.TH erl_features 3erl "stdlib 5.2.2" "Ericsson AB" "Erlang Module Definition"
.SH NAME
erl_features \- Feature support.
.SH DESCRIPTION
.LP
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\&. 
.SH DATA TYPES
.nf

\fBfeature()\fR\& = atom()
.br
.fi
.nf

\fBrelease()\fR\& = integer() >= 0
.br
.fi
.nf

\fBstatus()\fR\& = experimental | approved | permanent | rejected
.br
.fi
.nf

\fBtype()\fR\& = extension | backwards_incompatible_change
.br
.fi
.SH EXPORTS
.LP
.nf

.B
all() -> [feature()]
.br
.fi
.br
.RS
.LP
Return a list of all known features\&. This list will include features that have been removed (status \fIrejected\fR\&) and features that are no longer configurable (status \fIpermanent\fR\&)\&.
.RE

.LP
.nf

.B
configurable() -> [feature()]
.br
.fi
.br
.RS
.LP
Return a list of all configurable features, that is, features with status \fIexperimental\fR\& or \fIapproved\fR\&\&. These are the features that can be enabled or disabled\&.
.RE

.LP
.nf

.B
info(Feature :: feature()) -> FeatureInfoMap | no_return()
.br
.fi
.br
.RS
.LP
Types:

.RS 3
Description = string()
.br
FeatureInfoMap = 
.br
    #{description := Description,
.br
      short := Description,
.br
      type := type(),
.br
      keywords := [atom()],
.br
      status := status(),
.br
      experimental => release(),
.br
      approved => release(),
.br
      permanent => release(),
.br
      rejected => release()}
.br
.RE
.RE
.RS
.LP
Return a map containing information about the given feature\&.
.RE

.LP
.nf

.B
enabled() -> [feature()]
.br
.fi
.br
.RS
.LP
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\&.
.RE

.LP
.nf

.B
used(Module :: module() | file:filename()) -> [feature()]
.br
.fi
.br
.RS
.LP
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\&.
.RE