package overload;
-our $VERSION = '1.00';
-
-$overload::hint_bits = 0x20000;
+our $VERSION = '1.06';
sub nil {}
sub Method {
my $package = shift;
- $package = ref $package if ref $package;
+ if(ref $package) {
+ local $@;
+ local $!;
+ require Scalar::Util;
+ $package = Scalar::Util::blessed($package);
+ return undef if !defined $package;
+ }
#my $meth = $package->can('(' . shift);
ov_method mycan($package, '(' . shift), $package;
#return $meth if $meth ne \&nil;
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]";
+ local $@;
+ local $!;
+ 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"};
- my $p;
- foreach $p (@{$package . "::ISA"}) {
- my $out = mycan($p, $meth);
- return $out if $out;
+
+ my $mro = mro::get_linear_isa($package);
+ foreach my $p (@$mro) {
+ my $fqmeth = $p . q{::} . $meth;
+ return \*{$fqmeth} if defined &{$fqmeth};
}
+
return undef;
}
%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 .",
num_comparison => "< <= > >= == !=",
'3way_comparison'=> "<=> cmp",
str_comparison => "lt le gt ge eq ne",
- binary => "& | ^",
+ binary => '& &= | |= ^ ^=',
unary => "neg ! ~",
mutators => '++ --',
func => "atan2 cos sin exp abs log sqrt int",
}
else {
$^H{$_[0]} = $_[1];
- $^H |= $constants{$_[0]} | $overload::hint_bits;
+ $^H |= $constants{$_[0]};
}
shift, shift;
}
=head1 NAME
-overload - Package for overloading perl operations
+overload - Package for overloading Perl operations
=head1 SYNOPSIS
=back
-B<Warning.> Due to the presense of assignment versions of operations,
+B<Warning.> 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<explicitly> broken. You may get problems
"**", "**=", "<<", "<<=", ">>", ">>=", "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<abs>.
See L<"MAGIC AUTOGENERATION">, L<"Calling Conventions for Mutators"> and
=item * I<Bit operations>
- "&", "^", "|", "neg", "!", "~",
+ "&", "&=", "^", "^=", "|", "|=", "neg", "!", "~",
-"C<neg>" stands for unary minus. If the method for C<neg> is not
+C<neg> stands for unary minus. If the method for C<neg> 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<bool>", or "C<\"\">", or "C<0+>".
+subtraction. If the method for C<!> is not specified, it can be
+autogenerated using the methods for C<bool>, or C<"">, or C<0+>.
+
+The same remarks in L<"Arithmetic operations"> about
+assignment-variants and autogeneration apply for
+bit operations C<"&">, C<"^">, and C<"|"> as well.
=item * I<Increment and decrement>
=item * I<Boolean, string and numeric conversion>
- "bool", "\"\"", "0+",
+ 'bool', '""', '0+',
If one or two of these operations are not overloaded, the remaining ones can
be used instead. C<bool> is used in the flow control operators
-(like C<while>) and for the ternary "C<?:>" operation. These functions can
+(like C<while>) 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.
happens both for the I<read-filehandle> syntax C<E<lt>$varE<gt>> and
I<globbing> syntax C<E<lt>${var}E<gt>>.
+B<BUGS> Even in list context, the iterator is currently called only
+once and with scalar context.
+
=item * I<Dereferencing>
'${}', '@{}', '%{}', '&{}', '*{}'.
=item * I<Special>
- "nomethod", "fallback", "=",
+ "nomethod", "fallback", "=", "~~",
see L<SPECIAL SYMBOLS FOR C<use overload>>.
num_comparison => '< <= > >= == !=',
'3way_comparison'=> '<=> cmp',
str_comparison => 'lt le gt ge eq ne',
- binary => '& | ^',
+ binary => '& &= | |= ^ ^=',
unary => 'neg ! ~',
mutators => '++ --',
func => 'atan2 cos sin exp abs log sqrt',
B<Note.> C<"fallback"> inheritance via @ISA is not carved in stone
yet, see L<"Inheritance and overloading">.
+=head2 Smart Match
+
+The key C<"~~"> allows you to override the smart matching used by
+the switch construct. See L<feature>.
+
=head2 Copy Constructor
The value for C<"="> is a reference to a function with three
=back
+=head1 Minimal set of overloaded operations
+
+Since some operations can be automatically generated from others, there is
+a minimal set of operations that need to be overloaded in order to have
+the complete set of overloaded operations at one's disposal.
+Of course, the autogenerated operations may not do exactly what the user
+expects. See L<MAGIC AUTOGENERATION> above. The minimal set is:
+
+ + - * / % ** << >> x
+ <=> cmp
+ & | ^ ~
+ atan2 cos sin exp log sqrt int
+
+Additionally, you need to define at least one of string, boolean or
+numeric conversions because any one can be used to emulate the others.
+The string conversion can also be used to emulate concatenation.
+
=head1 Losing overloading
The restriction for the comparison operation is that even if, for example,
=item overload::StrVal(arg)
-Gives string value of C<arg> as in absence of stringify overloading.
+Gives string value of C<arg> 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<Scalar::Util::refaddr()>, which is faster.
=item overload::Overloaded(arg)
=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<overload::constant()>
+and C<overload::remove_constant()> functions.
These functions take a hash as an argument. The recognized keys of this hash
-are
+are:
=over 8
overload::constant integer => sub {Math::BigInt->new(shift)};
}
-B<BUGS> Currently overloaded-ness of constants does not propagate
-into C<eval '...'>.
-
=head1 IMPLEMENTATION
What follows is subject to change RSN.
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<as
far as all the mutators are called via overloaded access only>. The
way it is done is described in L<Copy Constructor>.
=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<pseudo-hash|perlref/"Pseudo-hashes: Using an array as a hash">
-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()} };
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<implemented> as a
Note that while we obtained this value using a nice little script,
there is no simple way to I<use> this value. In fact this value may
-be inspected in debugger (see L<perldebug>), but ony if
+be inspected in debugger (see L<perldebug>), but only if
C<bareStringify> B<O>ption is set, and not via C<p> command.
If one attempts to print this value, then the overloaded operator
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<symbolic>, since then the loop will not terminate.
https://perl5.git.perl.org / perl5.git / blobdiff