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Provide a list of deprecated and experimental items in parrot. All items in this list should have a corresponding Trac ticket[1].

Experimental Status

These features are not considered stable, even though they may have shipped in a stable release of parrot[2]. Use them at your own risk, as they can be removed or changed in any release. These items are marked below with [experimental].

Deprecated Status

Please see docs/project/support_policy.pod for the parrot project's policy regarding deprecated features.

Each item shows the first release in which it is eligible for removal, e.g. [eligible in 1.5]. If the release listed is one that has already shipped, this feature may be removed in any upcoming release, and you should no longer rely on it.

Whenever deprecated items are removed, information regarding how to cope with the removal should be added to

When running parrot, you can receive warnings about deprecated opcodes. Either run parrot with the -w option to enable all warnings, or specifically by including this PIR code:

 .include 'warnings.pasm'


moved to dynpmc [eligible in 1.1]

AddrRegistry, CodeString, Env, Eval, File, OS, PCCMETHOD_Test, StringHandle, and Timer.

multiple dispatch within core PMCs [eligible in 1.1]

Method stdhandle in ParrotInterpreter [experimental]

Use of undocumented variables in class_init [eligible in 2.1]

The current implementation allows the class_init vtable function body to use local symbols from the generated part. For example, some PMC used to use the pass counter. In the future, the class_init body from the PMC file may not be inserted directly in the body of the generated one, so this usage will not be allowed.

Overriding vtable invoke in PIR objects [experimental]

The VTABLE invoke in object.pmc puts SELF at the start of the signature call arguments when there is no current object and is not already here. This allows the usage of $P0() instead of $P0($P0).

CPointer PMC [eligible in 2.1]

And all uses in the Parrot calling conventions.


moved to dynop [eligible in 1.1]

Parts or all of: bit.ops, debug.ops, io.ops, math.ops, set.ops (the obscure and rarely used parts), sys.ops.

get_addr and set_addr [eligible in 1.5]

These opcodes are being repurposed. They will always return a unique memory address of the PMC. Uses of get_addr and set_addr that would set label values for Sub, Exception, and related PMC types will instead be handled by get_label and set_label.

All bitwise ops [eligible in 2.1]

All bitwise ops (all ops containing bitwise in their names) will be provided by dynops. NOTE: Before removing the bitwise ops, make sure that the equivalent dynops are available and that the major HLLs (Rakudo, Partcl, Lua, etc) have switched to using them.

get_results opcode order and features [eligible in 2.1]

Move get_results to follow invoke.

get_results no longer used to fetch exception object.

GC_SYS_NAME option to interpinfo_s_i [experimental]

Ability to get the string name of the current GC core from the interpinfo_s_i. See r43900 and r43904 for details.


packfile structure [experimental]

opcode numbering [experimental]

PMC numbering [experimental]


Assigning to registers [experimental]

PIR syntax

Assignment syntax with opcodes [eligible in 1.1]

named class/pmc lookup in pir syntax such as new, isa, subclass, get_class, etc [eligible in 1.1]

Class PMC name resolution will be the following.

if the arg is a STRING Relative to the current Namespace

if the arg is a Array (of any sort) or Key Relative to the current HLL Namespace

if the arg is a Namespace or Class PMC The passed in class or the class attached to the passed in namespace.

load or include paths prefixed with 'library/' or 'include/' [eligible in 1.5]

continuation-based ExceptionHandlers [eligible in 2.1]

implicit optional named parameters [eligible in 2.1]


mmd_cvt_to_types [eligible in 1.1]

Subs marked with :vtable/:method aren't in namespace [eligible in 1.1]

Subs marked with :vtable or :method flags are no longer given a namespace entry by default. Use the :nsentry flag to cause this to happen.

C API coding standards cleanup [eligible in 1.1]

All C API functions that aren't currently named according to the 'Parrot_<system>_*' scheme will be renamed. If you depend on these functions in an extending/embedding interface or C-level custom PMCs, check in 1.4 or 2.0 for the new names.

Sub/method invocation functions [eligible in 2.1]

The old 'Parrot_call_*' functions for invoking a sub/method object from C are deprecated, replaced by 'Parrot_ext_call'.

PMC Attributes Allocation Functions [experimental]

These items and related helper functions are added as experimental support for TT #895

PDB_compile and PDB_eval [eligible in 2.1]

The function PDB_compile doesn't work since some time, and his implementation was a hack. His functionality may be reimplemented in another way. Until the end of deprecation cycle it just throws an exception.

The PDB_eval function, that used in the debugger to support the eval command, was using PDB_compile. His functionality must be reimplemented in another way and with a name that follows current conventions, in the meantime and until the end of the deprecation cycle it just shows a diagnostic message.

Parrot_oo_get_namespace [eligible in 2.1]

STRING Out parameters in Parrot_str_* functions [eligible in 2.1]

All STRING modification functions will return a STRING pointer; capture and use this rather than relying on in-place modification of an existing pointer.

Compiler tools

PASM1 compiler

PASM1 compiler [eligible in 2.1]

See PDB_compile. Note that the current version of the PASM1 compiler issues a warning and is not functional. (However, it used to segfault.)

Parrot Grammar Engine (PGE)

Action methods in rules

Per Synopsis 5, all regexes will have an implied {*} token at the end which cause invocation of an action method if a :action object is supplied.

Parrot Compiler Toolkit

PCT::HLLCompiler stages [eligible in 1.1]

The interface of various methods for adding, removing, and modifying the list stages in a PCT::HLLCompiler object is subject to change. The existing actual stages will remain; only the mechanism for specifying the order of individual stages is likely to change.

PCT::HLLCompiler from Perl 5's Test::Harness [eligible in 1.1]

In order to facilitate using PCT::HLLCompiler with test harnesses, the command_line method of PCT::HLLCompiler object exits silently if it detects that it is being run in a sample run from Perl's Test::Harness. Currently this detection is done by checking the second command line argument for "@INC"; future releases may use a different detection mechanism or eliminate it altogether.

PAST::Val node generation [eligible in 1.5]

The PAST::Compiler may generate the code for PAST::Val nodes (i.e., constants) at the beginning of the block (Parrot sub) instead of the location where they occur in the PAST tree.

Not Quite Perl (NQP)

$(...) syntax [eligible in 1.5]

The $(...) syntax for obtaining a result object from a Match object will no longer work. The new syntax is to invoke the .ast method on the Match object.

Quoted items [eligible in 1.5]

Double-quoted strings will interpret unescaped $-names as interpolated variables in the string. Bare slashes will introduce regular expressions. The <foo bar> syntax will produce an array of strings instead of a single string.

PIR q:to:<xyz> inline PIR [eligible in 1.5]

The PIR q:to:<xyz> form of inline PIR in NQP scripts is deprecated. Use Q:PIR { ... } or Q:PIR {{ ... }} instead.

Parrot library

MT19937 [eligible in 2.1] - latest version now hosted at After 2.0, users will have to install via plumage.

JSON, JSON, and Config;JSON [eligible in 1.5]

Cross-HLL library loading [experimental]

OpenGL bindings and libraries [experimental]

Library name changes [eligible in 2.1]

The use of :: a namespace separator is deprecated. Core libraries will change to use multi-level keys instead. For example, Data::Dumper will change to Data; Dumper. Affected libraries also include: Parrot::Coroutine, SDL, Test::Builder, YAML::Dumper, and PCRE::NCI.


  1. Trac is parrot's primary issue tracking system.
  2. For an item to be considered experimental, it can never have shipped in a stable release without the [experimental] tag; otherwise, it must be deprecated normally before removal or incompatible change.
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