wvlet/airframe

Lightweight Building Blocks for Scala http://wvlet.org/airframe

Taro L. Saito

@xerial

Practically speaking, there is no difference in what they mean

Taro L. Saito

@xerial

Airframe 0.74 release https://wvlet.org/airframe/docs/release-notes.html#074

Duy Pham

@phamthaibaoduy

Hello, could someone please help me explain this snippet of code about in-trait injection

https://wvlet.org/airframe/docs/index.html#in-trait-injection

I don't get how airframe can know which name should be used for the database

Naoki Takezoe

@takezoe

@phamthaibaoduy This example may not work because name is not given.

@xerial Probably we should fix this example. Simply removing name from Connection is ok?

Naoki Takezoe

@takezoe

Sorry, it was removing from Database, not Connection.

Naoki Takezoe

@takezoe

I created a pull request: wvlet/airframe#354

Taro L. Saito

@xerial

thx for the fix

Duy Pham

@phamthaibaoduy

Thanks

Duy Pham

@phamthaibaoduy

Hello, I have one question. It is possible to do multi-binding with provider method?

I wanna inject a Logger into target class, but Logger should be created with target class name

Taro L. Saito

@xerial

https://wvlet.org/airframe/docs/bindings.html#multi-binding

Duy Pham

@phamthaibaoduy

@xerial Thank Taro, but this can not be used for my purpose

Taro L. Saito

@xerial

How about using bind { s:String => Logger} (provider binding)?

Duy Pham

@phamthaibaoduy

Yes that would be helpful, only if Airframe somehow can correctly pass target class name as input for the provider

Taro L. Saito

@xerial

def newLogger(name:String) = Logger(name), and
bind {newLogger}

will work

I see. We need to resolve the logger nave automatically

Duy Pham

@phamthaibaoduy

Yes

I'm wondering if it's possible to have some contextual param, which would be passed by airfame to provider

case class Context (target: ClassMetaData)

something like this

Taro L. Saito

@xerial

Unfortunately there is no feature like that.

Duy Pham

@phamthaibaoduy

design
  .bind[Logger].toInstanceProvider{ (context: Context) => 
    new Logger(context.target.getClass) 
  }

Are you a maintainer of the airframe

Taro L. Saito

@xerial

Yes. I’m the creator of Airframe :)

Duy Pham

@phamthaibaoduy

Do you happen to know if it's possible to implement this feature, I would love to work on it but I need some help, the airframe source code is quite complex to me, a scala beginner

Wow

Taro L. Saito

@xerial

For this logger example, we don’t need to use provider. Just binding a provider that creates a new logger:

bind { new Logger(this.getClass) }

Duy Pham

@phamthaibaoduy

I wanna keep dependencies injected via constructor args

Taro L. Saito

@xerial

Then you can try using val f = bindFactory[Context => Logger], then you need to manually call f(context)

Duy Pham

@phamthaibaoduy

I can think of a work-around, which is to inject the LoggerFactory into target

Taro L. Saito

@xerial

Actually we already have a ticket for this use case wvlet/airframe#190

Duy Pham

@phamthaibaoduy

But it would be nice if the DI framework auto-wiring can fully take care of building dependencies

wow

Do you have any plan to get that issue resolved any time soon :D

Taro L. Saito

@xerial

This functionality can be implemented by writing a helper class (e.g., creating a logger from a given LoggerFactory and a context class information), so I believe we should not add this functionality to Airframe (because it makes the framework much more complex). Just having an example for doing so will be enough in this case.

Duy Pham

@phamthaibaoduy

@xerial I just found out that Alias type binding does not work with Constructor, I guess it is because of constructor injecting is done at runtime

If it's true, maybe we should update the document https://wvlet.org/airframe/docs/bindings.html#type-alias-binding

Taro L. Saito

@xerial

Could you give me an example code which didn’t work?

Duy Pham

@phamthaibaoduy

Sorry Taro, I thought I left response for your questions

It was mistake from my side, I did not know exactly what it is, but the problem went away after a clean recompile

Taro L. Saito

@xerial

Good to know that. Thanks for reporting!

Duy Pham

@phamthaibaoduy

Thank you

Duy Pham

@phamthaibaoduy

@xerial is it possible to use life cycles with design binding

I guess it's only useable with in trait injection?

Taro L. Saito

@xerial

onXXX hooks are available only for in-trait injection. For regular classes, you can use JSR250 annotations

like PostConstruct, PreDestroy

Duy Pham

@phamthaibaoduy

Thanks for answering

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