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Programming Ruby The Pragmatic Programmer's Guide |
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Index:
Comparisons
between?
The Comparable mixin is used by classes whose objects may be
ordered. The class must define the <=>
operator, which
compares the receiver against another object, returning -1, 0,
or +1 depending on whether the receiver is less than, equal to, or
greater than the other object. Comparable uses <=> to implement the
conventional comparison operators (<, <=, ==, >=, and >) and the method between?.
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class SizeMatters
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include Comparable
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attr :str
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def <=>(anOther)
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str.size <=> anOther.str.size
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end
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def initialize(str)
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@str = str
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end
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def inspect
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@str
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end
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end
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s1 = SizeMatters.new("Z")
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s2 = SizeMatters.new("YY")
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s3 = SizeMatters.new("XXX")
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s4 = SizeMatters.new("WWWW")
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s5 = SizeMatters.new("VVVVV")
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s1 < s2
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true
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s4.between?(s1, s3)
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false
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s4.between?(s3, s5)
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true
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[ s3, s2, s5, s4, s1 ].sort
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[Z, YY, XXX, WWWW, VVVVV]
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instance methods
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Comparisons
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anObject < otherObject -> true or false
anObject <= otherObject -> true or false
anObject == otherObject -> true or false
anObject >= otherObject -> true or false
anObject > otherObject -> true or false
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Compares two objects based on the receiver's <=> method.
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between?
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anObject.between?( min, max )
-> true or false
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Returns false if anObject <=> min is less than
zero or if anObject <=> max is greater than zero, true otherwise.
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3.between?(1, 5)
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true
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6.between?(1, 5)
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false
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'cat'.between?('ant', 'dog')
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true
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'gnu'.between?('ant', 'dog')
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false
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Extracted from the book "Programming Ruby -
The Pragmatic Programmer's Guide"
Copyright
©
2001 by Addison Wesley Longman, Inc. This material may
be distributed only subject to the terms and conditions set forth in
the Open Publication License, v1.0 or later (the latest version is
presently available at http://www.opencontent.org/openpub/)).
Distribution of substantively modified versions of this document is
prohibited without the explicit permission of the copyright holder.
Distribution of the work or derivative of the work in any standard
(paper) book form is prohibited unless prior permission is obtained
from the copyright holder.
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