Slot

(Difference between revisions)

Latest revision as of 05:00, 8 November 2008

A Slot is an object which provides the behavior of the binding of a noun. "&" in the E language allows working with slots.

A slot can also be considered a zero-dimensional collection, i.e. one which has exactly one element.

Signature: get() :any

Returns the current value of this slot.

Signature: put(newValue :any) :void

Sets the current value to the (possibly coerced) provided value, if appropriate for this type of slot; throws if not allowed.

Signature: isFinal() :boolean

Says whether the Slot acts like a FinalSlot -- successive get()s on the same slot will always give the same value.

Note that final implies read-only, but read-only does not imply final.

Signature: readOnly() :Slot

Returns a facet allowing get/0 but not put/1.

@@ Line 6: / Line 6: @@
 * [[FinalSlot]]
-* [[VarSlot]]
+* [[SimpleSlot]]
+* [[GuardedSlot]]
+* [[CoercedSlot]]
 * [[LamportSlot]]
 ==Protocol==
-=== get/0 ===
+{{instance msgdoc|get|0||[[any]]}}
-get() :[[any]]
 Returns the current value of this slot.
-=== put/1 ===
+{{instance msgdoc|put|1|<var>newValue</var> :[[any]]|[[void]]}}
-put(<var>newValue</var> :[[any]]) :[[void]]
 Sets the current value to the (possibly coerced) provided value, if appropriate for this type of slot; [[throw]]s if not allowed.
-=== isFinal/0 ===
+{{instance msgdoc|isFinal|0||[[boolean]]}}
-isFinal() :boolean
 Says whether the Slot acts like a [[FinalSlot]] -- successive <code>[[#get/0|get]]()</code>s on the same slot will always give the same value.
-<!-- so an FinalSlot acts like an write once read many memory, no? -~~~~ -->
 Note that final implies read-only, but read-only does not imply final.
-=== readOnly/0 ===
+{{instance msgdoc|readOnly|0||[[Slot]]}}
-readOnly() :[[Slot]]
 Returns a facet allowing get/0 but not put/1.
 [[Category:Protocols]]
+[[Category:ELib specification]]