Re: [PATCH] Re: [perl #34632] perlintro: "Comments start with a hash symbol"

Message-Id: <200504021737.j32HbBNS000652@accognoscere.homeunix.org>

p4raw-id: //depot/perl@24139

1 files changed, 68 insertions, 68 deletions

diff --git a/pod/perltrap.pod b/pod/perltrap.pod
index 0ad0086a59..936d684f3d 100644
--- a/pod/perltrap.pod
+++ b/pod/perltrap.pod
@@ -418,7 +418,7 @@ a bug from perl4.
 
 =over 4
 
-=item * Discontinuance
+=item * Symbols starting with "_" no longer forced into main
 
 Symbols starting with "_" are no longer forced into package main, except
 for C<$_> itself (and C<@_>, etc.).
@@ -432,7 +432,7 @@ for C<$_> itself (and C<@_>, etc.).
     # perl4 prints: $_legacy is 1
     # perl5 prints: $_legacy is
 
-=item * Deprecation
+=item * Double-colon valid package separator in variable name
 
 Double-colon is now a valid package separator in a variable name.  Thus these
 behave differently in perl4 vs. perl5, because the packages don't exist.
@@ -462,7 +462,7 @@ always explicitly include the package name:
 
 Also see precedence traps, for parsing C<$:>.
 
-=item * BugFix
+=item * 2nd and 3rd args to C<splice()> are now in scalar context
 
 The second and third arguments of C<splice()> are now evaluated in scalar
 context (as the Camel says) rather than list context.
@@ -476,7 +476,7 @@ context (as the Camel says) rather than list context.
     # perl4 prints: a b
     # perl5 prints: c d e
 
-=item * Discontinuance
+=item * Can't do C<goto> into a block that is optimized away
 
 You can't do a C<goto> into a block that is optimized away.  Darn.
 
@@ -490,7 +490,7 @@ You can't do a C<goto> into a block that is optimized away.  Darn.
     # perl4 prints: Here I is!
     # perl5 errors: Can't "goto" into the middle of a foreach loop
 
-=item * Discontinuance
+=item * Can't use whitespace as variable name or quote delimiter
 
 It is no longer syntactically legal to use whitespace as the name
 of a variable, or as a delimiter for any kind of quote construct.
@@ -503,7 +503,7 @@ Double darn.
     # perl4 prints: a is foo bar, b is baz
     # perl5 errors: Bareword found where operator expected
 
-=item * Discontinuance
+=item * C<while/if BLOCK BLOCK> gone
 
 The archaic while/if BLOCK BLOCK syntax is no longer supported.
 
@@ -517,7 +517,7 @@ The archaic while/if BLOCK BLOCK syntax is no longer supported.
     # perl4 prints: True!
     # perl5 errors: syntax error at test.pl line 1, near "if {"
 
-=item * BugFix
+=item * C<**> binds tighter than unary minus
 
 The C<**> operator now binds more tightly than unary minus.
 It was documented to work this way before, but didn't.
@@ -527,7 +527,7 @@ It was documented to work this way before, but didn't.
     # perl4 prints: 16
     # perl5 prints: -16
 
-=item * Discontinuance
+=item * C<foreach> changed when iterating over a list
 
 The meaning of C<foreach{}> has changed slightly when it is iterating over a
 list which is not an array.  This used to assign the list to a
@@ -559,7 +559,7 @@ Otherwise changing $var will clobber the values of @list.  (This most often
 happens when you use C<$_> for the loop variable, and call subroutines in
 the loop that don't properly localize C<$_>.)
 
-=item * Discontinuance
+=item * C<split> with no args behavior changed
 
 C<split> with no arguments now behaves like C<split ' '> (which doesn't
 return an initial null field if $_ starts with whitespace), it used to
@@ -571,7 +571,7 @@ behave like C<split /\s+/> (which does).
     # perl4 prints: :hi:mom
     # perl5 prints: hi:mom
 
-=item * BugFix
+=item * B<-e> behavior fixed
 
 Perl 4 would ignore any text which was attached to an B<-e> switch,
 always taking the code snippet from the following arg.  Additionally, it
@@ -588,7 +588,7 @@ these behaviors have been fixed.
     # perl4 prints:
     # perl5 dies: No code specified for -e.
 
