Re: [Lazarus] Inversion of control (IoC) and Dependency injection (DI)
On Mon, Jan 5, 2015 at 5:07 PM, luiz americo pereira camara
luiz...@oi.com.br wrote:
Starting a new thread.
2015-01-05 15:16 GMT-03:00 silvioprog silviop...@gmail.com:
On Mon, Jan 5, 2015 at 12:54 PM, Marco van de Voort mar...@stack.nl
wrote:
As a first step in the 3.0.0 release process the stable branch was
branched
off to branches/fixes_3_0 and the version number was updated to 3.0.1
The version in trunk was raised to 3.1.1
Scripts might need modification accordingly.
Good news!
Chances of custom attributes[1] (or something like this) in release 3.0?
I have plans to use IoC[2] and DI using this feature.
I created a IoC Container that can be found at
https://code.google.com/p/luipack/source/browse/trunk/luicomponents/luiioccontainer.pas
. It has no dependencies.
Awesome!
With it is possible to implement Service Locator and Property Injection
patterns. Constructor Injection is not possible due to lacking of Extended
RTTI support in fpc.
Can you send a small (and isolated) sample showing how to use it?
While the C# crowd praises the Constructor Injection pattern (
http://www.devtrends.co.uk/blog/how-not-to-do-dependency-injection-the-static-or-singleton-container
), i had hard times figuring how it would work in real world / Lazarus
projects. Also, polluting the constructor signature is not something that
i like. And finally with Constructor Injection is not possible to use with
TComponent / TForm
So in the end, i use the service locator and have plans to use Property
Injection pattern
BTW: Custom Attributes support would help to have a nicer Property
Injection implementation
I've plan to use something like this (CDI inspirations: http://cdi-spec.org
):
The model:
uses
My.Company.MySDK.EntityAttributes, My.Company.MySDK.TableAttributes ...;
type
[Entity]
[Table('products')]
TProduct = class(TObject)
public
[Id][GeneratedValue]
property Id: LongInt ...;
[ManyToOne][JoinColumn('OrderId')]
property OrderId: LontInt ...;
[NotNull][NotEmpty][Size(1, 10)][Unique]
property Name: String ...;
[Nulls][Lenght(100)][Unique]
property Description: String ...;
[MyCustomCurrConversion(TypeInfo(Currency), TypeInfo(String), ',0.00')]
[MyCustomMinMax('Price must be = %d and = %d.', [1, 1000])]
property Price: Currency ...;
end;
The DAO:
type
[RequestScoped]
TProductDao = class(TObject)
private
[Inject] property Session: TSession ... ;
[Transational] procedure Add(AProduct: TProduct);
...
end;
...procedure TProductDao.Add(AProduct: TProduct);begin
Session.Save(AProduct);end;
The *produces* (to use external libs like *JCore*):
type
[ApplicationScoped]
TSessionCreator = class(TObject)
private
[Inject] property SessionFactory: TJCoreSession ... ;
[Produces] function GetSession: TSession;
...
end;
...
TSessionCreator.GetSession: TSession;begin
Result := ASessionFactory.OpenSession;end;
TSessionCreator.Close([Disposes]ASession: TSession) {begin if
ASession.IsOpenASession.Close;end;
The controller:
uses
My.Company.ControllerAttributes ... ;
type
[Controller]
TProcuctController = class(TObject)
public
[Post][Transational] procedure Add([Valid] AProduct: TProduct); //
[Valid]: to validade properties
[Get][Path('./product')][Transational] procedure
List([Pagination('page={[0-9]}rows={[0-9]}')] AProducts:
TArrayListTProduct); // to paginate products
[Inject] property ProductDao: TProductDao ...; // inject DAO
[Inject] property Result: TResponse ...; // inject Response
end;
...
procedure TProcuctController.Add(AProduct: TProduct);begin
ProductDao.Add(AProduct);
Result.SetAttribute(AProduct,
'product').RedirectTo(TProductController).List;end;
procedure TProcuctController.List(AProducts: TArrayListTProduct);begin
Result.SetAttribute(AProducts, 'products'); // to create a variable
products in my BSP viewend;
The view:
html
ul
c:forEach items=${products} var=product
li ${product.name} - fmt:currency value=${product.price}
mask=R$ ,0.00//li
/c:forEach
/ul
/html
But I think that I'll still wait some years to make it possible in Free
Pascal hehe ...
