Specs

eval_string(List.Chars.t(), binding(), Macro.Env.t() | keyword()) ::
  {term(), binding()}

Evaluates the contents given by string.

The binding argument is a list of variable bindings. The opts argument is a keyword list of environment options.

Warning: string can be any Elixir code and will be executed with the same privileges as the Erlang VM: this means that such code could compromise the machine (for example by executing system commands). Don't use eval_string/3 with untrusted input (such as strings coming from the network).

Options

Options can be:

• :file - the file to be considered in the evaluation

• :line - the line on which the script starts

Additionally, the following scope values can be configured:

• :aliases - a list of tuples with the alias and its target

• :requires - a list of modules required

• :functions - a list of tuples where the first element is a module and the second a list of imported function names and arity; the list of function names and arity must be sorted

• :macros - a list of tuples where the first element is a module and the second a list of imported macro names and arity; the list of function names and arity must be sorted

Note that setting any of the values above overrides Elixir's default values. For example, setting :requires to [] will no longer automatically require the Kernel module. In the same way setting :macros will no longer auto-import Kernel macros like Kernel.if/2, Kernel.SpecialForms.case/2, and so on.

Returns a tuple of the form {value, binding}, where value is the value returned from evaluating string. If an error occurs while evaluating string an exception will be raised.

binding is a list with all variable bindings after evaluating string. The binding keys are usually atoms, but they may be a tuple for variables defined in a different context.

Examples

iex> {result, binding} = Code.eval_string("a + b", [a: 1, b: 2], file: __ENV__.file, line: __ENV__.line)
iex> result
3
iex> Enum.sort(binding)
[a: 1, b: 2]

iex> {result, binding} = Code.eval_string("c = a + b", [a: 1, b: 2], __ENV__)
iex> result
3
iex> Enum.sort(binding)
[a: 1, b: 2, c: 3]

iex> {result, binding} = Code.eval_string("a = a + b", [a: 1, b: 2])
iex> result
3
iex> Enum.sort(binding)
[a: 3, b: 2]

For convenience, you can pass __ENV__/0 as the opts argument and all imports, requires and aliases defined in the current environment will be automatically carried over:

iex> {result, binding} = Code.eval_string("a + b", [a: 1, b: 2], __ENV__)
iex> result
3
iex> Enum.sort(binding)
[a: 1, b: 2]