action.adoc

Action! datatype

Table of Contents

• 1. Abstract
• 2. Creation
• 3. Conversions
• 4. Comparisons
• 5. Testing values
• 6. Predefined words

1. Abstract

Action! values represent datatype "methods" in the Red internal OO model. They are written in Red/System and define a fixed interface that each datatype may, or may not, provide an implementation for. Not all datatypes support all actions, but they all share the same set of possible actions.

Actions are used like normal function values.

Action! is a member of the following typesets: any-function!, default!

2. Creation

Action values cannot be created at runtime.

3. Conversions

No conversions are supported for action! values.

4. Comparisons

Action values can be compared for sameness and equality with same?, ==, equal?, strict-equal?, not-equal?, <>.

5. Testing values

Use action? to check if a value is of the action! datatype.

>> action? :to
== true

Use type? to return the datatype of a given value.

>> type? :to
== action!

6. Predefined words

Predefined action! values can be viewed by typing help action! in the Red console.