Update StringIO docs:

* More explanations/examples in class docs;
* Fix links to other methods (remove <code> tag);
* Fix wording of method docs (remove *stringio*
  receiver name, as it is not rendered by modern
  RDoc);
* Add  option mention to linereading
  methods (added in 2.4);
* Several other small fixes.

ext/stringio/stringio.c

@@ -429,7 +429,7 @@ strio_nil(VALUE self)
 }
 
 /*
- * Returns *strio* itself.  Just for compatibility to IO.
+ * Returns an object itself.  Just for compatibility to IO.
  */
 static VALUE
 strio_self(VALUE self)
@@ -505,7 +505,7 @@ strio_set_string(VALUE self, VALUE string)
  * call-seq:
  *   strio.close  -> nil
  *
- * Closes strio.  The *strio* is unavailable for any further data
+ * Closes a StringIO. The stream is unavailable for any further data
  * operations; an +IOError+ is raised if such an attempt is made.
  */
 static VALUE
@@ -521,7 +521,7 @@ strio_close(VALUE self)
  *   strio.close_read    -> nil
  *
  * Closes the read end of a StringIO.  Will raise an +IOError+ if the
- * *strio* is not readable.
+ * receiver is not readable.
  */
 static VALUE
 strio_close_read(VALUE self)
@@ -539,7 +539,7 @@ strio_close_read(VALUE self)
  *   strio.close_write    -> nil
  *
  * Closes the write end of a StringIO.  Will raise an  +IOError+ if the
- * *strio* is not writeable.
+ * receiver is not writeable.
  */
 static VALUE
 strio_close_write(VALUE self)
@@ -556,7 +556,7 @@ strio_close_write(VALUE self)
  * call-seq:
  *   strio.closed?    -> true or false
  *
- * Returns +true+ if *strio* is completely closed, +false+ otherwise.
+ * Returns +true+ if the stream is completely closed, +false+ otherwise.
  */
 static VALUE
 strio_closed(VALUE self)
@@ -570,7 +570,7 @@ strio_closed(VALUE self)
  * call-seq:
  *   strio.closed_read?    -> true or false
  *
- * Returns +true+ if *strio* is not readable, +false+ otherwise.
+ * Returns +true+ if the stream is not readable, +false+ otherwise.
  */
 static VALUE
 strio_closed_read(VALUE self)
@@ -584,7 +584,7 @@ strio_closed_read(VALUE self)
  * call-seq:
  *   strio.closed_write?    -> true or false
  *
- * Returns +true+ if *strio* is not writable, +false+ otherwise.
+ * Returns +true+ if the stream is not writable, +false+ otherwise.
  */
 static VALUE
 strio_closed_write(VALUE self)
@@ -599,8 +599,8 @@ strio_closed_write(VALUE self)
  *   strio.eof     -> true or false
  *   strio.eof?    -> true or false
  *
- * Returns true if *strio* is at end of file. The stringio must be
+ * Returns true if the stream is at the end of the data (underlying string).
- * opened for reading or an +IOError+ will be raised.
+ * The stream must be opened for reading or an +IOError+ will be raised.
  */
 static VALUE
 strio_eof(VALUE self)
@@ -634,7 +634,7 @@ strio_copy(VALUE copy, VALUE orig)
  * call-seq:
  *   strio.lineno    -> integer
  *
- * Returns the current line number in *strio*. The stringio must be
+ * Returns the current line number. The stream must be
  * opened for reading. +lineno+ counts the number of times  +gets+ is
  * called, rather than the number of newlines  encountered. The two
  * values will differ if +gets+ is  called with a separator other than
@@ -660,6 +660,13 @@ strio_set_lineno(VALUE self, VALUE lineno)
     return lineno;
 }
 
