Fix strings.rst style

Wrapped long lines and removed a few trailing spaces.

docs/advanced/cast/strings.rst

@@ -3,14 +3,23 @@ Strings, bytes and Unicode conversions
 
 .. note::
 
-    This section discusses string handling in terms of Python 3 strings. For Python 2.7, replace all occurrences of ``str`` with ``unicode`` and ``bytes`` with ``str``.  Python 2.7 users may find it best to use ``from __future__ import unicode_literals`` to avoid unintentionally using ``str`` instead of ``unicode``.
+    This section discusses string handling in terms of Python 3 strings. For
+    Python 2.7, replace all occurrences of ``str`` with ``unicode`` and
+    ``bytes`` with ``str``.  Python 2.7 users may find it best to use ``from
+    __future__ import unicode_literals`` to avoid unintentionally using ``str``
+    instead of ``unicode``.
 
 Passing Python strings to C++
 =============================
 
-When a Python ``str`` is passed from Python to a C++ function that accepts ``std::string`` or ``char *`` as arguments, pybind11 will encode the Python string to UTF-8. All Python ``str`` can be encoded in UTF-8, so this operation does not fail.
+When a Python ``str`` is passed from Python to a C++ function that accepts
+``std::string`` or ``char *`` as arguments, pybind11 will encode the Python
+string to UTF-8. All Python ``str`` can be encoded in UTF-8, so this operation
+does not fail.
 
-The C++ language is encoding agnostic. It is the responsibility of the programmer to track encodings. It's often easiest to simply `use UTF-8 everywhere <http://utf8everywhere.org/>`_.
+The C++ language is encoding agnostic. It is the responsibility of the
+programmer to track encodings. It's often easiest to simply `use UTF-8
+everywhere <http://utf8everywhere.org/>`_.
 
 .. code-block:: c++
 
@@ -39,20 +48,27 @@ The C++ language is encoding agnostic. It is the responsibility of the programme
 
 .. note::
 
-    Some terminal emulators do not support UTF-8 or emoji fonts and may not display the example above correctly.
+    Some terminal emulators do not support UTF-8 or emoji fonts and may not
+    display the example above correctly.
 
-The results are the same whether the C++ function accepts arguments by value or reference, and whether or not ``const`` is used.
+The results are the same whether the C++ function accepts arguments by value or
+reference, and whether or not ``const`` is used.
 
 Passing bytes to C++
 --------------------
 
-A Python ``bytes`` object will be passed to C++ functions that accept ``std::string`` or ``char*`` *without* conversion. 
+A Python ``bytes`` object will be passed to C++ functions that accept
+``std::string`` or ``char*`` *without* conversion.
 
 
 Returning C++ strings to Python
 ===============================
 
-When a C++ function returns a ``std::string`` or ``char*`` to a Python caller, **pybind11 will assume that the string is valid UTF-8** and will decode it to a native Python ``str``, using the same API as Python uses to perform ``bytes.decode('utf-8')``. If this implicit conversion fails, pybind11 will raise a ``UnicodeDecodeError``. 
+When a C++ function returns a ``std::string`` or ``char*`` to a Python caller,
+**pybind11 will assume that the string is valid UTF-8** and will decode it to a
+native Python ``str``, using the same API as Python uses to perform
+``bytes.decode('utf-8')``. If this implicit conversion fails, pybind11 will
+raise a ``UnicodeDecodeError``.
 
 .. code-block:: c++
 
@@ -68,16 +84,22 @@ When a C++ function returns a ``std::string`` or ``char*`` to a Python caller, *
     True
 
 
-Because UTF-8 is inclusive of pure ASCII, there is never any issue with returning a pure ASCII string to Python. If there is any possibility that the string is not pure ASCII, it is necessary to ensure the encoding is valid UTF-8.
+Because UTF-8 is inclusive of pure ASCII, there is never any issue with
+returning a pure ASCII string to Python. If there is any possibility that the
+string is not pure ASCII, it is necessary to ensure the encoding is valid
+UTF-8.
 
