Debugging Interface
For systems open to external user-created scripts, it is usually desirable to provide a debugging
experience to the user. The alternative is to provide a custom implementation of debug via
Engine::on_debug that traps debug output to show in a side panel, for example, which is actually
extremely simple.
Nevertheless, in some systems, it may not be convenient, or even possible, for the user to debug his
or her scripts simply via good-old print or debug statements – the system does not
have any facility for printed output, for instance.
Or the system may require more advanced debugging facilities than mere print statements –
such as break-points.
For these advanced scenarios, Rhai contains a Debugging interface, turned on via the debugging
feature (which implies the internals feature).
The debugging interface resides under the debugger sub-module.
The rhai-dbg bin tool shows a simple example of
employing the debugging interface to create a debugger for Rhai scripts!
Built-in Functions
The following functions (defined in the DebuggingPackage but excluded when
using a raw Engine) provides runtime information for debugging purposes.
| Function | Parameter(s) | Not available under | Description |
|---|---|---|---|
back_trace | none | no_function, no_index | returns an array of object maps or strings, each containing one level of function call;returns an empty array if no debugger is registered |
// This recursive function prints its own call stack during each run
fn foo(x) {
print(back_trace()); // prints the current call stack
if x > 0 {
foo(x - 1)
}
}