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craftMethod#

Wraps a generator so it can be called like an ordinary method — from a template, an event handler, anywhere outside the craft driver — while still resolving its dependencies with yield*.

Use it when a click handler or a component method needs a service. Not inside a craft factory — there, yield* works directly.

Import#

typescript
import { craftMethod } from '@craft-ts/core';

Overview#

craftMethod is designed for component methods such as click handlers and submit handlers. Keep the callback focused: event normalisation, pure input preparation, and at most one imperative Craft action belong here. When one event must coordinate several primitives, emit a source$ directly and let the affected query react with insertReactOnMutation(...) or another declarative insertion.

The returned method carries the yieldable-method contract. When it is consumed from a Craft component template, its template view can delegate it with yield*; the component renderer drives the callback with the Craft generator runtime while preserving the method's injector and wrappers.

The method runs inside the injection context captured when craftMethod(...) is created.

That makes it useful when a component method needs to:

  • call Browser Boundaries with yield*

  • compose crafted services through yield* SomeService()

  • keep the handler colocated with component-local signals

All dependencies are cached, which helps to detect missing providers at compile time.

Signatures#

typescript
function craftMethod<Name extends string, This, Args extends unknown[], Result>(
  name: Name,
  factory: (this: This, ...args: Args) => Generator<unknown, Result, unknown>,
): (this: This, ...args: Args) => Result;

function craftMethod<Name extends string, This, Args extends unknown[], Result>(
  name: Name,
  self: This,
  factory: (this: This, ...args: Args) => Generator<unknown, Result, unknown>,
): (...args: Args) => Result;

The first argument is the name: it is required and must match the property (or variable) the method is assigned to. It is the value used to tag the injector context — same role as provideHostName(...). The craft-ts/craft-method-name-match ESLint rule enforces the match and offers a quick fix.

The common case — inside a Craft component#

In a Craft component there is no this: declare the method with craftMethod(name, fn) and bind it where the template needs it.

typescript
import { button, craftComponent, div, p } from '@craft-ts/component';
import { Console, craftMethod, state } from '@craft-ts/core';

export const Counter = craftComponent('Counter', {}, function* () {
  const counter = yield* state('counter', 0, ({ update }) => ({ update }));

  const increment = yield* craftMethod('increment', function* (step = 1) {
    yield* Console.log('increment is called');
    yield* counter.update((value) => value + step);
  });

  return [p(counter), button({ click: increment }, 'Increment')];
});

counter does not belong to increment, so the method yields counter.update. Pass the method to the template (click: increment) rather than wrapping () => increment().

Composing crafted services#

craftMethod is not limited to Browser Boundaries — it consumes the same crafted service graph as craftService:

typescript
const increment = craftUse(craftMethod('increment', function* (value: number) {
  return yield* CounterWorker.set(value);
}));
Class-based wrappers — capturing `this`

When a class-based wrapper needs its instance, use one of the two this-aware overloads.

Use craftMethod(name, this, fn) when the generator needs component state.

typescript
import { Console, craftMethod, craftSignal, craftUse } from '@craft-ts/core';

export class Counter {
  readonly counter = craftSignal(0);

  readonly increment = craftUse(craftMethod('increment', this, function* (step = 1) {
    yield* Console.log('increment is called');
    this.counter.update((value) => value + step);
  }));
}

This overload captures the instance once, so the callback still works after extraction:

typescript
const increment = component.increment;
increment();

Receiver-based form#

Use craftMethod(name, fn) when you want the method to resolve this from its receiver, and are fine with the receiver-dependent behavior.

In strict TypeScript, annotate this explicitly inside the generator:

typescript
import { Console, craftMethod, craftSignal, craftUse } from '@craft-ts/core';

export class Counter {
  readonly counter = craftSignal(0);

  readonly increment = craftUse(craftMethod(
    'increment',
    function* (this: Counter, step = 1) {
      yield* Console.log('increment is called');
      this.counter.update((value) => value + step);
      return this.counter();
    },
  ));
}

Composing services from a class#

typescript
export class Counter {
  readonly increment = craftUse(craftMethod(
    'increment',
    this,
    function* (value: number) {
      return yield* CounterWorker.set(value);
    },
  ));
}

Caveats#

  • craftMethod(...) must be created inside an injection context, typically during component instantiation.

  • The first argument is a required name; it must match the property or variable name. The craft-ts/craft-method-name-match ESLint rule enforces this and provides a quick fix.

  • craftMethod(name, fn) depends on the receiver used at call time. If you extract the callback, this is no longer guaranteed unless you bind it yourself.

  • craftMethod(name, this, fn) is the recommended form whenever the generator reads or writes this.

  • onAppStart(...) is not supported inside craftMethod.

See Also#

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