X-Git-Url: https://perl5.git.perl.org/perl5.git/blobdiff_plain/719b43e8a7892cfc854b9123fcad88c53828b0b9..a1b1d0558e4f9a299f56def4b6400355a161005f:/pod/perldata.pod diff --git a/pod/perldata.pod b/pod/perldata.pod index 1b02b1e..d8edfe9 100644 --- a/pod/perldata.pod +++ b/pod/perldata.pod @@ -5,6 +5,7 @@ perldata - Perl data types =head1 DESCRIPTION =head2 Variable names +X X X X Perl has three built-in data types: scalars, arrays of scalars, and associative arrays of scalars, known as "hashes". A scalar is a @@ -23,10 +24,12 @@ containing letters, underscores, and digits. In some cases, it may be a chain of identifiers, separated by C<::> (or by the slightly archaic C<'>); all but the last are interpreted as names of packages, to locate the namespace in which to look up the final identifier -(see L for details). It's possible to substitute -for a simple identifier, an expression that produces a reference +(see L for details). For a more in-depth discussion +on identifiers, see L. It's possible to +substitute for a simple identifier, an expression that produces a reference to the value at runtime. This is described in more detail below and in L. +X Perl also has its own built-in variables whose names don't follow these rules. They have strange names so they don't accidentally @@ -36,11 +39,13 @@ containing only digits after the C<$> (see L and L). In addition, several special variables that provide windows into the inner working of Perl have names containing punctuation characters and control characters. These are documented in L. +X Scalar values are always named with '$', even when referring to a scalar that is part of an array or a hash. The '$' symbol works semantically like the English word "the" in that it indicates a single value is expected. +X $days # the simple scalar value "days" $days[28] # the 29th element of array @days @@ -48,14 +53,16 @@ single value is expected. $#days # the last index of array @days Entire arrays (and slices of arrays and hashes) are denoted by '@', -which works much like the word "these" or "those" does in English, +which works much as the word "these" or "those" does in English, in that it indicates multiple values are expected. +X @days # ($days[0], $days[1],... $days[n]) @days[3,4,5] # same as ($days[3],$days[4],$days[5]) @days{'a','c'} # same as ($days{'a'},$days{'c'}) Entire hashes are denoted by '%': +X %days # (key1, val1, key2, val2 ...) @@ -72,6 +79,7 @@ subroutine name, a format name, or a label. This means that $foo and @foo are two different variables. It also means that C<$foo[1]> is a part of @foo, not a part of $foo. This may seem a bit weird, but that's okay, because it is weird. +X Because variable references always start with '$', '@', or '%', the "reserved" words aren't in fact reserved with respect to variable @@ -83,6 +91,8 @@ uppercase filehandles also improves readability and protects you from conflict with future reserved words. Case I significant--"FOO", "Foo", and "foo" are all different names. Names that start with a letter or underscore may also contain digits and underscores. +X +X It is possible to replace such an alphanumeric name with an expression that returns a reference to the appropriate type. For a description @@ -95,7 +105,117 @@ C<$$>. (Most of these one character names have a predefined significance to Perl. For instance, C<$$> is the current process id.) +=head2 Identifier parsing +X + +Up until Perl 5.18, the actual rules of what a valid identifier +was were a bit fuzzy. However, in general, anything defined here should +work on previous versions of Perl, while the opposite -- edge cases +that work in previous versions, but aren't defined here -- probably +won't work on newer versions. +As an important side note, please note that the following only applies +to bareword identifiers as found in Perl source code, not identifiers +introduced through symbolic references, which have much fewer +restrictions. +If working under the effect of the C pragma, the following +rules apply: + + / (?[ ( \p{Word} & \p{XID_Start} ) + [_] ]) + (?[ ( \p{Word} & \p{XID_Continue} ) ]) * /x + +That is, a "start" character followed by any number of "continue" +characters. Perl requires every character in an identifier to also +match C<\w> (this prevents some problematic cases); and Perl +additionally accepts identfier names beginning with an underscore. + +If not under C, the source is treated as ASCII + 128 extra +controls, and identifiers should match + + / (?aa) (?!