Attribute Macro error 

#[error]

Chain extension error.

Description

Using #[obce::error] you can generate custom chain extension errors.

Errors marked with #[obce::error] have Debug, Copy, Clone, PartialEq, Eq, scale::Encode and scale::Decode automatically derived for them.

#[obce::error]
enum Error {
    FirstError,
    SecondError(u32)
}

Critical errors

#[obce::error] can automatically generate SupportCriticalError implementation for variant that you mark with #[obce(critical)]:

use obce::substrate::CriticalError;

#[obce::error]
enum Error {
    FirstError,

    #[obce(critical)]
    Two(CriticalError)
}

Only one enum variant can be marked as #[obce(critical)].

RetVal-convertible errors

You can mark error variants with #[obce(ret_val = "...")] to create an implementation of TryFrom<YourError> for pallet_contracts::chain_extension::RetVal, which will automatically convert suitable error variants to RetVal on implementation methods marked with #[obce(ret_val)].

Error variant’s #[obce(ret_val = "...")] accepts an expression that evaluates to u32:

#[obce::error]
enum Error {
    #[obce(ret_val = "10_001")]
    First,

    Second
}