[−][src]Derive Macro compound_error::CompoundError

#[derive(CompoundError)]
{
    // Attributes available to this derive:
    #[compound_error]
}

Implement CompoundError functionality for the target type.

If the target is an enum, From is implemented for each variant. Additionally, variants can be annotated with #[compound_error( inline_from(X) )] to specify that an "inlining from X" should be implemented. In addition to the From impls, by default also std::error::Error and std::fmt::Display are implemented for the target type. If the target type is a struct, no From impls, but only std::error::Error and std::fmt::Display impls are generated.

The generation of the Error and Display impls can by suppressed by specifying #[compound_error( skip_error )] and #[compound_error( skip_display )] on the target type.

If the target type is an enum, all variants must take exactly one argument. By default, this argument must implement std::error::Error. This can be circumvented by either specifying the skip_error attribute on the target type or by specifying the no_source attribute on the respective variant. no_source causes None to be returned by the implementation of std::error::Error::source() on the target type for the respective enum variant.

Attributes

Attributes are specified in the following form:

#[compound_error( attr1, attr2, attr3, ... )]
#[compound_error( attr4, attr5, ... )]
<ELEMENT>

<ELEMENT> can be the target type or an enum variant. The following attributes are available:

On the target type:

  • title = "<title>": Set the title of this error to "<title>". This is relevant for the automatic Display implementation on the target type.
  • description = "<description>": Set the description of this error to "<description>". This is relevant for the automatic Display implementation on the target type.
  • skip_display: Skip the automatic implementation of std::fmt::Display on the target type.
  • skip_error: Skip the automatic implementation of std::error::Error on the target type.

On each enum variant:

  • inline_from(A,B,C,...): Inline the Errors A, B, C, ... in the target type.
  • no_source: Return None from <Self as std::error::Error>::source() for this enum variant. This lifts the requirement that std::error::Error is implemented for the argument of this variant.
  • convert_source(fn): Applies fn to the error of this variant before returing it from <Self as std::error::Error>::source()