perlexperiment: document the private_use experiment

[perl5.git] / pod / perlop.pod

diff --git a/pod/perlop.pod b/pod/perlop.pod
index 3e6c10f..33e558a 100644 (file)
--- a/pod/perlop.pod
+++ b/pod/perlop.pod
@@ -128,7 +128,7 @@ values only, not array values.
     left       ->
     nonassoc   ++ --
     right      **
-    right      ! ~ \ and unary + and -
+    right      ! ~ ~. \ and unary + and -
     left       =~ !~
     left       * / % x
     left       + - .
@@ -137,8 +137,8 @@ values only, not array values.
     chained    < > <= >= lt gt le ge
     chain/na   == != eq ne <=> cmp ~~
     nonassoc    isa
-    left       &
-    left       | ^
+    left       & &.
+    left       | |. ^ ^.
     left       &&
     left       || //
     nonassoc   ..  ...
@@ -1594,6 +1594,8 @@ is a word character (meaning it matches C</\w/>):
 
 The following escape sequences are available in constructs that interpolate,
 and in transliterations whose delimiters aren't single quotes (C<"'">).
+In all the ones with braces, any number of blanks and/or tabs adjoining
+and within the braces are allowed (and ignored).
 X<\t> X<\n> X<\r> X<\f> X<\b> X<\a> X<\e> X<\x> X<\0> X<\c> X<\N> X<\N{}>
 X<\o{}>
 
@@ -1606,6 +1608,8 @@ X<\o{}>
     \a                  alarm (bell)      (BEL)
     \e                  escape            (ESC)
     \x{263A}     [1,8]  hex char          (example shown: SMILEY)
+    \x{ 263A }          Same, but shows optional blanks inside and
+                        adjoining the braces
     \x1b         [2,8]  restricted range hex char (example: ESC)
     \N{name}     [3]    named Unicode character or character sequence
     \N{U+263D}   [4,8]  Unicode character (example: FIRST QUARTER MOON)
@@ -1613,6 +1617,11 @@ X<\o{}>
     \o{23072}    [6,8]  octal char        (example: SMILEY)
     \033         [7,8]  restricted range octal char  (example: ESC)
 
+Note that any escape sequence using braces inside interpolated
+constructs may have optional blanks (tab or space characters) adjoining
+with and inside of the braces, as illustrated above by the second
+S<C<\x{ }>> example.
+
 =over 4
 
 =item [1]
@@ -1620,10 +1629,13 @@ X<\o{}>
 The result is the character specified by the hexadecimal number between
 the braces.  See L</[8]> below for details on which character.
 
-Only hexadecimal digits are valid between the braces.  If an invalid
-character is encountered, a warning will be issued and the invalid
-character and all subsequent characters (valid or invalid) within the
-braces will be discarded.
+Blanks (tab or space characters) may separate the number from either or
+both of the braces.
+
+Otherwise, only hexadecimal digits are valid between the braces.  If an
+invalid character is encountered, a warning will be issued and the
+invalid character and all subsequent characters (valid or invalid)
+within the braces will be discarded.
 
 If there are no valid digits between the braces, the generated character is
 the NULL character (C<\x{00}>).  However, an explicit empty brace (C<\x{}>)
@@ -1709,10 +1721,13 @@ To get platform independent controls, you can use C<\N{...}>.
 The result is the character specified by the octal number between the braces.
 See L</[8]> below for details on which character.
 
-If a character that isn't an octal digit is encountered, a warning is raised,
-and the value is based on the octal digits before it, discarding it and all
-following characters up to the closing brace.  It is a fatal error if there are
-no octal digits at all.
+Blanks (tab or space characters) may separate the number from either or
+both of the braces.
+
+Otherwise, if a character that isn't an octal digit is encountered, a
+warning is raised, and the value is based on the octal digits before it,
+discarding it and all following characters up to the closing brace.  It
+is a fatal error if there are no octal digits at all.
 
 =item [7]
 
@@ -2584,7 +2599,8 @@ Unless the C</r> option is used, the string specified with C<=~> must be a
 scalar variable, an array element, a hash element, or an assignment to one
 of those; in other words, an lvalue.
 
-If the characters delimiting I<SEARCHLIST> and I<REPLACEMENTLIST>
+The characters delimitting I<SEARCHLIST> and I<REPLACEMENTLIST>
+can be any printable character, not just forward slashes.  If they
 are single quotes (C<tr'I<SEARCHLIST>'I<REPLACEMENTLIST>'>), the only
 interpolation is removal of C<\> from pairs of C<\\>.
 
@@ -2670,8 +2686,8 @@ If the C</s> modifier is specified, sequences of characters, all in a
 row, that were transliterated to the same character are squashed down to
 a single instance of that character.
 
- my $a = "aaaba"
- $a =~ tr/a/a/s     # $a now is "aba"
+ my $a = "aaabbbca";
+ $a =~ tr/ab/dd/s;     # $a now is "dcd"
 
 If the C</d> modifier is used, the I<REPLACEMENTLIST> is always interpreted
 exactly as specified.  Otherwise, if the I<REPLACEMENTLIST> is shorter
@@ -3375,7 +3391,8 @@ way, so use with care.
 C<< <I<FILEHANDLE>> >>  may also be spelled C<readline(*I<FILEHANDLE>)>.
 See L<perlfunc/readline>.
 
-The null filehandle C<< <> >> is special: it can be used to emulate the
+The null filehandle C<< <> >> (sometimes called the diamond operator) is
+special: it can be used to emulate the
 behavior of B<sed> and B<awk>, and any other Unix filter program
 that takes a list of filenames, doing the same to each line
 of input from all of them.  Input from C<< <> >> comes either from
@@ -3416,7 +3433,8 @@ it interprets special characters, so if you have a script like this:
 and call it with S<C<perl dangerous.pl 'rm -rfv *|'>>, it actually opens a
 pipe, executes the C<rm> command and reads C<rm>'s output from that pipe.
 If you want all items in C<@ARGV> to be interpreted as file names, you
-can use the module C<ARGV::readonly> from CPAN, or use the double bracket:
+can use the module C<ARGV::readonly> from CPAN, or use the double
+diamond bracket:
 
     while (<<>>) {
         print;