synthesize

@fluidframework/synthesize

An Ioc type library for synthesizing a IFluidObject based on registered IFluidObject providers.

It allows for the creation of a DependencyContainer that can have IFluidObjects registered with it based on their interface Symbol. So for example if I wanted to register something as IFoo I would need to provide and object that implements IFoo along side it.

The DependencyContainer also exposes a synthesize method that returns an object with a Promise to the correct optional and required symbols requested.

So if I wanted an object with an optional IFoo and a required IBar I would get back:

{
    IFoo: Promise<IFoo | undefined>
    IBar: Promise<IBar>
}

Simple Example

const dc = new DependencyContainer();
dc.register(IFoo, new Foo());

const s = dc.synthesize({IFoo}, {});
const foo = await s.IFoo;
console.log(s.IFoo?.foo;)

API

• Providers
  • InstanceProvider
  • SingletonProvider
  • ValueProvider
  • FactoryProvider
• Synthesize
  • Optional Types
  • Required Types
  • Multiple Types
• Parent

Fluid object Providers

Fluid object Providers are the the different ways you can return a IFluidObject when registering.

There are four types of providers:

1. Value Provider
2. Async Value Provider
3. Factory Provider
4. Async Factory Provider

type FluidObjectProvider<T extends keyof IFluidObject> =
    IFluidObject[T]
    | Promise<IFluidObject[T]>
    | ((dependencyContainer: DependencyContainer) => IFluidObject[T])
    | ((dependencyContainer: DependencyContainer) => Promise<IFluidObject[T]>);

Value Provider

Provide an IFluidObject of a given type.

Usage

const dc = new DependencyContainer();

// Singleton
const foo = new Foo();
dc.register(IFoo, Foo);

// Instance
dc.register(IFoo, new Foo())

Async Value Provider

Provide a Promise to an IFluidObject of a given type.

Usage

const dc = new DependencyContainer();

const generateFoo: Promise<IFoo> = await() => {
    const foo = new Foo();
    await foo.initialize();
    return foo;
}

// Singleton
const foo = generateFoo();
dc.register(IFoo, foo);

// Instance
dc.register(IFoo, generateFoo());

Factory Provider

(dependencyContainer: DependencyContainer) => IFluidObject[T]

Provide a function that will resolve an IFluidObject of a given type.

Usage

const dc = new DependencyContainer();
const fooFactory = () => new Foo();
dc.register(IFoo, fooFactory);

// Factories can utilize the DependencyContainer if the IFluidObject depends
// on other providers
const barFactory = (dc) => new Bar(dc);
dc.register(IFoo, barFactory);

Async Factory Provider

(dependencyContainer: DependencyContainer) => Promise<IFluidObject[T]>

Provide a function that will resolve a Promise to an IFluidObject of a given type.

Usage

const dc = new DependencyContainer();

const generateFoo: Promise<IFoo> = await() => {
    const foo = new Foo();
    await foo.initialize();
    return foo;
}

dc.register(IFoo, generateFoo);

const generateBar: Promise<IBar> = await(dc) => {
    const bar = new Bar();
    await bar.initialize(dc);
    return bar;
}

dc.register(IBar, generateBar);

Synthesize

Once you have a DependencyContainer with registered providers you can synthesize/generate a new IFluidObject from it. The object that is returned will have the correct typing of optional and required types.

An Example:

If I wanted an object with an optional IFoo and a required IBar I would get back:

{
    IFoo: Promise<IFoo | undefined>
    IBar: Promise<IBar>
}

synthesize takes optionalTypes and requiredTypes as well as their corresponding types. FluidObjectSymbolProvider<> is a TypeScript type that ensures the types being passed match the ones in the object being provided.

Optional Types

Optional types will return a Promise to it's corresponding IFluidObject or undefined. Because of this we need to do an if check to validate the object or use the ? like in the example below.

const dc = new DependencyContainer();

const s = dc.synthesize<IFoo>({IFoo}, {});
const foo = await s.IFoo;
console.log(foo?.foo);

Note: Because of how generics in TypeScript work we need to provide an empty requiredTypes object even though we don't need to provide the type.

Required Types

Required types will return a Promise to it's corresponding IFluidObject or it will throw.

You can see below that we don't need to add the ? to check our requested type.

const dc = new DependencyContainer();

const scope = dc.synthesize<{}, IFoo>({}, {IFoo});
const foo = await s.IFoo;
console.log(foo.foo);

Multiple Types

You can declare multiple types for both Optional and Required using the & or creating a separate type.

const dc = new DependencyContainer();

const scope = dc.synthesize<IFoo & IBar>({IFoo, IBar}, {});
const fooP = s.IFoo;
const barP = s.IBar;
const [foo, bar] = Promise.all([foo, bar]);
console.log(foo?.foo);
console.log(bar?.bar);

const dc = new DependencyContainer();

const scope = dc.synthesize<{}, IFoo & IBar>({}, {IFoo, IBar});
const fooP = s.IFoo;
const barP = s.IBar;
const [foo, bar] = Promise.all([foo, bar]);
console.log(foo.foo);
console.log(bar.bar);

const dc = new DependencyContainer();

const scope = dc.synthesize<IFoo, IBar>({IFoo}, {IBar});
const fooP = s.IFoo;
const barP = s.IBar;
const [foo, bar] = Promise.all([foo, bar]);
console.log(foo?.foo);
console.log(bar.bar);

Parent

The DependencyContainer takes one optional parameter which is the parent. When resolving providers the DependencyContainer will first check the current container then look in the parent.

The parent can also be set after DependencyContainer creation.