gh-54874: Expand unicodedata module documentation (#138301)

Closes #54874

Co-authored-by: Alexander Belopolsky <[email protected]>

Author: StanFromIreland

Doc/library/unicodedata.rst

@@ -25,80 +25,133 @@ Standard Annex #44, `"Unicode Character Database"
 <https://www.unicode.org/reports/tr44/>`_.  It defines the
 following functions:
 
+.. seealso::
+
+   The :ref:`unicode-howto` for more information about Unicode and how to use
+   this module.
+
 
 .. function:: lookup(name)
 
    Look up character by name.  If a character with the given name is found, return
    the corresponding character.  If not found, :exc:`KeyError` is raised.
+   For example::
+
+      >>> unicodedata.lookup('LEFT CURLY BRACKET')
+      '{'
+
+   The characters returned by this function are the same as those produced by
+   ``\N`` escape sequence in string literals. For example::
+
+      >>> unicodedata.lookup('MIDDLE DOT') == '\N{MIDDLE DOT}'
+      True
 
    .. versionchanged:: 3.3
       Support for name aliases [#]_ and named sequences [#]_ has been added.
 
 
-.. function:: name(chr[, default])
+.. function:: name(chr, default=None, /)
 
    Returns the name assigned to the character *chr* as a string. If no
    name is defined, *default* is returned, or, if not given, :exc:`ValueError` is
-   raised.
+   raised. For example::
+
+      >>> unicodedata.name('½')
+      'VULGAR FRACTION ONE HALF'
+      >>> unicodedata.name('\uFFFF', 'fallback')
+      'fallback'
 
 
-.. function:: decimal(chr[, default])
+.. function:: decimal(chr, default=None, /)
 
    Returns the decimal value assigned to the character *chr* as integer.
    If no such value is defined, *default* is returned, or, if not given,
-   :exc:`ValueError` is raised.
+   :exc:`ValueError` is raised. For example::
 
+      >>> unicodedata.decimal('\N{ARABIC-INDIC DIGIT NINE}')
+      9
+      >>> unicodedata.decimal('\N{SUPERSCRIPT NINE}', -1)
+      -1
 
-.. function:: digit(chr[, default])
+
+.. function:: digit(chr, default=None, /)
 
    Returns the digit value assigned to the character *chr* as integer.
    If no such value is defined, *default* is returned, or, if not given,
-   :exc:`ValueError` is raised.
+   :exc:`ValueError` is raised::
+
+      >>> unicodedata.digit('\N{SUPERSCRIPT NINE}')
+      9
 
 
-.. function:: numeric(chr[, default])
+.. function:: numeric(chr, default=None, /)
 
    Returns the numeric value assigned to the character *chr* as float.
    If no such value is defined, *default* is returned, or, if not given,
-   :exc:`ValueError` is raised.
+   :exc:`ValueError` is raised::
+
+      >>> unicodedata.numeric('½')
+      0.5
 
 
 .. function:: category(chr)
 
    Returns the general category assigned to the character *chr* as
-   string.
+   string. General category names consist of two letters.
+   See the `General Category Values section of the Unicode Character
+   Database documentation <https://www.unicode.org/reports/tr44/#General_Category_Values>`_
+   for a list of category codes. For example::
+
+      >>> unicodedata.category('A')  # 'L'etter, 'u'ppercase
+      'Lu'
 
 
 .. function:: bidirectional(chr)
 
    Returns the bidirectional class assigned to the character *chr* as
    string. If no such value is defined, an empty string is returned.
+   See the `Bidirectional Class Values section of the Unicode Character
+   Database <https://www.unicode.org/reports/tr44/#Bidi_Class_Values>`_
+   documentation for a list of bidirectional codes. For example::
+
+      >>> unicodedata.bidirectional('\N{ARABIC-INDIC DIGIT SEVEN}') # 'A'rabic, 'N'umber
+      'AN'
 
 
 .. function:: combining(chr)
 
    Returns the canonical combining class assigned to the character *chr*
    as integer. Returns ``0`` if no combining class is defined.
+   See the `Canonical Combining Class Values section of the Unicode Character
+   Database <www.unicode.org/reports/tr44/#Canonical_Combining_Class_Values>`_
+   for more information.
 
 
 .. function:: east_asian_width(chr)
 
    Returns the east asian width assigned to the character *chr* as
-   string.
+   string. For a list of widths and or more information, see the
+   `Unicode Standard Annex #11 <https://www.unicode.org/reports/tr11/>`_.
 
 
 .. function:: mirrored(chr)
 
    Returns the mirrored property assigned to the character *chr* as
    integer. Returns ``1`` if the character has been identified as a "mirrored"
-   character in bidirectional text, ``0`` otherwise.
+   character in bidirectional text, ``0`` otherwise. For example::
+
+      >>> unicodedata.mirrored('>')
+      1
 
 
 .. function:: decomposition(chr)
 
    Returns the character decomposition mapping assigned to the character
    *chr* as string. An empty string is returned in case no such mapping is
-   defined.
+   defined. For example::
+
+      >>> unicodedata.decomposition('Ã')
+      '0041 0303'
 
 
 .. function:: normalize(form, unistr)
@@ -122,9 +175,9 @@ following functions:
    normally would be unified with other characters. For example, U+2160 (ROMAN
    NUMERAL ONE) is really the same thing as U+0049 (LATIN CAPITAL LETTER I).
    However, it is supported in Unicode for compatibility with existing character
-   sets (e.g. gb2312).
+   sets (for example, gb2312).
 
-   The normal form KD (NFKD) will apply the compatibility decomposition, i.e.
+   The normal form KD (NFKD) will apply the compatibility decomposition, that is,
    replace all compatibility characters with their equivalents. The normal form KC
    (NFKC) first applies the compatibility decomposition, followed by the canonical
    composition.
@@ -133,6 +186,7 @@ following functions:
    a human reader, if one has combining characters and the other
    doesn't, they may not compare equal.
 
+
 .. function:: is_normalized(form, unistr)
 
    Return whether the Unicode string *unistr* is in the normal form *form*. Valid
@@ -154,24 +208,6 @@ In addition, the module exposes the following constant:
    Unicode database version 3.2 instead, for applications that require this
    specific version of the Unicode database (such as IDNA).
 
-Examples:
-
-   >>> import unicodedata
-   >>> unicodedata.lookup('LEFT CURLY BRACKET')
-   '{'
-   >>> unicodedata.name('/')
-   'SOLIDUS'
-   >>> unicodedata.decimal('9')
-   9
-   >>> unicodedata.decimal('a')
-   Traceback (most recent call last):
-     File "<stdin>", line 1, in <module>
-   ValueError: not a decimal
-   >>> unicodedata.category('A')  # 'L'etter, 'u'ppercase
-   'Lu'
-   >>> unicodedata.bidirectional('\u0660') # 'A'rabic, 'N'umber
-   'AN'
-
 
 .. rubric:: Footnotes