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Various updates to README.rst (python#21)
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These include spelling/grammar fixes, removing some outdated prose,
updating some superseded prose, and adding/cleaning up some links.

Also rewraps the entire file at 79 columns.
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@zware
zware authored Feb 14, 2017
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Expand Up @@ -13,11 +13,8 @@ Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011,
2012, 2013, 2014, 2015, 2016, 2017 Python Software Foundation. All rights
reserved.

Python 3.x is a new version of the language, which is incompatible with the
2.x line of releases. The language is mostly the same, but many details,
especially how built-in objects like dictionaries and strings work,
have changed considerably, and a lot of deprecated features have finally
been removed.
See the end of this file for further copyright and license information.


Using Python
------------
Expand All @@ -40,16 +37,17 @@ On Unix, Linux, BSD, OSX, and Cygwin::

This will install Python as python3.

You can pass many options to the configure script; run ``./configure --help`` to
find out more. On OSX and Cygwin, the executable is called ``python.exe``;
You can pass many options to the configure script; run ``./configure --help``
to find out more. On OSX and Cygwin, the executable is called ``python.exe``;
elsewhere it's just ``python``.

On Mac OS X, if you have configured Python with ``--enable-framework``, you should
use ``make frameworkinstall`` to do the installation. Note that this installs the
Python executable in a place that is not normally on your PATH, you may want to
set up a symlink in ``/usr/local/bin``.
On Mac OS X, if you have configured Python with ``--enable-framework``, you
should use ``make frameworkinstall`` to do the installation. Note that this
installs the Python executable in a place that is not normally on your PATH,
you may want to set up a symlink in ``/usr/local/bin``.

On Windows, see PCbuild/readme.txt.
On Windows, see `PCbuild/readme.txt
<https://github.com/python/cpython/blob/master/PCbuild/readme.txt>`_.

If you wish, you can create a subdirectory and invoke configure from there.
For example::
Expand All @@ -60,57 +58,58 @@ For example::
make
make test

(This will fail if you *also* built at the top-level directory.
You should do a ``make clean`` at the toplevel first.)
(This will fail if you *also* built at the top-level directory. You should do
a ``make clean`` at the toplevel first.)

To get an optimized build of Python, ``configure --enable-optimizations`` before
you run ``make``. This sets the default make targets up to enable Profile Guided
Optimization (PGO) and may be used to auto-enable Link Time Optimization (LTO)
on some platforms. For more details, see the sections bellow.
To get an optimized build of Python, ``configure --enable-optimizations``
before you run ``make``. This sets the default make targets up to enable
Profile Guided Optimization (PGO) and may be used to auto-enable Link Time
Optimization (LTO) on some platforms. For more details, see the sections
below.


Profile Guided Optimization
---------------------------

PGO takes advantage of recent versions of the GCC or Clang compilers.
If ran, ``make profile-opt`` will do several steps.
PGO takes advantage of recent versions of the GCC or Clang compilers. If ran,
``make profile-opt`` will do several steps.

First, the entire Python directory is cleaned of temporary files that
may have resulted in a previous compilation.
First, the entire Python directory is cleaned of temporary files that may have
resulted in a previous compilation.

Then, an instrumented version of the interpreter is built, using suitable
compiler flags for each flavour. Note that this is just an intermediary
step and the binary resulted after this step is not good for real life
workloads, as it has profiling instructions embedded inside.
compiler flags for each flavour. Note that this is just an intermediary step
and the binary resulted after this step is not good for real life workloads, as
it has profiling instructions embedded inside.

After this instrumented version of the interpreter is built, the Makefile
will automatically run a training workload. This is necessary in order to
profile the interpreter execution. Note also that any output, both stdout
and stderr, that may appear at this step is suppressed.
After this instrumented version of the interpreter is built, the Makefile will
automatically run a training workload. This is necessary in order to profile
the interpreter execution. Note also that any output, both stdout and stderr,
that may appear at this step is suppressed.

Finally, the last step is to rebuild the interpreter, using the information
collected in the previous one. The end result will be a Python binary
that is optimized and suitable for distribution or production installation.
collected in the previous one. The end result will be a Python binary that is
optimized and suitable for distribution or production installation.


Link Time Optimization
----------------------

Enabled via configure's ``--with-lto`` flag. LTO takes advantages of recent
compiler toolchains ability to optimize across the otherwise arbitrary ``.o`` file
boundary when building final executables or shared libraries for additional
performance gains.
Enabled via configure's ``--with-lto`` flag. LTO takes advantage of the
ability of recent compiler toolchains to optimize across the otherwise
arbitrary ``.o`` file boundary when building final executables or shared
libraries for additional performance gains.


What's New
----------

We have a comprehensive overview of the changes in the `What's New in
Python 3.7 <https://docs.python.org/3.7/whatsnew/3.7.html>`_ document.

For a more detailed change log, read Misc/NEWS (though this file, too,
is incomplete, and also doesn't list anything merged in from the 2.7
release under development).
We have a comprehensive overview of the changes in the `What's New in Python
3.7 <https://docs.python.org/3.7/whatsnew/3.7.html>`_ document. For a more
detailed change log, read `Misc/NEWS
<https://github.com/python/cpython/blob/master/Misc/NEWS>`_, but a full
accounting of changes can only be gleaned from the `commit history
<https://github.com/python/cpython/commits/master>`_.

If you want to install multiple versions of Python see the section below
entitled "Installing multiple versions".
Expand All @@ -128,61 +127,56 @@ is primarily for documentation authors, translators, and people with special
formatting requirements.

