Make detail tuples typed-ish

[spuun]

WHAT is this pull request doing?

"detail tuples" are NamedTuples which causes a lot of limitations and struggle when refactoring.

One approach to mitigate this would have been to declare a lot of structs for every case we need, but that would require a lot of work and make the code less flexible.

This PR will introduce Metadata which is a wrapper around NamedTuple. This makes it possible to add helper methods on the details instead of doing a lot of "workarounds" where the data is accessed. Looking at the diff for src/lavinmq/http/controller.cr one will see that the code is simplified.

Values is wrapped in Metadata::Value which is for Metadata what JSON::Any is to JSON.

One thing that maybe needs to be thought through and fixed is Value#<=>. It will probably almost always compare to values of the same type and thereby compare correct, but other edge cases maybe needs to be changed.

HOW can this pull request be tested?

Run specs.

[carlhoerberg]

can you show how this will simplify something in a controller?

[spuun]

can you show how this will simplify something in a controller?

It simplifies Controller#page method.

[carlhoerberg]

can you show how this will simplify something in a controller?

It simplifies Controller#page method.

ok, i see it now. it's less code in Controller#page but does it have other benefits, like more correct, doesn't have to load all data to sort etc?

[carlhoerberg]

It's not like Metadata::Value#fetch is easily digestible, so in a sense one can say that the complexity has just been pushed around and we've added more indirection. That is if there are no other benefits that I don't see.

[spuun]

ok, i see it now. it's less code in Controller#page but does it have other benefits, like more correct, doesn't have to load all data to sort etc?

Not yet, but it enables other refactoring to improve it.

One purpose of this is to simplify the abstraction of different entities. I've struggled with detail_tuples and all of the Iterators when trying to abstract first Client and now Channel. I'm just trying to decouple in smaller steps.

It's not like Metadata::Value#fetch is easily digestible, so in a sense one can say that the complexity has just been pushed around and we've added more indirection. That is if there are no other benefits that I don't see.

The "tree traversing" is a little bit of a mess because of macro language limitations, but the generated code should be straight forward.

Moving the logic also makes it easier to test it.