Create a schema with custom directives first change for #156

[MarcoFuykschot]

modified:   juniper/src/lib.rs
modified:   juniper/src/schema/model.rs

(feat) create schema with custom directives

First change for #156

[MarcoFuykschot]

@MarcoFuykschot

First change for #156

Could you provide some grand vision/description of how it's supposed to work? And what would be the next steps?

From the provided example in the code and PR description, it's not very clear.

Step 1: is allow custom directives, added to a schema to pass validation. Step 2: Update graphql parser to support directive definitions Step 3: Create a mechanisme for user code to react on directives during execution.

[tyranron]

@MarcoFuykschot

Step 3: Create a mechanisme for user code to react on directives during execution.

Could you sketch your vision of API?

[MarcoFuykschot]

For the api, i have two idea's

1. A visitor like pattern, on the the incoming query,
2. Add a context like object as paramter to the fields.

Both i still need to reseach the code, on how to implement this in a non breaking way.