-=item * Discontinuance
+=item * C<push> returns number of elements in resulting list
 
 In Perl 4 the return value of C<push> was undocumented, but it was
 actually the last value being pushed onto the target list.  In Perl 5
@@ -601,17 +601,17 @@ number of elements in the resulting list.
     # perl4 prints: second new
     # perl5 prints: 3
 
-=item * Deprecation
+=item * Some error messages differ
 
 Some error messages will be different.
 
-=item * Discontinuance
+=item * C<split()> honors subroutine args
 
 In Perl 4, if in list context the delimiters to the first argument of
 C<split()> were C<??>, the result would be placed in C<@_> as well as
 being returned.   Perl 5 has more respect for your subroutine arguments.
 
-=item * Discontinuance
+=item * Bugs removed
 
 Some bugs may have been inadvertently removed.  :-)
 
@@ -623,7 +623,7 @@ Perl4-to-Perl5 traps from having to do with parsing.
 
 =over 4
 
-=item * Parsing
+=item * Space between . and = triggers syntax error
 
 Note the space between . and =
 
@@ -633,7 +633,7 @@ Note the space between . and =
     # perl4 prints: more string
     # perl5 prints: syntax error at - line 1, near ". ="
 
-=item * Parsing
+=item * Better parsing in perl 5
 
 Better parsing in perl 5
 
@@ -644,7 +644,7 @@ Better parsing in perl 5
     # perl4 prints: hello, world
     # perl5 prints: syntax error
 
-=item * Parsing
+=item * Function parsing
 
 "if it looks like a function, it is a function" rule.
 
@@ -654,7 +654,7 @@ Better parsing in perl 5
     # perl4 prints: is zero
     # perl5 warns: "Useless use of a constant in void context" if using -w
 
-=item * Parsing
+=item * String interpolation of C<$#array> differs
 
 String interpolation of the C<$#array> construct differs when braces
 are to used around the name.
@@ -671,7 +671,7 @@ are to used around the name.
     # perl4 prints: {a}
     # perl5 prints: 2
 
-=item * Parsing
+=item * Perl guesses on C<map>, C<grep> followed by C<{> whether C<{> starts BLOCK or hash ref
 
 When perl sees C<map {> (or C<grep {>), it has to guess whether the C<{>
 starts a BLOCK or a hash reference. If it guesses wrong, it will report
@@ -690,7 +690,7 @@ operands, or output from same.
 
 =over 5
 
-=item * Numerical
+=item * Formatted output and significant digits
 
 Formatted output and significant digits.  In general, Perl 5
 tries to be more precise.  For example, on a Solaris Sparc:
@@ -711,7 +711,7 @@ Notice how the first result looks better in Perl 5.
 Your results may vary, since your floating point formatting routines
 and even floating point format may be slightly different.
 
-=item * Numerical
+=item * Auto-increment operator over signed int limit deleted
 
 This specific item has been deleted.  It demonstrated how the auto-increment
 operator would not catch when a number went over the signed int limit.  Fixed
@@ -720,7 +720,7 @@ If in doubt:
 
    use Math::BigInt;
 
-=item * Numerical
+=item * Assignment of return values from numeric equality tests doesn't works
 
 Assignment of return values from numeric equality tests
 does not work in perl5 when the test evaluates to false (0).
@@ -768,7 +768,7 @@ within certain expressions and/or context.
 
 =over 5
 
-=item * (Arrays)
+=item * Negative array subscripts now count from the end of array
 
 Negative array subscripts now count from the end of the array.
 
