A struct that holds compile time environment information.

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

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-item tuples, where the first item is the aliased name and the second 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
• vars - a list keeping all defined variables as {var, context}
• export_vars - a list keeping all variables to be exported in a construct (may be nil)
• lexical_tracker - PID of the lexical tracker which is responsible for keeping user info
• local - the module to expand local functions to