78 lines
2.5 KiB
Markdown
78 lines
2.5 KiB
Markdown
Dynamic Values
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==============
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{{#include ../links.md}}
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A `Dynamic` value can be _any_ type, as long as it implements `Clone`.
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~~~admonish warning.small "`Send + Sync`"
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Under the [`sync`] feature, all types must also be `Send + Sync`.
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~~~
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```rust
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let x = 42; // value is an integer
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x = 123.456; // value is now a floating-point number
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x = "hello"; // value is now a string
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x = x.len > 0; // value is now a boolean
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x = [x]; // value is now an array
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x = #{x: x}; // value is now an object map
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```
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Use `type_of()` to Get Value Type
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---------------------------------
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Because [`type_of()`] a `Dynamic` value returns the type of the actual value,
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it is usually used to perform type-specific actions based on the actual value's type.
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```js
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let mystery = get_some_dynamic_value();
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switch type_of(mystery) {
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"()" => print("Hey, I got the unit () here!"),
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"i64" => print("Hey, I got an integer here!"),
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"f64" => print("Hey, I got a float here!"),
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"decimal" => print("Hey, I got a decimal here!"),
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"range" => print("Hey, I got an exclusive range here!"),
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"range=" => print("Hey, I got an inclusive range here!"),
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"string" => print("Hey, I got a string here!"),
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"bool" => print("Hey, I got a boolean here!"),
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"array" => print("Hey, I got an array here!"),
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"blob" => print("Hey, I got a BLOB here!"),
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"map" => print("Hey, I got an object map here!"),
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"Fn" => print("Hey, I got a function pointer here!"),
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"timestamp" => print("Hey, I got a time-stamp here!"),
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"TestStruct" => print("Hey, I got the TestStruct custom type here!"),
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_ => print(`I don't know what this is: ${type_of(mystery)}`)
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}
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```
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Parse from JSON
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---------------
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~~~admonish warning.side "Requires `metadata`"
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`parse_json` is defined in the [`LanguageCorePackage`][built-in packages], which is excluded when using a [raw `Engine`].
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It also requires the [`metadata`] feature; the [`no_index`] and [`no_object`] features must _not_ be set.
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~~~
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Use `parse_json` to parse a JSON string into a [`Dynamic`] value.
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| JSON type | Rhai type |
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| :---------------------------: | :----------: |
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| `number` (no decimal point) | `INT` |
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| `number` (with decimal point) | `FLOAT` |
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| `string` | [string] |
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| `boolean` | `bool` |
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| `Array` | [array] |
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| `Object` | [object map] |
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| `null` | [`()`] |
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