Provided by: libscalar-properties-perl_1.100860-3_all 
NAME
Scalar::Properties - Run-time properties on scalar variables
VERSION
version 1.100860
SYNOPSIS
use Scalar::Properties;
my $val = 0->true;
if ($val && $val == 0) {
print "yup, its true alright...\n";
}
my @text = (
'hello world'->greeting(1),
'forget it',
'hi there'->greeting(1),
);
print grep { $_->is_greeting } @text;
my $l = 'hello world'->length;
DESCRIPTION
Scalar::Properties attempts to make Perl more object-oriented by taking an idea from Ruby:
Everything you manipulate is an object, and the results of those manipulations are objects
themselves.
'hello world'->length
(-1234)->abs
"oh my god, it's full of properties"->index('g')
The first example asks a string to calculate its length. The second example asks a number
to calculate its absolute value. And the third example asks a string to find the index of
the letter 'g'.
Using this module you can have run-time properties on initialized scalar variables and
literal values. The word 'properties' is used in the Perl 6 sense: out-of-band data,
little sticky notes that are attached to the value. While attributes (as in Perl 5's
attribute pragma, and see the "Attribute::*" family of modules) are handled at compile-
time, properties are handled at run-time.
Internally properties are implemented by making their values into objects with overloaded
operators. The actual properties are then simply hash entries.
Most properties are simply notes you attach to the value, but some may have deeper
meaning. For example, the "true" and "false" properties plays a role in boolean context,
as the first example of the Synopsis shows.
Properties can also be propagated between values. For details, see the EXPORTS section
below. Here is an example why this might be desirable:
pass_on('approximate');
my $pi = 3->approximate(1);
my $circ = 2 * $rad * $pi;
# now $circ->approximate indicates that this value was derived
# from approximate values
Please don't use properties whose name start with an underscore; these are reserved for
internal use.
You can set and query properties like this:
"$var->myprop(1)"
sets the property to a true value.
"$var->myprop(0)"
sets the property to a false value. Note that this doesn't delete the property (to do
so, use the "del_props" method described below).
"$var->is_myprop", "$var->has_myprop"
returns a true value if the property is set (i.e., defined and has a true value). The
two alternate interfaces are provided to make querying attributes sound more natural.
For example:
$foo->is_approximate;
$bar->has_history;
Values thus made into objects also expose various utility methods. All of those methods
(unless noted otherwise) return the result as an overloaded value ready to take properties
and method calls itself, and don't modify the original value.
METHODS
get_props
Get a list of names of the value's properties.
del_props(LIST)
Deletes one or more properties from the value. This is different than setting the property
value to zero.
del_all_props
Deletes all of the value's properties.
plus(EXPR)
Returns the value that is the sum of the value whose method has been called and the
argument value. This method also overloads addition, so:
$a = 7 + 2;
$a = 7->plus(2); # the same
minus(EXPR)
Returns the value that is the the value whose method has been called minus the argument
value. This method also overloads subtraction.
times(EXPR)
Returns the value that is the the value whose method has been called times the argument
value. This method also overloads multiplication.
divide(EXPR)
Returns the value that is the the value whose method has been called divided by the
argument value. This method also overloads division.
modulo(EXPR)
Returns the value that is the the value whose method has been called modulo the argument
value. This method also overloads the modulo operator.
exp(EXPR)
Returns the value that is the the value whose method has been called powered by the
argument value. This method also overloads the exponentiation operator.
abs
Returns the absolute of the value.
zero
Returns a boolean value indicating whether the value is equal to 0.
length
Returns the result of the built-in "length" function applied to the value.
size
Same as "length()".
reverse
Returns the reverse string of the value.
uc
Returns the result of the built-in function "uc()" applied to the value.
ucfirst
Returns the result of the built-in function "ucfirst()" applied to the value.
lc
Returns the result of the built-in function "lc()" applied to the value.
lcfirst
Returns the result of the built-in function "lcfirst()" applied to the value.
hex
Returns the result of the built-in function "hex()" applied to the value.
oct
Returns the result of the built-in function "oct()" applied to the value.
concat(EXPR)
Returns the result of the argument expression appended to the value.
append(EXPR)
Same as "concat(EXPR)".
swapcase
Returns a version of the value with every character's case reversed, i.e. a lowercase
character becomes uppercase and vice versa.
split /PATTERN/, LIMIT
Returns a list of overloaded values that is the result of splitting (according to the
built-in "split" function) the value along the pattern, into a number of values up to the
limit.
numcmp(EXPR)
Returns the (overloaded) value of the numerical three-way comparison. This method also
overloads the "<=>" operator.
cmp(EXPR)
Returns the (overloaded) value of the alphabetical three-way comparison. This method also
overloads the "cmp" operator.
eq(EXPR)
Return the (overloaded) boolean value of the "eq" string comparison. This method also
overloads that operators.
ne(EXPR)
Return the (overloaded) boolean value of the "ne" string comparison. This method also
overloads that operators.
lt(EXPR)
Return the (overloaded) boolean value of the "lt" string comparison. This method also
overloads that operators.
gt(EXPR)
Return the (overloaded) boolean value of the "gt" string comparison. This method also
overloads that operators.
le(EXPR)
Return the (overloaded) boolean value of the "le" string comparison. This method also
overloads that operators.
ge(EXPR)
Return the (overloaded) boolean value of the "ge" string comparison. This method also
overloads that operators.
eqi
Same as "eq()", but is case-insensitive.
nei>
Same as "ne()", but is case-insensitive.
lti
Same as "lt()", but is case-insensitive.
gti
Same as "gt()", but is case-insensitive.
lei
Same as "le()", but is case-insensitive.
gei
Same as "ge()", but is case-insensitive.
is_true
Returns whether the (overloaded) boolean status of the value is true.
is_false
Returns whether the (overloaded) boolean status of the value is false.
create
FIXME
del_prop
FIXME
do_downto
FIXME
do_downto_step
FIXME
do_upto
FIXME
do_upto_step
FIXME
false
FIXME
gen_meth
FIXME
handle
FIXME
times_do
FIXME
true
FIXME
value
FIXME
FUNCTIONS
pass_on(LIST)
Sets (replaces) the list of properties that are passed on. There is only one such list for
the whole mechanism. The whole property interface is experimental, but this one in
particular is likely to change in the future. This function is exported automatically.
passed_on(STRING)
Tests whether a property is passed on and returns a boolean value. This function is
exported automatically.
get_pass_on
Returns a list of names of properties that are passed on. This function is exported
automatically.
INSTALLATION
See perlmodinstall for information and options on installing Perl modules.
BUGS AND LIMITATIONS
No bugs have been reported.
Please report any bugs or feature requests through the web interface at
<http://rt.cpan.org/Public/Dist/Display.html?Name=Scalar-Properties>.
AVAILABILITY
The latest version of this module is available from the Comprehensive Perl Archive Network
(CPAN). Visit <http://www.perl.com/CPAN/> to find a CPAN site near you, or see
<http://search.cpan.org/dist/Scalar-Properties/>.
The development version lives at <http://github.com/hanekomu/Scalar-Properties/>. Instead
of sending patches, please fork this project using the standard git and github
infrastructure.
AUTHOR
Marcel Gruenauer <marcel@cpan.org>
COPYRIGHT AND LICENSE
This software is copyright (c) 2001 by Marcel Gruenauer.
This is free software; you can redistribute it and/or modify it under the same terms as
the Perl 5 programming language system itself.