Hi,

After reading the reference documentation on classes, I have a couple of easy aspects of the documentation that were unclear to me.

(1) Is there the concept of "static field" or "class field" (meaning a field that is not instanciated, but remains the same var for all the instances)? I know this can be easily made with an external variable, but I consider it to be a different concept.
The syntax diagrams of classes show that a method can be preceded by the keyword "class" (and I failed to find where it is explained what for?), but does not seem to admit this keyword before a field.

(2) In the documentation, it is said "The Inherited keyword will not jump to the inherited method, if virtual was used." and also "The compiler will compile it, but using Inherited can produce strange effects." (where neither of the examples shows the word "Inherited"), but I fail to understand if these sentences refer to the case in which you do it wrong, and declare both MyProc as virtual (instead as "virtual" and "override", respectively).
So should I understand that I can use Inherited without problems if I do it right? (means virtual/override).

Aitor

Not yet in 1.0.10 . I believe it is implemented in 1.1

This is correct.

Yes. I will check the wording.

Michael.

And what is the effect on a method? I suppose that any static method is a "class" method, right?

Aitor

Written in Delphi, so use Delphi compatibility mode when testing in fpc....

program TestStatic;
uses sysutils;
type
  Test = class
  public
    class function TestValue( x: integer = -1): integer; //unless you pass a
value, returns static value. If pass value, returns new value.
  end;

{ Test }

class function Test.TestValue(x: integer): integer;
const
  v: integer = 0;
begin
  if x  -1 then
    v := x;
  result := v;
end;
var
  a, b, c: Test;
begin
  a := Test.Create;
  b := Test.Create;
  c := Test.Create;
  writeln('a ', a.testvalue); // 'a 0'
  writeln('b = 10 ', b.testvalue(10)); // 'b=10 10'
  writeln('c ', c.testvalue); //'c 10'
  writeln('Test.TestValue := 25 ', Test.testvalue(25) ); // 'TestValue := 25
25'
  writeln('a ', a.testvalue); // 'a 25'
  writeln('b ', b.testvalue); 'b 25'
  writeln('c ', c.testvalue); 'c 25'
  readln; //pause (for running under windows...
end.

AFAIK, that's as close as you can get without additional language support... You may need FPC 1.1 if 1.0 doesn't support assignable typed constants.

Hope that helps,

Matt

It depends what you mean with 'static'. In classes, the term 'static' has no defined meaning. You have 'normal' methods (where SELF is defined) and class methods (where SELF is not defined).

Michael.

It depends what you mean with 'static'. In classes, the term 'static' has no defined meaning. You have 'normal' methods (where SELF is defined) and class methods (where SELF is not defined).

Note also that Class Methods kind of act as if they are external to the class - like tacked on procedures and functions. You can test this by using the following example:

type
  TMyTestClass = class
  public
    class procedure Test( AString: string ); //test calls
'writeln(AString);'
  end;

...

TMyTestClass.Test('Hello'); //no instance variable.. output is 'Hello' to
console

Hope that helps...

Matt