Elixir v1.1.0 Access behaviour
Dictionary-like access to data structures via the foo[bar] syntax.
This module also empowers Kernels nested update functions
Kernel.get_in/2, Kernel.put_in/3, Kernel.update_in/3 and
Kernel.get_and_update_in/3.
Examples
Out of the box, Access works with built-in dictionaries: Keyword
and Map:
iex> keywords = [a: 1, b: 2]
iex> keywords[:a]
1
iex> map = %{a: 1, b: 2}
iex> map[:a]
1
iex> star_ratings = %{1.0 => "★", 1.5 => "★☆", 2.0 => "★★"}
iex> star_ratings[1.5]
"★☆"Furthermore, Access transparently ignores nil values:
iex> keywords = [a: 1, b: 2]
iex> keywords[:c][:unknown]
nilThe key comparison must be implemented using the === operator.
Summary
Functions
Fetches the container’s value for the given key
Gets the container’s value for the given key
Gets and updates the container’s value for the given key, in a single pass
Types
Functions
Specs
fetch(t, term) :: {:ok, term} | :errorFetches the container’s value for the given key.
Specs
get(t, term, term) :: termGets the container’s value for the given key.
Gets and updates the container’s value for the given key, in a single pass.
The argument function fun must receive the value for the given key (or
nil if the key doesn’t exist in container). It must return a tuple
containing the get value and the new value to be stored in the container.
This function returns a two-element tuple.
The first element is the get value, as returned by fun.
The second element is the container, updated with the value returned by fun.