Params := TParams.Create;
WriteLn(Params.Int2.IntVal);
WriteLn(TInteger(Params.FieldAddress('Int2')).IntVal);The third line does not work (the zipped code is attached). On 1/21/24 23:43, Michael Van Canneyt via fpc-pascal wrote:
On Sun, 21 Jan 2024, Amir--- via fpc-pascal wrote:How can I set the value? I tried something like Test := TTest.Create Ptr := Pointer(Test); TSub(Ptr+8) := TSub.Create; But it is not working?Depending on your platform, it can be an alignment issue. Use function TObject.FieldAddress(const name : shortstring) : pointer; This function is used internally by the streaming system (see TComponent.SetReference), so it should always work. Michael.You can use the PVmtFieldTable and PVmtFieldEntry types from the TypInfo unit:=== code begin === program tfield; {$mode objfpc}{$H+} uses TypInfo; type {$M+} TSub = class end; TTest = class published fTest: TSub; end; var vft: PVmtFieldTable; vfe: PVmtFieldEntry; i: SizeInt; begin vft := PVmtFieldTable(PVMT(TTest)^.vFieldTable);Writeln(vft^.Count, ' field(s) with ', vft^.ClassTab^.Count, ' type(s)');for i := 0 to vft^.Count - 1 do begin vfe := vft^.Field[i];Writeln(i, ' -> ', vfe^.Name, ' @ ', vfe^.FieldOffset, ' of type ', vft^.ClassTab^.ClassRef[vfe^.TypeIndex - 1]^.ClassName);end; end. === code end === === output begin === PS C:\fpc\git> .\testoutput\tfield.exe 1 field(s) with 1 type(s) 0 -> fTest @ 8 of type TSub === output end ===Side note: contrary to what I had originally written only classes, but not interfaces are allowed for published fields and they need to have $M enabled.Regards, Sven _______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal_______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal_______________________________________________ fpc-pascal maillist - fpc-pascal@lists.freepascal.org https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
FieldAddress.lpr.gz
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