One of the things I appreciate about the design of Shards is the ability for multiple owners to contribute their own shard for a purpose – I can build a redis adapter and share it, and so can you. And someone else. We can work together and avoid a landrush. But how do I write a library that is capa…

So basically the solution to this is Dependency inversion principle - Wikipedia . This use case is the core reason Athena provides a bunch of interface modules. It allows Athena to base its implementation on the interface itself, and not a specific concrete implementation. I.e. If you wanted to custo…

I was just posting a lengthy reply about what I wish we could do… But yes, the exercise just showed me I still have much to learn sensei :sweat_smile: Haha just a little humor, you’ve got the patience of a saint my friend!

So, you’re right on the money that the community would need a single “redis” shard that did everything we need. But, that would mean we need a tool like Ruby Gems but for Crystal (which I’d love, but that’s a bigger hurdle to overcome I think). I think it would be worth adding decoupling behavior t…

I’ll have to read the wikipedia article you linked sitting next to my compsci bookshelf :wink: I think this is what you mean, translated to this specific example: ##### in my library module Library module RedisInterface abstract def del(key) abstract def expire(key, seconds) abstract…

[image] crimson-knight: But, that would mean we need a tool like Ruby Gems but for Crystal (which I’d love, but that’s a bigger hurdle to overcome I think). Is that not just shards? Granted I’m not super familiar with Ruby, but my assumption was it’s just their package manager for libs. […

Just wanted to add that you can declare types on those abstract methods for the interface: module RedisInstance abstract def flushall : Nil abstract def zcount(key : String, min : Int32, max : Int32) : Int32 abstract def hgetall(key) : Array(String) # etc. end class MyClass include Redi…

[image] Blacksmoke16: Close, but instead of monkey patching the external redis library yourself; you would (or require the user to) provide additional types(s) that wrap the external lib implementation to transform its methods to your interface. Yeah, that’s what I intended to show happening.…

[image] rob: Yeah, that’s what I intended to show happening. The “install instructions” would highlight needing to decorate whatever Redis class with my abstract module Perfect yea. Could also provide a default adapter for your library’s preferred Redis lib. That would make getting started a …

[image] Blacksmoke16: [image] crimson-knight: But, that would mean we need a tool like Ruby Gems but for Crystal (which I’d love, but that’s a bigger hurdle to overcome I think). Is that not just shards? Granted I’m not super familiar with Ruby, but my assumption was it’s just their packa…

In Crystal 1.5, Warn on positional parameter mismatches for abstract def implementations by HertzDevil · Pull Request #11915 · crystal-lang/crystal · GitHub “Warn on positional parameter mismatches for abstract def implementations” means this technique will probably be difficult to implement as I’v…

Abstracting out adapters - Dependency Injection

Help & Support

Blacksmoke16 July 13, 2022, 6:24pm 12

Answered in [RFC] Standardized Abstractions - #17 by Blacksmoke16. Posting here for posterity.

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Abstracting out adapters - Dependency Injection

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