bpo-43044: [2.7] Doc: Stop linking to non-existent pages.

[verhovsky]

Currently, visiting https://docs.python.org/2/library/stringio.html and clicking the "You should upgrade and read the Python documentation for the current stable release." link in the header sends you to https://docs.python.org/3/library/stringio.html which is a 404 Error page. This pull requests changes that link to https://docs.python.org/3/library/io.html#io.StringIO

Pages that have been completely removed in Python 3 now link to https://docs.python.org/3/index.html

I also added a few alternatives in comments if someone has any thoughts. (See python/pythondotorg#1719 for details)

https://bugs.python.org/issue43044

[tirkarthi]

Adding @benjaminp since this is changes for 2.7 and has reached EoL.

[verhovsky]

Here's a clickable list of the redirects I've added:

Python 2	Python 3
library/fpformat
library/mutex
library/new
library/statvfs
library/dircache
library/macpath
library/dbhash
library/bsddb
library/someos
library/popen2
library/mhlib
library/mimetools
library/mimewriter
library/mimify
library/multifile
library/sgmllib
library/imageop
library/hotshot
library/future_builtins
library/user
library/fpectl
library/restricted
library/rexec
library/bastion
library/imputil
library/compiler
library/dl
library/posixfile
library/commands
library/mac
library/ic
library/macos
library/macostools
library/easydialogs
library/framework
library/autogil
library/carbon
library/colorpicker
library/macosa
library/gensuitemodule
library/aetools
library/aepack
library/aetypes
library/miniaeframe
library/sgi
library/al
library/cd
library/fl
library/fm
library/gl
library/imgfile
library/jpeg
library/sun
library/sunaudio
c-api/int
c-api/string
c-api/class
c-api/cobject
howto/doanddont
howto/webservers
library/strings	library/text.html
library/stringio	library/io.html#io.StringIO
library/sets
library/userdict	library/collections.html#userdict-objects
library/repr	library/reprlib.html
library/copy_reg	library/copyreg.html
library/anydbm	library/dbm.html
library/whichdb	library/dbm.html#dbm.whichdb
library/dumbdbm	library/dbm.html#module-dbm.dumb
library/dbm	library/dbm.html#module-dbm.ndbm
library/gdbm	library/dbm.html#module-dbm.gnu
library/robotparser	library/urllib.robotparser.html
library/md5
library/sha
library/thread	library/_thread.html
library/dummy_thread
library/email-examples	library/email.examples.html
library/rfc822
library/htmlparser	library/html.parser.html
library/htmllib
library/urllib2	library/urllib.request.html
library/httplib	library/http.client.html
library/urlparse	library/urllib.parse.html
library/basehttpserver	library/http.server.html
library/simplehttpserver	library/http.server.html#http.server.SimpleHTTPRequestHandler
library/cgihttpserver	library/http.server.html#http.server.CGIHTTPRequestHandler
library/cookielib	library/http.cookiejar.html
library/cookie	library/http.cookies.html
library/xmlrpclib	library/xmlrpc.client.html
library/simplexmlrpcserver	library/xmlrpc.server.html
library/docxmlrpcserver	library/xmlrpc.server.html#documenting-xmlrpc-server
library/ttk	library/tkinter.ttk.html
library/tix	library/tkinter.tix.html
library/scrolledtext	library/tkinter.scrolledtext.html
library/__builtin__	library/builtins.html
library/_winreg	library/winreg.html

And the code to generate it:

