# Copyright (C) 2011, Parrot Foundation.

=head1 NAME

docs/deprecations/how_to_deprecate.pod - How to Deprecate Parrot Code

=head1 How to Deprecate Parrot Code

So you've found a crufty bit of code in Parrot that's just screaming to be
removed.  Welcome to the club.  There's a lot of them.  This page documents
the proper procedure to go through to get that junk code out of Parrot while
causing minimal pain to Parrot's users (i.e. people who develop HLLs or
libraries on top of Parrot).

=head2 Step 1: Give Notice

=over 4

=item *

file a ticket

=item *

add a note to api.yaml

=item *

maybe post to parrot-dev and/or parrot-users depending on the nature of the
change

=item *

get some feedback indicating that the change is sane

=item *

set up automatic usage detection using api.yaml regexes (static usage
detection) and/or Parrot_warn_deprecated (dynamic usage detection)

=back

=head2 Step 2: Wait

=over 4

=item *

pick an eligible release for the deprecation policy

=item *

backwards-incompatible changes can't happen until a stable release has gone out
the door with a notification of the coming deprecation

=item *

see:
http://docs.parrot.org/parrot/latest/html/docs/project/support_policy.pod.html
Parrot Release and Support Policy for more information

=back

=head2 Step 3: Patch

=over 4

=item *

write the code, possibly in a branch

=item *

unless it's highly impractical, maintain backwards-compatibility to ease the
migration - this also means you can commit your changes immediately and remove
the deprecated interface later

=item *

test your changes with current HLLs and libraries such as partcl-nqp, Rakudo,
winxed, Kakapo, etc

=back

=head2 Step 4: Document

=over 4

=item *

add a summary of your change to ParrotDeprecations

=item *

add a complete description to the appropriate version transition deprecations
page (e.g. [wiki:ParrotDeprecationsFor2.6 ParrotDeprecationsFor2.6])

=item *

walk through the the documentation to ensure that it's sufficient for a user to
use to upgrade his or her code

=item *

Add the tag of "completed" to the entry in api.yaml

=back

=head2 Step 5: Apply

=over 4

=item *

make sure the HLLs and libraries are ready for the deprecation (and submit
patches if not)

=item *

merge or commit your backwards-incompatible changes to master

=item *

close the deprecation ticket, linking to the wiki transition documentation

=item *

bump PBC_COMPAT and run mk_native_pbc if needed

=item *

that's it

=back

=cut
