TITLE

Use pack/unpack for marshalling

VERSION

  Maintainer: Ilya Zakharevich <ilya@math.ohio-state.edu>
  Date: 16 September 2000
  Mailing List: perl6-language-data@perl.org
  Number: 249
  Version: 1
  Status: Developing

ABSTRACT

This RFC extends pack/unpack builtins to store/extract the TEMPLATE to/from the packed data. This allows storage of arbitrary Perl data.

DESCRIPTION

• t

on unpack(): remove the last extracted value and use it as if it replaces this t. For example, the following two calls are equivalent:

  unpack 'A5  t A5', 'aCx6,AcX6...0123456'
  unpack 'aCx6, A5',      'AcX6...0123456'

on pack(): store the next argument so that it is extractable with 't', this t acts as a modifier for the previous type. For example,

  pack 'A3 t', [5,6,[7,8],0]

may be stored in many ways, one of them (most readable?)

  'A7t' . ' A21 t ' . ' g[ A A g[ A A ] A ] ' . '56780'

When this is unpacked with 'A3 t', the first 3 chars are used as a new template, then the next 7 chars are used as a new template, then the next 21 chars are used as a new template, which finally extracts the structure.

This example shows that an arbitrary large structure can be extracted using the template 'A3 t'.

• T

behaves the same as the A4 t. (Syntactic sugar, optional). As shown above, arbitrary data is restorable by a simple 'T'. For example,

  pack 'T', [5,6,[7,8],0]

may be stored in many ways, one of them (most readable?)

  'A21t' . ' g[ A A g[ A A ] A ] ' . '56780'

MIGRATION ISSUES

None.

IMPLEMENTATION

Straightforward.

REFERENCES

RFC142: Enhanced Pack/Unpack

RFC 246: pack/unpack uncontrovercial enhancements

RFC 248: enhanced groups in pack/unpack