@@ -778,7 +778,7 @@ Negative array subscripts now count from the end of the array.
     # perl4 prints: The third element of the array is 4 also expressed as
     # perl5 prints: The third element of the array is 4 also expressed as 4
 
-=item * (Arrays)
+=item * Setting C<$#array> lower now discards array elements
 
 Setting C<$#array> lower now discards array elements, and makes them
 impossible to recover.
@@ -793,7 +793,7 @@ impossible to recover.
     # perl4 prints: Before: abcde, After: ab, Recovered: abcd
     # perl5 prints: Before: abcde, After: ab, Recovered: ab
 
-=item * (Hashes)
+=item * Hashes get defined before use
 
 Hashes get defined before use
 
@@ -808,7 +808,7 @@ Hashes get defined before use
 Perl will now generate a warning when it sees defined(@a) and
 defined(%h).
 
-=item * (Globs)
+=item * Glob assignment from localized variable to variable
 
 glob assignment from variable to variable will fail if the assigned
 variable is localized subsequent to the assignment
@@ -821,7 +821,7 @@ variable is localized subsequent to the assignment
     # perl4 prints: This is Perl 4
     # perl5 prints:
 
-=item * (Globs)
+=item * Assigning C<undef> to glob
 
 Assigning C<undef> to a glob has no effect in Perl 5.   In Perl 4
 it undefines the associated scalar (but may have other side effects
@@ -839,7 +839,7 @@ has quite a few effects.
     # perl5 prints: bar
     # perl5 warns: "Undefined value assigned to typeglob" if using -w
 
-=item * (Scalar String)
+=item * Changes in unary negation (of strings)
 
 Changes in unary negation (of strings)
 This change effects both the return value and what it
@@ -853,7 +853,7 @@ does to auto(magic)increment.
     # perl4 prints: aab : -0 : 1
     # perl5 prints: aab : -aab : aac
 
-=item * (Constants)
+=item * Modifying of constants prohibited
 
 perl 4 lets you modify constants:
 
@@ -879,7 +879,7 @@ perl 4 lets you modify constants:
     # Modification of a read-only value attempted at foo.pl line 12.
     # before: a
 
-=item * (Scalars)
+=item * C<defined $var> behavior changed
 
 The behavior is slightly different for:
 
@@ -888,7 +888,7 @@ The behavior is slightly different for:
     # perl 4: 1
     # perl 5: <no output, $x is not called into existence>
 
-=item * (Variable Suicide)
+=item * Variable Suicide
 
 Variable suicide behavior is more consistent under Perl 5.
 Perl5 exhibits the same behavior for hashes and scalars,
@@ -931,7 +931,7 @@ that perl4 exhibits for only scalars.
 
 =over 5
 
-=item * (list context)
+=item * Elements of argument lists for formats evaluated in list context
 
 The elements of argument lists for formats are now evaluated in list
 context.  This means you can interpolate list values now.
@@ -946,7 +946,7 @@ context.  This means you can interpolate list values now.
     # perl4 errors:  Please use commas to separate fields in file
     # perl5 prints: foo     bar      baz
 
-=item * (scalar context)
+=item * C<caller()> returns false value in scalar context if no caller present
 
 The C<caller()> function now returns a false value in a scalar context
 if there is no caller.  This lets library files determine if they're
@@ -957,7 +957,7 @@ being required.
     # perl4 errors: There is no caller
     # perl5 prints: Got a 0
 
-=item * (scalar context)
+=item * Comma operator in scalar context gives scalar context to args
 
 The comma operator in a scalar context is now guaranteed to give a
 scalar context to its arguments.
@@ -969,7 +969,7 @@ scalar context to its arguments.
     # Perl4 prints:  x = c   # Thinks list context interpolates list
     # Perl5 prints:  x = 3   # Knows scalar uses length of list
 
-=item * (list, builtin)
+=item * C<sprintf()> prototyped as C<($;@)>
 
 C<sprintf()> is prototyped as ($;@), so its first argument is given scalar
 context. Thus, if passed an array, it will probably not do what you want,
@@ -1002,7 +1002,7 @@ inconsistencies that made the behavior differ from what was documented.
 
