Option go lang implementation

A container struct which may not contain a non-null value. If a value is present, IsPresent() will return true and Get() will return the value. Additional methods that depend on the presence or absence of a contained value are provided, such as OrElse() (return a default value if value not present).

Methods

empty

Returns an empty Option instance. No value is present for this Option. Returns:

an empty Option

usage:

emptyOption := option.empty()

Of

Returns an Option with the specified present non-null value.

Returns:

an Optional with the value present

usage:

optionInstance := option.Of("test")

Get

If a value is present in this Option, returns the value, otherwise return None

Returns:

the non-null value held by this Option

usage:

 optionInstance := option.Of("test")
 optionValue := optionInstance.Get()

IsPresent

Return true if there is a value present, otherwise false.

Returns:

true if there is a value present, otherwise false

usage:

 optionInstance := option.Of("test")
 isPresent := optionInstance.IsPresent()

OrElse

Return the value if present, otherwise return other.

Returns:

Return the value if present, otherwise return other.

usage:

 emptyOption := option.empty()
 optionValue := optionInstance.OrElse("myDefaultValue")

OrElseError

Return the contained value, if present, otherwise returns error

Returns:

Return the contained value, if present, otherwise returns error

usage:

emptyOption := option.empty()
err := optionInstance.OrElseError(errors.New("My custom error"))

or

optionInstance := option.Of("test")
value := optionInstance.OrElseError(errors.New("My custom error"))

Filter

Returns this option if present and math with the given predicate, otherwise returns None

There are some predicates available. Have a look file option/predicates.go but you could develop your own ones. Just follow this signature

type Predicate func(interface{}) bool

Returns:

Returns this option if present and math with the given predicate, otherwise returns None

usage:

option := Of(1)
optionValue := optionInstance.Filter(equalInt(1))

Note: equalInt is a predefined predicate created as an example of how to use the type Predicate type Predicate func(interface{}) bool. You could have a look how is implemented and develop your own predicates for your custom struts.

FilterNot

Returns this option if present and not math with the given predicate, otherwise returns None

There are some predicates available. Have a look file option/predicates.go but you could develop your own ones. Just follow this signature

type Predicate func(interface{}) bool

• Input interface represents the option value.
• output bool represents if there are a value that match with the given inputValue

Returns:

Returns this option if present and not math with the given predicate, otherwise returns None

usage:

option := Of(2)
optionValue := optionInstance.FilterNot(equalInt(1))

Note: equalInt is a predefined predicate created as an example of how to use the type Predicate type Predicate func(interface{}) bool. You could have a look how is implemented and develop your own predicates for your custom struts.

Find

Finds elements of an array satisfying a finder function. If any element match with the given function then returns None.

There are some finders available. Have a look file option/finders.go but you could develop your own ones. Just follow this signature

type Finder func(interface{}) (bool, interface{})

• Input interface represents the option value.
• output bool represents if there are a value that match with the given inputValue
• output interface represents the value or values that match with the inputValue

Returns:

Returns this option or a slice of this option if present and math with the given finder function, otherwise returns None

usage:

option := Of([]int{2, 3, 5, 7, 11, 13})
result := option.Find(FindElemIntArrayGreaterThan(5))

Note: FindElemIntArrayGreaterThan is a predefined finder created as an example of how to use the type finder type Finder func(interface{}) (bool, interface{}). You could have a look how is implemented and develop your own finders for your custom struts.

Map

apply a f action function to option value.

There are some actions function available. Have a look file option/actions.go but you could develop your own ones. Just follow this signature

type Action func(interface{}) (err error, result interface{})

• Input interface represents the option value.
• output error represents if there are any error in the mapping action
• output interface represents the option value mapped

Returns:

Returns input interface (option.value) mapped by an action function

usage:

option := Of([]string{"madrid", "toledo"})
option.Map(UpperCaseArrayString())
result := option.Get()

Note: UpperCaseString is a predefined action created as an example of how to use the type action type Action func(interface{}) (err error, result interface{}). You could have a look how is implemented and develop your own actions for your custom struts.