Elixir v1.1.0 Protocol

Functions for working with protocols.

Summary

Functions

assert_impl!(protocol, base)

Checks if the given module is loaded and is an implementation of the given protocol

assert_protocol!(module)

Checks if the given module is loaded and is protocol

consolidate(protocol, types)

Receives a protocol and a list of implementations and consolidates the given protocol

consolidated?(protocol)

Returns true if the protocol was consolidated

extract_impls(protocol, paths)

Extracts all types implemented for the given protocol from the given paths

extract_protocols(paths)

Extracts all protocols from the given paths

Macros

def(signature)

Defines a new protocol function

derive(protocol, module, options \\ [])

Derives the protocol for module with the given options

Functions

assert_impl!(protocol, base)

Specs

assert_impl!(module, module) :: :ok | no_return

Checks if the given module is loaded and is an implementation of the given protocol.

Returns :ok if so, otherwise raises ArgumentError.

assert_protocol!(module)

Specs

assert_protocol!(module) :: :ok | no_return

Checks if the given module is loaded and is protocol.

Returns :ok if so, otherwise raises ArgumentError.

consolidate(protocol, types)

Specs

consolidate(module, [module]) ::
  {:ok, binary} |
  {:error, :not_a_protocol} |
  {:error, :no_beam_info}

Receives a protocol and a list of implementations and consolidates the given protocol.

Consolidation happens by changing the protocol impl_for in the abstract format to have fast lookup rules. Usually the list of implementations to use during consolidation are retrieved with the help of extract_impls/2.

It returns the updated version of the protocol bytecode. A given bytecode or protocol implementation can be checked to be consolidated or not by analyzing the protocol attribute:

Protocol.consolidated?(Enumerable)

If the first element of the tuple is true, it means the protocol was consolidated.

This function does not load the protocol at any point nor loads the new bytecode for the compiled module. However each implementation must be available and it will be loaded.

consolidated?(protocol)

Specs

consolidated?(module) :: boolean

Returns true if the protocol was consolidated.

extract_impls(protocol, paths)

Specs

extract_impls(module, [char_list | String.t]) :: [atom]

Extracts all types implemented for the given protocol from the given paths.

The paths can be either a char list or a string. Internally they are worked on as char lists, so passing them as lists avoid extra conversion.

Does not load any of the implementations.

Examples

# Get Elixir's ebin and retrieve all protocols
iex> path = :code.lib_dir(:elixir, :ebin)
iex> mods = Protocol.extract_impls(Enumerable, [path])
iex> List in mods
true

extract_protocols(paths)

Specs

extract_protocols([char_list | String.t]) :: [atom]

Extracts all protocols from the given paths.

The paths can be either a char list or a string. Internally they are worked on as char lists, so passing them as lists avoid extra conversion.

Does not load any of the protocols.

Examples

# Get Elixir's ebin and retrieve all protocols
iex> path = :code.lib_dir(:elixir, :ebin)
iex> mods = Protocol.extract_protocols([path])
iex> Enumerable in mods
true

Macros

def(signature)

Defines a new protocol function.

Protocols do not allow functions to be defined directly, instead, the regular Kernel.def/* macros are replaced by this macro which defines the protocol functions with the appropriate callbacks.

derive(protocol, module, options \\ [])

Derives the protocol for module with the given options.