Spellframes and categories

_{Beginner. The organizing half of every address.}

A spellframe is the category half of the Address Law. It is a plain string when you just want grouping, or a Protocol when you want a contract. Nothing else is a spellframe: a concrete class is refused at bind() with a TypeError that names the two forms (pass spellframe="Name" to group under its name, or declare the shape as a typing.Protocol).

# strings — organize by role
book.bind(spell=UsersRepo, existence="unique",
          spellframe="storage", binding_name="users")
book.bind(spell=UsersApi,  existence="unique",
          spellframe="web",     binding_name="users")

repo = conduit.meld(spellframe="storage", binding_name="users")
api  = conduit.meld(spellframe="web",     binding_name="users")

This is an excerpt: define UsersRepo and UsersApi, bind them before conjure, then resolve each full address. The result is a repository and an API object in separate categories, even though both bindings are named users.

Same binding_name, two categories, two distinct addresses — names never collide across spellframes. A string frame is only a label: it groups, it is addressable, and it never makes its members providers of anything. A Protocol frame is a label and a contract: bind() checks the spell against the Protocol's own public members, records the Protocol on the binding, and a parameter annotated with that Protocol resolves exactly its recorded implementers — which is what collection DI gathers:

book.bind(spell=EmailHandler, existence="unique",
          spellframe=Handler, binding_name="email")

Runnable examples

Spellframe grouping — Beginner 09
Protocols as shapes — Beginner 17
Frames as dict classification — Beginner 25
Meld a frame as dict — Beginner 38

All beginner examples · Level contents · Full contents

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