Usage Guide

Once Shapt is one of his dependencies. You gonna need to create a feature toggle module:

defmodule TestModule do
  use Shapt,
    adapter: [
      prod: {Shapt.Adapters.Env, []}
    ],
    toggles: [
      feature_x?: %{
        force: true,
        key: "MYAPP_FEATURE_X",
        deadline: ~D[2019-12-31]
      },
      feature_y?: %{
        deadline: ~D[2009-12-31]
      }
    ]
end

Options

• adapter: receives a keyword list of adapters by environment.
• toggles: receives a keyword list of toggles to be configured.

Default configurations

If no adapter is provided Shapt gonna set by default, Shapt.Adapters.Env as the production adapter and Shapt.Adapters.DotEnv as develompment and test adapter. toggles option has no default values.

Provided functions

Just by using Shapt you gonna have some extra functions on your feature toggle module:

key_name/0

For each key in the toggles option keyword list you gonna have a fucntion that represents that feature toggle. From the example above you would have in TestModule the functions feature_x?/0 and feature_y?/0, those functions always return only true or false.

toggle/2

Besides the key named functions you gonna have toggle/2. It can be used to evaluate the feature toggle and what to do when it's on or off. Some usage examples:

# just returning values
TestModule.toggle(:feature_x?, on: FeatureX, off: OldFeature)

# applying functions that receive the same parameters
TestModule.toggle(:feature_x?, env: [params, options], on: &Feature.x/2, off: &Feature.old/2)

# applying functions with different parameters:
TestModule.toggle(:feature_x?, on: {ModuleX, :function, [paramsx]}, off: {Module, :fuction, [params]})

In those two last examples we use the apply function, be aware of that when using this feature. So make sure that the env or the third element tuple is always a list which the size is the same as the provided function arity.

expired?/1

It receives the name of a toggle and says if it's expired or not.

enabled?/1

It receives the name of a toggle and says if it's enabled or not.

expired_toggles/0

List all expired toggles

output_template/0

Return the binary representing the template file generated by the Adapter.

start_link/0

A function to start the Adapter GenServer with the provided config. Some Adapters might not require to be started.

Env Adapter

Shapt.Adapters.Env will work directly with environment variables using the System.get_env/1. This is why the adapter doesn't receive any configuration.

DotEnv Adapter

Shapt.Adapters.DotEnv will read a .env file. If no option is provided it gonna try to read a .env file in the root of the mix project you're running. To provide a file you can set {Shapt.Adapters.DotEnv, [file: "filename"]} on your adapter configuration. This adapter loads the values into a ets table and it requires to be started with the start_link/0 function.

Testing

Shapt is built having in mind that you probably gonna use Mox to write tests. By using Mox you only need mock enabled?/2 callback. You can have more info on Shapt.Adapter behaviour docs.