 =over 5
 
-=item * Precedence
+=item * LHS vs. RHS of any assignment operator
 
 LHS vs. RHS of any assignment operator.  LHS is evaluated first
 in perl4, second in perl5; this can affect the relationship
@@ -1015,7 +1015,7 @@ between side-effects in sub-expressions.
     # perl4 prints: left
     # perl5 prints: right
 
-=item * Precedence
+=item * Semantic errors introduced due to precedence
 
 These are now semantic errors because of precedence:
 
@@ -1029,7 +1029,7 @@ These are now semantic errors because of precedence:
     # perl4 prints: n is 3, m is 6
     # perl5 errors and fails to compile
 
-=item * Precedence
+=item * Precedence of assignment operators same as the precedence of assignment
 
 The precedence of assignment operators is now the same as the precedence
 of assignment.  Perl 4 mistakenly gave them the precedence of the associated
@@ -1051,7 +1051,7 @@ On the other hand,
 
 now works as a C programmer would expect.
 
-=item * Precedence
+=item * C<open> requires parentheses around filehandle
 
     open FOO || die;
 
@@ -1063,7 +1063,7 @@ Otherwise, perl5 leaves the statement as its default precedence:
     # perl4 opens or dies
     # perl5 opens FOO, dying only if 'FOO' is false, i.e. never
 
-=item * Precedence
+=item * C<$:> precedence over C<$::> gone
 
 perl4 gives the special variable, C<$:> precedence, where perl5
 treats C<$::> as main C<package>
@@ -1073,7 +1073,7 @@ treats C<$::> as main C<package>
     # perl 4 prints: -:a
     # perl 5 prints: x
 
-=item * Precedence
+=item * Precedence of file test operators documented
 
 perl4 had buggy precedence for the file test operators vis-a-vis
 the assignment operators.  Thus, although the precedence table
@@ -1086,7 +1086,7 @@ In perl5, the precedence is as documented.
     # perl4 prints: no output
     # perl5 prints: Can't modify -e in concatenation
 
-=item * Precedence
+=item * C<keys>, C<each>, C<values> are regular named unary operators
 
 In perl4, keys(), each() and values() were special high-precedence operators
 that operated on a single hash, but in perl5, they are regular named unary
@@ -1111,7 +1111,7 @@ All types of RE traps.
 
 =over 5
 
-=item * Regular Expression
+=item * C<s'$lhs'$rhs'> interpolates on either side
 
 C<s'$lhs'$rhs'> now does no interpolation on either side.  It used to
 interpolate $lhs but not $rhs.  (And still does not match a literal
@@ -1125,7 +1125,7 @@ interpolate $lhs but not $rhs.  (And still does not match a literal
     # perl4 prints: $b 2 $a $b
     # perl5 prints: 1 2 $a $b
 
-=item * Regular Expression
+=item * C<m//g> attaches its state to the searched string
 
 C<m//g> now attaches its state to the searched string rather than the
 regular expression.  (Once the scope of a block is left for the sub, the
@@ -1140,7 +1140,7 @@ state of the searched string is lost)
     # perl4 prints: Got blah Got blah Got blah Got blah
     # perl5 prints: infinite loop blah...
 
-=item * Regular Expression
+=item * C<m//o> used within an anonymous sub
 
 Currently, if you use the C<m//o> qualifier on a regular expression
 within an anonymous sub, I<all> closures generated from that anonymous
@@ -1166,7 +1166,7 @@ build_match() will always return a sub which matches the contents of
 $left and $right as they were the I<first> time that build_match()
 was called, not as they are in the current call.
 
