# `Enviable.Credo.UnsafeAtom`
[🔗](https://github.com/halostatue/enviable/blob/v2.3.0/lib/enviable/credo/unsafe_atom.ex#L5)

## Basics

> #### This check is disabled by default. {: .neutral}
>
> [Learn how to enable it](`e:credo:config_file.html#checks`) via `.credo.exs`.

This check has a base priority of `high` and works with any version of Elixir.

## Explanation

Creating atoms from environment variables dynamically is a potentially unsafe
because atoms are not garbage-collected by the runtime.

Enviable functions that convert to atoms or modules should use the `:allowed`
option to restrict which atoms can be created:

    Enviable.get_env_as_atom("VAR", allowed: [:foo, :bar])
    Enviable.fetch_env_as_module!("MODULE", allowed: [MyApp.Foo, MyApp.Bar])

Or use the safe variants that only work with existing atoms:

    Enviable.get_env_as_safe_atom("VAR")
    Enviable.fetch_env_as_safe_module("MODULE")

This also applies to generic conversion functions and encoded types:

    # Unsafe
    Enviable.get_env_as("VAR", :atom)
    Enviable.get_env_as("VAR", {:base64, :module})
    Enviable.get_env_as_list("ITEMS", as: :atom)

    # Safe alternatives
    Enviable.get_env_as("VAR", :safe_atom)
    Enviable.get_env_as("VAR", {:base64, :safe_module})
    Enviable.get_env_as_list("ITEMS", as: :safe_atom)

When using `import Enviable`, the check applies to bare function calls:

    import Enviable

    # Unsafe
    get_env_as_atom("VAR")
    fetch_env_as_list!("ITEMS", as: :module)

    # Safe
    get_env_as_safe_atom("VAR")
    fetch_env_as_list!("ITEMS", as: :safe_module)

This check can be configured to always warn even when using the `:allowed`
option:

    {Enviable.Credo.UnsafeAtom, permit_with_allowed: false}

## Check-Specific Parameters

Use the following parameters to configure this check:

### `:permit_with_allowed`

  Allow unsafe functions if :allowed option is present

*This parameter defaults to* `true`.

## General Parameters

Like with all checks, [general params](`e:credo:check_params.html`) can be applied.

Parameters can be configured via the [`.credo.exs` config file](`e:credo:config_file.html`).

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*Consult [api-reference.md](api-reference.md) for complete listing*