What does the compiler do when translating "procedure ... message" ?

I need to know this as I want to create a non-GUI workalike of the TApplication class that can do things like "TTimer" "TThread.Synchronize", Message events, etc, using Windows messages in Windows (for testing purpose) and system V message queues in Linux.

-Michael

afaict it does the same as delphi does, puts them in some form of table which is used by the dispatch method in tobject (which on delphi at least is called from wndproc which is called from mainwindowproc which is registered as the window procedure for the window and hence called by windows when the mainloop calls the windows api function dispatchmessage).

Thanks a lot for your answer.

That is the result of what is happening. Most of it is done by the library (the compiler can't do this by itself), and I am trying to use some home-brew library functions here.

What I wanted to know is how the compiler does this (or how I can find out what exactly it does).

I _assume_ that when it sees "procedure ... message" the compiler in the "initialization" section generates a call to a library function that is supposed to register the message with the procedure. I need to know the name of this function so that I can do it in my new library.

I suppose in the end WidgetSet.AddEventHandler is called, but as the compiler does not know about a WidgetSet object that is created by the initialization of the RTL done by the library, I suppose some mechanism in the library is catching the stuff the compiler magic creates for "procedure ... message".

-Michael

I see you are still a bit lost. Maybe the documentation can help: http://www.freepascal.org/docs-html/ref/refsu24.html

Vincent

>>>

That is the result of what is happening. Most of it is done by the library (the compiler can't do this by itself), and I am trying to use some home-brew library functions here.

What I wanted to know is how the compiler does this (or how I can find out what exactly it does).

I _assume_ that when it sees "procedure ... message" the compiler in the "initialization" section generates a call to a library function that is supposed to register the message with the procedure. I need to know the name of this function so that I can do it in my new library. <<<<

Your assumption is totally wrong. What happens is that the compiler creates an try in the message table of the RTTI for the class. Check out the implementation of Tobject.Dispatch to see how that is used.

Cheers,
Thorsten

I see you are still a bit lost. Maybe the documentation can help: http://www.freepascal.org/docs-html/ref/refsu24.html

I in fact am lost (as I still don't dare to try to look into the compiler's source code).

Unfortunately the docs text does not say what code the compiler generates to make the library assign the message to the function it generates from the users source code.

-Michael

What happens is that the compiler creates an try in the message table of the RTTI for the class. Check out the implementation of Tobject.Dispatch to see how that is used.

Thanks. That seems to give me a clue. I have no idea what "creates a try" means but maybe I'll find out.

Thanks again,

-Michael

That is because the compiler doesn't generate that code.

Somewhere user code must call
   MyObject.Dispatch(MyMessage);

See implementation of dispatch. It gets the message number and looks for the corresponding method in a table. The compiler generates this table at compile time.

This may not be the completely accurate description, but this is how I model things in my mind and in my experiments reality hasn't falsified this model.

Vincent

"creates an entry" most probably.

Micha

Thanks. That seems to give me a clue. I have no idea what "creates a try" means but maybe I'll find out.

Should have been "an entry".

See implementation of dispatch. It gets the message number and looks for the corresponding method in a table. The compiler generates this table at compile time.

Thanks. I did try to find it but am lost up till now. regarding Thorsten's message I assume it is a member function to some class (e.g. TObject), but my usual means to find such functions don't show it to me.

This may not be the completely accurate description, but this is how I model things in my mind and in my experiments reality hasn't falsified this model.

I do believe that you are right. Thorsten's hint that the compiler moves the information in the RTTI might point into the the correct direction, but up I still need to find out what the exactly RTTI contains and how to extract it from there.

-Michael

Thorsten Engler wrote

> Thanks. That seems to give me a clue. I have no idea what > "creates a try" means but maybe I'll find out. > Should have been "an entry"

Sorry for not guessing this :-\ .

Now I need to find out what exactly it puts into the RTTI and how to extract it from there.

Also I failed to find the implementation of TObject.Dispatch. Have you any hint where to search ?

Thanks again,
-Michael

"creates an entry" most probably.

Right. Thanks.
-Michael (not a native speaker :-( )

Also I failed to find the implementation of TObject.Dispatch. Have you any hint where to search ?

Sorry.

Found it !

Thanks again.

-Michael

Thanks. I did try to find it but am lost up till now. regarding Thorsten's message I assume it is a member function to some class (e.g. TObject), but my usual means to find such functions don't show it to me.

Sorry.

Found it !

Thanks again.

-Michael

Somewhere user code must call MyObject.Dispatch(MyMessage);

This looks as if this might be good news. The dispatch mechanism seems to be completely platform independent and so it seems I just need to fire the normal (obviously hierarchical) dispatch mechanism when a message arrives.

Thanks a lot !

-Michael