Comments on Entropy Overload: Somewhat more efficient smart pointers

It is possible to implement it using 64bit memory ...

2011-05-17T13:42:13.589+01:00

It is possible to implement it using 64bit memory block; eliminating ref-count field.
AddRef/Release in such way should replace vtable pointer to next/prev vtable from some amount of predefined vtables. Vtable0::Release should free the memory.
In a very rare case, when there are more references to an object than the amount of predefined vtables available, a special dynamically allocated vtable with real ref-count field should be used.

Fabricio - I don't think you understood that parti...

2009-01-14T20:36:00.000Z

Fabricio - I don't think you understood that particular quote.

Delphi for .NET is a GC language, while classes in C++ that use overloaded operators are generally used on a value basis, not allocated on the heap (i.e. you overload the operators on values of type T, not type T*).

Barry said:
User-defined operators on heap-a...

2009-01-14T19:08:00.000Z
Barry said:
User-defined operators on heap-allocated object instances are next to useless in a non-GC language.

Talk for yourself. I've used overloaded operators in C++ and Delphi.Net. Nice. And useful.

They are a useful in ANY language, whether it have a GC or not.

This is, of course, in my humble opinion.
I'll see if overloaded operators for classes have a open QC# and vote.

Nice. I'm also working on similar solutions:

2008-12-30T22:57:00.000Z
Nice. I'm also working on similar solutions:

https://forums.codegear.com/thread.jspa?threadID=9481

Vincent,

Yes, it's like this:

class ...

2008-11-17T11:30:00.000Z
Vincent,

Yes, it's like this:

class operator In(Left, Right): Boolean;

Hi Barry.

Not related to your main post, bu...

2008-11-17T10:56:00.000Z
Hi Barry.

Not related to your main post, but you said in your comment : "[using records] then you can override almost all operators (even including the 'in' operator used by set operations)"

Is there a hidden operator for implementing 'if a in set' (from your comment I assume that you didn't refer to an iterator 'for a in set' but to set inclusion). That would be very useful but I couldn't find any reference on it...

Thanks, that all makes sense now

2008-11-09T20:26:00.000Z
Thanks, that all makes sense now

Sean,

  TFunc<T> = reference to funct...

2008-11-07T17:06:00.000Z
Sean,

  TFunc<T> = reference to function: T;

is directly equivalent to:

  TFunc<T> = interface
    function Invoke: T;
  end;

except that locations of a method reference type are assignable using values of a function, method or anonymous method.

Anonymous methods are implemented as interfaces that look just like the method reference, on a hidden class. Location capture is implemented as moving (for locals) and copying (for parameters) to fields on the hidden class. Any accesses of captured locations in the body of the main procedure are converted to access the fields on the hidden class; a local variable, called $frame, points to an instance of this hidden class.

Multiple anonymous methods in a procedure get converted into multiple interfaces implemented on the hidden class.

Nested anonymous methods are processed in a normal way, recursively, treating the outer anonymous method just like any other method; however, accesses to symbols from the outer scope are resolved by adding a Parent field to the inner hidden class, that points to the outer hidden class's instance, so that the location can be accessed.

Barry,

I don't understand where the Invoke ...

2008-11-07T04:09:00.000Z
Barry,

I don't understand where the Invoke method fits in. I assume TFunc is an interface requiring function Invoke: T; but I don't understand the mechanism behind it. Can you explain that please?

D'Oh!
Sorry, please skip/delete all my prev...

2008-11-04T06:16:00.000Z
D'Oh!
Sorry, please skip/delete all my previous comments... seems I only looked at the code, not at the text accompanying it... <blush />

Oliver

Good stuff! Maybe its because I'm pretty much a D...

2008-11-04T01:00:00.000Z
Good stuff! Maybe its because I'm pretty much a Delphi-only person, I don't know, but I for one find this version easier to follow than the other versions. In fact, more generally, finding out that anonymous methods in Delphi were implemented using interfaces made the very concept of anonymous methods easier to understand in the first place.

Hmm, OK, I have now verified this works indeed but...

2008-11-03T21:15:00.000Z
Hmm, OK, I have now verified this works indeed but I still don't quite get why... ;)

Why is TFunc<T> treated as an interface here and by what does TObjectHandle implement it?

animal,

T is constrained to be of a class t...

2008-11-03T13:51:00.000Z
animal,

T is constrained to be of a class type, as part of TObjectHandle<T: class>. The other use of T is as a type parameter, not an interface to implement: specifically, TFunc<T> is the interface that is implemented.

The code works just like Test2 before, except instead of OHCanary.Wrap, one uses OHCanary.Create; that's pretty much it.

Now I'm really confused... Is the example real...

2008-11-03T12:45:00.000Z
Now I'm really confused... Is the example really correct? I somehow fail to see how the line:

TObjectHandle<T: class> = class(TInterfacedObject, TFunc<T>)

is supposed to be valid code. Wouldn't T have to be an interface type (yet, the constraint at the beginning says "class")? Also, I'm suprised by the impression that this gives that you can specify the interface to be implemented via a function reference (which to my understanding would be evaluated at runtime only) whereas I would have thought that this had to be evaluated at compile time...

Can you maybe repost the updated complete code including sample usage?

Preemptive comment: Actually, it would be 96 bits ...

2008-11-03T02:31:00.000Z
Preemptive comment: Actually, it would be 96 bits including vtable pointer. :)

Cesar,

User-defined operators on heap-alloc...

2008-11-03T02:03:00.000Z
Cesar,

User-defined operators on heap-allocated object instances are next to useless in a non-GC language.

If you are willing to wrap your object in a record, take on lifetime management, and redirect methods and properties appropriately, then you can override almost all operators (even including the 'in' operator used by set operations).

Hi Barry,

That is something that thought re...

2008-11-03T01:38:00.000Z
Hi Barry,

That is something that thought reading your previous post, and I really misse class operators in classes, is class operators possible to be part of delphi sintax any time?

Comments on Entropy Overload: Somewhat more efficient smart pointers

It is possible to implement it using 64bit memory ...

Fabricio - I don't think you understood that parti...

Barry said:User-defined operators on heap-a...

Nice. I'm also working on similar solutions: 2008-12-30T22:57:00.000Z Nice. I'm also working on similar solutions:https://forums.codegear.com/thread.jspa?threadID=9481

Vincent,Yes, it's like this:class ...

Hi Barry.Not related to your main post, bu...

Thanks, that all makes sense now

Sean, TFunc<T> = reference to funct...

Barry,I don't understand where the Invoke ...

D'Oh!Sorry, please skip/delete all my prev...

Good stuff! Maybe its because I'm pretty much a D...

Hmm, OK, I have now verified this works indeed but...

animal,T is constrained to be of a class t...

Now I'm really confused... Is the example real...

Preemptive comment: Actually, it would be 96 bits ...

Cesar,User-defined operators on heap-alloc...

Hi Barry,That is something that thought re...

Barry said:
User-defined operators on heap-a...

Nice. I'm also working on similar solutions:

2008-12-30T22:57:00.000Z
Nice. I'm also working on similar solutions:

https://forums.codegear.com/thread.jspa?threadID=9481

Vincent,

Yes, it's like this:

class ...

Hi Barry.

Not related to your main post, bu...

Sean,

TFunc<T> = reference to funct...

Barry,

I don't understand where the Invoke ...

D'Oh!
Sorry, please skip/delete all my prev...

animal,

T is constrained to be of a class t...

Cesar,

User-defined operators on heap-alloc...

Hi Barry,

That is something that thought re...