If you would like to contribute to the development of Python, relevant
documentation is available at: `Python Developer's Guide
documentation is available in the `Python Developer's Guide
<https://docs.python.org/devguide/>`_.

For information about building Python's documentation, refer to Doc/README.txt.
For information about building Python's documentation, refer to `Doc/README.txt
<https://github.com/python/cpython/blob/master/Doc/README.txt>`_.


Converting From Python 2.x to 3.x
---------------------------------

Python starting with 2.6 contains features to help locating code that needs to
be changed, such as optional warnings when deprecated features are used, and
backported versions of certain key Python 3.x features.

A source-to-source translation tool, ``2to3``, can take care of the mundane task
of converting large amounts of source code. It is not a complete solution but
is complemented by the deprecation warnings in 2.6. See
`2to3 documentation <https://docs.python.org/3.7/library/2to3.html>`_ for more
information.
Significant backward incompatible changes were made for the release of Python
3.0, which may cause programs written for Python 2 to fail when run with Python
3. For more information about porting your code from Python 2 to Python 3, see
the `Porting HOWTO <https://docs.python.org/3/howto/pyporting.html>`_.


Testing
-------

To test the interpreter, type ``make test`` in the top-level directory.
The test set produces some output. You can generally ignore the messages
about skipped tests due to optional features which can't be imported.
If a message is printed about a failed test or a traceback or core dump
is produced, something is wrong.
To test the interpreter, type ``make test`` in the top-level directory. The
test set produces some output. You can generally ignore the messages about
skipped tests due to optional features which can't be imported. If a message
is printed about a failed test or a traceback or core dump is produced,
something is wrong.

By default, tests are prevented from overusing resources like disk space and
memory. To enable these tests, run ``make testall``.

IMPORTANT: If the tests fail and you decide to mail a bug report, *don't*
include the output of ``make test``. It is useless. Run the failing test
manually, as follows::
If any tests fail, you can re-run the failing test(s) in verbose mode::

./python -m test -v test_whatever
make test TESTOPTS="-v test_that_failed"

(substituting the top of the source tree for '.' if you built in a different
directory). This runs the test in verbose mode.
If the failure persists and appears to be a problem with Python rather than
your environment, you can `file a bug report <https://bugs.python.org>`_ and
include relevant output from that command to show the issue.


Installing multiple versions
----------------------------

On Unix and Mac systems if you intend to install multiple versions of Python
using the same installation prefix (``--prefix`` argument to the configure script)
you must take care that your primary python executable is not overwritten by the
installation of a different version. All files and directories installed using
``make altinstall`` contain the major and minor version and can thus live
side-by-side. ``make install`` also creates ``${prefix}/bin/python3`` which refers to
``${prefix}/bin/pythonX.Y``. If you intend to install multiple versions using the
same prefix you must decide which version (if any) is your "primary" version.
Install that version using ``make install``. Install all other versions using
``make altinstall``.
using the same installation prefix (``--prefix`` argument to the configure
script) you must take care that your primary python executable is not
overwritten by the installation of a different version. All files and
directories installed using ``make altinstall`` contain the major and minor
version and can thus live side-by-side. ``make install`` also creates
``${prefix}/bin/python3`` which refers to ``${prefix}/bin/pythonX.Y``. If you
intend to install multiple versions using the same prefix you must decide which
version (if any) is your "primary" version. Install that version using ``make
install``. Install all other versions using ``make altinstall``.

For example, if you want to install Python 2.7, 3.6, and 3.7 with 3.7 being the
primary version, you would execute ``make install`` in your 3.7 build directory
Expand All @@ -192,26 +186,26 @@ and ``make altinstall`` in the others.
Issue Tracker and Mailing List
------------------------------

We're soliciting bug reports about all aspects of the language. Fixes are also
welcome, preferably in unified diff format. Please use the issue tracker:
`bugs.python.org <https://bugs.python.org/>`_.
Bug reports are welcome! You can use the `issue tracker
<https://bugs.python.org>`_ to report bugs, and/or submit pull requests `on
GitHub <https://github.com/python/cpython>`_.

If you're not sure whether you're dealing with a bug or a feature, use the
mailing list: [email protected]. To subscribe to the list, use the mailman
form: `python-dev <https://mail.python.org/mailman/listinfo/python-dev/>`_
You can also follow development discussion on the `python-dev mailing list
<https://mail.python.org/mailman/listinfo/python-dev/>`_.


Proposals for enhancement
-------------------------

If you have a proposal to change Python, you may want to send an email to the
comp.lang.python or `python-ideas`_ mailing lists for initial feedback. A Python
Enhancement Proposal (PEP) may be submitted if your idea gains ground. All
current PEPs, as well as guidelines for submitting a new PEP, are listed at
comp.lang.python or `python-ideas`_ mailing lists for initial feedback. A
Python Enhancement Proposal (PEP) may be submitted if your idea gains ground.
All current PEPs, as well as guidelines for submitting a new PEP, are listed at
`python.org/dev/peps/ <https://www.python.org/dev/peps/>`_.

.. _python-ideas: https://mail.python.org/mailman/listinfo/python-ideas/


Release Schedule
----------------

Expand All @@ -231,8 +225,8 @@ rights reserved.

Copyright (c) 1991-1995 Stichting Mathematisch Centrum. All rights reserved.

See the file "LICENSE" for information on the history of this software,
terms & conditions for usage, and a DISCLAIMER OF ALL WARRANTIES.
See the file "LICENSE" for information on the history of this software, terms &
conditions for usage, and a DISCLAIMER OF ALL WARRANTIES.

This Python distribution contains *no* GNU General Public License (GPL) code,
so it may be used in proprietary projects. There are interfaces to some GNU
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