I was going to delegate to our resident Windows expert, but that's you. :-(
Can you suggest someone else? I really don't want to swap in what I once knew about the Windows registry... On Fri, Jul 15, 2016 at 3:20 PM, Steve Dower <steve.do...@python.org> wrote: > Hi all > > I'd like to get this PEP approved (status changed to Active, IIUC). > > So far (to my knowledge), Anaconda is writing out the new metadata and > Visual Studio is reading it. Any changes to the schema now will require > somewhat public review anyway, so I don't see any harm in approving the PEP > right now. > > To reiterate, this doesn't require changing anything about CPython at all > and has no backwards compatibility impact on official releases (but > hopefully it will stop alternative distros from overwriting our essential > metadata and causing problems). > > I suppose I look to Guido first, unless he wants to delegate to one of the > other Windows contributors? > > Cheers, > Steve > > URL: https://www.python.org/dev/peps/pep-0514/ > > Full text > ------- > > PEP: 514 > Title: Python registration in the Windows registry > Version: $Revision$ > Last-Modified: $Date$ > Author: Steve Dower <steve.do...@python.org> > Status: Draft > Type: Informational > Content-Type: text/x-rst > Created: 02-Feb-2016 > Post-History: 02-Feb-2016, 01-Mar-2016 > > Abstract > ======== > > This PEP defines a schema for the Python registry key to allow third-party > installers to register their installation, and to allow applications to > detect > and correctly display all Python environments on a user's machine. No > implementation changes to Python are proposed with this PEP. > > Python environments are not required to be registered unless they want to be > automatically discoverable by external tools. > > The schema matches the registry values that have been used by the official > installer since at least Python 2.5, and the resolution behaviour matches > the > behaviour of the official Python releases. > > Motivation > ========== > > When installed on Windows, the official Python installer creates a registry > key > for discovery and detection by other applications. This allows tools such as > installers or IDEs to automatically detect and display a user's Python > installations. > > Third-party installers, such as those used by distributions, typically > create > identical keys for the same purpose. Most tools that use the registry to > detect > Python installations only inspect the keys used by the official installer. > As a > result, third-party installations that wish to be discoverable will > overwrite > these values, resulting in users "losing" their Python installation. > > By describing a layout for registry keys that allows third-party > installations > to register themselves uniquely, as well as providing tool developers > guidance > for discovering all available Python installations, these collisions should > be > prevented. > > Definitions > =========== > > A "registry key" is the equivalent of a file-system path into the registry. > Each > key may contain "subkeys" (keys nested within keys) and "values" (named and > typed attributes attached to a key). > > ``HKEY_CURRENT_USER`` is the root of settings for the currently logged-in > user, > and this user can generally read and write all settings under this root. > > ``HKEY_LOCAL_MACHINE`` is the root of settings for all users. Generally, any > user can read these settings but only administrators can modify them. It is > typical for values under ``HKEY_CURRENT_USER`` to take precedence over those > in > ``HKEY_LOCAL_MACHINE``. > > On 64-bit Windows, ``HKEY_LOCAL_MACHINE\Software\Wow6432Node`` is a special > key > that 32-bit processes transparently read and write to rather than accessing > the > ``Software`` key directly. > > Structure > ========= > > We consider there to be a single collection of Python environments on a > machine, > where the collection may be different for each user of the machine. There > are > three potential registry locations where the collection may be stored based > on > the installation options of each environment:: > > HKEY_CURRENT_USER\Software\Python\<Company>\<Tag> > HKEY_LOCAL_MACHINE\Software\Python\<Company>\<Tag> > HKEY_LOCAL_MACHINE\Software\Wow6432Node\Python\<Company>\<Tag> > > Environments are uniquely identified by their Company-Tag pair, with two > options > for conflict resolution: include everything, or give priority to user > preferences. > > Tools that include every installed environment, even where the Company-Tag > pairs > match, should ensure users can easily identify whether the registration was > per-user or per-machine. > > When tools are selecting a single installed environment from all registered > environments, the intent is that user preferences from ``HKEY_CURRENT_USER`` > will override matching Company-Tag pairs in ``HKEY_LOCAL_MACHINE``. > > Official Python releases use ``PythonCore`` for Company, and the value of > ``sys.winver`` for Tag. Other registered environments may use any values for > Company and Tag. Recommendations are made in the following sections. > > Python environments are not required to register themselves unless they want > to > be automatically discoverable by external tools. > > Backwards Compatibility > ----------------------- > > Python 3.4 and earlier did not distinguish between 32-bit and 64-bit builds > in > ``sys.winver``. As a result, it is possible to have valid side-by-side > installations of both 32-bit and 64-bit interpreters. > > To ensure backwards compatibility, applications should treat environments > listed > under the following two registry keys as distinct, even when the Tag > matches:: > > HKEY_LOCAL_MACHINE\Software\Python\PythonCore\<Tag> > HKEY_LOCAL_MACHINE\Software\Wow6432Node\Python\PythonCore\<Tag> > > Environments listed under ``HKEY_CURRENT_USER`` may be treated as distinct > from > both of the above keys, potentially resulting in three environments > discovered > using the same Tag. Alternatively, a tool may determine whether the per-user > environment is 64-bit or 32-bit and give it priority over the per-machine > environment, resulting in a maximum of two discovered