+/*
+ * call-seq:
+ *   strio.binmode    -> stringio
+ *
+ * Puts stream into binary mode. See IO#binmode.
+ *
+ */
 static VALUE
 strio_binmode(VALUE self)
 {
@@ -684,7 +691,7 @@ strio_binmode(VALUE self)
  *   strio.reopen(other_StrIO)     -> strio
  *   strio.reopen(string, mode)    -> strio
  *
- * Reinitializes *strio* with the given <i>other_StrIO</i> or _string_
+ * Reinitializes the stream with the given <i>other_StrIO</i> or _string_
  * and _mode_ (see StringIO#new).
  */
 static VALUE
@@ -702,7 +709,7 @@ strio_reopen(int argc, VALUE *argv, VALUE self)
  *   strio.pos     -> integer
  *   strio.tell    -> integer
  *
- * Returns the current offset (in bytes) of *strio*.
+ * Returns the current offset (in bytes).
  */
 static VALUE
 strio_get_pos(VALUE self)
@@ -714,7 +721,7 @@ strio_get_pos(VALUE self)
  * call-seq:
  *   strio.pos = integer    -> integer
  *
- * Seeks to the given position (in bytes) in *strio*.
+ * Seeks to the given position (in bytes).
  */
 static VALUE
 strio_set_pos(VALUE self, VALUE pos)
@@ -732,7 +739,7 @@ strio_set_pos(VALUE self, VALUE pos)
  * call-seq:
  *   strio.rewind    -> 0
  *
- * Positions *strio* to the beginning of input, resetting
+ * Positions the stream to the beginning of input, resetting
  * +lineno+ to zero.
  */
 static VALUE
@@ -900,7 +907,7 @@ strio_extend(struct StringIO *ptr, long pos, long len)
  * call-seq:
  *   strio.ungetc(string)   -> nil
  *
- * Pushes back one character (passed as a parameter) onto *strio*
+ * Pushes back one character (passed as a parameter)
  * such that a subsequent buffered read will return it.  There is no
  * limitation for multiple pushbacks including pushing back behind the
  * beginning of the buffer string.
@@ -1047,7 +1054,7 @@ strio_each_char(VALUE self)
 }
 
 /*
- *  This is a deprecated alias for <code>each_char</code>.
+ *  This is a deprecated alias for #each_char.
  */
 static VALUE
 strio_chars(VALUE self)
@@ -1091,7 +1098,7 @@ strio_each_codepoint(VALUE self)
 }
 
 /*
- *  This is a deprecated alias for <code>each_codepoint</code>.
+ *  This is a deprecated alias for #each_codepoint.
  */
 static VALUE
 strio_codepoints(VALUE self)
@@ -1281,9 +1288,9 @@ strio_getline(struct getline_arg *arg, struct StringIO *ptr)
 
 /*
  * call-seq:
- *   strio.gets(sep=$/)     -> string or nil
+ *   strio.gets(sep=$/, chomp: false)     -> string or nil
- *   strio.gets(limit)      -> string or nil
+ *   strio.gets(limit, chomp: false)      -> string or nil
- *   strio.gets(sep, limit) -> string or nil
+ *   strio.gets(sep, limit, chomp: false) -> string or nil
  *
  * See IO#gets.
  */
@@ -1305,9 +1312,9 @@ strio_gets(int argc, VALUE *argv, VALUE self)
 
 /*
  * call-seq:
- *   strio.readline(sep=$/)     -> string
+ *   strio.readline(sep=$/, chomp: false)     -> string
- *   strio.readline(limit)      -> string or nil
+ *   strio.readline(limit, chomp: false)      -> string or nil
- *   strio.readline(sep, limit) -> string or nil
+ *   strio.readline(sep, limit, chomp: false) -> string or nil
  *
  * See IO#readline.
  */
@@ -1321,15 +1328,15 @@ strio_readline(int argc, VALUE *argv, VALUE self)
 
