PEP 540: truncate to 72 columns

pep-0540.txt

@@ -18,10 +18,13 @@ Abstract
 Add a new "UTF-8 Mode" to enhance Python's use of UTF-8.  When UTF-8 Mode
 is active, Python will:
 
-* use the ``utf-8`` locale, irregardless of the locale currently set by the current platform, and
+* use the ``utf-8`` locale, irregardless of the locale currently set by
-* change the ``stdin`` and ``stdout`` error handlers to ``surrogateescape``.
+  the current platform, and
+* change the ``stdin`` and ``stdout`` error handlers to
+  ``surrogateescape``.
 
-This mode is off by default, but is automatically activated when using the "POSIX" locale.
+This mode is off by default, but is automatically activated when using
+the "POSIX" locale.
 
 Add the ``-X utf8`` command line option and ``PYTHONUTF8`` environment
 variable to control UTF-8 Mode.
@@ -42,17 +45,20 @@ locale, but are unable change the locale for various reasons.  This
 encoding is very limited in term of Unicode support: any non-ASCII
 character is likely to cause trouble.
 
-It isn't always easy to get an accurate locale.  Locales don't get
+It isn't always easy to get an accurate locale.  Locales don't get the
-the exact same name on different Linux distributions, FreeBSD, macOS, etc.
+exact same name on different Linux distributions, FreeBSD, macOS, etc.
 And some locales, like the recent ``C.UTF-8`` locale, are only supported
-by a few platforms.  The current locale can even vary on the *same* platform
+by a few platforms.  The current locale can even vary on the *same*
-depending on context; for example, a SSH connection can use a different
+platform depending on context; for example, a SSH connection can use a
-encoding than the filesystem or local terminal encoding on the same machine.
+different encoding than the filesystem or local terminal encoding on the
+same machine.
 
-On the flip side, Python 3.6 is already using UTF-8 by default on
+On the flip side, Python 3.6 is already using UTF-8 by default on macOS,
-macOS, Android and Windows (:pep:`529`) for most functions--although ``open()`` is a notable exception here. UTF-8 is also the default encoding of Python
+Android and Windows (:pep:`529`) for most functions -- although
-scripts, XML and JSON file formats. The Go programming language uses
+``open()`` is a notable exception here. UTF-8 is also the default
-UTF-8 for all strings.
+encoding of Python scripts, XML and JSON file formats. The Go
+programming language
+uses UTF-8 for all strings.
 
 UTF-8 support is nearly ubiquitous for data read and written by modern
 platforms.  It also has excellent support in Python.  The problem is
@@ -63,8 +69,9 @@ suggests itself: ignore the locale encoding and use UTF-8.
 Passthough for undecodable bytes: surrogateescape
 -------------------------------------------------
 
-When decoding bytes from UTF-8 using the default ``strict`` error handler,
+When decoding bytes from UTF-8 using the default ``strict`` error
-Python 3 raises a ``UnicodeDecodeError`` on the first undecodable byte.
+handler, Python 3 raises a ``UnicodeDecodeError`` on the first
+undecodable byte.
 
 Unix command line tools like ``cat`` or ``grep`` and most Python 2
 applications simply do not have this class of bugs: they don't decode
@@ -72,18 +79,18 @@ data, but process data as a raw bytes sequence.
 
 Python 3 already has a solution to behave like Unix tools and Python 2:
 the ``surrogateescape`` error handler (:pep:`383`). It allows processing
-data as if it were bytes, but uses Unicode in practice; undecodable bytes
+data as if it were bytes, but uses Unicode in practice; undecodable
-are stored as surrogate characters.
+bytes are stored as surrogate characters.
 
 UTF-8 Mode sets the ``surrogateescape`` error handler for ``stdin``
 and ``stdout``, since these streams as commonly associated to Unix
 command line tools.
 
 However, users have a different expectation on files. Files are expected
-to be properly encoded, and Python is expected to fail early when ``open()``
+to be properly encoded, and Python is expected to fail early when
-is called with the wrong options, like opening a JPEG picture in text
+``open()`` is called with the wrong options, like opening a JPEG picture
-mode. The ``open()`` default error handler remains ``strict`` for these
+in text mode. The ``open()`` default error handler remains ``strict``
-reasons.
+for these reasons.
 
 
 No change by default for best backward compatibility
@@ -92,14 +99,14 @@ No change by default for best backward compatibility
 While UTF-8 is perfect in most cases, sometimes the locale encoding is
 actually the best encoding.
 
-This PEP changes the behaviour for the POSIX locale since this locale
+This PEP changes the behaviour for the POSIX locale since this locale is
-is usually equivalent to the ASCII encoding, whereas UTF-8 is a much better
+usually equivalent to the ASCII encoding, whereas UTF-8 is a much better
-choice. It does not change the behaviour for other locales to prevent any
+choice. It does not change the behaviour for other locales to prevent
-risk or regression.
+any risk or regression.
 
-As users are responsible to enable explicitly the new UTF-8 Mode for these
+As users are responsible to enable explicitly the new UTF-8 Mode for
-other locales, they are responsible for any potential mojibake issues caused
+these other locales, they are responsible for any potential mojibake
-by UTF-8 Mode.
+issues caused by UTF-8 Mode.
 
 
 Proposal
@@ -109,11 +116,14 @@ Add a new UTF-8 Mode to use the UTF-8 encoding, ignore the locale
 encoding, and change ``stdin`` and ``stdout`` error handlers to
 ``surrogateescape``.
 
-Add the new ``-X utf8`` command line option and ``PYTHONUTF8`` environment
+Add the new ``-X utf8`` command line option and ``PYTHONUTF8``
-variable.  Users can explicitly activate UTF-8 Mode with the command-line option ``-X utf8`` or by setting the environment variable ``PYTHONUTF8=1``.
+environment variable.  Users can explicitly activate UTF-8 Mode with the
+command-line option ``-X utf8`` or by setting the environment variable
+``PYTHONUTF8=1``.
 
-This mode is disabled by default and enabled by the POSIX locale.
+This mode is disabled by default and enabled by the POSIX locale.  Users
-Users can explicitly disable UTF-8 Mode with the command-line option ``-X utf8=0`` or by setting the environment variable ``PYTHONUTF8=0``.
+can explicitly disable UTF-8 Mode with the command-line option ``-X
+utf8=0`` or by setting the environment variable ``PYTHONUTF8=0``.
 
 For standard streams, the ``PYTHONIOENCODING`` environment variable has
 priority over UTF-8 Mode.
@@ -142,14 +152,15 @@ Relationship with the locale coercion (PEP 538)
 ===============================================
 
 The POSIX locale enables the locale coercion (:pep:`538`) and the UTF-8
-mode (:pep:`540`). When the locale coercion is enabled, enabling the UTF-8
+mode (:pep:`540`). When the locale coercion is enabled, enabling the
-mode has no additional effect.
+UTF-8 mode has no additional effect.
 
 The UTF-8 Mode has the same effect as locale coercion:
 
 * ``sys.getfilesystemencoding()`` returns ``'UTF-8'``,
 * ``locale.getpreferredencoding()`` returns ``UTF-8``, and
-* the ``sys.stdin`` and ``sys.stdout`` error handlers are set to ``surrogateescape``.
+* the ``sys.stdin`` and ``sys.stdout`` error handlers are set to
+  ``surrogateescape``.
 
 These changes only affect Python code. But the locale coercion has
 addiditonal effects: the ``LC_CTYPE`` environment variable and the