This method is used to compare the receiver object (this
)
with the argument object (arg0
) for equivalence
This method is used to compare the receiver object (this
)
with the argument object (arg0
) for equivalence.
The default implementations of this method is an equivalence relation:
x
of type Any
,
x.equals(x)
should return true
.x
and y
of type
Any
, x.equals(y)
should return true
if and only
if y.equals(x)
returns true
.x
, y
, and z
of type AnyRef
if x.equals(y)
returns true
and
y.equals(z)
returns
true
, then x.equals(z)
should return true
.
If you override this method, you should verify that
your implementation remains an equivalence relation.
Additionally, when overriding this method it is often necessary to
override hashCode
to ensure that objects that are
"equal" (o1.equals(o2)
returns true
)
hash to the same Int
(o1.hashCode.equals(o2.hashCode)
).
the object to compare against this object for equality.
true
if the receiver object is equivalent to the argument; false
otherwise.
Returns a hash code value for the object
Returns a hash code value for the object.
The default hashing algorithm is platform dependent.
Note that it is allowed for two objects to have identical hash
codes (o1.hashCode.equals(o2.hashCode)
) yet not be
equal (o1.equals(o2)
returns false
). A
degenerate implementation could always return 0
.
However, it is required that if two objects are equal
(o1.equals(o2)
returns true
) that they
have identical hash codes
(o1.hashCode.equals(o2.hashCode)
). Therefore, when
overriding this method, be sure to verify that the behavior is
consistent with the equals
method.
Returns a string representation of the object
Returns a string representation of the object.
The default representation is platform dependent.
Retrieve the current value
Retrieve the current value
Change the currently bound value, discarding the old value
Change the currently bound value, discarding the old value.
Usually withValue()
gives better semantics.
Set the value of the variable while executing the specified thunk
Set the value of the variable while executing the specified thunk.
The value to which to set the variable
The code to evaluate under the new setting
DynamicVariables provide a binding mechanism where the current value is found through dynamic scope, but where access to the variable itself is resolved through static scope.
The current value can be retrieved with the
value
method. New values should be pushed using thewithValue
method. Values pushed viawithValue
only stay valid while thewithValue
's second argument, a parameterless closure, executes. When the second argument finishes, the variable reverts to the previous value.Usage of
withValue
looks like this:Each thread gets its own stack of bindings. When a new thread is created, the DynamicVariable gets a copy of the stack of bindings from the parent thread, and from then on the bindings for the new thread are independent of those for the original thread.