README
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errors
errors is an extension of and drop in replacement for the standard library
errors package. Multiple errors can be composed into a single error with the
Compose function, or a single error can be extended by adding context using
the Extend function. The result can be checked for the presense of a specific
error using Contains. If any of the underlying composed or extended errors or
extensions match, Contains will return true.
This package is especially beneficial during testing, where you may wish to check for presense of a specific error, but that specific error may be extending another error or may have been extended by another function somewhere else in the call stack.
Example:
var errOne = errors.New("one")
var errTwo = errors.New("two")
_, errDNE = os.Open("file.txt")
extended := errors.Extend(errOne, errDNE) // "[one; open file.txt: no such file or directory]"
extended2 := errors.Extend(errTwo, extended) // "[two; one; open file.txt: no such file or directory]"
errors.IsOSNotExist(extended) // true
errors.Contains(extended, errDNE) // true
errors.Contains(extended, errOne) // true
errors.Contains(extended, errTwo) // false
errors.Contains(extended2, errTwo) // true
The Compose function works similarly to extend, however instead of simply
combining the two errors into a joined set, a new Error is created that contains
both underlying errors individually. The Contains and IsOSNotExist functions
will still work as expected, returning true if they apply to any of the nested
underlying errors.
var errOne = errors.New("one")
var errTwo = errors.New("two")
composed := errors.Compose(errOne, errTwo) // "[[one]; [two]]"
composed2 := errors.Compose(errOne, errors.Extend(errTwo, errTwo)) // "[[one]; [two; two]]"
errors.Contains(composed2, errTwo) // true
Documentation
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Overview ¶
Package errors is an extension of and drop in replacement for the standard library errors package. Multiple errors can be composed into a single error, and single errors can be extended with new errors or with context. You can also check whether any of the extensions or compositions contains a certain error, allowing for more flexible error handling for complex processes.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func AddContext ¶
AddContext will add a string context to an error if the error is not nil. If the error is nil, then nil will be returned regardless of the context.
func Compose ¶
Compose will compose all errors together into a single error, remembering each component error so that they can be checked for matches later using the `Contains` function.
Any `nil` input errors will be ignored. If all input errors are `nil`, then `nil` will be returned.
func Contains ¶
Contains will check whether the base error contains the cmp error. If the base err is a Error, then it will check whether there is a match on any of the underlying errors.
func Extend ¶
Extend will extend the first error with the second error, remembering each component error so that they can be checked for matches later using the `Contains` function.
Any `nil` input will be ignored. If both inputs are `nil, then `nil` will be returned.
func IsOSNotExist ¶
IsOSNotExist returns true if any of the errors in the underlying composition return true for os.IsNotExist.
Source Files