@proc7ts/context-modules

IoC Context Modules

Dynamically loadable IoC context modules conforming to @proc7ts/context-values API

Context module can be used to provide multiple assets for IoC context at once. Unloading the module revokes all assets provided by it.

Usage example:

import { CxModule } from '@proc7ts/context-modules';

// Construct new module.
const myModule = new CxModule('my module', {
  setup(setup) {
    // Provide assets for `Foo` entry.
    setup.provide(cxConstAsset(Foo, 'foo'));
  },
});

// Add the module to context.
const myModuleSupply = cxBuilder.provide(myModule);

// Start using the module.
// The first usage of the module loads it.
const myModuleUse = await context.get(myModule).use();

// Await for the module to load.
await myModuleUse.whenReady;

// Access the value provided by module.
console.log(context.get(Foo)); // 'foo'

// Stop using the module.
// Once tha last usage stopped, the module is unloaded.
myModuleUse.supply.off();

// Revoke the module.
myModuleSupply.off();

Context module's constructor accepts a human-readable module name, and options object.

The following options supported:

• needs - A module or modules the constructed one requires.

  The listed modules will be loaded prior to loading the constructed one.

• has - A module or modules the constructed one provides.

  When specified, the constructed module will be loaded instead of the listed ones.

• setup() - A method that sets up constructed module.

  May be synchronous or asynchronous.

  Accepts a CxModule.Setup instance with the following properties:

  • get() - For accessing context values.

    Inherited from ContextValues interface.

  • provide() - For providing context entry assets.

    The same as in CxBuilder.

    All assets provided by this method will be revoked once the module unloaded.

  • initBy() - For registering module initializers.

To use a module:

1. Create its implementation.

2. Provide it by CxBuilder.provide(module) call.

3. Obtain its handle from context by calling CxValues.get(module).

4. Start using it by calling the .use() method of obtained module handle.

5. Wait for the module to load and become ready to use: await use.whenReady.

6. When no longer needed, cut off the module use supply: use.supply.off().

   The module will be unloaded once no longer uses remain.

   Note that the module can be in use indirectly when required by another one.