I’ve cleaned up some code by declaring uses in the implementation and using
generic untyped variables like TObject for parameters. This compiles but I’m
left with lots of ugly type casting in the implementation because the
parameters for methods are untyped. Yes it works but I feel like the compiler
could be helping more.
Just as an idea to float out here’s a suggestion for a “hint” syntax which
would be used to solve the type casting issue by doing some dynamic typing.
Sure you could put those all in file for this example but in the real world
there may be dozens of TClassB subclasses which would make the unit 10,000’s of
lines long and impossible to navigate. The other solution as mentioned would be
to use $includes and still use the single unit approach (how reliable is this?
I’ve never tried).
Does this look like more work than using $includes? Maybe I need to seriously
considering reorganizing my projects to work like this but it just feels wrong
for some reason.
=====================
unit Globals;
interface
type
HClassB = 'TClassB'; // declare a hint to the class name
implementation
end.
=====================
unit ClassB;
interface
uses
ClassA;
type
TClassB = class
procedure DoSomething (sender: TClassA);
end;
implementation
procedure TClassB.DoSomething (sender: TClassA);
begin
// full access to TClassA
end;
end.
=====================
unit ClassA;
interface
uses
Globals;
type
TClassA = class
// The interface section can't know about TClassB so we declare
a
// class name hint from Globals.pas (HClassB) and assign the
paramter with it
// using the "hint" syntax
procedure SetValue (value: TObject[HClassB]);
end;
implementation
// use ClassB now so hints evaluate
uses
ClassB;
procedure TClassA.SetValue (value: TObject[HClassB]);
begin
// behind the scenes the compiler (or preparser if FPC has one)
replaces the text "TObject[HClassB]" to “TClassB" or throws an error if the
identifier TClassB is not found
value.DoSomething(self);
end;
end.
Regards,
Ryan Joseph
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