\d) \w+ /x + +That is, any word character in the ASCII range, as long as the first +character is not a digit. + +There are two package separators in Perl: A double colon (C<::>) and a single +quote (C<'>). Normal identifiers can start or end with a double colon, and +can contain several parts delimited by double colons. +Single quotes have similar rules, but with the exception that they are not +legal at the end of an identifier: That is, C<$'foo> and C<$foo'bar> are +legal, but C<$foo'bar'> is not. + +Additionally, if the identifier is preceded by a sigil -- +that is, if the identifier is part of a variable name -- it +may optionally be enclosed in braces. + +While you can mix double colons with singles quotes, the quotes must come +after the colons: C<$::::'foo> and C<$foo::'bar> are legal, but C<$::'::foo> +and C<$foo'::bar> are not. + +Put together, a grammar to match a basic identifier becomes + + / + (?(DEFINE) + (? + (?&sigil) + (?: + (?&normal_identifier) + | \{ \s* (?&normal_identifier) \s* \} + ) + ) + (? + (?: :: )* '? + (?&basic_identifier) + (?: (?= (?: :: )+ '? | (?: :: )* ' ) (?&normal_identifier) )? + (?: :: )* + ) + (? + # is use utf8 on? + (?(?{ (caller(0))[8] & $utf8::hint_bits }) + (?&Perl_XIDS) (?&Perl_XIDC)* + | (?aa) (?!\d) \w+ + ) + ) + (? [&*\$\@\%]) + (? (?[ ( \p{Word} & \p{XID_Start} ) + [_] ]) ) + (? (?[ \p{Word} & \p{XID_Continue} ]) ) + ) + /x + +Meanwhile, special identifiers don't follow the above rules; For the most +part, all of the identifiers in this category have a special meaning given +by Perl. Because they have special parsing rules, these generally can't be +fully-qualified. They come in four forms: + +=over + +=item A sigil, followed solely by digits matching \p{POSIX_Digit}, like C<$0>, +C<$1>, or C<$10000>. + +=item A sigil, followed by either a caret and a single POSIX uppercase letter, +like C<$^V> or C<$^W>, or a sigil followed by a literal control character +matching the C<\p{POSIX_Cntrl}> property. +Due to a historical oddity, if not +running under C, the 128 extra controls in the C<[0x80-0xff]> range +may also be used in length one variables. The use of a literal control +character is deprecated. Support for this form will be removed in a future +version of perl. + +=item Similar to the above, a sigil, followed by bareword text in brackets, +where the first character is either a caret followed by an uppercase letter, +or a literal control, like C<${^GLOBAL_PHASE}> or C<${\7LOBAL_PHASE}>. The use +of a literal control character is deprecated. Support for this form will be +removed in a future version of perl. + +=item A sigil followed by a single character matching the C<\p{POSIX_Punct}> +property, like C<$!> or C<%+>. + +=back + +Note that as of Perl 5.20, literal control characters in variable names +are deprecated. + =head2 Context +X X X The interpretation of operations and values in Perl sometimes depends on the requirements of the context around the operation or value. @@ -130,7 +250,7 @@ to determine the context for the right argument. Assignment to a scalar evaluates the right-hand side in scalar context, while assignment to an array or hash evaluates the righthand side in list context. Assignment to a list (or slice, which is just a list -anyway) also evaluates the righthand side in list context. +anyway) also evaluates the right-hand side in list context. When you use the C pragma or Perl's B<-w> command-line option, you may see warnings @@ -148,6 +268,7 @@ for how you would dynamically discern your function's calling context. =head2 Scalar values +X X X X All data in Perl is a scalar, an array of scalars, or a hash of scalars. A scalar may contain one single value in any of three @@ -168,10 +289,12 @@ are considered pretty much the same thing for nearly all purposes, references are strongly-typed, uncastable pointers with builtin reference-counting and destructor invocation. -A scalar value is interpreted as TRUE in the Boolean sense if it is not -the null string or the number 0 (or its string equivalent, "0"). The +A scalar value is interpreted as FALSE in the Boolean sense +if it is undefined, the null string or the number 0 (or its +string equivalent, "0"), and TRUE if it is anything else. The Boolean context is just a special kind of scalar context where no conversion to a string or a number is ever performed. +X X X X X There are actually two varieties of null strings (sometimes referred to as "empty" strings), a defined one and an undefined one. The @@ -186,6 +309,7 @@ rare cases of autovivification as explained in L. You can use the defined() operator to determine whether a scalar value is defined (this has no meaning on arrays or hashes), and the undef() operator to produce an undefined value. +X X X X X To find out whether a given string is a valid non-zero number, it's sometimes enough to test it against both numeric 0 and also lexical @@ -218,8 +342,8 @@ which is a different value since there is ordinarily a 0th element. Assigning to