Man1 - perlpolicy.1perl

perlpolicy - Various and sundry policies and commitments related to the Perl core

This document is the master document which records all written policies about how the Perl 5 Porters collectively develop and maintain the Perl core.

Perl 5 is developed by a community, not a corporate entity. Every change contributed to the Perl core is the result of a donation. Typically, these donations are contributions of code or time by individual members of our community. On occasion, these donations come in the form of corporate or organizational sponsorship of a particular individual or project.

As a volunteer organization, the commitments we make are heavily dependent on the goodwill and hard work of individuals who have no obligation to contribute to Perl.

That being said, we value Perl’s stability and security and have long had an unwritten covenant with the broader Perl community to support and maintain releases of Perl.

This document codifies the support and maintenance commitments that the Perl community should expect from Perl’s developers:

• We officially support the two most recent stable release series. 5.26.x and earlier are now out of support. As of the release of 5.32.0, we will officially end support for Perl 5.28.x, other than providing security updates as described below.
• To the best of our ability, we will attempt to fix critical issues in the two most recent stable 5.x release series. Fixes for the current release series take precedence over fixes for the previous release series.
• To the best of our ability, we will provide critical security patches / releases for any major version of Perl whose 5.x.0 release was within the past three years. We can only commit to providing these for the most recent .y release in any 5.x.y series.
• We will not provide security updates or bug fixes for development releases of Perl.
• We encourage vendors to ship the most recent supported release of Perl at the time of their code freeze.
• As a vendor, you may have a requirement to backport security fixes beyond our 3 year support commitment. We can provide limited support and advice to you as you do so and, where possible will try to apply those patches to the relevant -maint branches in git, though we may or may not choose to make numbered releases or official patches available. See SECURITY VULNERABILITY CONTACT INFORMATION in perlsec for details on how to begin that process.

Our community has a long-held belief that backward-compatibility is a virtue, even when the functionality in question is a design flaw.

We would all love to unmake some mistakes we’ve made over the past decades. Living with every design error we’ve ever made can lead to painful stagnation. Unwinding our mistakes is very, very difficult. Doing so without actively harming our users is nearly impossible.

Lately, ignoring or actively opposing compatibility with earlier versions of Perl has come into vogue. Sometimes, a change is proposed which wants to usurp syntax which previously had another meaning. Sometimes, a change wants to improve previously-crazy semantics.

Down this road lies madness.

Requiring end-user programmers to change just a few language constructs, even language constructs which no well-educated developer would ever intentionally use is tantamount to saying you should not upgrade to a new release of Perl unless you have 100% test coverage and can do a full manual audit of your codebase. If we were to have tools capable of reliably upgrading Perl source code from one version of Perl to another, this concern could be significantly mitigated.

We want to ensure that Perl continues to grow and flourish in the coming years and decades, but not at the expense of our user community.

Existing syntax and semantics should only be marked for destruction in very limited circumstances. If they are believed to be very rarely used, stand in the way of actual improvement to the Perl language or perl interpreter, and if affected code can be easily updated to continue working, they may be considered for removal. When in doubt, caution dictates that we will favor backward compatibility. When a feature is deprecated, a statement of reasoning describing the decision process will be posted, and a link to it will be provided in the relevant perldelta documents.

Using a lexical pragma to enable or disable legacy behavior should be considered when appropriate, and in the absence of any pragma legacy behavior should be enabled. Which backward-incompatible changes are controlled implicitly by a ’use v5.x.y’ is a decision which should be made by the steering council in consultation with the community.

Historically, we’ve held ourselves to a far higher standard than backward-compatibility Ω- bugward-compatibility. Any accident of implementation or unintentional side-effect of running some bit of code has been considered to be a feature of the language to be defended with the same zeal as any other feature or functionality. No matter how frustrating these unintentional features may be to us as we continue to improve Perl, these unintentional features often deserve our protection. It is very important that existing software written in Perl continue to work correctly. If end-user developers have adopted a bug as a feature, we need to treat it as such.

New syntax and semantics which don’t break existing language constructs and syntax have a much lower bar. They merely need to prove themselves to be useful, elegant, well designed, and well tested. In most cases, these additions will be marked as experimental for some time. See below for more on that.

New releases of maintenance branches should only contain changes that fall into one of the acceptable categories set out below, but must not contain any changes that fall into one of the unacceptable categories. (For example, a fix for a crashing bug must not be included if it breaks binary compatibility.)

It is not necessary to include every change meeting these criteria, and in general the focus should be on addressing security issues, crashing bugs, regressions and serious installation issues. The temptation to include a plethora of minor changes that don’t affect the installation or execution of perl (e.g. spelling corrections in documentation) should be resisted in order to reduce the overall risk of overlooking something. The intention is to create maintenance releases which are both worthwhile and which users can have full confidence in the stability of. (A secondary concern is to avoid burning out the maint-release manager or overwhelming other committers voting on changes to be included (see Getting changes into a maint branch below).)

