// Basic traits from your example trait Topology {} trait Score: Clone + std::fmt::Debug { fn get_interpret(&self) -> Box>; fn name(&self) -> String; } trait Interpret { fn execute(&self); } struct Maestro { topology: T } impl Maestro { pub fn new(topology: T) -> Self { Maestro { topology } } pub fn register_score(&self, score: S) { println!("Registering score: {}", score.name()); } pub fn execute_score(&self, score: S) { println!("Executing score: {}", score.name()); score.get_interpret::().execute(); } } // Capability traits - these are used to enforce requirements trait CommandExecution { fn execute_command(&self, command: &[String]) -> Result; } trait FileSystem { fn read_file(&self, path: &str) -> Result; fn write_file(&self, path: &str, content: &str) -> Result<(), String>; } // A concrete topology implementation #[derive(Clone, Debug)] struct LinuxHostTopology { hostname: String, } impl Topology for LinuxHostTopology {} // Implement the capabilities for LinuxHostTopology impl CommandExecution for LinuxHostTopology { fn execute_command(&self, command: &[String]) -> Result { println!("Executing command on {}: {:?}", self.hostname, command); // In a real implementation, this would use std::process::Command Ok(format!("Command executed successfully on {}", self.hostname)) } } impl FileSystem for LinuxHostTopology { fn read_file(&self, path: &str) -> Result { println!("Reading file {} on {}", path, self.hostname); Ok(format!("Content of {} on {}", path, self.hostname)) } fn write_file(&self, path: &str, content: &str) -> Result<(), String> { println!("Writing to file {} on {}: {}", path, self.hostname, content); Ok(()) } } // Another topology that doesn't support command execution #[derive(Clone, Debug)] struct BareMetalTopology { device_id: String, } impl Topology for BareMetalTopology {} impl FileSystem for BareMetalTopology { fn read_file(&self, path: &str) -> Result { println!("Reading file {} on device {}", path, self.device_id); Ok(format!("Content of {} on device {}", path, self.device_id)) } fn write_file(&self, path: &str, content: &str) -> Result<(), String> { println!("Writing to file {} on device {}: {}", path, self.device_id, content); Ok(()) } } // CommandScore implementation #[derive(Clone, Debug)] struct CommandScore { name: String, args: Vec, } impl CommandScore { pub fn new(name: String, args: Vec) -> Self { CommandScore { name, args } } } impl Score for CommandScore { fn get_interpret(&self) -> Box> { // This is the key part: we constrain T to implement CommandExecution // If T doesn't implement CommandExecution, this will fail to compile Box::new(CommandInterpret::::new(self.clone())) } fn name(&self) -> String { self.name.clone() } } // CommandInterpret implementation struct CommandInterpret { score: CommandScore, _marker: std::marker::PhantomData, } impl CommandInterpret { pub fn new(score: CommandScore) -> Self { CommandInterpret { score, _marker: std::marker::PhantomData, } } } impl Interpret for CommandInterpret { fn execute(&self) { println!("Command interpret is executing: {:?}", self.score.args); // In a real implementation, you would call the topology's execute_command method // topology.execute_command(&self.score.args); } } // FileScore implementation - a different type of score that requires FileSystem capability #[derive(Clone, Debug)] struct FileScore { name: String, path: String, content: Option, } impl FileScore { pub fn new_read(name: String, path: String) -> Self { FileScore { name, path, content: None } } pub fn new_write(name: String, path: String, content: String) -> Self { FileScore { name, path, content: Some(content) } } } impl Score for FileScore { fn get_interpret(&self) -> Box> { // This constrains T to implement FileSystem Box::new(FileInterpret::::new(self.clone())) } fn name(&self) -> String { self.name.clone() } } // FileInterpret implementation struct FileInterpret { score: FileScore, _marker: std::marker::PhantomData, } impl FileInterpret { pub fn new(score: FileScore) -> Self { FileInterpret { score, _marker: std::marker::PhantomData, } } } impl Interpret for FileInterpret { fn execute(&self) { match &self.score.content { Some(content) => { println!("File interpret is writing to {}: {}", self.score.path, content); // In a real implementation: topology.write_file(&self.score.path, content); }, None => { println!("File interpret is reading from {}", self.score.path); // In a real implementation: let content = topology.read_file(&self.score.path); } } } } fn main() { // Create our topologies let linux = LinuxHostTopology { hostname: "server1.example.com".to_string() }; let bare_metal = BareMetalTopology { device_id: "device001".to_string() }; // Create our maestros let linux_maestro = Maestro::new(linux); let bare_metal_maestro = Maestro::new(bare_metal); // Create scores let command_score = CommandScore::new( "List Files".to_string(), vec!["ls".to_string(), "-la".to_string()] ); let file_read_score = FileScore::new_read( "Read Config".to_string(), "/etc/config.json".to_string() ); // This will work because LinuxHostTopology implements CommandExecution linux_maestro.execute_score(command_score.clone()); // This will work because LinuxHostTopology implements FileSystem linux_maestro.execute_score(file_read_score.clone()); // This will work because BareMetalTopology implements FileSystem bare_metal_maestro.execute_score(file_read_score); // This would NOT compile because BareMetalTopology doesn't implement CommandExecution: // bare_metal_maestro.execute_score(command_score); // The error would occur at compile time, ensuring type safety println!("All scores executed successfully!"); }