X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2Foverload.pm;h=8a07efec6974a1d237abc7f820d3cc3b7d1b5758;hb=7b9ef14019d3c4d1aa14641dbd421c81c2cd18a4;hp=d355f6aa85a834e234ca654f7bc11e4357f6822c;hpb=bbc7dcd2bd43efd6773e46b614c6eb1db5af78d2;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/overload.pm b/lib/overload.pm index d355f6a..8a07efe 100644 --- a/lib/overload.pm +++ b/lib/overload.pm @@ -1,8 +1,8 @@ package overload; -our $VERSION = '1.00'; +our $VERSION = '1.03'; -$overload::hint_bits = 0x20000; +$overload::hint_bits = 0x20000; # HINT_LOCALIZE_HH sub nil {} @@ -84,18 +84,17 @@ sub Method { sub AddrRef { my $package = ref $_[0]; return "$_[0]" unless $package; - bless $_[0], overload::Fake; # Non-overloaded package - my $str = "$_[0]"; - bless $_[0], $package; # Back - $package . substr $str, index $str, '='; -} -sub StrVal { - (OverloadedStringify($_[0]) or ref($_[0]) eq 'Regexp') ? - (AddrRef(shift)) : - "$_[0]"; + require Scalar::Util; + my $class = Scalar::Util::blessed($_[0]); + my $class_prefix = defined($class) ? "$class=" : ""; + my $type = Scalar::Util::reftype($_[0]); + my $addr = Scalar::Util::refaddr($_[0]); + return sprintf("$class_prefix$type(0x%x)", $addr); } +*StrVal = *AddrRef; + sub mycan { # Real can would leave stubs. my ($package, $meth) = @_; return \*{$package . "::$meth"} if defined &{$package . "::$meth"}; @@ -108,11 +107,11 @@ sub mycan { # Real can would leave stubs. } %constants = ( - 'integer' => 0x1000, - 'float' => 0x2000, - 'binary' => 0x4000, - 'q' => 0x8000, - 'qr' => 0x10000, + 'integer' => 0x1000, # HINT_NEW_INTEGER + 'float' => 0x2000, # HINT_NEW_FLOAT + 'binary' => 0x4000, # HINT_NEW_BINARY + 'q' => 0x8000, # HINT_NEW_STRING + 'qr' => 0x10000, # HINT_NEW_RE ); %ops = ( with_assign => "+ - * / % ** << >> x .", @@ -171,7 +170,7 @@ __END__ =head1 NAME -overload - Package for overloading perl operations +overload - Package for overloading Perl operations =head1 SYNOPSIS @@ -267,7 +266,7 @@ is called with arguments C<($a,undef,'')> when $a++ is executed. Two types of mutators have different calling conventions: -=over 4 +=over =item C<++> and C<--> @@ -298,7 +297,7 @@ if C<+=> is not overloaded. =back -B Due to the presense of assignment versions of operations, +B Due to the presence of assignment versions of operations, routines which may be called in assignment context may create self-referential structures. Currently Perl will not free self-referential structures until cycles are C broken. You may get problems @@ -333,9 +332,9 @@ The following symbols can be specified in C directive: "**", "**=", "<<", "<<=", ">>", ">>=", "x", "x=", ".", ".=", For these operations a substituted non-assignment variant can be called if -the assignment variant is not available. Methods for operations "C<+>", -"C<->", "C<+=>", and "C<-=>" can be called to automatically generate -increment and decrement methods. The operation "C<->" can be used to +the assignment variant is not available. Methods for operations C<+>, +C<->, C<+=>, and C<-=> can be called to automatically generate +increment and decrement methods. The operation C<-> can be used to autogenerate missing methods for unary minus or C. See L<"MAGIC AUTOGENERATION">, L<"Calling Conventions for Mutators"> and @@ -355,10 +354,10 @@ arrays, C is used to compare values subject to C. "&", "^", "|", "neg", "!", "~", -"C" stands for unary minus. If the method for C is not +C stands for unary minus. If the method for C is not specified, it can be autogenerated using the method for -subtraction. If the method for "C" is not specified, it can be -autogenerated using the methods for "C", or "C<\"\">", or "C<0+>". +subtraction. If the method for C is not specified, it can be +autogenerated using the methods for C, or C<"">, or C<0+>. =item * I @@ -382,11 +381,11 @@ C<0+>. =item * I - "bool", "\"\"", "0+", + 'bool', '""', '0+', If one or two of these operations are not overloaded, the remaining ones can be used instead. C is used in the flow control operators -(like C) and for the ternary "C" operation. These functions can +(like C) and for the ternary C operation. These functions can return any arbitrary Perl value. If the corresponding operation for this value is overloaded too, that operation will be called again with this value. @@ -404,6 +403,9 @@ glob (which may require a stringification). The