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Date: Tue, 11 Nov 2014 00:39:43 +0100
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 <CAGT3RRNj2qnXLxR0f-5qeLVv-z5oUF2wZh=NThO3KfpEDSSEuQ@mail.gmail.com>
Subject: Re: Make DependencyManager API more fluent?
From: Pierre De Rop <pierre.derop@gmail.com>
To: "dev@felix.apache.org" <dev@felix.apache.org>
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Hello Christian;

The improvements you are proposing would require a major version bump since
it's an incompatible API change. But I personally like what you are
suggesting, and I could quickly do it in the upcoming Dependency Manager
4.0.0, which is a new major version.

But before, I need to know if Marcel is agree to go ahead with all this; so
for the moment, may be you can just create a Jira issue, and let's wait for
Marcel to see if he's OK.

Just one remark: the setters can be easily removed, however I think we
can't manage to make the "component()" method automatically add the
Component to the DependencyManager, because technically; when you add a
Component to a DependencyManager, the Component is actually *activated*,
and at this point, all the necessary dependencies have to be already in
place.

So, the only possible improvement I'm thinking about for now could have the
form of this:

    public void init(BundleContext context, DependencyManager manager)
throws Exception {
        component()
            .implementation(DataGenerator.class)
            .add(serviceDependency(Store.class).required())
            .add(serviceDependency(LogService.class))
            .addTo(manager);
    }

(notice the addTo method at the end of the sample above, which could just
add the fully built component to the DependencyManager "manager" object).

but I propose you first create the Jira issue and see what Marcel thinks.

I will possible add more suggestions in your Jira issue once you will have
created it (like also using a builder pattern for the aspects/adapters:
this would allow to reduce the number of method signatures for the
createAdapter/createAspect methods).

kind regards (and thanks for proposing to improve Dependency Manager :-))

/Pierre

On Mon, Nov 10, 2014 at 11:40 AM, Christian Schneider <
chris@die-schneider.net> wrote:

> I wonder if the DependencyManager API could be made a bit more fluent.
> Technically it already uses the fluent builder pattern
> but all the builder verbs still look a lot like traditional setters.
>
> I know what I propose is mostly syntactic sugar but I think the result
> looks more readable and crisp. See below for some ideas.
>
> Christian
>
> ----
>
> This is from samples.dependonservice:
>     public void init(BundleContext context, DependencyManager manager)
> throws Exception {
>         manager.add(createComponent()
>             .setImplementation(DataGenerator.class)
>             .add(createServiceDependency()
>                 .setService(Store.class)
>                 .setRequired(true)
>             )
>             .add(createServiceDependency()
>                 .setService(LogService.class)
>                 .setRequired(false)
>             )
>         );
>     }
>
> Why not make it look like this:
>     public void init(BundleContext context, DependencyManager manager)
> throws Exception {
>         component()
>             .implementation(DataGenerator.class)
>             .add(serviceDependency(Store.class).required())
>             .add(serviceDependency(LogService.class))
>             );
>         );
>     }
>
> component() could create and add the component.
>
> Or for configuration:
>     public void init(BundleContext context, DependencyManager manager)
> throws Exception {
>         manager.add(createComponent()
>             .setImplementation(Task.class)
>             .add(createConfigurationDependency()
>                 .setPid("config.pid")
>                 // The following is optional and allows to display our
> configuration from webconsole
>                 .setHeading("Task Configuration")
>                 .setDescription("Configuration for the Task Service")
>                 .add(createPropertyMetaData()
>                      .setCardinality(0)
>                      .setType(String.class)
>                      .setHeading("Task Interval")
>                      .setDescription("Declare here the interval used to
> trigger the Task")
>                      .setDefaults(new String[] {"10"})
>                      .setId("interval"))));
>     }
>
> could be:
>     public void init(BundleContext context, DependencyManager manager)
> throws Exception {
>         component().implementation(Task.class)
>             .configuration("config.pid")
>                 .add(meta("Task Configuration)
>                     .description("Configuration for the Task Service")
>                     .add(property("interval")
>                             .cardinality(0)
>                             .type(String.class)
>                             .heading("Task Interval")
>                             .description("Declare here the interval used
> to trigger the Task")
>                             .default("10"))
>     }
>
> --
> Christian Schneider
> http://www.liquid-reality.de
>
> Open Source Architect
> http://www.talend.com
>
>

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