error-handling

🚨 RUST ERROR HANDLING STANDARDS

TL;DR: Comprehensive error handling guidelines using thiserror for libraries and anyhow for binaries, with centralized error definitions per crate.

🔍 ERROR HANDLING STRATEGY SELECTION

graph TD
    Project["Project Analysis"] --> CrateType{"Crate Type?"}

    CrateType -->|"lib"| LibCrate["Library Crate"]
    CrateType -->|"bin"| BinCrate["Binary Crate"]

    LibCrate --> ThiserrorChoice["Use thiserror"]
    BinCrate --> AnyhowChoice["Use anyhow"]

    ThiserrorChoice --> LibFeatures["Library Features:"]
    AnyhowChoice --> BinFeatures["Binary Features:"]

    LibFeatures --> Structured["• Structured errors"]
    LibFeatures --> Derived["• Derive Error trait"]
    LibFeatures --> Transparent["• Error forwarding"]
    LibFeatures --> Documentation["• Error documentation"]

    BinFeatures --> Simple["• Simple error handling"]
    BinFeatures --> Context["• Rich context"]
    BinFeatures --> Chaining["• Error chaining"]
    BinFeatures --> EndUser["• End-user messages"]

    style Project fill:#4da6ff,stroke:#0066cc,color:white
    style CrateType fill:#ffa64d,stroke:#cc7a30,color:white
    style LibCrate fill:#4dbb5f,stroke:#36873f,color:white
    style BinCrate fill:#d94dbb,stroke:#a3378a,color:white

📚 LIBRARY CRATE ERROR HANDLING (thiserror)

Error Definition Pattern

// lib_crate/src/errors.rs
use thiserror::Error;

#[derive(Error, Debug)]
pub enum MyLibError {
    #[error("Invalid input: {message}")]
    InvalidInput { message: String },

    #[error("File not found: {path}")]
    FileNotFound { path: String },

    #[error("Permission denied")]
    PermissionDenied,

    #[error("Network error")]
    Network(#[from] reqwest::Error),

    #[error("IO error")]
    Io(#[from] std::io::Error),

    #[error("Parse error: {0}")]
    Parse(#[from] serde_json::Error),

    #[error("Configuration error: {message}")]
    Config { message: String },

    #[error("Internal error: {0}")]
    Internal(String),
}

// Additional result type alias for convenience
pub type Result<T> = std::result::Result<T, MyLibError>;

// Error construction helpers
impl MyLibError {
    pub fn invalid_input(message: impl Into<String>) -> Self {
        Self::InvalidInput {
            message: message.into(),
        }
    }

    pub fn file_not_found(path: impl Into<String>) -> Self {
        Self::FileNotFound {
            path: path.into(),
        }
    }

    pub fn config(message: impl Into<String>) -> Self {
        Self::Config {
            message: message.into(),
        }
    }

    pub fn internal(message: impl Into<String>) -> Self {
        Self::Internal(message.into())
    }
}