-=item * Regular Expression
+=item * C<$+> isn't set to whole match
 
 If no parentheses are used in a match, Perl4 sets C<$+> to
 the whole match, just like C<$&>. Perl5 does not.
@@ -1177,7 +1177,7 @@ the whole match, just like C<$&>. Perl5 does not.
     # perl4 prints: bcde
     # perl5 prints:
 
-=item * Regular Expression
+=item * Substitution now returns null string if it fails
 
 substitution now returns the null string if it fails
 
@@ -1190,7 +1190,7 @@ substitution now returns the null string if it fails
 
 Also see L<Numerical Traps> for another example of this new feature.
 
-=item * Regular Expression
+=item * C<s`lhs`rhs`> is now a normal substitution
 
 C<s`lhs`rhs`> (using backticks) is now a normal substitution, with no
 backtick expansion
@@ -1202,7 +1202,7 @@ backtick expansion
     # perl4 prints: <the local hostname>
     # perl5 prints: hostname
 
-=item * Regular Expression
+=item * Stricter parsing of variables in regular expressions
 
 Stricter parsing of variables used in regular expressions
 
@@ -1224,7 +1224,7 @@ C<[$opt]> is a character class in perl4 and an array subscript in perl5
     # perl4 prints: foo
     # perl5 prints: foobar
 
-=item * Regular Expression
+=item * C<m?x?> matches only once
 
 Under perl5, C<m?x?> matches only once, like C<?x?>. Under perl4, it matched
 repeatedly, like C</x/> or C<m!x!>.
@@ -1243,7 +1243,7 @@ repeatedly, like C</x/> or C<m!x!>.
     # perl4 prints: perl4
     # perl5 prints: perl5
 
-=item * Regular Expression
+=item * Failed matches don't reset the match variables
 
 Unlike in Ruby, failed matches in Perl do not reset the match variables
 ($1, $2, ..., C<$`>, ...).
@@ -1258,7 +1258,7 @@ general subroutine traps.  Includes some OS-Specific traps.
 
 =over 5
 
-=item * (Signals)
+=item * Barewords that used to look like strings look like subroutine calls if a subroutine by that name is defined
 
 Barewords that used to look like strings to Perl will now look like subroutine
 calls if a subroutine by that name is defined before the compiler sees them.
@@ -1272,7 +1272,7 @@ calls if a subroutine by that name is defined before the compiler sees them.
 
 Use B<-w> to catch this one
 
-=item * (Sort Subroutine)
+=item * Reverse is no longer allowed as the name of a sort subroutine
 
 reverse is no longer allowed as the name of a sort subroutine.
 
@@ -1283,7 +1283,7 @@ reverse is no longer allowed as the name of a sort subroutine.
     # perl5 prints: 123
     # perl5 warns (if using -w): Ambiguous call resolved as CORE::reverse()
 
-=item * warn() won't let you specify a filehandle.
+=item * C<warn()> won't let you specify a filehandle.
 
 Although it _always_ printed to STDERR, warn() would let you specify a
 filehandle in perl4.  With perl5 it does not.
@@ -1299,7 +1299,7 @@ filehandle in perl4.  With perl5 it does not.
 
 =over 5
 
-=item * (SysV)
+=item * SysV resets signal handler correctly
 
 Under HPUX, and some other SysV OSes, one had to reset any signal handler,
 within  the signal handler function, each time a signal was handled with
@@ -1326,7 +1326,7 @@ Since version 5.002, Perl uses sigaction() under SysV.
     # perl4 (HPUX) prints: Got INT...
     # perl5 (HPUX) prints: Got INT... Got INT...
 
-=item * (SysV)
+=item * SysV C<seek()> appends correctly
 
 Under SysV OSes, C<seek()> on a file opened to append C<<< >> >>> now does
 the right thing w.r.t. the fopen() manpage. e.g., - When a file is opened
@@ -1356,7 +1356,7 @@ within certain expressions, statements, contexts, or whatever.
 
 =over 5
 
-=item * Interpolation
+=item * C<@> always interpolates an array in double-quotish strings
 
 @ now always interpolates an array in double-quotish strings.
 
