Thanks for the answer Ben and Stephane.��

I already read��A Mentoring Course on Smalltalk, Valloud, there is nothing there I could use in this case :( . I will look after for��The Design Patterns Smalltalk Companion. Most of the sources provided I already know of or went in the same lines lines of what I have already found.��

About TDD, I am experienced with the discipline and have tested it on Pharo living system already, but I could not understand how this is related with object wiring, DI and service locator.

From ben:

"I'm not really familiar with IoC or DI patterns, so just taking your example at face value, in Pharo I'd do...

MovieLister>>moviesDirectedBy: director
�� allMovies := finder allMovies.
�� ^ allMovies select: [ :movie | movie��getDirector = director ].
�� "although typically #getDirector would be renamed #director"

MovieLister>>finder: movieFinder
�� finder := movieFinder.

to be used like this...
�� lister := MovieLister new finder: (ColonDelimitedMovieFinder on: 'movies1.txt').
�� movies := lister��moviesDirectedBy: 'Tarantino'."

and Stephane:

Why don't you simply pass the class and use that class in your MovieLister?

MovieLister new
�� finderClass: MySuperCoolFinderClass

...
MovieLister finder
�� finderClass new .....

What is wrong with that.

That was what I meant when I said: "I know that in Smalltalk I can make MovieLister to receive, upon construction, a class representing MovieFinder and call it construction message.". The code I had in mind is a bit of mix from the one provided by you both:

MovieLister>>moviesDirectedBy: director
�� allMovies := finder allMovies.
�� ^ allMovies select: [ :movie | movie��getDirector = director ].
�� "although typically #getDirector would be renamed #director"

MovieLister>>finder: aMovieFinderBuilder
�� finder := aMovieFinderClass new.

to be used like this...
�� lister := MovieLister new finder: (ColonDelimitedMovieFinder builderOn: 'movies1.txt').
�� movies := lister��moviesDirectedBy: 'Tarantino'."

But that means I will have to wire dependencies by hand whenever I create a MovieLister and seek through code when and if those dependencies change. When there are lot's of dependencies it's is a considerable and tedious work. Let's see an image from Fowlers article:

In this case, the service locator provides me with an instance and I configure the instance in the assembler, the scheme is alike for an IoC, and that would mean my implementation could be like this:

MovieLister>>moviesDirectedBy: director
�� allMovies := finder allMovies.
�� ^ allMovies select: [ :movie | movie��getDirector = director ].
�� "although typically #getDirector would be renamed #director"

MovieLister>>initialize
�� finder :=��ServiceLocator locate: FinderClass �� <--- This would bring the instance of finder class configured by the assembler

to be used like this...
�� lister := MovieLister new.
�� movies := lister��moviesDirectedBy: 'Tarantino'."

and the assembler:

Assember class>>configure:

aMap put:��(ColonDelimitedMovieFinder builderOn: 'movies1.txt')��at: FinderClass��

My assembler and service locator could be even more elaborated, and provide a different MovieFinder in test scope, for different classes or wharever.��

It is a little convenience for Smalltalk, I will give that, but I was wandering if there was something alike in Pharo, by your answers I assuming there is nothing like that.

If you do not want to have a reference at runtime to a Finder then you
need to use announcement and registration.

I didn't understand that, could you elaborate?

On Mon, Jun 5, 2017 at 6:41 AM, Stephane Ducasse <stepharo.self@gmail.com> wrote:

Why don't you simply pass the class and use that class in your MovieLister?

MovieLister new
�� finderClass: MySuperCoolFinderClass

...
MovieLister finder
�� finderClass new .....

What is wrong with that.

If you do not want to have a reference at runtime to a Finder then you
need to use announcement and registration.

Stef

On Sun, Jun 4, 2017 at 11:17 PM, Vitor Medina Cruz <vitormcruz@gmail.com> wrote:
> Hello,
>
> I would like to know how people in Pharo ecosystem do to deal with object
> wiring, as described by Marting Fowler in
> https://martinfowler.com/articles/injection.html#FormsOfDependencyInjection:
>
> "A common issue to deal with is how to wire together different elements: how
> do you fit together this web controller architecture with that database
> interface backing when they were built by different teams with little
> knowledge of each other."
>
> He gives an example, I will leave it in java as it is simple enough to
> understand:
>
> "class MovieLister...
>
>�� public Movie[] moviesDirectedBy(String arg) {
>�� List allMovies = finder.findAll();
>�� for (Iterator it = allMovies.iterator(); it.hasNext();) {
>�� Movie movie = (Movie) it.next();
>�� if (!movie.getDirector().equals(arg)) it.remove();
>�� }
>�� return (Movie[]) allMovies.toArray(new Movie[allMovies.size()]);
>
>�� }"
>
> The question is how to provide the finder object in a decoupled matter, a
> naive approach would be:
>
> " private MovieFinder finder;
>
>�� public MovieLister() {
>�� finder = new ColonDelimitedMovieFinder("movies1.txt");
>
>�� }"
>
> Which couples the MovieLister to the specific ColonDelimitedMovieFinder
> class.
>
> Fowler explains how to decouple using an IoC framework or a Service Locator.
> In Java and .Net IoC is used most of the time. I Googled how this problem is
> approached in Smalltalk/Pharo, and I generally I found answers "that is easy
> to do in Smalltalk, so there is no need of a framework", what I miss is a
> description on *how* to do that:
>
> https://stackoverflow.com/questions/243905/smalltalk-and-ioc
> https://stackoverflow.com/questions/2684326/is-there-a-dependency-injection-framework-for-smalltalk
> https://stackoverflow.com/questions/243905/smalltalk-and-ioc/347477#347477
>
> I know that in Smalltalk I can make MovieLister to receive, upon
> construction, a class representing MovieFinder and call it construction
> message. As long an object that responds to this message is provided, I can
> create as many derivations I want and the MovieLister will be decoupled from
> the MovieFinder. That way, however, I still have to wire things by hand, and
> I am not sure if this is what I am supposed to do in order to solve the
> decouple problem.
>
> Can you explain me how this is done in Pharo? It's is usually wiring by
> hand? Is there a simple construction that deals with the wiring problem that
> I cannot foresee?
>
> Thanks in advance,
> Vitor
>
>
>