44 lines
1.5 KiB
Markdown
44 lines
1.5 KiB
Markdown
Special Support for OOP via Object Maps
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=======================================
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{{#include ../links.md}}
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```admonish info.side "See also"
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See the pattern on [_Simulating Object-Oriented Programming_][OOP] for more details.
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```
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[Object maps] can be used to simulate [object-oriented programming (OOP)][OOP] by storing data
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as properties and methods as properties holding [function pointers].
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If an [object map]'s property holds a [function pointer], the property can simply be called like
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a normal method in method-call syntax.
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This is a _short-hand_ to avoid the more verbose syntax of using the `call` function keyword.
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When a property holding a [function pointer] or a [closure] is called like a method, it is replaced
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as a method call on the [object map] itself.
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```rust
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let obj = #{
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data: 40,
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action: || this.data += x // 'action' holds a closure
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};
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obj.action(2); // calls the function pointer with 'this' bound to 'obj'
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obj.call(obj.action, 2); // <- the above de-sugars to this
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obj.data == 42;
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// To achieve the above with normal function pointer call will fail.
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fn do_action(map, x) { map.data += x; } // 'map' is a copy
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obj.action = do_action; // <- de-sugars to 'Fn("do_action")'
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obj.action.call(obj, 2); // a copy of 'obj' is passed by value
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obj.data == 42; // 'obj.data' is not changed
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```
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