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Refine docs.

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Stephen Chung
2020-06-22 22:02:49 +08:00
parent b08f85a8b1
commit a9b168ba99
32 changed files with 260 additions and 221 deletions
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26
doc/src/rust/fallible.md
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@@ -8,11 +8,6 @@ If a function is _fallible_ (i.e. it returns a `Result<_, Error>`), it can be re
The function must return `Result<Dynamic, Box<EvalAltResult>>`.
`Box<EvalAltResult>` implements `From<&str>` and `From<String>` etc.
and the error text gets converted into `Box<EvalAltResult::ErrorRuntime>`.
The error values are `Box`-ed in order to reduce memory footprint of the error path, which should be hit rarely.
```rust
use rhai::{Engine, EvalAltResult, Position};
use rhai::RegisterResultFn; // use 'RegisterResultFn' trait for 'register_result_fn'
@@ -27,15 +22,20 @@ fn safe_divide(x: i64, y: i64) -> Result<Dynamic, Box<EvalAltResult>> {
}
}
fn main()
{
let engine = Engine::new();
let mut engine = Engine::new();
// Fallible functions that return Result values must use register_result_fn()
engine.register_result_fn("divide", safe_divide);
// Fallible functions that return Result values must use register_result_fn()
engine.register_result_fn("divide", safe_divide);
if let Err(error) = engine.eval::<i64>("divide(40, 0)") {
println!("Error: {:?}", *error); // prints ErrorRuntime("Division by zero detected!", (1, 1)")
}
if let Err(error) = engine.eval::<i64>("divide(40, 0)") {
println!("Error: {:?}", *error); // prints ErrorRuntime("Division by zero detected!", (1, 1)")
}
```
Create a `Box<EvalAltResult>`
----------------------------
`Box<EvalAltResult>` implements `From<&str>` and `From<String>` etc.
and the error text gets converted into `Box<EvalAltResult::ErrorRuntime>`.
The error values are `Box`-ed in order to reduce memory footprint of the error path, which should be hit rarely.