1.2.3

## Packager Stage

Once the Generator has been properly encoded in the Encoder stage, Rubinius packages the bytecode up as a CompiledMethod by creating a new CompiledMethod and setting a number of properties on it.

These properties are available on any CompiledMethod. You can retrieve the CompiledMethod from a Ruby Method object by calling `executable` on it.

- iseq: a Tuple containing the raw instruction sequence
- literals: a Tuple contaning the literals used in the method. Literals are used internally by Rubinius for values like Strings, and are used by the `push_literal` and `set_literal` instructions.
- lines: an Array containing the first instruction pointer for each line represented by the bytecode
- required_args: the number of arguments required by the method
- total_args: the total number of arguments, including optional arguments but not `*args`
- splat: the position of the splat argument, if any
- local_count: the number of local variables, including parameters
- local_names: a Tuple containing a list of all of the local variable names. The first names will be the required, optional, splat and block arguments, in that order.
- file: the name of the file that will be used in stack traces and other debugging information
- name: the name of the method
- primitive: the name of the primitive associated with this method, if any
- metadata: it is possible to store additional structured metadata on a compiled method. The compiled method has a piece of metadata named `for_block` with the value `true` if the original generator was created for a block.

The Packager stage also makes sure that any child generators (such as generators for blocks or methods) are also converted into compiled methods. These child compiled methods are included in the literals tuple of the parent compiled method.

Once the Generator has finished packaging itself as a CompiledMethod, it invokes the Writer stage, passing in the CompiledMethod as its input.

## Files Referenced

- kernel/bootstrap/compiled_method.rb: the basic implementation of CompiledMethod, mostly composed of wiring up primitives
- kernel/common/compiled_method.rb: a more robust implementation of CompiledMethod, a combination of primitive methods and methods written in Ruby
- vm/builtin/compiledmethod.cpp: the C++ implementation of the CompiledMethod primitives
- lib/compiler/generator.rb: The implementation of the `package` method, which populates the CompiledMethod with information from the Generator object.

## Customization

In general, the `package` method is designed to populate the CompiledMethod with a group of variables. However, you could also use the packager to populate another object with the same interface. However, it would not necessarily be useful on its own, without additional customizations later on