# erl_features

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Module

erl_features

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Module Summary

Feature support.

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Since

Module erl_features was introduced in OTP 25.0.

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Description

This module contains functions for supporting features that can be enabled/disabled in Erlang. It should be considered as mostly for internal use, although there are some functions that might be useful when writing tools.

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Data Types

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feature() = atom()

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release() = integer() >= 0

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status() = experimental | approved | permanent | rejected

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type() = extension | backwards_incompatible_change

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Exports

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all() -> [feature()]
OTP 25.0

Return a list of all known features. This list will include features that have been removed (status rejected) and features that are no longer configurable (status permanent).

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configurable() -> [feature()]
OTP 25.1

Return a list of all configurable features, that is, features with status experimental or approved. These are the features that can be enabled or disabled.

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info(Feature :: feature()) -> FeatureInfoMap | no_return()
OTP 25.0

### Types

Description = string()
FeatureInfoMap =
#{description := Description,
short := Description,
type := type(),
keywords := [atom()],
status := status(),
experimental => release(),
approved => release(),
permanent => release(),
rejected => release()}

Return a map containing information about the given feature.

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enabled() -> [feature()]
OTP 25.0

Return a list of the features that are currently enabled. Note that the set of enabled is set during startup and can then not be changed.

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used(Module :: module() | file:filename()) -> [feature()]
OTP 25.0

Return the list of features enabled when compiling the module. The module need not be loaded, but is found if it exists in the loadpath. If not all features used by the module are enabled in the runtime, loading the module is not allowed.