Incorrect parameter for custom event handler

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  • 1. Creating a new event
    Hi everybody, I'm creating a component and i would like to add an event, this event will work when a private var of my class change, (for example a integer) is it possible, how? I looking information in internet but i can find anything. Thanks.
  • 2. Addressing event at run time
    Hello, In CPPB 6 I made a custom control class named TMyDBGrid derived from TDBGrid. Then I declared a new event handler declaration: class TMyDBGrid; typedef void __fastcall (__closure *TCustomizeMyDBGrid)(System::TObject* Sender, TMyDBGrid * Grid); class PACKAGE TMyDBGrid : public TDBGrid { ... __published: _property TCustomizeMyDBGrid OnCustomizeGrid = {read=FOnCustomizeGrid, write=FOnCustomizeGrid}; }; It works fine so that I can use it normally in my projects. Now I need to assign possible different events at run-time, into end-user projects: class TFormBase : public TForm { ... __published: // IDE-managed Components void __fastcall CustomizeGrid1(TObject *Sender, TMyDBGrid *Grid); void __fastcall CustomizeGrid2(TObject *Sender, TMyDBGrid *Grid); etc... } But am not able to proceed when I try to do this: MyDBGrid->OnCustomizeGrid = CustomizeGrid1; or: MyDBGrid->OnCustomizeGrid = (TCustomizeMyDBGrid) CustomizeGrid1; After many attempts with different casting and/or addressing options, I concluded that I am still. Any suggestion? Regards, Giovanni Benintende
  • 3. Weird behavior in CB2007 with function calls
    Sorry for the cross post. Hi, This is very odd. I've created a component X inherited from TScrollbox, with a function foo. The component is in a package and installed. (the component has been ported from bcb6.0). When i call the func from a test application, as in MyX->Foo, the compiler takes me to some point half way in the function? If i rename the function to foo1, re-build both the package and the app, and call MyX->Foo1, then all is well, and from the debugger i can see the function is being called from the top. However, if i rename back to Foo, and re-build both the package and the test app, again, when tracking with the debugger, i'm taken to the middle of the function?? I've seen this behaviour when you re-build a package, and re-run an app that uses this package without re-compiling the app - but naturally this goes away when the app is re-built. But I don't understand what's happening here on this new compiler, and how i can rebuild my component set without having to rename ally the functions? Thanks tom.

Incorrect parameter for custom event handler

Postby Myles Rippenhagen » Wed, 26 Oct 2005 02:43:50 GMT

Hi,

I have created several custom components and generally have had great 
success with them, but I am currently running into a problem where when I 
double-click on a published custom event (on the "Events" tab of the "Object 
Inspector" in the IDE), the inserted method declaration contains the wrong 
variable name.  The signature matches another, similar custom event, and it 
seems to be picking up the parameter name from this other definition.  I 
have double-checked that I am referencing the correct typedef in the 
definition of my custom component and I didn't see any problem.  I am using 
BCB6 Enterprise on WinXP.  Following are the important bits of the code.

...
typedef void __fastcall (__closure *BeforePostEvent) (TObject* Sender, bool 
&CanPost);
typedef void __fastcall (__closure *OnPutToDatabaseEvent) (TObject* Sender, 
bool &DoDefault);
...
private:
   OnPutToDatabaseEvent FOnPutToDatabaseEvent;
...
__published:
   __property OnPutToDatabaseEvent OnPutToDatabase = 
{read=FOnPutToDatabaseEvent, write=FOnPutToDatabaseEvent};
...

When I double-click on the "OnPutToDatabase" event in the IDE, the inserted 
code labels the bool parameter "CanPost" instead of "DoDefault".  It appears 
to just pick up the first typedef with a matching signature instead of using 
the typdef that I specified.

Any suggestions??



Re: Incorrect parameter for custom event handler

Postby Remy Lebeau (TeamB) » Wed, 26 Oct 2005 03:12:24 GMT







That is a long-standing known issue.  The OI matches events by signatures
only, not names.  You have two different events that have the exact same
signature (return value, calling convention, parameter data types, and
parameter ordering).  The OI always generates code using the first event
type that matches the required signature.


That is exactly why you are seeing what you have described.  There is
nothing you can do to prevent the OI from behaving that way.  You will just
have to change the signature of one of your events so that they no longer
match each other.


The OI does not care about typedefs.  It only cares about signatures.


Gambit



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