same overloading happens both for the I syntax C$varE> and I syntax C${var}E>. +B Even in list context, the iterator is currently called only +once and with scalar context. + =item * I '${}', '@{}', '%{}', '&{}', '*{}'. @@ -420,7 +422,7 @@ The dereference operators must be specified explicitly they will not be passed t =item * I - "nomethod", "fallback", "=", + "nomethod", "fallback", "=", "~~", see L>. @@ -450,7 +452,7 @@ A computer-readable form of the above table is available in the hash Inheritance interacts with overloading in two ways. -=over 4 +=over =item Strings as values of C directive @@ -515,6 +517,11 @@ The key C<"fallback"> governs what to do if a method for a particular operation is not found. Three different cases are possible depending on the value of C<"fallback">: +=head2 Smart Match + +The key C<"~~"> allows you to override the smart matching used by +the switch construct. See L. + =over 16 =item * C @@ -698,7 +705,10 @@ Package C provides the following public functions: =item overload::StrVal(arg) -Gives string value of C as in absence of stringify overloading. +Gives string value of C as in absence of stringify overloading. If you +are using this to get the address of a reference (useful for checking if two +references point to the same thing) then you may be better off using +C, which is faster. =item overload::Overloaded(arg) @@ -712,12 +722,12 @@ Returns C or a reference to the method that implements C. =head1 Overloading constants -For some application Perl parser mangles constants too much. It is possible -to hook into this process via overload::constant() and overload::remove_constant() -functions. +For some applications, the Perl parser mangles constants too much. +It is possible to hook into this process via C +and C functions. These functions take a hash as an argument. The recognized keys of this hash -are +are: =over 8 @@ -852,7 +862,7 @@ C<$a = $b> values of $a and $b become I. On the other hand, anyone who has used algebraic notation knows the expressive power of the arithmetic metaphor. Overloading works hard to enable this metaphor while preserving the Perlian way as far as -possible. Since it is not not possible to freely mix two contradicting +possible. Since it is not possible to freely mix two contradicting metaphors, overloading allows the arithmetic way to write things I. The way it is done is described in L. @@ -919,10 +929,7 @@ numeric value.) This prints: =head2 Two-face references Suppose you want to create an object which is accessible as both an -array reference and a hash reference, similar to the -L -builtin Perl type. Let's make it better than a pseudo-hash by -allowing index 0 to be treated as a normal element. +array reference and a hash reference. package two_refs; use overload '%{}' => \&gethash, '@{}' => sub { $ {shift()} }; @@ -969,7 +976,7 @@ TIEHASH() method is a scalar reference. Second, we create a new tied hash each time the hash syntax is used. This allows us not to worry about a possibility of a reference loop, -would would lead to a memory leak. +which would lead to a memory leak. Both these problems can be cured. Say, if we want to overload hash dereference on a reference to an object which is I as a @@ -1028,7 +1035,7 @@ reference to the intermediate array, which keeps a reference to an actual array, and the access hash. The tie()ing object for the access hash is a reference to a reference to the actual array, so -=over 4 +=over =item * @@ -1058,8 +1065,8 @@ Put this in F in your Perl library directory: } This module is very unusual as overloaded modules go: it does not -provide any usual overloaded operators, instead it provides the -L operator C. In this example the corresponding +provide any usual overloaded operators, instead it provides the L operator C. In this example the corresponding subroutine returns an object which encapsulates operations done over the objects: C contains C<['n', 3]>, C<2 + new symbolic 3> contains C<['+', 2, ['n', 3]]>. @@ -1135,7 +1142,7 @@ which outputs and one can inspect the value in debugger using all the possible methods. -Something is is still amiss: consider the loop variable $cnt of the +Something is still amiss: consider the loop variable $cnt of the script. It was a number, not an object. We cannot make this value of type C, since then the loop will not terminate.