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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 will 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'


random [eligible in 1.1]

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]

Hash changes to AssociativePMCArray [eligible in 1.5]

Also OrderedHash to OrderedAssociativePMCArray.

Method stdhandle in ParrotInterpreter [experimental]

VTABLE nomenclature. [eligible in 1.5]

Current list of VTABLE functions will be reviewed and cleaned.


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.


packfile structure [eligible in 1.1]

opcode numbering [eligible in 1.1]

PMC numbering [eligible in 1.1]

Class Features

[Nothing at this time.]


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 attatched to the passed in namespace.

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


mmd_cvt_to_types [eligible in 1.1]

src/pic.c and src/pic_jit.c [eligible in 1.1]

These two files were a thin prototype implementation of Polymorphic Inline Caching that only ever applied to 4 opcodes, one of which has now been removed. The files (and all functions in them) are deprecated, and will be removed.

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.

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 excpetion.

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.

Compiler tools

PASM1 compiler

PASM1 compiler [eligible in 2.1]

See PDB_compile.

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.

build tools

tools/build/ and tools/build/ [eligible in 1.1]

Replaced with makefiles.

pmc2c syntax

"pmclass" with name not matching file's basename [eligible in 1.5]

When foo.pmc contains a the line "pmclass bar", pmc2c generates a pmc_foo.h but tries to include pmc_bar.h. This is a bug, but it's possible someone out there is using it. This usage will result in a warning for now; after the 1.4 release, this warning will be upgraded to an error.

Parrot library

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

Cross-HLL library loading [experimental]

OpenGL bindings and libraries [experimental]


  1. Trac is parrot's primary issue tracking system.

    Older tickets may be listed at RT.

  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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