 .. warning::
 
-    Implicit conversion assumes that a returned ``char *`` is null-terminated. If there is no null terminator a buffer overrun will occur.
+    Implicit conversion assumes that a returned ``char *`` is null-terminated.
+    If there is no null terminator a buffer overrun will occur.
 
 Explicit conversions
 --------------------
 
-If some C++ code constructs a ``std::string`` that is not a UTF-8 string, one can perform a explicit conversion and return a ``py::str`` object. Explicit conversion has the same overhead as implicit conversion.
+If some C++ code constructs a ``std::string`` that is not a UTF-8 string, one
+can perform a explicit conversion and return a ``py::str`` object. Explicit
+conversion has the same overhead as implicit conversion.
 
 .. code-block:: c++
 
@@ -95,15 +117,20 @@ If some C++ code constructs a ``std::string`` that is not a UTF-8 string, one ca
     >>> str_output()
     'Send your résumé to Alice in HR'
 
-The `Python C API <https://docs.python.org/3/c-api/unicode.html#built-in-codecs>`_ provides several built-in codecs.
+The `Python C API
+<https://docs.python.org/3/c-api/unicode.html#built-in-codecs>`_ provides
+several built-in codecs.
 
 
-One could also use a third party encoding library such as libiconv to transcode to UTF-8.
+One could also use a third party encoding library such as libiconv to transcode
+to UTF-8.
 
 Return C++ strings without conversion
 -------------------------------------
 
-If the data in a C++ ``std::string`` does not represent text and should be returned to Python as ``bytes``, then one can return the data as a ``py::bytes`` object.
+If the data in a C++ ``std::string`` does not represent text and should be
+returned to Python as ``bytes``, then one can return the data as a
+``py::bytes`` object.
 
 .. code-block:: c++
 
@@ -120,7 +147,8 @@ If the data in a C++ ``std::string`` does not represent text and should be retur
     b'\xba\xd0\xba\xd0'
 
 
-Note the asymmetry: pybind11 will convert ``bytes`` to ``std::string`` without encoding, but cannot convert ``std::string`` back to ``bytes`` implicitly.
+Note the asymmetry: pybind11 will convert ``bytes`` to ``std::string`` without
+encoding, but cannot convert ``std::string`` back to ``bytes`` implicitly.
 
 .. code-block:: c++
 
@@ -142,7 +170,12 @@ Note the asymmetry: pybind11 will convert ``bytes`` to ``std::string`` without e
 Wide character strings
 ======================
 
-When a Python ``str`` is passed to a C++ function expecting ``std::wstring``, ``wchar_t*``, ``std::u16string`` or ``std::u32string``, the ``str`` will be encoded to UTF-16 or UTF-32 depending on how the C++ compiler implements each type, in the platform's endian. When strings of these types are returned, they are assumed to contain valid UTF-16 or UTF-32, and will be decoded to Python ``str``.
+When a Python ``str`` is passed to a C++ function expecting ``std::wstring``,
+``wchar_t*``, ``std::u16string`` or ``std::u32string``, the ``str`` will be
+encoded to UTF-16 or UTF-32 depending on how the C++ compiler implements each
+type, in the platform's endian. When strings of these types are returned, they
+are assumed to contain valid UTF-16 or UTF-32, and will be decoded to Python
+``str``.
 
 .. code-block:: c++
 
@@ -171,17 +204,23 @@ When a Python ``str`` is passed to a C++ function expecting ``std::wstring``, ``
 
 .. warning::
 
-    Wide character strings may not work as described on Python 2.7 or Python 3.3 compiled with ``--enable-unicode=ucs2``.
+    Wide character strings may not work as described on Python 2.7 or Python
+    3.3 compiled with ``--enable-unicode=ucs2``.
 
-Strings in multibyte encodings such as Shift-JIS must transcoded to a UTF-8/16/32 before being returned to Python.
+Strings in multibyte encodings such as Shift-JIS must transcoded to a
+UTF-8/16/32 before being returned to Python.
 
