confide

#[confide] is a proc-macro for config structs: generates Default + Debug with serde defaults in one attribute.

Quick Start

use confide::confide;
use std::time::Duration;

#[confide]
pub struct MyConfig {
    #[confide(default = 8080)]
    pub port: u16,

    #[confide(default_duration = "30s")]
    pub timeout: Duration,

    #[confide(default_bytes = "1 MiB")]
    pub buffer_size: u64,

    #[confide(default)]
    pub mode: String,

    #[confide(default = "127.0.0.1".to_string(), secret)]
    pub bind_address: String,
}

This generates Default, Debug, and per-field #[serde(default = ...)] so missing keys in config files are filled in automatically.

Macro Arguments

Argument	Effect
(none)	Generates both Default and Debug
no_default	Suppresses impl Default
no_debug	Suppresses impl Debug

Combine freely: #[confide(no_default, no_debug)].

Field Annotations

#[confide(default)]

Use the type's Default::default(). Adds #[serde(default)].

#[confide(default = expr)]

Use the given Rust expression. If the expression is a bare path (e.g. Vec::new), serde calls it directly. Otherwise a hidden helper function is generated.

#[confide(default = vec![1, 2, 3])]
pub allowed_ports: Vec<u16>,

#[confide(default = 42)]
pub retries: u32,

#[confide(default_duration = "...")]

Parse a humantime duration string at compile time. The field type should be std::time::Duration. The generated code also adds #[serde(with = "confide::humantime_serde")] so durations serialize as human-readable strings like "5m" / "2h".

#[confide(default_duration = "10s")]
pub heartbeat: Duration,

#[confide(default_bytes = "...")]

Parse a bytesize string at compile time. The field should be an integer type (u64, u32, usize, etc.). Serialization produces IEC-formatted strings (e.g. "1 MiB"); deserialization accepts both raw integers and strings like "500 KB" / "2 GiB".

#[confide(default_bytes = "16 MiB")]
pub max_size: u64,

#[confide(secret)]

Masks the field in Debug output (shows "***"). The field is still serialized/deserialized normally.

#[confide(default = "".to_string(), secret)]
pub api_key: String,

Multiple annotations can be combined: #[confide(default_bytes = "1 MiB", secret)].

Requirements

• Named fields only. Tuple structs and unit structs are not supported.
• Every field needs a default annotation unless you pass no_default to the macro. Without it the generated Default impl will be incomplete.
• The serde crate must be in scope (as a dependency of your crate) for #[serde(...)] attributes to resolve.
• The confide crate must be in your dependencies for generated code references confide::humantime_serde and confide::bytesize::ByteSize at runtime.

License

Licensed under either of Apache License 2.0 or MIT license at your option.