--
Silvio Clécio
My public projects - github.com/silvioprog
--
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Re: [Lazarus] Inversion of control (IoC) and Dependency injection (DI)
2015-01-11 17:12 GMT-03:00 silvioprog silviop...@gmail.com: On Mon, Jan 5, 2015 at 5:07 PM, luiz americo pereira camara luiz...@oi.com.br wrote: I created a IoC Container that can be found at https://code.google.com/p/luipack/source/browse/trunk/luicomponents/luiioccontainer.pas . It has no dependencies. Awesome! Thanks. With it is possible to implement Service Locator and Property Injection patterns. Constructor Injection is not possible due to lacking of Extended RTTI support in fpc. Can you send a small (and isolated) sample showing how to use it? There's a demo in demos/ioccontainer folder In a real project, in the app start, i do: FPresentations := TPresentationManager.Create(Self); Services.Register(IPresentationManager, FPresentations); When i need the service i do: FPresentations := IPresentationManager(Services.Resolve(IPresentationManager)); The global, nor the actual implementation is exposed, making easier to test. There's still a dependency to the container (Services), this is the whole point of criticism to service locator pattern. In the other side there always be a place where the dependency is set, even in other DI patterns. BTW: Custom Attributes support would help to have a nicer Property Injection implementation I've plan to use something like this (CDI inspirations: http://cdi-spec.org): Seems a full ORM plus a MVC like framework. I'm more modest. I use these classes to make modular code thus a bit more maintanable. All in all i use the IoC container little, in my project i register only two interfaces. In other places, i configure the dependency manually Luiz -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
Re: [Lazarus] Inversion of control (IoC) and Dependency injection (DI)
2015-01-05 21:44 GMT-03:00 Marcos Douglas m...@delfire.net: On Mon, Jan 5, 2015 at 6:07 PM, luiz americo pereira camara I created a IoC Container that can be found at https://code.google.com/p/luipack/source/browse/trunk/luicomponents/luiioccontainer.pas . It has no dependencies. So in the end, i use the service locator and have plans to use Property Injection pattern BTW: Custom Attributes support would help to have a nicer Property Injection implementation Interesting. Could you give us some example how this class works? There's a demo in demos/ioccontainer In a working project i use a IPresentationManager https://code.google.com/p/luipack/source/browse/trunk/luicontrols/presentationmanager.pas#36 When a class needs to use it, resolves from a TIoCContainer (Service Locator pattern). The global variable and concrete class are not exposed. In the other hand depends of the IoCContainer. I have plans to switch to a Property Injection pattern that helps to decouple a bit more. Luiz -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
[Lazarus] Inversion of control (IoC) and Dependency injection (DI)
Starting a new thread. 2015-01-05 15:16 GMT-03:00 silvioprog silviop...@gmail.com: On Mon, Jan 5, 2015 at 12:54 PM, Marco van de Voort mar...@stack.nl wrote: As a first step in the 3.0.0 release process the stable branch was branched off to branches/fixes_3_0 and the version number was updated to 3.0.1 The version in trunk was raised to 3.1.1 Scripts might need modification accordingly. Good news! Chances of custom attributes[1] (or something like this) in release 3.0? I have plans to use IoC[2] and DI using this feature. I created a IoC Container that can be found at https://code.google.com/p/luipack/source/browse/trunk/luicomponents/luiioccontainer.pas . It has no dependencies. With it is possible to implement Service Locator and Property Injection patterns. Constructor Injection is not possible due to lacking of Extended RTTI support in fpc. While the C# crowd praises the Constructor Injection pattern ( http://www.devtrends.co.uk/blog/how-not-to-do-dependency-injection-the-static-or-singleton-container ), i had hard times figuring how it would work in real world / Lazarus projects. Also, polluting the constructor signature is not something that i like. And finally with Constructor Injection is not possible to use with TComponent / TForm So in the end, i use the service locator and have plans to use Property Injection pattern BTW: Custom Attributes support would help to have a nicer Property Injection implementation Luiz -- ___ Lazarus mailing list Lazarus@lists.lazarus.freepascal.org http://lists.lazarus.freepascal.org/mailman/listinfo/lazarus
