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Add namespace test.

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Stephen Chung
2020-12-07 21:54:52 +08:00
parent c5babac3da
commit bd52333802
3 changed files with 73 additions and 13 deletions
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47
doc/src/language/fn-namespaces.md
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@@ -15,28 +15,51 @@ allow combining all functions in one [`AST`] into another, forming a new, unifie
In general, there are two types of _namespaces_ where functions are looked up:
| Namespace | Source | Lookup method | Sub-modules? | Variables? |
| --------- | ------------------------------------------------------------------------------------- | --------------------------------- | :----------: | :--------: |
| Global | 1) `Engine::register_XXX` API<br/>2) [`AST`] being evaluated<br/>3) [packages] loaded | simple function name | ignored | ignored |
| Module | [`Module`] | namespace-qualified function name | yes | yes |
| Namespace | How Many | Source | Lookup method | Sub-modules? | Variables? |
| --------- | :------: | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------- | :----------: | :--------: |
| Global | One | 1) [`AST`] being evaluated<br/>2) `Engine::register_XXX` API<br/>3) [packages] loaded<br/>4) functions in [modules] loaded via `Engine::register_module` and marked _global_ | simple function name | ignored | ignored |
| Module | Many | [`Module`] | namespace-qualified function name | yes | yes |
Module Namespace
----------------
There can be multiple module namespaces at any time during a script evaluation, loaded via the
[`import`] statement.
Functions and variables in module namespaces are isolated and encapsulated within their own environments.
They must be called or accessed in a _namespace-qualified_ manner.
```rust
import "my_module" as m; // new module namespace 'm' created via 'import'
let x = m::calc_result(); // namespace-qualified function call
let y = m::MY_NUMBER; // namespace-qualified variable (constant) access
let x = calc_result(); // <- error: function 'calc_result' not found
// in global namespace!
```
Global Namespace
----------------
There is one _global_ namespace for every [`Engine`], which includes:
There is one _global_ namespace for every [`Engine`], which includes (in the following search order):
* All the native Rust functions registered via the `Engine::register_XXX` API.
* All functions defined in the [`AST`] currently being evaluated.
* All the Rust functions defined in [packages] that are loaded into the [`Engine`].
* All native Rust functions and iterators registered via the `Engine::register_XXX` API.
* All the [modules] imported via [`import`] statements.
* All functions and iterators defined in [packages] that are loaded into the [`Engine`].
In addition, during evaluation of an [`AST`], all script-defined functions bundled together within
the [`AST`] are added to the global namespace and override any existing registered functions of
the same names and number of parameters.
* Functions defined in [modules] loaded via `Engine::register_module` that are specifically marked
for exposure to the global namespace (e.g. via the `#[rhai(global)]` attribute in a [plugin module]).
Anywhere in a Rhai script, when a function call is made, the function is searched within the
global namespace, in the above search order.
Anywhere in a Rhai script, when a function call is made, it is searched within the global namespace.
Therefore, function calls in Rhai are _late_ bound - meaning that the function called cannot be
determined or guaranteed and there is no way to _lock down_ the function being called.
This aspect is very similar to JavaScript before ES6 modules.