Macro gerr 

macro_rules! gerr {
    ($fmt:literal $(, $arg:expr)* $(,)?) => { ... };
    ($message:expr $(,)?) => { ... };
    (
        $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.

Error message and its metadata are separated by ;.

Supported metadata

• config: infer auto-generating config type for id and code from return type, and auto-generate both.
• config=$type: set auto-generating config type for id and code, and auto-generate both.
• id=$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 id and code.

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);