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https://github.com/sleipnir/injectx

Elixir dependency injection
https://github.com/sleipnir/injectx

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Elixir dependency injection

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# Injectx

**Context Dependency Injection for Elixir**

## Installation

If [available in Hex](https://hex.pm/docs/publish), the package can be installed
by adding `injectx` to your list of dependencies in `mix.exs`:

```elixir
def deps do
[
{:injectx, "~> 0.1.0"}
]
end
```

`Injectx` module is a entrypoint to CDI.

## Usage:

Define your Behavior module:

```elixir
defmodule FooBehavior do
@callback greetings(String.t()) :: String.t()
end
```

Implement it:

```elixir
defmodule FooImpl do
@behavior FooBehavior

@impl true
def greetings(_name) do
"Hello from FooImpl"
end
end
```

Initialize Injectx Context on Application bootstrap:

```elixir
defmodule App do
use Application

alias Injectx.Context

@impl true
def start(_type, _args) do
context = %Context{
bindings: [
%Context.Binding{
behavior: FooBehavior,
definitions: [
%Context.BindingDefinition{module: FooImpl, default: true}
]
}
]
}

Context.from(context)

children = [
...
]

opts = [strategy: :one_for_one, name: App.Supervisor]
Supervisor.start_link(children, opts)
end
end
```

### Use your behavior via Implementation resolved in runtime (using inject macro with same sintaxe of alias):

```elixir
defmodule Bar do
use Injectx

inject TestBehaviour

def greetings(name), do: TestBehaviour.greetings(name)
end
```

### Or you can inject all implementations at once (using inject_all function):

```elixir
defmodule Caller do
use Injectx

# resolve all injection bindings for certain behavior
@all inject_all(TestBehaviour)

....
def call(),
do: Enum.each(@all, fn impl -> impl.greetings("Teddy") end)
end
```

## Dispatching

Injectx also provides the ability to dynamically dispatch your implementations.
For this it is only necessary to use the dispatcher function. Sync and Async are possible options:

```elixir
defmodule SomeBehaviour do
@callback test(integer()) :: {:ok, integer()}
end

defmodule SomeImpl1 do
@behaviour SomeBehaviour

def test(1), do: {:ok, 1}
end

defmodule SomeImpl2 do
@behaviour SomeBehaviour

def test(1), do: {:ok, 2}
end

... bootstrap
@impl true
def start(_type, _args) do
context = %Context{
bindings: [
%Context.Binding{
behavior: SomeBehaviour,
definitions: [
%Context.BindingDefinition{module: SomeImpl1, default: true},
%Context.BindingDefinition{module: SomeImpl2}
]
}
]
}

Context.from(context)
....
end

...write some client module...

defmodule SomeClientModule do
use Injectx

def call(arg), do: dispatching(TestBehaviour, :test, [arg], async: true)

end

...then call it `iex -S mix`

iex(1)> SomeClientModule.call(1)
[{:ok, InjectxTest.TestImpl2, {:ok, 2}}, {:ok, InjectxTest.TestImpl1, {:ok, 1}}]
```