C<$#days> actually changes the length of the array. Shortening an array this way destroys intervening values. Lengthening an array that was previously shortened does not recover values -that were in those elements. (It used to do so in Perl 4, but we -had to break this to make sure destructors were called when expected.) +that were in those elements. +X<$#> X You can also gain some minuscule measure of efficiency by pre-extending an array that is going to get big. You can also extend an array @@ -235,13 +359,7 @@ of the array. (Note that this is not true of lists, which return the last value, like the C comma operator, nor of built-in functions, which return whatever they feel like returning.) The following is always true: - - scalar(@whatever) == $#whatever - $[ + 1; - -Version 5 of Perl changed the semantics of C<$[>: files that don't set -the value of C<$[> no longer need to worry about whether another -file changed its value. (In other words, use of C<$[> is deprecated.) -So in general you can assume that +X scalar(@whatever) == $#whatever + 1; @@ -260,8 +378,9 @@ set. For example, you stick 10,000 things in a hash, but evaluating %HASH in scalar context reveals C<"1/16">, which means only one out of sixteen buckets has been touched, and presumably contains all 10,000 of your items. This isn't supposed to happen. If a tied hash -is evaluated in scalar context, a fatal error will result, since this -bucket usage information is currently not available for tied hashes. +is evaluated in scalar context, the C method is called (with a +fallback to C). +X X X You can preallocate space for a hash by assigning to the keys() function. This rounds up the allocated buckets to the next power of two: @@ -269,6 +388,7 @@ This rounds up the allocated buckets to the next power of two: keys(%users) = 1000; # allocate 1024 buckets =head2 Scalar value constructors +X X Numeric literals are specified in any of the following floating point or integer formats: @@ -280,13 +400,16 @@ integer formats: 4_294_967_296 # underscore for legibility 0xff # hex 0xdead_beef # more hex - 0377 # octal + 0377 # octal (only numbers, begins with 0) 0b011011 # binary You are allowed to use underscores (underbars) in numeric literals -between digits for legibility. You could, for example, group binary +between digits for legibility (but not multiple underscores in a row: +C<23__500> is not legal; C<23_500> is). +You could, for example, group binary digits by threes (as for a Unix-style mode argument such as 0b110_100_100) or by fours (to represent nibbles, as in 0b1010_0110) or in other groups. +X String literals are usually delimited by either single or double quotes. They work much like quotes in the standard Unix shells: @@ -295,6 +418,7 @@ substitution; single-quoted strings are not (except for C<\'> and C<\\>). The usual C-style backslash rules apply for making characters such as newline, tab, etc., as well as some more exotic forms. See L for a list. +X Hexadecimal, octal, or binary, representations in string literals (e.g. '0xff') are not automatically converted to their integer @@ -310,18 +434,26 @@ scalar variables, arrays, and array or hash slices. (In other words, names beginning with $ or @, followed by an optional bracketed expression as a subscript.) The following code segment prints out "The price is $Z<>100." +X $Price = '$100'; # not interpolated print "The price is $Price.\n"; # interpolated There is no double interpolation in Perl, so the C<$100> is left as is. +By default floating point numbers substituted inside strings use the +dot (".") as the decimal separator. If C is in effect, +and POSIX::setlocale() has been called, the character used for the +decimal separator is affected by the LC_NUMERIC locale. +See L and L. + As in some shells, you can enclose the variable name in braces to disambiguate it from following alphanumerics (and underscores). You must also do this when interpolating a variable into a string to separate the variable name from a following double-colon or an apostrophe, since these would be otherwise treated as a package separator: +X $who = "Larry"; print PASSWD "${who}::0:0:Superuser:/:/bin/perl\n"; @@ -332,8 +464,8 @@ C<$who::0>, and a C<$who's> variable. The last two would be the $0 and the $s variables in the (presumably) non-existent package C. -In fact, an identifier within such curlies is forced to be a string, -as is any simple identifier within a hash subscript. Neither need +In fact, a simple identifier within such curlies is forced to be +a string, and likewise within a hash subscript. Neither need quoting. Our earlier example, C<$days{'Feb'}> can be written as C<$days{Feb}> and the quotes will be assumed automatically. But anything more complicated in