Moar v1.15.0

View Source Moar.Opts (Moar v1.15.0)

Extracts keys and values from enumerables, especially from function options.

There are two main functions, each of which takes an opts enumerable as input. get/3 extracts one value from the opts with an optional default value. take/2 extracts multiple values from the opts with optional default values for some or all keys.

get/3 and take/2 differ from their Map and Keyword counterparts in the following ways:

  • get/3 and take/2 accept any enumerable, including maps and keyword lists.
  • get/3 and take/2 will fall back to the default value if the given key's value is blank as defined by Moar.Term.blank?/1 (nil, empty strings, strings made up only of whitespace, empty lists, and empty maps). The corresponding Map and Keyword functions only fall back to the default value if the value is exactly nil.
  • take/2 allows default values to be specified.
  • take/2 will return the value for a requested key even if the key is not in the input enumerable.

Example using get/2 and get/3:

def build_url(path, opts \\ []) do
  %URI{
    path: path,
    host: Moar.Opts.get(opts, :host, "localhost"),
    port: Moar.Opts.get(opts, :port),
    scheme: "https"
  } |> URI.to_string()
end

Examples using take/2:

# example using pattern matching
def build_url(path, opts \ []) do
  %{host: h, port: p} = Moar.Opts.take(opts, [:port, host: "localhost"])
  %URI{path: path, host: h, port: p, scheme: "https"} |> URI.to_string()
end

# example rebinding `opts` to the parsed opts
def build_url(path, opts \ []) do
  opts = Moar.Opts.take(opts, [:port, host: "localhost"])
  %URI{path: path, host: opts.host, port: opts.port, scheme: "https"} |> URI.to_string()
end

Link to this section Summary

Functions

get(input, key, default \\ nil)

Get the value of key from input, falling back to optional default if the key does not exist, or if its value is blank (via Moar.Term.blank?/1).

take(input, keys)

Get the value each key in keys from input, falling back to optional default values for keys that do not exist, or for values that are blank (via Moar.Term.blank?/1).

Link to this section Functions

Link to this function

get(input, key, default \\ nil)

View Source 
@spec get(Enum.t(), binary() | atom(), any()) :: any()

Get the value of key from input, falling back to optional default if the key does not exist, or if its value is blank (via Moar.Term.blank?/1).

iex> [a: 1, b: 2] |> Moar.Opts.get(:a)
1

iex> [a: 1, b: 2] |> Moar.Opts.get(:c)
nil

iex> [a: 1, b: 2, c: ""] |> Moar.Opts.get(:c)
nil

iex> [a: 1, b: 2, c: %{}] |> Moar.Opts.get(:c)
nil

iex> [a: 1, b: 2, c: "   "] |> Moar.Opts.get(:c, 300)
300
Link to this function

take(input, keys)

View Source 
@spec take(Enum.t(), list()) :: map()

Get the value each key in keys from input, falling back to optional default values for keys that do not exist, or for values that are blank (via Moar.Term.blank?/1).

If key does not exist in keys, return nil, or return the default value if provided.

keys is a list of keys (e.g., [:a, :b]), a keyword list of keys and default values (e.g., [a: 1, b: 2]), or a hybrid list/keyword list (e.g., [:a, b: 2])

iex> [a: 1, b: 2] |> Moar.Opts.take([:a, :c])
%{a: 1, c: nil}

iex> [a: 1, b: 2] |> Moar.Opts.take([:a, b: 0, c: 3])
%{a: 1, b: 2, c: 3}