 /*
  * call-seq:
- *   strio.each(sep=$/) {|line| block }         -> strio
+ *   strio.each(sep=$/, chomp: false) {|line| block }         -> strio
- *   strio.each(limit) {|line| block }          -> strio
+ *   strio.each(limit, chomp: false) {|line| block }          -> strio
- *   strio.each(sep, limit) {|line| block }     -> strio
+ *   strio.each(sep, limit, chomp: false) {|line| block }     -> strio
- *   strio.each(...)                            -> anEnumerator
+ *   strio.each(...)                                          -> anEnumerator
  *
- *   strio.each_line(sep=$/) {|line| block }    -> strio
+ *   strio.each_line(sep=$/, chomp: false) {|line| block }     -> strio
- *   strio.each_line(limit) {|line| block }     -> strio
+ *   strio.each_line(limit, chomp: false) {|line| block }      -> strio
- *   strio.each_line(sep,limit) {|line| block } -> strio
+ *   strio.each_line(sep, limit, chomp: false) {|line| block } -> strio
- *   strio.each_line(...)                       -> anEnumerator
+ *   strio.each_line(...)                                      -> anEnumerator
  *
  * See IO#each.
  */
@@ -1353,7 +1360,7 @@ strio_each(int argc, VALUE *argv, VALUE self)
 }
 
 /*
- *  This is a deprecated alias for <code>each_line</code>.
+ *  This is a deprecated alias for #each_line.
  */
 static VALUE
 strio_lines(int argc, VALUE *argv, VALUE self)
@@ -1366,9 +1373,9 @@ strio_lines(int argc, VALUE *argv, VALUE self)
 
 /*
  * call-seq:
- *   strio.readlines(sep=$/)    ->   array
+ *   strio.readlines(sep=$/, chomp: false)     ->   array
- *   strio.readlines(limit)     ->   array
+ *   strio.readlines(limit, chomp: false)      ->   array
- *   strio.readlines(sep,limit) ->   array
+ *   strio.readlines(sep, limit, chomp: false) ->   array
  *
  * See IO#readlines.
  */
@@ -1395,7 +1402,7 @@ strio_readlines(int argc, VALUE *argv, VALUE self)
  *   strio.write(string, ...) -> integer
  *   strio.syswrite(string)   -> integer
  *
- * Appends the given string to the underlying buffer string of *strio*.
+ * Appends the given string to the underlying buffer string.
  * The stream must be opened for writing.  If the argument is not a
  * string, it will be converted to a string using <code>to_s</code>.
  * Returns the number of bytes written.  See IO#write.
@@ -1669,7 +1676,7 @@ strio_size(VALUE self)
  * call-seq:
  *   strio.truncate(integer)    -> 0
  *
- * Truncates the buffer string to at most _integer_ bytes. The *strio*
+ * Truncates the buffer string to at most _integer_ bytes. The stream
  * must be opened for writing.
  */
 static VALUE
@@ -1693,7 +1700,8 @@ strio_truncate(VALUE self, VALUE len)
  *     strio.external_encoding   => encoding
  *
  *  Returns the Encoding object that represents the encoding of the file.
- *  If strio is write mode and no encoding is specified, returns <code>nil</code>.
+ *  If the stream is write mode and no encoding is specified, returns
+ *  +nil+.
  */
 
 static VALUE
@@ -1708,7 +1716,7 @@ strio_external_encoding(VALUE self)
  *     strio.internal_encoding   => encoding
  *
  *  Returns the Encoding of the internal string if conversion is
- *  specified.  Otherwise returns nil.
+ *  specified.  Otherwise returns +nil+.
  */
 
 static VALUE
@@ -1763,17 +1771,24 @@ strio_set_encoding_by_bom(VALUE self)
 }
 
 /*
- * Pseudo I/O on String object.
+ * Pseudo I/O on String object, with interface corresponding to IO.
  *
- * Commonly used to simulate `$stdio` or `$stderr`
+ * Commonly used to simulate <code>$stdio</code> or <code>$stderr</code>
  *
  * === Examples
  *
  *   require 'stringio'
  *
+ *   # Writing stream emulation
  *   io = StringIO.new
  *   io.puts "Hello World"
  *   io.string #=> "Hello World\n"
+ *
+ *   # Reading stream emulation
+ *   io = StringIO.new "first\nsecond\nlast\n"
+ *   io.getc #=> "f"
+ *   io.gets #=> "irst\n"
+ *   io.read #=> "second\nlast\n"
  */
 void
 Init_stringio(void)