at:tutorial:appendix
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=== Futures === | === Futures === | ||
- | The module ''/ | + | The module ''/ |
The module exports the type tags '' | The module exports the type tags '' | ||
Line 464: | Line 464: | ||
==== Dynamic Variables ==== | ==== Dynamic Variables ==== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | A dynamic variable can be defined as follows: | ||
+ | < | ||
+ | def name := dynamicVariable: | ||
+ | </ | ||
+ | |||
+ | It can be read as follows: | ||
+ | < | ||
+ | ?name or name.value | ||
+ | </ | ||
+ | |||
+ | It can be assigned only within a limited dynamic scope, as follows: | ||
+ | < | ||
+ | with: name is: newval do: { code } | ||
+ | // or | ||
+ | name.is: newval in: { code } | ||
+ | </ | ||
+ | |||
+ | When '' | ||
+ | |||
+ | By convention, we prefix the names of dynamic variables with a '' | ||
+ | |||
+ | You can find more usage examples of dynamic variables in the unit test included in the file '' | ||
==== Ambient References ==== | ==== Ambient References ==== | ||
+ | |||
+ | Ambient references are defined in the module ''/ | ||
+ | |||
+ | < | ||
+ | import / | ||
+ | deftype Printer; | ||
+ | def printers := ambient: Printer; | ||
+ | </ | ||
+ | |||
+ | In the above code, '' | ||
+ | |||
+ | Ambient references ship with two so-called " | ||
==== Structural Types ==== | ==== Structural Types ==== | ||
+ | |||
+ | The module ''/ | ||
+ | |||
+ | A structural type can be branded with type tags. In this case, objects only conform to the type if they are structurally conformant **and** if they are tagged with the structural type's brands. | ||
+ | |||
+ | Use the '' | ||
+ | |||
+ | < | ||
+ | def PersonProtocol := protocol: { | ||
+ | def name; | ||
+ | def age; | ||
+ | } named: `Person; | ||
+ | </ | ||
+ | |||
+ | The '' | ||
+ | |||
+ | < | ||
+ | def tom := object: { | ||
+ | def name := " | ||
+ | def age() { 24 }; | ||
+ | } implements: PersonProtocol; | ||
+ | </ | ||
+ | |||
+ | You can also create a protocol from an object: | ||
+ | < | ||
+ | |||
+ | You can test protocol conformance in either of two styles: | ||
+ | * '' | ||
+ | * '' | ||
+ | |||
+ | You can also force a '' | ||
+ | | ||
+ | | ||
+ | |||
+ | More usage examples of structural types can be found in the unit test defined in the file '' | ||
==== Traits ==== | ==== Traits ==== |
at/tutorial/appendix.txt · Last modified: 2021/09/24 10:28 by elisag