environments. > > It is not possible to detect side-by-side installations of both 64-bit and > 32-bit versions of Python prior to 3.5 when they have been installed for the > current user. Python 3.5 and later always uses different Tags for 64-bit and > 32-bit versions. > > Environments registered under other Company names must use distinct Tags to > support side-by-side installations. Tools consuming these registrations are > not required to disambiguate tags other than by preferring the user's > setting. > > Company > ------- > > The Company part of the key is intended to group related environments and to > ensure that Tags are namespaced appropriately. The key name should be > alphanumeric without spaces and likely to be unique. For example, a > trademarked > name, a UUID, or a hostname would be appropriate:: > > HKEY_CURRENT_USER\Software\Python\ExampleCorp > HKEY_CURRENT_USER\Software\Python\6C465E66-5A8C-4942-9E6A-D29159480C60 > HKEY_CURRENT_USER\Software\Python\www.example.com > > The company name ``PyLauncher`` is reserved for the PEP 397 launcher > (``py.exe``). It does not follow this convention and should be ignored by > tools. > > If a string value named ``DisplayName`` exists, it should be used to > identify > the environment category to users. Otherwise, the name of the key should be > used. > > If a string value named ``SupportUrl`` exists, it may be displayed or > otherwise > used to direct users to a web site related to the environment. > > A complete example may look like:: > > HKEY_CURRENT_USER\Software\Python\ExampleCorp > (Default) = (value not set) > DisplayName = "Example Corp" > SupportUrl = "http://www.example.com"; > > Tag > --- > > The Tag part of the key is intended to uniquely identify an environment > within > those provided by a single company. The key name should be alphanumeric > without > spaces and stable across installations. For example, the Python language > version, a UUID or a partial/complete hash would be appropriate; an integer > counter that increases for each new environment may not:: > > HKEY_CURRENT_USER\Software\Python\ExampleCorp\3.6 > HKEY_CURRENT_USER\Software\Python\ExampleCorp\6C465E66 > > If a string value named ``DisplayName`` exists, it should be used to > identify > the environment to users. Otherwise, the name of the key should be used. > > If a string value named ``SupportUrl`` exists, it may be displayed or > otherwise > used to direct users to a web site related to the environment. > > If a string value named ``Version`` exists, it should be used to identify > the > version of the environment. This is independent from the version of Python > implemented by the environment. > > If a string value named ``SysVersion`` exists, it must be in ``x.y`` or > ``x.y.z`` format matching the version returned by ``sys.version_info`` in > the > interpreter. Otherwise, if the Tag matches this format it is used. If not, > the > Python version is unknown. > > Note that each of these values is recommended, but optional. A complete > example > may look like this:: > > HKEY_CURRENT_USER\Software\Python\ExampleCorp\6C465E66 > (Default) = (value not set) > DisplayName = "Distro 3" > SupportUrl = "http://www.example.com/distro-3"; > Version = "3.0.12345.0" > SysVersion = "3.6.0" > > InstallPath > ----------- > > Beneath the environment key, an ``InstallPath`` key must be created. This > key is > always named ``InstallPath``, and the default value must match > ``sys.prefix``:: > > HKEY_CURRENT_USER\Software\Python\ExampleCorp\3.6\InstallPath > (Default) = "C:\ExampleCorpPy36" > > If a string value named ``ExecutablePath`` exists, it must be a path to the > ``python.exe`` (or equivalent) executable. Otherwise, the interpreter > executable > is assumed to be called ``python.exe`` and exist in the directory referenced > by > the default value. > > If a string value named ``WindowedExecutablePath`` exists, it must be a path > to > the ``pythonw.exe`` (or equivalent) executable. Otherwise, the windowed > interpreter executable is assumed to be called ``pythonw.exe`` and exist in > the > directory referenced by the default value. > > A complete example may look like:: > > HKEY_CURRENT_USER\Software\Python\ExampleCorp\6C465E66\InstallPath > (Default) = "C:\ExampleDistro30" > ExecutablePath = "C:\ExampleDistro30\ex_python.exe" > WindowedExecutablePath = "C:\ExampleDistro30\ex_pythonw.exe" > > Help > ---- > > Beneath the environment key, a ``Help`` key may be created. This key is > always > named ``Help`` if present and has no default value. > > Each subkey of ``Help`` specifies a documentation file, tool, or URL > associated > with the environment. The subkey may have any name, and the default value is > a > string appropriate for passing to ``os.startfile`` or equivalent. > > If a string value named ``DisplayName`` exists, it should be used to > identify > the help file to users. Otherwise, the key name should be used. > > A complete example may look like:: > > HKEY_CURRENT_USER\Software\Python\ExampleCorp\6C465E66\Help > Python\ > (Default) = "C:\ExampleDistro30\python36.chm" > DisplayName = "Python Documentation" > Extras\ > (Default) = "http://www.example.com/tutorial"; > DisplayName = "Example Distro Online Tutorial" > > Other Keys > ---------- > > Some other registry keys are used for defining or inferring search paths > under > certain conditions. A third-party installation is permitted to define these > keys > under their Company-Tag key, however, the interpreter must be modified and > rebuilt in order to read these values. Alternatively, the interpreter may be > modified to not use any registry keys for determining search paths. Making > such > changes is a decision for the third party; this PEP makes no recommendation > either way. > > Copyright > ========= > > This document has been placed in the public domain. > _______________________________________________ > Python-Dev mailing list > Python-Dev@python.org > https://mail.python.org/mailman/listinfo/python-dev > Unsubscribe: > https://mail.python.org/mailman/options/python-dev/guido%40python.org -- --Guido van Rossum (python.org/~guido) _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
