Slot

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Revision as of 02:25, 2 July 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.

Contents 1 Notable implementations 2 Protocol 2.1 get/0 2.2 put/1 2.3 isFinal/0 2.4 readOnly/0

Notable implementations

• FinalSlot
• SimpleSlot
• GuardedSlot
• LamportSlot

Protocol

get/0

Signature: get() :any

Returns the current value of this slot.

put/1

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.

isFinal/0

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.

readOnly/0

Signature: readOnly() :Slot

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