Macro gerr 

macro_rules! gerr {
    ($message:literal $(,)?) => { ... };
    ($fmt:literal, $($arg:expr),+ $(,)?) => { ... };
    ($message:expr $(,)?) => { ... };
    (
        $message:literal ;
        $($rest:tt)*
    ) => { ... };
    (
        $fmt:literal, $($arg:expr),+ ;
        $($rest:tt)*
    ) => { ... };
    (
        $message:expr ;
        $($rest:tt)*
    ) => { ... };
    (@build $err:ident) => { ... };
    (@build $err:ident,) => { ... };
    (
        @build $err:ident,
        config
        $(, $($rest:tt)*)?
    ) => { ... };
    (
        @build $err:ident,
        config = $config:ty
        $(, $($rest:tt)*)?
    ) => { ... };
    (
        @build $err:ident,
        id = $id:expr
        $(, $($rest:tt)*)?
    ) => { ... };
    (
        @build $err:ident,
        code = $code:expr
        $(, $($rest:tt)*)?
    ) => { ... };
    (
        @build $err:ident,
        data_type
        $(, $($rest:tt)*)?
    ) => { ... };
    (
        @build $err:ident,
        data_type = $data_type:ty
        $(, $($rest:tt)*)?
    ) => { ... };
    (
        @build $err:ident,
        data = $data:expr
        $(, $($rest:tt)*)?
    ) => { ... };
    (
        @build $err:ident,
        source = $source:expr
        $(, $($rest:tt)*)?
    ) => { ... };
    (
        @build $err:ident,
        gerr = $source:expr
        $(, $($rest:tt)*)?
    ) => { ... };
    (
        @build $err:ident,
        tag = $tag:expr
        $(, $($rest:tt)*)?
    ) => { ... };
    (
        @build $err:ident,
        tags = $tags:expr
        $(, $($rest:tt)*)?
    ) => { ... };
    (
        @build $err:ident,
        help = $help:expr
        $(, $($rest:tt)*)?
    ) => { ... };
}

GErr macro.

Creates GErr easily with formatting support and rich data.

Without metadatas, the default config is DefaultConfig and default data is NoData.

Format

• Without formatting and without metadata: gerr!("error message goes here");.
• Without formatting and with metadata: gerr!("error message goes here"; <metadata>), metadata are separated by ;.
• With formatting and with metadata: gerr!("error message goes here {}", 123; <metadata>), formatting args are separated by , and metadata by ;.

Error message and its metadata are separated by ;.

Metadata’s items are separated by ,.

Supported metadata

• config: infer auto-generating config type from return type.
• config=$type: set auto-generating config type.
• id=$expr: set id manually with id type as set by config=$type.
• code=$expr: set code string.
• data_type: infer error data type from return type.
• data_type=$type: define error data type.
• data=$expr: set data, along with its type.
• source=$expr: set non-GErr error source.
• gerr=$expr: set GErr error source, or any error convertible to GErrSource.
• tag=$expr: add tag.
• tags=$expr: add multiple tags, e.g: ["tag1", "tag2",...].
• help=$expr: set help message.

You can override the metadatas, and latest ones will be used.

NOTE

The order of config param matters because it calls .with_config method which will regenerate values from new config type.

Example

use g_err::{gerr, Config};

struct U32;
impl Config for U32 {
    type Id = u32;
}

let inner = gerr!("parsing integer");
let external_error = "anu".parse::<i32>().unwrap_err();
let err = gerr!(
    "failed {}",
    500;
    config=U32,
    id = 999, // set id
    code = "HTTP", // set code
    tag = "server", // set a tag
    tags = ["api", "v1"], // set tags
    data = "payload", // set error data
    code = "E-HTTP", // update code
    source = external_error, // set general error as source
    gerr = inner, // set `Into<GErrSource>` error as source
    help = "Try parsing valid signed integer 32", // set help hint
);

assert_eq!(err.message(), "failed 500");
assert_eq!(err.id().unwrap(), &999);
assert_eq!(err.code(), Some("E-HTTP"));
assert_eq!(err.data(), Some(&"payload"));

let tags = err.tags().unwrap();
assert_eq!(tags.len(), 3);

let sources = err.sources().unwrap();
assert_eq!(sources.len(), 2);