Display / Debug

Diagnostic only — not a stable wire or log schema. Do not treat either format as a protocol or long-term log contract.

Display currently equals Debug for generated decoders ({car} and {car:?} print the same text). Prefer Debug in logs if you want that intent to stay obvious when/if the two diverge later.

#![allow(unused)]
fn main() {
pub fn demo_display_debug(valid_car: &[u8]) -> Result<(), Box<dyn std::error::Error>> {
    let car = CarDecoder::try_from(valid_car)?;
    let display = format!("{car}");
    let debug = format!("{car:#?}");

    // Display is a compact one-liner; field names use the schema's camelCase.
    assert!(display.contains("serialNumber: 1234"));
    assert!(display.contains("modelYear: 2013"));
    assert!(display.contains("available: true"));
    assert!(display.contains(r#"code: A"#));
    assert!(display.contains("manufacturer: \"Honda\""));
    assert!(display.contains("model: \"Civic VTi\""));
    assert!(display.contains("fuelFigures: ["));
    assert!(display.contains("performanceFigures: ["));
    assert!(display.contains(r#"activationCode: "abcdef""#));

    // Pretty Debug ({:#?}) shows each field on its own line with indentation.
    for expected in &[
        "serialNumber: 1234",
        "modelYear: 2013",
        "available: true",
        r#"manufacturer: "Honda""#,
        r#"model: "Civic VTi""#,
        r#"activationCode: "abcdef""#,
        r#"usageDescription: Urban"#,
        "speed: 30",
        "mpg: 35.9",
        "octaneRating: 95",
    ] {
        assert!(
            debug.contains(expected),
            "Debug missing: {expected}\n--- full debug ---\n{debug}"
        );
    }

    // ── CarDomain DTO ───────────────────────────────────────────────────
    // Owned, heap-allocated, serialisable snapshot of the full message tree.
    // Generated by `with_domain_objects(DomainVarData::Strings)`.
    let dto = CarDomain::try_from_decoder(car)?;
    let dto_dbg = format!("{dto:#?}");
    // DTO field names use Rust snake_case (different from wire decoder camelCase).
    assert!(dto_dbg.contains("serial_number: 1234"));
    assert!(dto_dbg.contains("model_year: 2013"));
    assert!(dto_dbg.contains("available: true"));
    assert!(dto_dbg.contains("fuel_figures: ["));
    assert!(dto_dbg.contains(r#"usage_description: "Urban""#));
    assert!(dto_dbg.contains(r#"manufacturer: "Honda""#));
    assert!(dto_dbg.contains(r#"activation_code: "abcdef""#));

    Ok(())
}
}

(This code comes from the sbe-feature-tour sample crate.)

Real output from the feature-tour Car (demo_car_size_and_encode → CarDecoder):

CarDecoder { serialNumber: 1234, modelYear: 2013, available: true, code: A, fuelFigures: ["{ speed: 30, mpg: 35.9, usageDescription: Urban }", "{ speed: 60, mpg: 25.0, usageDescription: Highway }"], performanceFigures: ["{ octaneRating: 95, acceleration: [{ mph: 30, seconds: 4.0 }, { mph: 60, seconds: 7.5 }] }"], manufacturer: "Honda", model: "Civic VTi", activationCode: "abcdef" }

Truncated / incomplete buffers omit missing tails rather than panicking.