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Macro.Env

A struct that holds compile time environment information.

The current environment can be accessed at any time as __ENV__/0. Inside macros, the caller environment can be accessed as __CALLER__/0.

An instance of Macro.Env must not be modified by hand. If you need to create a custom environment to pass to Code.eval_quoted/3, use the following trick:

def make_custom_env do
  import SomeModule, only: [some_function: 2]
  alias A.B.C
  __ENV__
end

You may then call make_custom_env() to get a struct with the desired imports and aliases included.

It contains the following fields:

module - the current module name
file - the current file name as a binary
line - the current line as an integer
function - a tuple as {atom, integer}, where the first element is the function name and the second its arity; returns nil if not inside a function
context - the context of the environment; it can be nil (default context), inside a guard or inside a match
aliases - a list of two-element tuples, where the first element is the aliased name and the second one the actual name
requires - the list of required modules
functions - a list of functions imported from each module
macros - a list of macros imported from each module
macro_aliases - a list of aliases defined inside the current macro
context_modules - a list of modules defined in the current context
lexical_tracker - PID of the lexical tracker which is responsible for keeping user info
vars - a list keeping all defined variables as {var, context}

The following fields are private and must not be accessed or relied on:

export_vars - a list keeping all variables to be exported in a construct (may be nil)
match_vars - controls how “new” variables are handled. Inside a match it is a list with all variables in a match. Outside of a match is either :warn or :apply
prematch_vars - a list of variables defined before a match (is nil when not inside a match)

Summary

Types

aliases()
context()
context_modules()
export_vars()
file()
functions()
lexical_tracker()
line()
local()
macro_aliases()
macros()
match_vars()
name_arity()
prematch_vars()
requires()
t()
vars()

Functions

in_guard?(env): Returns whether the compilation environment is currently inside a guard
in_match?(env): Returns whether the compilation environment is currently inside a match clause
location(env): Returns a keyword list containing the file and line information as keys
stacktrace(env): Returns the environment stacktrace
to_match(env): Returns a Macro.Env in the match context

Types

aliases()

aliases() :: [{module(), module()}]

context()

context() :: :match | :guard | nil

context_modules()

context_modules() :: [module()]

export_vars()

export_vars()

file()

file() :: binary()

functions()

functions() :: [{module(), [name_arity()]}]

lexical_tracker()

lexical_tracker() :: pid() | nil

line()

line() :: non_neg_integer()

local()

local() :: atom() | nil

macro_aliases()

macro_aliases() :: [{module(), {integer(), module()}}]

macros()

macros() :: [{module(), [name_arity()]}]

match_vars()

match_vars()

name_arity()

name_arity() :: {atom(), arity()}

prematch_vars()

prematch_vars()

requires()

requires() :: [module()]

t()

t() :: %Macro.Env{module: atom(), file: file(), line: line(), function: name_arity() | nil, context: context(), requires: requires(), aliases: aliases(), functions: functions(), macros: macros(), macro_aliases: aliases(), context_modules: context_modules(), vars: vars(), export_vars: export_vars(), match_vars: match_vars(), prematch_vars: prematch_vars(), lexical_tracker: lexical_tracker()}

vars()

vars() :: [{atom(), atom() | non_neg_integer()}]

Functions

in_guard?(env)

in_guard?(t()) :: boolean()

Returns whether the compilation environment is currently inside a guard.

in_match?(env)

in_match?(t()) :: boolean()

Returns whether the compilation environment is currently inside a match clause.

location(env)

location(t()) :: keyword()

Returns a keyword list containing the file and line information as keys.

stacktrace(env)

stacktrace(t()) :: list()

Returns the environment stacktrace.

to_match(env)

to_match(t()) :: t()

Returns a Macro.Env in the match context.