Iterate over ivar's annotations/annotation keys

[Blacksmoke16]

Currently an ivar's annotation can only be accessed manually, one by one, where the name has to be known. Being able get an array of annotations on an ivar would dramatically simplify this.

On a similar note the only way to get a value from an annotation is knowing the name of the key. Having a method to return an array of keys on the annotation would further simply things.

Could look something like:

{% for ivar in @type.instance_vars %}
  {% for annotation in ivar.annotations %}
    {{annotation.keys.map { |k| annotation[k] }.join(',').id}}
  {% end %}
{% end %}

Based on #6980 (comment)

[bew]

Whats your usecase?

[Blacksmoke16]

@bew I would be using this for https://github.com/Blacksmoke16/CrSerializer.

I'm working on changing the syntax to like:

@[Serialize::Assertions::NotBlank(message: "Password should not be blank")]
@[Serialize::Assertions::Size(range: 0..50, min_message: "Password is too short", max_message: "Password is too long")]
property password : String

Currently i'm having to define a hash that contains the annotation name and fields. like:

TYPES = {
    NotBlank => [] of Symbol,
    Size => [:range, :min_message, :max_message]
  }

{% for ivar in @type.instance_vars %}
  {% for t, v in TYPES %}
    {% ann = ivar.annotation(t.resolve) %}
      {{t.id}}Assertion.new({{v.map { |f| ann[f]}.join(',').id}}) # new up assertion class
  {% end %}
{% end %}

Having this would drastically reduce the complexity, and make it easier to use. The ideal solution would be something like

{% for ivar in @type.instance_vars %}
  {% for annotation in ivar.annotations %}
    {{annotation.name.id}}Assertion.new({{annotation.keys.map { |f| "#{f.id}: #{annotation[f]}"}.join(',').id}})
  {% end %}
{% end %}

[asterite]

That won't work because you are assuming the only annotations an ivar will have are the ones you are interested in.

[Blacksmoke16]

Would have to have some logic to make sure the current annotation is of a given name or something yea. I don't think there is a name property on an annotation, so that wouldn't be doable atm.

[RX14]

@Blacksmoke16 By the time you add in the required {% if TYPES.includes? annotation %} to your ideal solution they're about the same complexity and code.

[Blacksmoke16]

Ideally would go with like {% if annotation.name.starts_with? "MyAnnotation" %} to remove the need for the mapping hash. Also would remove the need for a macro to add user defined annotations to the mapping.

Was unsure of the effort to implement this, if its too much can go ahead and close, just an idea i had working with this a lot.