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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 supported, even though they may have shipped in a supported 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.

If you find a feature you once used was removed after a deprecation cycle, Otherwise please open a documentation ticket via Trac[1].

Are you using any Deprecated Features?

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


GzipHandle [experimental]

PackfileDebug [experimental]

CodeString [eligible in 2.7]

multiple dispatch within core PMCs [eligible in 1.1]

Method stdhandle in ParrotInterpreter [experimental]

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).

NCI without signature ("raw" pointers) [eligible in 2.4]

No equivalent functionality is promised. You shouldn't be using this. Here be segfaults.

UnManagedStruct handling nested structure [eligible in 2.4]

UnManagedStruct will be simplified to only support flat structures. This means that elements which themselves have structure - struct pointers and function pointers will be stored as void * and void (*)(void) respectively. To use these, they will need to be cast to the appropriate signature on access.

UnManagedStruct initializer structure [eligible in 2.4]

The initializer structure will cease to be an array of triples. In stead, an array of flags (no counts or offsets), or a string representation of the same information may be used.

UnManagedStruct get_integer, set_integer_native [eligible in 2.4]

These will no longer refer to the byte length of the buffer, but to the number of times the struct is repeated; emulating an array of structs.

ManagedStruct reallocations based on shape changes [eligible in 2.4]

Since shape changes may simply be used for re-interpreting data, and may also occur in several steps, re-allocating after any one shape change may be undesirable. In stead, an explicit allocate/reallocate method will be provided.

Auto-vivification of nested aggregates [eligible in 2.4]


$P0 = new ['Hash']
$S1 = $P0['foo';'bar';'baz']

will not auto-vivify nested hashes and return PMCNULL early.

Method lower on String [eligible in 2.7]

Use the downcase opcode or subclass with a method name consistent with your HLL.

Method unescape on String [experimental]

This is a helper method for testing of Parrot_str_unescape_string.

logical_* vtables [eligiblie in 2.7]

These can be replaced by get_bool and intval ops unless you're using them for things that aren't really logical ops (don't do that!).


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.

get_results opcode order and features [eligible in 2.1]

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.

NCI_FB_CB and NCI_FB_UD in iglobals [experimental]

Hooks allowing a runtime-loadable dynamic frame builder.

loadlib_p_s_p [experimental]

Ability to use non-default dynamic loading behaviour.

new_callback_p_p_p_s [eligible in 2.4]

To be replaced with new_callback_p_p_p_p_s.

dlfunc and new_callback signature string format [eligible in 2.4]

These will be changed to allow more flexibility in types.

find_lex [eligible in 2.4]

find_lex will not throw exception for non-existing lexicals.

inplace string updates. [eligible in 2.4]

All "inplace" string update ops are deprecated. E.g. "chopn_s", etc. Part of COW removal.

find_codepoint [experimental]

Intended to replace the CodeString charname_to_ord method.

All opcodes that modify non-argument registers. [eligible in 2.7]

E.g. "cleari", etc.

exchange [eligible in 2.7]

This op is too low level for Parrot in its current form.

finalize [experimental]

Finalize exception handler, unrolling inner runloops if needed.

logical PMC ops [eligible in 2.7]

These fall out from the logical vtables deprecation.


packfile structure [experimental]

opcode numbering [experimental]

PMC numbering [experimental]


Assigning to registers [experimental]

PIR syntax

Assignment syntax with opcodes [eligible in 1.1]

continuation-based ExceptionHandlers [eligible in 2.1]

implicit optional named parameters [eligible in 2.1]

:unique_reg flag [eligible in 2.7]

.nci_call [eligible in 2.7]

As of the latest PCC changes, there is nothing special about calling an NCI sub.

.meth_call [eligible in 2.7]

As of the latest PCC changes, this does nothing different from '.call'.


mmd_cvt_to_types [eligible in 1.1]

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. A list of renamed functions will be kept in the ticket at:

Parrot_find_global_s and Parrot_store_global_s

This function is not used or tested anywhere.

PMC Attributes Allocation Functions [experimental]

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

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.

STRING COW [eligible in 2.4]

COW strings are to be removed. All "inplace" string modification functions and all "inplace" string ops are deprecated.

Parrot_str_unescape_string [experimental]

This function is an experimental addition to enhance and maybe replace Parrot_str_unescape

Parrot_get_runtime_prefix [eligible in 2.7]

Use Parrot_get_runtime_path instead.

Compiler tools

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.

Parrot library

PARROT_LIBRARY and PARROT_INCLUDE environment variables [experimental]

A way to provide an equivalent of -L and -I parrot command line options to language that doesn't support it.

Protoobject [eligible in 2.7]

Use P6Object instead.

Archive::Tar & Archive::Zip [experimental]

LWP, HTTP::Message & URI [experimental]

JSON and Config;JSON [eligible in 1.5]

Cross-HLL library loading [experimental]

OpenGL bindings and libraries [experimental]


Threads and Parallelism [experimental]


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

  2. For an item to be considered experimental, it can never have shipped in a supported release without the [experimental] tag; otherwise, it must be deprecated normally before removal or incompatible change.