Do you wanna see an enormous potential tool? Here’s the pascal for Java and Android

Yes, this is very cool. I’m not a Java hater, in terms of language (and I dont want to start a language-war), but some Java features, IMHO, are a bit uncomfortable for me.
However, Java is very powerful and there are an enormous amount of good open source project for Java. So, seeing java libraries used in simil-pascal code (is not Delphi’s Pascal, but enough similar), is nice. In this way, you can use all the java libraries in Pascal!
I’d like to have this integration in Delphi IDE too with a good designer for Android activities.

I’m testing Oxygene for Java (form RemObjects) for a couple of things, specifically Android related.
This is my first console project in Oxygene for Java, just to see some code.

Oxygene for Java - Simple console app using specific Java libraries
Oxygene for Java – Simple console app using specific Java libraries

 

IMHO there is an enormous potential for the Delphi developer and for all the developers that need a unique language to do server, mobile and native ultra fast app.

I dream to have this technology into the Delphi IDE.

Duck Typing in Delphi

During a new dorm feature development, I’m faced a nice problem:

I want to have a generic access to a “kind” of list

Let’s say:

procedure DoSomething(Obj: TMyListType);
begin
...
end;

But, I want to have that generic access without a Layer Supertype object, because I need to be able to use objects from other libraries or 3rd party. In this case traditional polimorphism is not usable, so I’ve opted for an interface…

procedure DoSomething(MyIntf: IMyListInterface);
begin
...
end;

Cool, but I want to have that access without any change to that object. So implement an interface is not a viable solution. This is particulary true because the generics data structure in Delphi do not implement an interface. Will be nice to have a fully interfaced list and dictionaries in a future Delphi version.

So, how I could implement a generic access to a generic list?

procedure DoSomething(MySomething: ???);
begin
...
end;

However, operations on that list are few and well known, so I’ve opted for a “DuckTyping“.

Introducing the duck
Introducing the duck

The name of the concept refers to the duck test, attributed to James Whitcomb Riley, which may be phrased as follows:

“When I see a bird that walks like a duck and swims like a duck and quacks like a duck, I call that bird a duck.”

So, in my case, I’ve created an Adapter object wich adapts the external interface (few, well know operations) to the “duck” inside it.

The adapter is useful because I can use the compiler checking that the RAW RTTI access doesn’t allow.

Write an “RTTI adapter” using the new Delphi RTTI, is very simple. This is the code of the class TDuckTypedList that allow to use any object as a “list”. How I can define that the object is actually a list?

The criteria is:

If the object has
– An “Add” method with one parameter of type TObject (or descendant);
– A “Count” property;
– A “GetItem” method that have an integer parameter and return an object;
– A “Clear” method;
then, that object is a list.

So I can write the following:

DuckObject := TDuckTypedList.Create(Coll);  //the adapter
for x := 0 to DuckObject.Count - 1 do
  DoSomething(DuckObject.GetItem(x));  

I’ve done some speed tests comparing this way to the classic static way, and the speed is almost the same because the RTTI lookup is cached in the constructor of the adapter. So, so far so good.

This solution is already in use inside the dorm code in a feature branch.

Full code is available in the dorm SVN

Any comments?

dorm, “The Delphi ORM”, officially published at ITDevCon

As all the attendees have seen, at the last ITDevCon, I’ve officially published dorm as an OpenSource project.

dorm, The Delphi ORM
dorm, The Delphi ORM

You can find the project on google code: http://code.google.com/p/delphi-orm/

An introduction to dorm is available on google docs.

dorm begins as a my personal project more than one year ago, and now is sponsored by bitTime Software that offers custom development, consultancy, mentoring and so on.

Why dorm?

These are my personal reasons of because I’ve started to write dorm:
I WANT an ORM for Delphi… but:
I dont want (or I cant) change my database
I want persistence ignorance
I want to access to the «metal»
I want to persist PODO
I don’t hate SQL, but I know that 90% of it is boilerplate and errors prone

First example

Insert and retrieve object with dorm
Insert and retrieve object with dorm

 

You can persist anything you want.
bitTime actively use dorm, so it’s continuosly updated and evolved.

Repeat, you can find the project on google code and an introduction to dorm is available on google docs.

Let me know what do you think about.

Do you need an ORM like dorm in Delphi?