moved_files = {
    "library/fpformat": None,
    "library/mutex": None,
    "library/new": None,
    "library/statvfs": None,
    "library/dircache": None,
    "library/macpath": None,
    "library/dbhash": None,
    "library/bsddb": None,
    # 'library/someos': 'library/index',
    "library/someos": None,
    # 'library/popen2': 'library/subprocess',
    "library/popen2": None,
    # 'library/mhlib': 'library/mailbox',
    "library/mhlib": None,
    # 'library/mimetools': 'library/email',
    "library/mimetools": None,
    # 'library/mimewriter': 'library/email',
    "library/mimewriter": None,
    # 'library/mimify': 'library/email',
    "library/mimify": None,
    # 'library/multifile': 'library/email',
    "library/multifile": None,
    "library/sgmllib": None,
    "library/imageop": None,
    # 'library/hotshot': 'library/profile',
    "library/hotshot": None,
    "library/future_builtins": None,
    "library/user": None,
    "library/fpectl": None,
    "library/restricted": None,
    "library/rexec": None,
    "library/bastion": None,
    "library/imputil": None,
    "library/compiler": None,
    # 'library/dl': 'library/ctypes',
    "library/dl": None,
    "library/posixfile": None,
    # 'library/commands': 'library/subprocess',
    "library/commands": None,
    "library/mac": None,
    "library/ic": None,
    "library/macos": None,
    "library/macostools": None,
    "library/easydialogs": None,
    "library/framework": None,
    "library/autogil": None,
    "library/carbon": None,
    "library/colorpicker": None,
    "library/macosa": None,
    "library/gensuitemodule": None,
    "library/aetools": None,
    "library/aepack": None,
    "library/aetypes": None,
    "library/miniaeframe": None,
    "library/sgi": None,
    "library/al": None,
    "library/cd": None,
    "library/fl": None,
    "library/fm": None,
    "library/gl": None,
    "library/imgfile": None,
    "library/jpeg": None,
    "library/sun": None,
    "library/sunaudio": None,
    # 'c-api/int': 'c-api/long',
    "c-api/int": None,
    # 'c-api/string': 'c-api/bytes',
    "c-api/string": None,
    "c-api/class": None,
    # 'c-api/cobject': 'c-api/capsule',
    "c-api/cobject": None,
    "howto/doanddont": None,
    "howto/webservers": None,
    "library/strings": "library/text",
    "library/stringio": ("library/io", "io.StringIO"),
    # 'library/sets': ('library/stdtypes', 'set'),
    # 'library/sets': ('library/stdtypes', 'set-types-set-frozenset'),
    "library/sets": None,
    "library/userdict": ("library/collections", "userdict-objects"),
    "library/repr": "library/reprlib",
    "library/copy_reg": "library/copyreg",
    "library/anydbm": "library/dbm",
    "library/whichdb": ("library/dbm", "dbm.whichdb"),
    "library/dumbdbm": ("library/dbm", "module-dbm.dumb"),
    "library/dbm": ("library/dbm", "module-dbm.ndbm"),
    "library/gdbm": ("library/dbm", "module-dbm.gnu"),
    "library/robotparser": "library/urllib.robotparser",
    # 'library/md5': 'library/hashlib',
    "library/md5": None,
    # 'library/sha': 'library/hashlib',
    "library/sha": None,
    "library/thread": "library/_thread",
    # Renamed to _dummy_thread but has since been removed completely
    # 'library/dummy_thread': 'library/_dummy_thread',
    "library/dummy_thread": None,
    "library/email-examples": "library/email.examples",
    # 'library/rfc822': 'library/email',
    "library/rfc822": None,
    "library/htmlparser": "library/html.parser",
    "library/htmllib": None,
    # 'library/urllib2': 'library/urllib',
    "library/urllib2": "library/urllib.request",
    "library/httplib": "library/http.client",
    "library/urlparse": "library/urllib.parse",
    "library/basehttpserver": "library/http.server",
    "library/simplehttpserver": ("library/http.server", "http.server.SimpleHTTPRequestHandler"),
    "library/cgihttpserver": ("library/http.server", "http.server.CGIHTTPRequestHandler"),
    "library/cookielib": "library/http.cookiejar",
    "library/cookie": "library/http.cookies",
    "library/xmlrpclib": "library/xmlrpc.client",
    "library/simplexmlrpcserver": "library/xmlrpc.server",
    "library/docxmlrpcserver": ("library/xmlrpc.server", "documenting-xmlrpc-server"),
    "library/ttk": "library/tkinter.ttk",
    "library/tix": "library/tkinter.tix",
    "library/scrolledtext": "library/tkinter.scrolledtext",
    "library/__builtin__": "library/builtins",
    "library/_winreg": "library/winreg",
}

from tabulate import tabulate

rows = []
for old, new in moved_files.items():
    if new is None:
        new = ""
    elif isinstance(new, str):
        new = f"[`{new}.html`](https://docs.python.org/3/{new}.html)"
    else:
        new = f"[`{new[0]}.html#{new[1]}`](https://docs.python.org/3/{new[0]}.html#{new[1]})"
    rows.append([f"[`{old}`](https://docs.python.org/2/{old}.html)", new])

print(
    tabulate(
        rows,
        headers=["Python 2", "Python 3"],
        tablefmt="github",
    )
)

You can find a list of all the files that are missing between Python 2.7 and Python 3.8 by downloading a copy of the documentation, then using comm against the output of find in the two directories. This misses any files that are completely different but still named the same but I don't think that happened.

wget https://docs.python.org/2/archives/python-2.7.18-docs-html.zip
unzip python-2.7.18-docs-html.zip

wget https://docs.python.org/3/archives/python-3.9.1-docs-html.zip  # new link at https://docs.python.org/3/download.html
unzip python-3.9.1-docs-html.zip

comm -23 <(find python-2.7.18-docs-html/ | cut -d'/' -f2- | sort) <(find python-3.9.1-docs-html/ | cut -d'/' -f2- | sort)

[ned-deily]

Sorry, the PR was closed automatically when the 2.7 branch was recently deleted, not through explicit action. The behavior you describe is certainly not ideal. Perhaps there is another way to solve the problem: create redirects or some such in the 3 doc tree or server config rather than modifying the now-frozen 2.7 source? Pinging @JulienPalard. And, to pursue this further, please open an issue on the Python bug tracker: https://bugs.python.org.

[JulienPalard]

Yes I'd prefer doing this on the nginx config instead on the non-existing 2.7 branch, as I previously did a few times here: https://github.com/python/psf-salt/blob/3f0c2941fe7df2dad29fe669811291b991eb677a/salt/docs/config/nginx.docs-backend.conf#L38

@verhovsky would you mind converting your PR to nginx syntax, on https://github.com/python/psf-salt/?