eidiom

Documentation

Index

• type Closer
• type Outcome
• type UnconfirmedOutcome

Types

type Closer

type Closer interface {
	Close() error
}

type Outcome

type Outcome interface {
	// Stringer Outcome instance returns empty string if an operation succeed, otherwise returns an error string.
	fmt.Stringer

	// IsOk Returns true if an operation succeed.
	IsOk() bool

	// IfOk Perform f if an operation succeed, otherwise does nothing.
	IfOk(f func())

	// IsError Returns true if an operation got an error.
	IsError() bool

	// IfError Perform f if an operation got an error, otherwise does nothing.
	IfError(f func() Outcome) Outcome

	// Cause Return Outcome as an error instance if an operation got an error, otherwise returns nil.
	Cause() error
}

Outcome is the alternative for the `error`. Outcome instance must not be nil. And Outcome implementation should implement specific error cases with the prefix `IsXxx`. For example: file operation.

type FileCreateOutcome interface {
  Outcome
  IsPermissionDenied() bool
  IsInvalidPath() bool
  IsOperationNotAllowed() bool
}

Consumer can handle errors like below.

f, out := file.Create("/path/to/create")
switch {
case out.IsOk():
    // success
case out.IsPermissionDenied(), out.IsOperationNotAllowed():
    // handle permission issue
case out.IsInvalidPath():
    // handle path issue
default:
    // handle other errors
}

type UnconfirmedOutcome

type UnconfirmedOutcome interface {
	// HasError Returns true if an operation got at least one error.
	HasError() bool

	// IfError Perform f if an operation got at least one error, otherwise does nothing.
	IfError(f func() UnconfirmedOutcome) UnconfirmedOutcome

	// Cause Returns an error if UnconfirmedOutcome has as an obvious error (such as network error for REST call),
	// otherwise returns nil.
	// Inherited UnconfirmedOutcome interface should define a function like additional information like
	// StatusCode(), LastErr(), etc.
	Cause() error
}

UnconfirmedOutcome is similar to Outcome, that replaces `error`. But UnconfirmedOutcome does not include the operation's actual result. For example, when REST api client interface got a network error, that is obviously error. However, if a REST API call result contains an error, the caller need to verify response body or status code to determine the operation succeed or not.