COM library once again
lazarus / 67-Windows

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korba812 · 2024-10-13 19:30

I am playing around with creating a COM library and have some
questions/ doubts.

1. The dispinterface generated with "Import Type Library" tool
contains methods from parent interfaces.
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 // IDemo :
IDemo - demo interface  IDemo = interface(IDispatch) 
 ['{B621769D-04FD-420C-AFDD-35227C29B9BF}']    // DoSomething : Do
something with DemoEmu1    function DoSomething(SomeValue:DemoEnum1):
WideString;safecall;  end;  // IDemo : IDemo - demo
interface  IDemoDisp = dispinterface 
 ['{B621769D-04FD-420C-AFDD-35227C29B9BF}']    // QueryInterface :   
 procedure QueryInterface(var riid:{!! GUID !!} OleVariant;out
ppvObj:{!! Ppointer !!} OleVariant);dispid 1610612736;    // AddRef :
  function AddRef: LongWord;dispid 1610612737;    // Release :   
 function Release: LongWord;dispid 1610612738;    // GetTypeInfoCount
:     procedure GetTypeInfoCount(out pctinfo:UInt);dispid 1610678272; 
  // GetTypeInfo :     procedure
GetTypeInfo(itinfo:UInt;lcid:LongWord;out pptinfo:{!! Ppointer !!}
OleVariant);dispid 1610678273;    // GetIDsOfNames :     procedure
GetIDsOfNames(var riid:{!! GUID !!} OleVariant;var rgszNames:{!!
PShortInt !!} OleVariant;cNames:UInt;lcid:LongWord;out
rgdispid:Integer);dispid 1610678274;    // Invoke :     procedure
Invoke(dispidMember:Integer;var riid:{!! GUID !!}
OleVariant;lcid:LongWord;wFlags:Word;var pdispparams:{!! DISPPARAMS
!!} OleVariant;out pvarResult:OleVariant;out pexcepinfo:{!! EXCEPINFO
!!} OleVariant;out puArgErr:UInt);dispid 1610678275;    // DoSomething
: Do something with DemoEmu1    function
DoSomething(SomeValue:DemoEnum1): WideString;dispid 0;  end; Are they
needed? I get warnings during compilation.
Code: [Select]comdemo_1_0_tlb.pas(68,14) Warning: An inherited method
is hidden by "QueryInterface(var OleVariant;out OleVariant);"
comdemo_1_0_tlb.pas(74,14) Warning: An inherited method is hidden by
"GetTypeInfoCount(out LongWord);"
comdemo_1_0_tlb.pas(76,14) Warning: An inherited method is hidden by
"GetTypeInfo(LongWord;LongWord;out OleVariant);"
comdemo_1_0_tlb.pas(78,14) Warning: An inherited method is hidden by
"GetIDsOfNames(var OleVariant;var OleVariant;LongWord;LongWord;out
LongInt);"
comdemo_1_0_tlb.pas(80,14) Warning: An inherited method is hidden by
"Invoke(LongInt;var OleVariant;LongWord;Word;var OleVariant;out
OleVariant;out OleVariant;out LongWord);"

2. When compiling methods that are in safecall convention, I get a
warning that the function result is not set. I understand that such a
method is converted to a function resturned of type HRESULT, is
wrapped in try..except, etc. So why this warning?
Code: [Select]udemo.pas(43,16) Warning: Function result does not seem
to be set
Same warning occurs when compiling:
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
Project1; procedure Foo; safecall;beginend; beginend. Code:
[Select]project1.lpr(3,11) Warning: Function result does not seem to
be set

3. Is there a generally accepted way to communicate additional
information about failure/error/exception of a method call? The
information provided by IErrorInfo is insufficient and I would like to
provide more information. Probably this can be done in many ways.