RFP - Add try_ prefixed variants to rhai functions that can throw

[sphilipakis]

RFP: Add try_ prefixed variants to rhai functions that can throw

Overview

Some functions available to the rhai scripts may throw on failure. For example:

// will throw
let content = file::load("some_non_existant_file");

// will throw if no internet
let content = web::get("some_url");

The proposal is to define try_ variants of these functions that return null instead of throwing an exception. This enables the use of the ?? null coalescing operator for elegant fallback handling:

// won't fail, returns "default content" if file not found
let content = file::try_load("some_non_existant_file") ?? "default content";

// won't fail, returns "default content" if request fails
let content = web::try_get("some_url") ?? "default content";

Motivation

• Provides a more ergonomic way to handle potential failures in rhai scripts
• Enables cleaner fallback patterns using the ?? operator
• Reduces need for try/catch blocks which can make scripts harder to read
• Follows common programming patterns where try_ prefixed functions return optional values

Proposed Implementation

Similar to how the devai module functions are implemented, we can wrap the throwing functions with a try_ variant that catches errors and returns null. Example implementation pattern:

// In the respective rhai module files
fn try_load(path: &str) -> RhaiResult {
    match file::load(path) {
        Ok(content) => Ok(content.into()),
        Err(_) => Ok(Dynamic::NULL),
    }
}

fn try_get(url: &str) -> RhaiResult {
    match web::get(url) {
        Ok(content) => Ok(content.into()),
        Err(_) => Ok(Dynamic::NULL),
    }
}

Example Usage

// File operations with fallbacks
let content = file::try_load("config.json") ?? "{}";
let backup = file::try_load("backup.txt") ?? "";

// Web requests with defaults
let api_data = web::try_get("https://api.example.com/data") ?? "[]";
let user_info = web::try_get("https://api.example.com/user") ?? "{}";

// Chaining multiple attempts
let config = 
    file::try_load("config.local.json") ??
    file::try_load("config.json") ??
    "{}";

Future Considerations

• Consider adding try_ variants for other functions that can throw
• Evaluate if certain functions should only have try_ versions
• Consider adding result type information to function documentation
• May want to standardize error logging/handling for try_ variants