The following types of change may be considered acceptable, as long as they do not also fall into any of the unacceptable categories set out below:

• Patches that fix CVEs or security issues. These changes should be passed using the security reporting mechanism rather than applied directly; see SECURITY VULNERABILITY CONTACT INFORMATION in perlsec.
• Patches that fix crashing bugs, assertion failures and memory corruption but which do not otherwise change perl’s functionality or negatively impact performance.
• Patches that fix regressions in perl’s behavior relative to previous releases, no matter how old the regression, since some people may upgrade from very old versions of perl to the latest version.
• Patches that fix bugs in features that were new in the corresponding 5.x.0 stable release.
• Patches that fix anything which prevents or seriously impacts the build or installation of perl.
• Portability fixes, such as changes to Configure and the files in the hints/ folder.
• Minimal patches that fix platform-specific test failures.
• Documentation updates that correct factual errors, explain significant bugs or deficiencies in the current implementation, or fix broken markup.
• Updates to dual-life modules should consist of minimal patches to fix crashing bugs or security issues (as above). Any changes made to dual-life modules for which CPAN is canonical should be coordinated with the upstream author.

The following types of change are NOT acceptable:

• Patches that break binary compatibility. (Please talk to the steering council.)
• Patches that add or remove features.
• Patches that add new warnings or errors or deprecate features.
• Ports of Perl to a new platform, architecture or OS release that involve changes to the implementation.
• New versions of dual-life modules should NOT be imported into maint. Those belong in the next stable series.

If there is any question about whether a given patch might merit inclusion in a maint release, then it almost certainly should not be included.

Perl’s documentation is an important resource for our users. It’s incredibly important for Perl’s documentation to be reasonably coherent and to accurately reflect the current implementation.

Just as P5P collectively maintains the codebase, we collectively maintain the documentation. Writing a particular bit of documentation doesn’t give an author control of the future of that documentation. At the same time, just as source code changes should match the style of their surrounding blocks, so should documentation changes.

Examples in documentation should be illustrative of the concept they’re explaining. Sometimes, the best way to show how a language feature works is with a small program the reader can run without modification. More often, examples will consist of a snippet of code containing only the important bits. The definition of important varies from snippet to snippet. Sometimes it’s important to declare use strict and use warnings, initialize all variables and fully catch every error condition. More often than not, though, those things obscure the lesson the example was intended to teach.

As Perl is developed by a global team of volunteers, our documentation often contains spellings which look funny to somebody. Choice of American/British/Other spellings is left as an exercise for the author of each bit of documentation. When patching documentation, try to emulate the documentation around you, rather than changing the existing prose.

In general, documentation should describe what Perl does now rather than what it used to do. It’s perfectly reasonable to include notes in documentation about how behaviour has changed from previous releases, but, with very few exceptions, documentation isn’t dual-life Ω- it doesn’t need to fully describe how all old versions used to work.

The official forum for the development of perl is the perl5-porters mailing list, mentioned above, and its bugtracker at GitHub. Posting to the list and the bugtracker is not a right: all participants in discussion are expected to adhere to a standard of conduct.

• Always be civil.
• Heed the moderators.

Civility is simple: stick to the facts while avoiding demeaning remarks, belittling other individuals, sarcasm, or a presumption of bad faith. It is not enough to be factual. You must also be civil. Responding in kind to incivility is not acceptable. If you relay otherwise-unposted comments to the list from a third party, you take responsibility for the content of those comments, and you must therefore ensure that they are civil.

While civility is required, kindness is encouraged; if you have any doubt about whether you are being civil, simply ask yourself, Am I being kind? and aspire to that.

If the list moderators tell you that you are not being civil, carefully consider how your words have appeared before responding in any way. Were they kind? You may protest, but repeated protest in the face of a repeatedly reaffirmed decision is not acceptable. Repeatedly protesting about the moderators’ decisions regarding a third party is also unacceptable, as is continuing to initiate off-list contact with the moderators about their decisions.

Unacceptable behavior will result in a public and clearly identified warning. A second instance of unacceptable behavior from the same individual will result in removal from the mailing list and GitHub issue tracker, for a period of one calendar month. The rationale for this is to provide an opportunity for the person to change the way they act.

After the time-limited ban has been lifted, a third instance of unacceptable behavior will result in a further public warning. A fourth or subsequent instance will result in an indefinite ban. The rationale is that, in the face of an apparent refusal to change behavior, we must protect other community members from future unacceptable actions. The moderators may choose to lift an indefinite ban if the person in question affirms they will not transgress again.

Removals, like warnings, are public.

The list of moderators will be public knowledge. At present, it is: Karen Etheridge, Neil Bowers, Nicholas Clark, Ricardo Signes, Todd Rinaldo.

Social Contract about Contributed Modules originally by Russ Allbery <rra@stanford.edu> and the perl5-porters.