Trait ResourceOracle 

pub trait ResourceOracle:
    Send
    + Sync
    + 'static {
    // Required method
    fn resolve(&self, kind: &str, name: &str) -> Result<(), String>;
}

Answers whether a definition that a config names exists, such as a connector a deployment declares, and why not when it does not.

A Compiler given one through CompileOptions::resources checks each Reference a host function’s spec declares. A field holding a literal string the oracle does not resolve is an UNRESOLVED_REFERENCE Defect, whose message leads with the oracle’s reason when it gives one. A computed or absent value is not checked.

use dataflow_rs::program::ResourceOracle;

/// The deployment's connectors: `orders` a database, `sessions` a cache.
struct Connectors;

impl ResourceOracle for Connectors {
    fn resolve(&self, _kind: &str, name: &str) -> Result<(), String> {
        match name {
            "orders" => Ok(()),
            "sessions" => Err(format!("connector `{name}` is a cache, not a database")),
            _ => Err(String::new()),
        }
    }
}

Required Methods

fn resolve(&self, kind: &str, name: &str) -> Result<(), String>

Ok when a kind named name exists: the connector db1, say. Err(why) when it does not. A why that is not empty is the issue’s message, after what did not resolve: `sessions` does not resolve as a connector: connector `sessions` is a cache, not a database. An empty one gives the plain message: no connector named `db2` resolves.

Errors

Why name does not resolve, or nothing more to say: an empty string.

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors