View Source Macro.Env (Elixir v1.13.0)
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__
endYou may then call make_custom_env() to get a struct with the desired
imports and aliases included.
It contains the following fields:
context- the context of the environment; it can benil(default context),:guard(inside a guard) or:match(inside a match)context_modules- a list of modules defined in the current contextfile- the current file name as a binaryfunction- a tuple as{atom, integer}, where the first element is the function name and the second its arity; returnsnilif not inside a functionline- the current line as an integermodule- the current module name
The following fields are private to Elixir's macro expansion mechanism and must not be accessed directly:
aliasesfunctionsmacro_aliasesmacroslexical_trackerrequirestracersversioned_vars
Link to this section Summary
Functions
Fetches the alias for the given atom.
Fetches the macro alias for the given atom.
Checks if a variable belongs to the environment.
Returns whether the compilation environment is currently inside a guard.
Returns whether the compilation environment is currently inside a match clause.
Returns a keyword list containing the file and line information as keys.
Returns the modules from which the given {name, arity} was
imported.
Prepend a tracer to the list of tracers in the environment.
Returns true if the given module has been required.
Returns the environment stacktrace.
Returns a Macro.Env in the match context.
Returns a list of variables in the current environment.
Link to this section Types
@type context() :: :match | :guard | nil
@type context_modules() :: [module()]
@type file() :: binary()
@type line() :: non_neg_integer()
@type t() :: %Macro.Env{ aliases: aliases(), context: context(), context_modules: context_modules(), file: file(), function: name_arity() | nil, functions: functions(), lexical_tracker: lexical_tracker(), line: line(), macro_aliases: macro_aliases(), macros: macros(), module: module(), requires: requires(), tracers: tracers(), versioned_vars: versioned_vars() }
Link to this section Functions
Fetches the alias for the given atom.
Returns {:ok, alias} if the alias exists, :error
otherwise.
Examples
iex> alias Foo.Bar, as: Baz
iex> Baz
Foo.Bar
iex> Macro.Env.fetch_alias(__ENV__, :Baz)
{:ok, Foo.Bar}
iex> Macro.Env.fetch_alias(__ENV__, :Unknown)
:errorFetches the macro alias for the given atom.
Returns {:ok, macro_alias} if the alias exists, :error
otherwise.
A macro alias is only used inside quoted expansion. See
fetch_alias/2 for a more general example.
Checks if a variable belongs to the environment.
Examples
iex> x = 13
iex> x
13
iex> Macro.Env.has_var?(__ENV__, {:x, nil})
true
iex> Macro.Env.has_var?(__ENV__, {:unknown, nil})
falseReturns whether the compilation environment is currently inside a guard.
Returns whether the compilation environment is currently inside a match clause.
Returns a keyword list containing the file and line information as keys.
@spec lookup_import(t(), name_arity()) :: [{:function | :macro, module()}]
Returns the modules from which the given {name, arity} was
imported.
It returns a list of two element tuples in the shape of
{:function | :macro, module}. The elements in the list
are in no particular order and the order is not guaranteed.
Examples
iex> Macro.Env.lookup_import(__ENV__, {:duplicate, 2})
[]
iex> import Tuple, only: [duplicate: 2], warn: false
iex> Macro.Env.lookup_import(__ENV__, {:duplicate, 2})
[{:function, Tuple}]
iex> import List, only: [duplicate: 2], warn: false
iex> Macro.Env.lookup_import(__ENV__, {:duplicate, 2})
[{:function, List}, {:function, Tuple}]
iex> Macro.Env.lookup_import(__ENV__, {:def, 1})
[{:macro, Kernel}]Prepend a tracer to the list of tracers in the environment.
Examples
Macro.Env.prepend_tracer(__ENV__, MyCustomTracer)Returns true if the given module has been required.
Examples
iex> Macro.Env.required?(__ENV__, Integer)
false
iex> require Integer
iex> Macro.Env.required?(__ENV__, Integer)
true
iex> Macro.Env.required?(__ENV__, Kernel)
trueReturns the environment stacktrace.
Returns a Macro.Env in the match context.
Returns a list of variables in the current environment.
Each variable is identified by a tuple of two elements, where the first element is the variable name as an atom and the second element is its context, which may be an atom or an integer.