[DUG] basic question

[David Moorhouse]

The Delphi compiler creates an implicit parameter to Self and places it before the
other params to the method.

Take a look at the TMethod class to see how this works and can be used successfully
to redirect code and data.

The code pointer is share by all instances of the object and exists even if the
object has not been created (just declared).  The converse is that each object
instance has its own data pointer which is not initialised until the object is
created by the constructor.

To see this in action, change your execute method to access a property/field of
FormB.  Boom !

Compiler magic - we love it !


D


On Wed, 25 Jul 2007 08:28:03 +0530, you wrote:

>Hi,
>
>Is it possible to call a method of a class without creating a object of it,
>even if the method is not a class function in Delphi ? I wrote the below
>code just to test -
>
>1. Created a simple form A and a button on it.
>2. Created another simple form B, written a procedure in it as -
>    FormB.Execute;
>    begin
>      ShowMessage("xyz");
>    end;
>3. Commented out auto creation of FormB in application.
>4. On Button Click in FormA I called the Execute of FormB and it worked
>perfectly okay.
>
>What could be the reason for this? I had the idea that either I need to
>create an object before calling any method or I need to declare a class
>function.
>
>In the above steps when I am trying to call Show in Execute function of Form
>B I got Access violation which is perfectly fine according to the above
>statement.
>
>May be I am missing something simple here, but any pointers will be great.
>This was done in D2005 and it's win32 app.
>
>Thanks
>-Ani