIDs: Translated name:
ZastitniKodIzracunSearchIDs: GetIDsOfNames result = 00000000SearchIDs:
ID[0] = 1610743821DispatchInvoke: Got 7 arguments   NamedArgs =
0DispatchInvoke: Params = 0145FF1CTranslating var ansistring argument
99.99DispatchInvoke: Params = 0145FF20Translating var ansistring
argument 333DispatchInvoke: Params = 0145FF24Translating var
ansistring argument P1DispatchInvoke: Params = 0145FF28Translating var
ansistring argument 100DispatchInvoke: Params = 0145FF2CTranslating
var ansistring argument 19.11.2020 09:09:32DispatchInvoke: Params =
0145FF30Translating var ansistring argument 98765432109DispatchInvoke:
Params = 0145FF34Translating var ansistring argument FISKAL
4DispatchInvoke: MethodID: 1610743821 InvokeKind:
3f9990122fd1b5fb0abe6bd43b54f94b6

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PascalDragon · 2020-11-24 12:36

Quote from: dseligo on November 24, 2020, 02:40:13 amYou are right,
that was the problem.
Okay, then I'll make sure that the fixes I've done are merged to 3.2.1
so that they'll be in 3.2.2.