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)