the subscript will be interpreted as an @@ -341,11 +473,7 @@ expression. This means for example that C<$version{2.0}++> is equivalent to C<$version{2}++>, not to C<$version{'2.0'}++>. =head3 Version Strings - -B Version Strings (v-strings) have been deprecated. They will -be removed in some future release after Perl 5.8.1. The marginal -benefits of v-strings were greatly outweighed by the potential for -Surprise and Confusion. +X X X A literal of the form C is parsed as a string composed of characters with the specified ordinals. This form, known as @@ -356,46 +484,54 @@ Unicode strings, and for comparing version "numbers" using the string comparison operators, C, C, C etc. If there are two or more dots in the literal, the leading C may be omitted. - print v9786; # prints UTF-8 encoded SMILEY, "\x{263a}" + print v9786; # prints SMILEY, "\x{263a}" print v102.111.111; # prints "foo" print 102.111.111; # same Such literals are accepted by both C and C for -doing a version check. The C<$^V> special variable also contains the -running Perl interpreter's version in this form. See L. -Note that using the v-strings for IPv4 addresses is not portable unless -you also use the inet_aton()/inet_ntoa() routines of the Socket package. +doing a version check. Note that using the v-strings for IPv4 +addresses is not portable unless you also use the +inet_aton()/inet_ntoa() routines of the Socket package. Note that since Perl 5.8.1 the single-number v-strings (like C) are not v-strings before the C<< => >> operator (which is usually used -to separate a hash key from a hash value), instead they are interpreted +to separate a hash key from a hash value); instead they are interpreted as literal strings ('v65'). They were v-strings from Perl 5.6.0 to Perl 5.8.0, but that caused more confusion and breakage than good. Multi-number v-strings like C and C<65.66.67> continue to be v-strings always. =head3 Special Literals +X X<__END__> X<__DATA__> X X +X X X<^D> X<^Z> The special literals __FILE__, __LINE__, and __PACKAGE__ represent the current filename, line number, and package name at that -point in your program. They may be used only as separate tokens; they +point in your program. __SUB__ gives a reference to the current +subroutine. They may be used only as separate tokens; they will not be interpolated into strings. If there is no current package (due to an empty C directive), __PACKAGE__ is the undefined -value. +value. (But the empty C is no longer supported, as of version +5.10.) Outside of a subroutine, __SUB__ is the undefined value. __SUB__ +is only available in 5.16 or higher, and only with a C or +C declaration. +X<__FILE__> X<__LINE__> X<__PACKAGE__> X<__SUB__> +X X X The two control characters ^D and ^Z, and the tokens __END__ and __DATA__ may be used to indicate the logical end of the script before the actual end of file. Any following text is ignored. -Text after __DATA__ but may be read via the filehandle C, +Text after __DATA__ may be read via the filehandle C, where C is the package that was current when the __DATA__ token was encountered. The filehandle is left open pointing to the -contents after __DATA__. It is the program's responsibility to -C when it is done reading from it. For compatibility with -older scripts written before __DATA__ was introduced, __END__ behaves -like __DATA__ in the toplevel script (but not in files loaded with -C or C) and leaves the remaining contents of the -file accessible via C. +line after __DATA__. The program should C when it is done +reading from it. (Leaving it open leaks filehandles if the module is +reloaded for any reason, so it's a safer practice to close it.) For +compatibility with older scripts written before __DATA__ was +introduced, __END__ behaves like __DATA__ in the top level script (but +not in files loaded with C or C) and leaves the remaining +contents of the file accessible via C. See L for more description of __DATA__, and an example of its use. Note that you cannot read from the DATA @@ -404,14 +540,18 @@ as it is seen (during compilation), at which point the corresponding __DATA__ (or __END__) token has not yet been seen. =head3 Barewords +X A word that has no other interpretation in the grammar will be treated as if it were a quoted string. These are known as "barewords". As with filehandles and labels, a bareword that consists entirely of lowercase letters risks conflict with future reserved words, and if you use the C pragma or the B<-w> switch, -Perl will warn you about any -such words. Some people may wish to outlaw barewords entirely. If you +Perl will warn you about any such words. Perl limits barewords (like +identifiers) to about 250 characters. Future versions of Perl are likely +to eliminate these