Tim Chilvers

Hi, I am in the process of writting a plugin system for my application and would like to return a dynamic array of interfaces from the plugin DLLs. The function that is returning the array is below function TTestWizard.GetCategories(var ArrayCount: Integer): Pointer; var LArray: TArray<IProjectItemCategory>; LManager: IProjectItemCategoryServices; LCategory: IProjectItemCategory; begin SetLength(LArray, 0); LManager := Services as IProjectItemCategoryServices; if LManager <> nil then begin LCategory := LManager.FindCategory('New'); LArray[0] := LCategory; ArrayCount := Length(LArray); Result := LArray[0]; end; end; However when I'm trying to run a comparison of the returned interface fields I am getting an AV: To method that does the work, calls the function, loops through the array and adds the resulting data to a TList<> procedure TProjectItemDialog.TreeViewFocusChanged(Sender: TBaseVirtualTree; Node: PVirtualNode; Column: TColumnIndex); function IsGalleryCategory(const ACategory: IProjectItemCategory; const AIdString: string): Boolean; begin Result := (ACategory <> nil) and (ACategory.IdString = AIdString); end; function IsInGalleryCategories(const ACategories: TArray<IProjectItemCategory>; const AIdString: string): Boolean; var LArrayCount: Integer; begin Result := False; if ACategories <> nil then begin for LArrayCount := Low(ACategories) to High(ACategories) do begin Result := IsGalleryCategory(ACategories[LArrayCount], AIdString); if Result then begin Exit; end; end; end; end; var LData: PCategoryNodeData; LServices: IWizardServices; LCount: Integer; LCategoryCount: Integer; LWizard: IProjectItemWizard; LCategory: IProjectItemCategory; LCategories: TArray<IProjectItemCategory>; LPtrArrayData: Pointer; begin WizardControlList.ItemCount := 0; try FWizardList.Clear; LData := GetNodeData(Node); if LData <> nil then begin LServices := Services as IWizardServices; if LServices <> nil then begin for LCount := 0 to LServices.WizardCount - 1 do begin if Supports(LServices.Wizard[LCount], IProjectItemWizard, LWizard) then begin LCategory := LWizard.Category; // LCategories := LWizard.Categories; LCategoryCount := 0; LWizard.GetCategories(LPtrArrayData, LCategoryCount); SetLength(LCategories, LCategoryCount); Move(LPtrArrayData^, LCategories[0], LCategoryCount); if IsGalleryCategory(LCategory, LData.Id) or IsInGalleryCategories(LCategories, LData.Id) then begin FWizardList.Add(LWizard); end; end; end; end; end; finally WizardControlList.ItemCount := FWizardList.Count; end; end; The AV is happening in the function IsGalleryCategory when it is being called by IsInGalleryCategories. If I change to using another function within the DLL to return a TArray<IProjectItemCategory> then everything works correctly. The reason for trying to resurn an array like this is so I can allow people to develop plugins for my application without having to rely on them using Delphi Tim

Hi Remy, Thanks for the help, this works perfectly both as an "internel" plugin and also via a DLL. I had to make a slight change to the VarArrayCreate call as it wanted the parameters to be: VarArrayCreate([0, 1], varUnknown). This maybe different as I am using Delphi 10.4.2