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() (opaque)

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() (opaque)

match_vars()

name_arity()

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

prematch_vars() (opaque)

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.