 
 Character literals
 ==================
 
-C++ functions that accept character literals as input will receive the first character of a Python ``str`` as their input. If the string is longer than one Unicode character, trailing characters will be ignored.
+C++ functions that accept character literals as input will receive the first
+character of a Python ``str`` as their input. If the string is longer than one
+Unicode character, trailing characters will be ignored.
 
-When a character literal is returned from C++ (such as a ``char`` or a ``wchar_t``), it will be converted to a ``str`` that represents the single character.
+When a character literal is returned from C++ (such as a ``char`` or a
+``wchar_t``), it will be converted to a ``str`` that represents the single
+character.
 
 .. code-block:: c++
 
@@ -193,7 +232,9 @@ When a character literal is returned from C++ (such as a ``char`` or a ``wchar_t
     >>> example.pass_char('A')
     'A'
 
-While C++ will cast integers to character types (``char c = 0x65;``), pybind11 does not convert Python integers to characters implicitly. The Python function ``chr()`` can be used to convert integers to characters.
+While C++ will cast integers to character types (``char c = 0x65;``), pybind11
+does not convert Python integers to characters implicitly. The Python function
+``chr()`` can be used to convert integers to characters.
 
 .. code-block:: python
 
@@ -203,12 +244,18 @@ While C++ will cast integers to character types (``char c = 0x65;``), pybind11 d
     >>> example.pass_char(chr(0x65))
     'A'
 
-If the desire is to work with an 8-bit integer, use ``int8_t`` or ``uint8_t`` as the argument type.
+If the desire is to work with an 8-bit integer, use ``int8_t`` or ``uint8_t``
+as the argument type.
 
 Grapheme clusters
 -----------------
 
-A single grapheme may be represented by two or more Unicode characters. For example 'é' is usually represented as U+00E9 but can also be expressed as the combining character sequence U+0065 U+0301 (that is, the letter 'e' followed by a combining acute accent). The combining character will be lost if the two-character sequence is passed as an argument, even though it renders as a single grapheme.
+A single grapheme may be represented by two or more Unicode characters. For
+example 'é' is usually represented as U+00E9 but can also be expressed as the
+combining character sequence U+0065 U+0301 (that is, the letter 'e' followed by
+a combining acute accent). The combining character will be lost if the
+two-character sequence is passed as an argument, even though it renders as a
+single grapheme.
 
 .. code-block:: python
 
@@ -226,18 +273,22 @@ A single grapheme may be represented by two or more Unicode characters. For exam
     >>> example.pass_wchar(combining_e_acute)
     'e'
 
-Normalizing combining characters before passing the character literal to C++ may resolve *some* of these issues:
+Normalizing combining characters before passing the character literal to C++
+may resolve *some* of these issues:
 
 .. code-block:: python
 
     >>> example.pass_wchar(unicodedata.normalize('NFC', combining_e_acute))
     'é'
 
-In some languages (Thai for example), there are `graphemes that cannot be expressed as a single Unicode code point <http://unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries>`_, so there is no way to capture them in a C++ character type.
+In some languages (Thai for example), there are `graphemes that cannot be
+expressed as a single Unicode code point
+<http://unicode.org/reports/tr29/#Grapheme_Cluster_Boundaries>`_, so there is
+no way to capture them in a C++ character type.
 
 
 References
 ==========
 
-* `The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!) <https://www.joelonsoftware.com/2003/10/08/the-absolute-minimum-every-software-developer-absolutely-positively-must-know-about-unicode-and-character-sets-no-excuses/>`_
+* `The Absolute Minimum Every Software Developer Absolutely, Positively Must Know About Unicode and Character Sets (No Excuses!) <https://www.joelonsoftware.com/2003/10/08/the-absolute-minimum-every-software-developer-absolutely-positively-must-know-about-unicode-and-character-sets-no-excuses/>`
 * `C++ - Using STL Strings at Win32 API Boundaries <https://msdn.microsoft.com/en-ca/magazine/mt238407.aspx>`_