value keyword idea / proposal

[pkieltyka]

It's convenient to use webrpc as a schema source of truth for types, but sometimes it's nice to do use it for simple constants / configs / values across clients.

I'm proposing a new "value" type,

RIDL

# we can just define some json here
value NetworkNames: map<string,Chain> = '''{
  "blah": { etc }
}'''

value AuthorName: string = "Peter"

JSON

  "values": [
    {
      "name": "AuthorName",
      "type": "string",
      "value": "Peter"
    },
    {
      "name": "AuthorCredits",
      "type": "map<string,User>",
      "value": {
        "joe": {
          "id": 1,
          "username": "joe",
          "role": "friend",
          "kind": "USER"
        }
      }
    }
  ]

[VojtechVitek]

OpenAPI has examples - values that can be useful for documentation or for creating stub servers.

https://swagger.io/docs/specification/adding-examples/

I wonder if we could find an overlap between these two - example values vs. something that would make it to the generated code as constants too.

[VojtechVitek]

See potential implementation from Peter's branch:

https://github.com/webrpc/webrpc/blob/1bbee6ae9b44fb74cdd31c9d8bd596715c0e6e8b/schema/_value.go

package schema

import (
	"fmt"
	"strings"
)

// in the future.. see: https://github.com/webrpc/webrpc/issues/122

type Value struct {
	Name  string      `json:"name"`
	Type  string      `json:"type"`
	Value interface{} `json:"value"`

	// Schema *WebRPCSchema `json:"-"` // denormalize/back-reference
}

func (s *Value) Parse(schema *WebRPCSchema) error {
	if s.Name == "" {
		return fmt.Errorf("schema error: name cannot be empty")
	}
	if s.Value == nil {
		return fmt.Errorf("schema error: value cannot be empty")
	}

	// check for duplicate names
	nameList := map[string]struct{}{}
	for _, sval := range schema.Values {
		nName := strings.ToLower(sval.Name)
		if _, ok := nameList[nName]; ok {
			return fmt.Errorf("schema error: detected duplicate value name of '%s'", sval.Name)
		}
		nameList[nName] = struct{}{}
	}

	return nil
}