Question about grammar

[sungam3r]

Hi. I have long wanted to ask what these modifiers mean. I did not find explanations in the specification. Thanks.

[benjie]

Link to spec screenshotted above: https://spec.graphql.org/draft/#sec-Language.Arguments

Link to source: https://github.com/graphql/graphql-spec/blame/main/spec/Section%202%20--%20Language.md#L410

Arguments[Const] : ( Argument[?Const]+ )

---

The list is relatively straightforward to explain - it relates to the + in the grammar and means that it represents a list of that keyword (i.e. "Arguments is an open paren ( followed by a list of Argument followed by a close paren )")

---

For the [Const]:

Introduced via this PR: https://github.com/graphql/graphql-spec/pull/90/files

But specifically this commit: eeb1a2c

Description: "Ensure directives cannot reference variables in SDL"

This seems to be subscripting indicating that when you reference Arguments[Const] (i.e. when you write SDL), you cannot reference variables. If, however, Arguments is referenced without the [Const] subscript (e.g. Field) then variables are allowed.

To be more explicit, the following would be invalid:

type Query {
  str: String @deprecated(reason: $reason)
}

And that is enforced at a grammar level.