Note 5.8.8-RC1

[p5sagit/p5-mst-13.2.git] / pod / perlop.pod

diff --git a/pod/perlop.pod b/pod/perlop.pod
index 6aa762d..d9dc77f 100644 (file)
--- a/pod/perlop.pod
+++ b/pod/perlop.pod
@@ -41,7 +41,7 @@ values only, not array values.
     left       << >>
     nonassoc   named unary operators
     nonassoc   < > <= >= lt gt le ge
-    nonassoc   == != <=> eq ne cmp
+    nonassoc   == != <=> eq ne cmp ~~
     left       &
     left       | ^
     left       &&
@@ -199,7 +199,11 @@ the operand is an identifier, a string consisting of a minus sign
 concatenated with the identifier is returned.  Otherwise, if the string
 starts with a plus or minus, a string starting with the opposite sign
 is returned.  One effect of these rules is that -bareword is equivalent
-to the string "-bareword".
+to the string "-bareword".  If, however, the string begins with a
+non-alphabetic character (exluding "+" or "-"), Perl will attempt to convert
+the string to a numeric and the arithmetic negation is performed. If the
+string cannot be cleanly converted to a numeric, Perl will give the warning
+B<Argument "the string" isn't numeric in negation (-) at ...>.
 X<-> X<negation, arithmetic>
 
 Unary "~" performs bitwise negation, i.e., 1's complement.  For
@@ -426,6 +430,12 @@ argument is stringwise less than, equal to, or greater than the right
 argument.
 X<cmp>
 
+Binary "~~" does a smart match between its arguments. Smart matching
+is described in L<perlsyn/"Smart Matching in Detail">.
+This operator is only available if you enable the "~~" feature:
+see L<feature> for more information.
+X<~~>
+
 "lt", "le", "ge", "gt" and "cmp" use the collation (sort) order specified
 by the current locale if C<use locale> is in effect.  See L<perllocale>.
 
@@ -578,9 +588,12 @@ As a scalar operator:
 
     if (101 .. 200) { print; } # print 2nd hundred lines, short for
                                #   if ($. == 101 .. $. == 200) ...
-    next line if (1 .. /^$/);  # skip header lines, short for
+
+    next LINE if (1 .. /^$/);  # skip header lines, short for
                                #   ... if ($. == 1 .. /^$/);
-    s/^/> / if (/^$/ .. eof());        # quote body
+                               # (typically in a loop labeled LINE)
+
+    s/^/> / if (/^$/ .. eof());  # quote body
 
     # parse mail messages
     while (<>) {
@@ -603,16 +616,14 @@ the two range operators:
               "1  - Baz",
               "   - Quux");
 
-    foreach(@lines)
-    {
-        if (/0/ .. /1/)
-        {
+    foreach (@lines) {
+        if (/0/ .. /1/) {
             print "$_\n";
         }
     }
 
-This program will print only the line containing "Bar". If 
-the range operator is changed to C<...>, it will also print the 
+This program will print only the line containing "Bar". If
+the range operator is changed to C<...>, it will also print the
 "Baz" line.
 
 And now some examples as a list operator:
@@ -687,7 +698,7 @@ That should probably be written more simply as:
 
 =head2 Assignment Operators
 X<assignment> X<operator, assignment> X<=> X<**=> X<+=> X<*=> X<&=>
-X<<< <<= >>> X<&&=> X<-=> X</=> X<|=> X<<< >>= >>> X<||=> X<.=>
+X<<< <<= >>> X<&&=> X<-=> X</=> X<|=> X<<< >>= >>> X<||=> X<//=> X<.=>
 X<%=> X<^=> X<x=>
 
 "=" is the ordinary assignment operator.
@@ -706,8 +717,8 @@ The following are recognized:
 
     **=    +=    *=    &=    <<=    &&=
            -=    /=    |=    >>=    ||=
-           .=    %=    ^=
-                x=
+           .=    %=    ^=           //=
+                 x=
 
 Although these are grouped by family, they all have the precedence
 of assignment.
@@ -825,10 +836,12 @@ takes higher precedence.
 
 Then again, you could always use parentheses.
 
-Binary "err" is equivalent to C<//>--it's just like binary "or", except it tests
-its left argument's definedness instead of its truth.  There are two ways to 
-remember "err":  either because many functions return C<undef> on an B<err>or,
-or as a sort of correction:  C<$a=($b err 'default')>
+Binary "err" is equivalent to C<//>--it's just like binary "or", except it
+tests its left argument's definedness instead of its truth.  There are two
+ways to remember "err":  either because many functions return C<undef> on
+an B<err>or, or as a sort of correction:  C<$a = ($b err 'default')>. This
+keyword is only available when the 'err' feature is enabled: see
+L<feature> for more information.
 
 Binary "xor" returns the exclusive-OR of the two surrounding expressions.
 It cannot short circuit, of course.
@@ -867,7 +880,7 @@ function as operators, providing various kinds of interpolating and
 pattern matching capabilities.  Perl provides customary quote characters
 for these behaviors, but also provides a way for you to choose your
 quote character for any of them.  In the following table, a C<{}> represents
-any pair of delimiters you choose.  
+any pair of delimiters you choose.
 
     Customary  Generic        Meaning       Interpolates
        ''       q{}          Literal             no
@@ -884,11 +897,11 @@ any pair of delimiters you choose.
 
 Non-bracketing delimiters use the same character fore and aft, but the four
 sorts of brackets (round, angle, square, curly) will all nest, which means
-that 
+that
 
-       q{foo{bar}baz} 
+       q{foo{bar}baz}
 
-is the same as 
+is the same as
 
        'foo{bar}baz'