arbitrary limitations. + +Some people may wish to outlaw barewords entirely. If you say use strict 'subs'; @@ -421,7 +561,8 @@ produces a compile-time error instead. The restriction lasts to the end of the enclosing block. An inner block may countermand this by saying C. -=head3 Array Joining Delimiter +=head3 Array Interpolation +X X X<$"> Arrays and slices are interpolated into double-quoted strings by joining the elements with the delimiter specified in the C<$"> @@ -448,6 +589,7 @@ which used to be here, that's been moved to L. =head2 List value constructors +X List values are denoted by separating individual values by commas (and enclosing the list in parentheses where precedence requires it): @@ -512,7 +654,7 @@ array had been interpolated at that point. This interpolation combines with the facts that the opening and closing parentheses are optional (except when necessary for precedence) and lists may end with an optional comma to mean that -multiple commas within lists are legal syntax. The list C<1,,3> is a +multiple commas within lists are legal syntax. The list C<1,,3> is a concatenation of two lists, C<1,> and C<3>, the first of which ends with that optional comma. C<1,,3> is C<(1,),(3)> is C<1,3> (And similarly for C<1,,,3> is C<(1,),(,),3> is C<1,3> and so on.) Not that @@ -559,16 +701,16 @@ which when assigned produces a 0, which is interpreted as FALSE. It's also the source of a useful idiom for executing a function or performing an operation in list context and then counting the number of return values, by assigning to an empty list and then using that -assignment in scalar context. For example, this code: +assignment in scalar context. For example, this code: $count = () = $string =~ /\d+/g; will place into $count the number of digit groups found in $string. This happens because the pattern match is in list context (since it is being assigned to the empty list), and will therefore return a list -of all matching parts of the string. The list assignment in scalar +of all matching parts of the string. The list assignment in scalar context will translate that into the number of elements (here, the -number of times the pattern matched) and assign that to $count. Note +number of times the pattern matched) and assign that to $count. Note that simply using $count = $string =~ /\d+/g; @@ -601,9 +743,9 @@ key/value pairs. That's why it's good to use references sometimes. It is often more readable to use the C<< => >> operator between key/value pairs. The C<< => >> operator is mostly just a more visually distinctive synonym for a comma, but it also arranges for its left-hand operand to be -interpreted as a string -- if it's a bareword that would be a legal simple -identifier (C<< => >> doesn't quote compound identifiers, that contain -double colons). This makes it nice for initializing hashes: +interpreted as a string if it's a bareword that would be a legal simple +identifier. C<< => >> doesn't quote compound identifiers, that contain +double colons. This makes it nice for initializing hashes: %map = ( red => 0x00f, @@ -633,21 +775,45 @@ Note that just because a hash is initialized in that order doesn't mean that it comes out in that order. See L for examples of how to arrange for an output ordering. +If a key appears more than once in the initializer list of a hash, the last +occurrence wins: + + %circle = ( + center => [5, 10], + center => [27, 9], + radius => 100, + color => [0xDF, 0xFF, 0x00], + radius => 54, + ); + + # same as + %circle = ( + center => [27, 9], + color => [0xDF, 0xFF, 0x00], + radius => 54, + ); + +This can be used to provide overridable configuration defaults: + + # values in %args take priority over %config_defaults + %config = (%config_defaults, %args); + =head2 Subscripts -An array is subscripted by specifying a dollar sign (C<$>), then the +An array can be accessed one scalar at a +time by specifying a dollar sign (C<$>), then the name of the array (without the leading C<@>), then the subscript inside square brackets. For example: @myarray = (5, 50, 500, 5000); - print "Element Number 2 is", $myarray[2], "\n"; + print "The Third Element is", $myarray[2], "\n"; -The array indices start with 0. A negative subscript retrieves its +The array indices start with 0. A negative subscript retrieves its value from the end. In our example, C<$myarray[-1]> would have been 5000, and C<$myarray[-2]> would have been 500. Hash subscripts are similar, only instead of square brackets curly brackets -are used. For example: +are used. For example: %scientists = ( @@ -659,14 +825,26 @@ are used. For example: print "Darwin's First Name is ", $scientists{"Darwin"}, "\n"; -=head2 Slices +You can also subscript a list to get a single element from it: + + $dir = (getpwnam("daemon"))[7]; + +=head2 Multi-dimensional array emulation -A common way to access an array or a hash is one scalar element at a -time. You can also subscript a list to get a single element from it. +Multidimensional arrays may be emulated by subscripting a hash with a +list. The elements of the list are joined with the subscript separator +(see L). - $whoami = $ENV{"USER"}; # one element from the hash - $parent = $ISA[0]; # one element from the array - $dir = (getpwnam("daemon"))[7]; # likewise, but with list + $foo{$a,$b,$c} + +is equivalent to + + $foo{join($;, $a, $b, $c)} + +The default subscript separator is "\034", the same as SUBSEP in B. + +=head2 Slices +X X X A slice accesses several elements of a list, an array, or a hash simultaneously using a list of subscripts. It's more convenient @@ -709,13 +887,18 @@ A slice of an empty list is still an empty list. Thus: @a = ()[1,0]; # @a has no elements @b = (@a)[0,1]; # @b has no elements - @c = (0,1)[2,3]; # @c has no elements But: @a = (1)[1,0]; # @a has two elements @b = (1,undef)[1,0,2]; # @b has three elements +More generally, a slice yields the empty list if it indexes only +beyond the end of a list: + + @a = (1)[ 1,2]; # @a has no elements + @b = (1)[0,1,2]; # @b has three elements + This makes it easy to write loops that terminate when a null list is returned: @@ -728,6 +911,13 @@ is the number of elements on the right-hand side of the assignment. The null list contains no elements, so when the password file is exhausted, the result is 0, not 2. +Slices in scalar context return the last item of the slice. + + @a = qw/first second third/; + %h = (first => 'A', second => 'B'); + $t = @a[0, 1]; # $t is now 'second' + $u = @h{'first', 'second'}; # $u is now 'B' + If you're confused about why you use an '@' there on a hash slice instead of a '%', think of it like this. The type of bracket (square or curly) governs whether it's an array or a hash being looked at. @@ -735,7 +925,32 @@ On the other hand, the leading symbol ('$' or '@') on the array or hash indicates whether you are getting back a singular value (a scalar) or a plural one (a list). +=head3 Key/Value Hash Slices + +Starting in Perl 5.20, a hash slice operation +with the % symbol is a variant of slice operation +returning a list of key/value pairs rather than just values: + + %h = (blonk => 2, foo => 3, squink => 5, bar => 8); + %subset = %h{'foo', 'bar'}; # key/value hash slice + # %subset is now (foo => 3, bar => 8) + +However, the result of such a slice cannot be localized, deleted or used +in assignment. These are otherwise very much consistent with hash slices +using the @ symbol. + +=head3 Index/Value Array Slices + +Similar to key/value hash slices (and also introduced +in Perl 5.20), the % array slice syntax returns a list +of index/value pairs: + + @a = "a".."z"; + @list = %a[3,4,6]; + # @list is now (3, "d", 4, "e", 6, "g") + =head2 Typeglobs and Filehandles +X X X<*> Perl uses an internal type called a I to hold an entire symbol table entry. The type prefix of a typeglob is a C<*>, because @@ -787,7 +1002,7 @@ For example: Now that we have the C<*foo{THING}> notation, typeglobs aren't used as much for filehandle manipulations, although they're still needed to pass brand -new file and directory handles into or out of functions. That's because +new file and directory handles into or out of functions. That's because C<*HANDLE{IO}> only works if HANDLE has already been used as a handle. In other words, C<*FH> must be used to create new symbol table entries; C<*foo{THING}> cannot. When in doubt, use C<*FH>. @@ -795,10 +1010,10 @@ C<*foo{THING}> cannot. When in doubt, use C<*FH>. All functions that are capable of creating filehandles (open(), opendir(), pipe(), socketpair(), sysopen(), socket(), and accept()) automatically create an anonymous filehandle if the handle passed to -them is an uninitialized scalar variable. This allows the constructs +them is an uninitialized scalar variable. This allows the constructs such as C and C to be used to create filehandles that will conveniently be closed automatically when -the scope ends, provided there are no other references to them. This +the scope ends, provided there are no other references to them. This largely eliminates the need for typeglobs when opening filehandles that must be passed around, as in the following example: @@ -822,7 +1037,7 @@ C forbids such practice. Another way to create anonymous filehandles is with the Symbol module or with the IO::Handle module and its ilk. These modules have the advantage of not hiding different types of the same name -during the local(). See the bottom of L for an +during the local(). See the bottom of L for an example. =head1 SEE ALSO