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Add docs for closures.

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This commit is contained in:
Stephen Chung
2020-08-04 16:27:55 +08:00
parent 3d6c83c6d8
commit 4878a69503
13 changed files with 200 additions and 64 deletions
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18
doc/src/rust/register-raw.md
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@@ -35,12 +35,12 @@ engine.register_raw_fn(
// Therefore, get a '&mut' reference to the first argument _last_.
// Alternatively, use `args.split_at_mut(1)` etc. to split the slice first.
let y: i64 = *args[1].downcast_ref::<i64>() // get a reference to the second argument
let y: i64 = *args[1].read_lock::<i64>() // get a reference to the second argument
.unwrap(); // then copying it because it is a primary type
let y: i64 = std::mem::take(args[1]).cast::<i64>(); // alternatively, directly 'consume' it
let x: &mut i64 = args[0].downcast_mut::<i64>() // get a '&mut' reference to the
let x: &mut i64 = args[0].write_lock::<i64>() // get a '&mut' reference to the
.unwrap(); // first argument
*x += y; // perform the action
@@ -84,12 +84,12 @@ Extract Arguments
To extract an argument from the `args` parameter (`&mut [&mut Dynamic]`), use the following:
| Argument type | Access (`n` = argument position) | Result |
| ------------------------------ | -------------------------------------- | ---------------------------------------------------------- |
| [Primary type][standard types] | `args[n].clone().cast::<T>()` | Copy of value. |
| Custom type | `args[n].downcast_ref::<T>().unwrap()` | Immutable reference to value. |
| Custom type (consumed) | `std::mem::take(args[n]).cast::<T>()` | The _consumed_ value.<br/>The original value becomes `()`. |
| `this` object | `args[0].downcast_mut::<T>().unwrap()` | Mutable reference to value. |
| Argument type | Access (`n` = argument position) | Result |
| ------------------------------ | ------------------------------------- | ---------------------------------------------------------- |
| [Primary type][standard types] | `args[n].clone().cast::<T>()` | Copy of value. |
| Custom type | `args[n].read_lock::<T>().unwrap()` | Immutable reference to value. |
| Custom type (consumed) | `std::mem::take(args[n]).cast::<T>()` | The _consumed_ value.<br/>The original value becomes `()`. |
| `this` object | `args[0].write_lock::<T>().unwrap()` | Mutable reference to value. |
When there is a mutable reference to the `this` object (i.e. the first argument),
there can be no other immutable references to `args`, otherwise the Rust borrow checker will complain.
@@ -156,5 +156,5 @@ let this_ptr = first[0].downcast_mut::<A>().unwrap();
// Immutable reference to the second value parameter
// This can be mutable but there is no point because the parameter is passed by value
let value = rest[0].downcast_ref::<B>().unwrap();
let value_ref = rest[0].read_lock::<B>().unwrap();
```