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class Struct
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Parent:
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Object
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Version:
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1.6
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Index:
new
new
members
==
[ ]
[ ]=
each
length
members
size
to_a
values
Subclasses: Struct::Tms
A Struct is a convenient way to bundle a number of attributes
together, using accessor methods, without having to write an explicit
class.
The Struct class is a generator of specific classes, each one of
which is defined to hold a set of variables and their accessors. In
these examples, we'll call the generated class `` CustomerClass,'' and
we'll show an example instance of that class as `` CustomerInst.''
In the descriptions that follow, the
parameter aSymbol refers to a symbol, which is either a
quoted string or a Symbol (such as :name).
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mixins
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| Enumerable:
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collect, detect, each_with_index, entries, find, find_all, grep,
include?, map, max, member?, min, reject, select, sort, to_a |
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class methods
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new
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Struct.new( [
aString
] [, aSym
]+
)
-> CustomerClass
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Creates a new class, named by aString, containing
accessor methods for the given symbols.
If the name aString is omitted, an anonymous structure
class will be created. Otherwise, the name of this struct will
appear as a constant in class Struct, so it must be unique
for all Structs in the system and should start with a
capital letter.
Struct.new
returns a new Class object, which can then be used
to create specific instances of the new structure.
The remaining methods listed below (class and instance) are
defined for this generated class. See the description that follows
for an example.
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new
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CustomerClass.new( [
anObject
]+
)
-> CustomerInst
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Creates a new instance. The number of actual parameters must be
less than or equal to the number of attributes defined for this
class; unset parameters default to nil. Passing too many
parameters will raise an ArgumentError.
Customer = Struct.new( "Customer", :name, :address, :zip )
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joe = Customer.new( "Joe Smith", "123 Maple, Anytown NC", 12345 )
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joe.name
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� |
"Joe Smith"
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joe.zip
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� |
12345
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members
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CustomerClass.members
-> anArray
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Returns an array of strings representing the names of the
instance variables.
Customer = Struct.new( "Customer", :name, :address, :zip )
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Customer.members
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� |
["name", "address", "zip"]
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instance methods
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==
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CustomerInst == anOtherStruct
-> true or false
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Equality---Returns true if anOtherStruct is equal to this
one: they must be of the same class as generated by
Struct.new
, and the values of
all instance variables must be equal (according to
Object#==
).
Customer = Struct.new( "Customer", :name, :address, :zip )
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joe = Customer.new( "Joe Smith", "123 Maple, Anytown NC", 12345 )
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joejr = Customer.new( "Joe Smith", "123 Maple, Anytown NC", 12345 )
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jane = Customer.new( "Jane Doe", "456 Elm, Anytown NC", 12345 )
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joe == joejr
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� |
true
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joe == jane
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� |
false
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[ ]
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CustomerInst[ aSymbol ] -> anObject
CustomerInst[ anInteger ] -> anObject
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Attribute Reference---Returns the value of the instance variable
named by aSymbol, or indexed (0..length-1) by
anInteger. Will raise NameError if the named
variable does not exist, or IndexError if the index is out of range.
Customer = Struct.new( "Customer", :name, :address, :zip )
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joe = Customer.new( "Joe Smith", "123 Maple, Anytown NC", 12345 )
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joe["name"]
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� |
"Joe Smith"
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joe[:name]
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� |
"Joe Smith"
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joe[0]
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� |
"Joe Smith"
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[ ]=
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CustomerInst[ aSymbol ] = anObject -> anObject
CustomerInst[ anInteger ] = anObject -> anObject
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Attribute Assignment---Assigns to the instance variable named by
aSymbol or anInteger
the value anObject and returns it. Will raise
a NameError if the named variable does not exist, or an
IndexError if the index is out of range.
Customer = Struct.new( "Customer", :name, :address, :zip )
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joe = Customer.new( "Joe Smith", "123 Maple, Anytown NC", 12345 )
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joe["name"] = "Luke"
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joe[:zip] = "90210"
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joe.name
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� |
"Luke"
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joe.zip
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� |
"90210"
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each
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CustomerInst.each {| anObject | block }
-> CustomerInst
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Calls block once for each instance variable, passing the
value as a parameter.
Customer = Struct.new( "Customer", :name, :address, :zip )
joe = Customer.new( "Joe Smith", "123 Maple, Anytown NC", 12345 )
joe.each {|x| puts(x) }
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produces:
Joe Smith
123 Maple, Anytown NC
12345
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length
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CustomerInst.length
-> anInteger
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Returns the number of instance variables.
Customer = Struct.new( "Customer", :name, :address, :zip )
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joe = Customer.new( "Joe Smith", "123 Maple, Anytown NC", 12345 )
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joe.length
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� |
3
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members
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CustomerInst.members
-> anArray
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Returns an array of strings representing the names of the
instance variables.
Customer = Struct.new( "Customer", :name, :address, :zip )
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joe = Customer.new( "Joe Smith", "123 Maple, Anytown NC", 12345 )
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joe.members
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["name", "address", "zip"]
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size
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CustomerInst.size
-> anInteger
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Synonym for
Struct#length
.
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to_a
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CustomerInst.to_a
-> anArray
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Returns the values for this instance as an array.
Customer = Struct.new( "Customer", :name, :address, :zip )
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joe = Customer.new( "Joe Smith", "123 Maple, Anytown NC", 12345 )
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joe.to_a[1]
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� |
"123 Maple, Anytown NC"
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values
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CustomerInst.values
-> anArray
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Synonym for to_a.
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