@@ -1366,7 +1366,7 @@ within certain expressions, statements, contexts, or whatever.
     # perl < 5.6.1, error : In string, @somewhere now must be written as \@somewhere
     # perl >= 5.6.1, warning : Possible unintended interpolation of @somewhere in string
 
-=item * Interpolation
+=item * Double-quoted strings may no longer end with an unescaped $
 
 Double-quoted strings may no longer end with an unescaped $.
 
@@ -1378,7 +1378,7 @@ Double-quoted strings may no longer end with an unescaped $.
 
 Note: perl5 DOES NOT error on the terminating @ in $bar
 
-=item * Interpolation
+=item * Arbitrary expressions are evaluated inside braces that occur within double quotes
 
 Perl now sometimes evaluates arbitrary expressions inside braces that occur
 within double quotes (usually when the opening brace is preceded by C<$>
@@ -1395,7 +1395,7 @@ or C<@>).
 
 Note that you can C<use strict;> to ward off such trappiness under perl5.
 
-=item * Interpolation
+=item * C<$$x> now tries to dereference $x
 
 The construct "this is $$x" used to interpolate the pid at that point, but
 now tries to dereference $x.  C<$$> by itself still works fine, however.
@@ -1407,7 +1407,7 @@ now tries to dereference $x.  C<$$> by itself still works fine, however.
     # perl4 prints: this is XXXx   (XXX is the current pid)
     # perl5 prints: this is a reference
 
-=item * Interpolation
+=item * Creation of hashes on the fly with C<eval "EXPR"> requires protection of C<$>'s or both curlies
 
 Creation of hashes on the fly with C<eval "EXPR"> now requires either both
 C<$>'s to be protected in the specification of the hash name, or both curlies
@@ -1448,7 +1448,7 @@ causes the following result:
     # and is compatible for both versions
 
 
-=item * Interpolation
+=item * Bugs in earlier perl versions
 
 perl4 programs which unconsciously rely on the bugs in earlier perl versions.
 
@@ -1457,7 +1457,7 @@ perl4 programs which unconsciously rely on the bugs in earlier perl versions.
     # perl4 prints: This is not perl5
     # perl5 prints: This is perl5
 
-=item * Interpolation
+=item * Array and hash brackets during interpolation
 
 You also have to be careful about array and hash brackets during
 interpolation.
@@ -1479,9 +1479,9 @@ to mimic the behavior of Perl 4, you must escape the bracket like so.
     print "$foo\[";
     print "$foo\{";
 
-=item * Interpolation
+=item * Interpolation of C<\$$foo{bar}>
 
-Similarly, watch out for:
+Similarly, watch out for: C<\$$foo{bar}>
 
     $foo = "baz";
     print "\$$foo{bar}\n";
@@ -1493,7 +1493,7 @@ Perl 5 is looking for C<$foo{bar}> which doesn't exist, but perl 4 is
 happy just to expand $foo to "baz" by itself.  Watch out for this
 especially in C<eval>'s.
 
-=item * Interpolation
+=item * C<qq()> string passed to C<eval> will not find string terminator
 
 C<qq()> string passed to C<eval>
 
@@ -1514,7 +1514,7 @@ General DBM traps.
 
 =over 5
 
-=item * DBM
+=item * Perl5 must have been linked with the same dbm/ndbm as the default for C<dbmopen()> to function properly without C<tie>'ing
 
 Existing dbm databases created under perl4 (or any other dbm/ndbm tool)
 may cause the same script, run under perl5, to fail.  The build of perl5
@@ -1528,7 +1528,7 @@ to function properly without C<tie>'ing to an extension dbm implementation.
     # perl5 prints: ok (IFF linked with -ldbm or -lndbm)
 
 
-=item * DBM
+=item * DBM exceeding the limit on the key/value size will cause perl5 to exit immediately
 
 Existing dbm databases created under perl4 (or any other dbm/ndbm tool)
 may cause the same script, run under perl5, to fail.  The error generated