README
¶
Optional
Optional is a tool that generates 'optional' type wrappers around a given type T.
It is also a library that provides optional types for the primitive Go types.
Motivation
Ever had to write a test where you want to assert something only if a value is present?
tests := []struct {
catchPhrase string
catchPhrasePresent bool
} {
{ "wubba dub dub", true },
{ "", false },
}
...
if test.catchPhrasePresent {
assert.Equal(t, test.catchPhrase, catchPhrase)
}
Now you can simplify all that with optional types:
tests := []struct {
catchPhrase optional.String
} {
{ optional.OfString("wubba dub dub") },
{ optional.EmptyString() },
}
}
...
if test.catchPhrase.Present() {
assert.Equal(t, test.catchPhrase.Get(), catchPhrase)
}
Inspiration
- Java Optional
- https://github.com/leighmcculloch/go-optional
- https://github.com/golang/go/issues/7054
Tool
Install
go get -u github.com/markphelps/optional/cmd/optional
Usage
Typically this process would be run using go generate, like this:
//go:generate optional -type=Foo
running this command:
optional -type=Foo
in the same directory will create the file optional_foo.go containing a definition of:
type OptionalFoo struct {
...
}
The default type is OptionalT or optionalT (depending on if the type is exported) and output file is optional_t.go. This can be overridden with the -output flag.
Library
- bool
- byte
- complex128
- complex64
- float32
- float64
- int
- int16
- int32
- int64
- int8
- rune
- string
- uint
- uint16
- uint32
- uint64
- uint8
- uintptr
- error
Usage
import (
"fmt"
"github.com/markphelps/optional"
)
s := optional.OfString("foo")
if s.Present() {
fmt.Println(s.Get())
}
t := optional.EmptyString()
fmt.Println(t.OrElse("bar"))
See example_test.go and the documentation for more usage.
Contributing
- Fork it (https://github.com/markphelps/optional/fork)
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create a new Pull Request
Documentation
¶
Overview ¶
Example (Get) ¶
package main
import (
"fmt"
"github.com/markphelps/optional"
)
func main() {
values := []optional.String{
optional.OfString("foo"),
optional.OfString(""),
optional.OfString("bar"),
optional.EmptyString(),
}
for _, v := range values {
if v.Present() {
fmt.Println(v.Get())
}
}
}
Output: foo bar
Example (If) ¶
package main
import (
"fmt"
"github.com/markphelps/optional"
)
func main() {
values := []optional.String{
optional.OfString("foo"),
optional.OfString(""),
optional.OfString("bar"),
optional.EmptyString(),
}
for _, v := range values {
v.If(func(s string) {
fmt.Println("present")
})
}
}
Output: present present present
Example (OrElse) ¶
package main
import (
"fmt"
"github.com/markphelps/optional"
)
func main() {
values := []optional.String{
optional.OfString("foo"),
optional.OfString(""),
optional.OfString("bar"),
optional.EmptyString(),
}
for _, v := range values {
fmt.Println(v.OrElse("not present"))
}
}
Output: foo bar not present
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Bool ¶
type Bool struct {
// contains filtered or unexported fields
}
Bool is an optional bool
type Byte ¶
type Byte struct {
// contains filtered or unexported fields
}
Byte is an optional byte
type Complex128 ¶
type Complex128 struct {
// contains filtered or unexported fields
}
Complex128 is an optional complex128
func EmptyComplex128 ¶
func EmptyComplex128() Complex128
EmptyComplex128 returns an empty optional.Complex128
func OfComplex128 ¶
func OfComplex128(c complex128) Complex128
OfComplex128 creates a optional.Complex128 from a complex128
func (*Complex128) If ¶ added in v0.2.0
func (o *Complex128) If(f func(c complex128))
If calls the function f with the value if the value is present
func (*Complex128) OrElse ¶
func (o *Complex128) OrElse(c complex128) complex128
OrElse returns the complex128 value or a default value if the value is not present
func (*Complex128) Present ¶
func (o *Complex128) Present() bool
Present returns whether or not the value is present
type Complex64 ¶
type Complex64 struct {
// contains filtered or unexported fields
}
Complex64 is an optional complex64
func EmptyComplex64 ¶
func EmptyComplex64() Complex64
EmptyComplex64 returns an empty optional.Complex64
func OfComplex64 ¶
OfComplex64 creates a optional.Complex64 from a complex64
func (*Complex64) If ¶ added in v0.2.0
If calls the function f with the value if the value is present
func (*Complex64) OrElse ¶
OrElse returns the complex64 value or a default value if the value is not present
type Error ¶
type Error struct {
// contains filtered or unexported fields
}
Error is an optional error
func (*Error) OrElse ¶
OrElse returns the error value or a default value if the value is not present
type Float32 ¶
type Float32 struct {
// contains filtered or unexported fields
}
Float32 is an optional float32
func (*Float32) OrElse ¶
OrElse returns the float32 value or a default value if the value is not present
type Float64 ¶
type Float64 struct {
// contains filtered or unexported fields
}
Float64 is an optional float64
func (*Float64) OrElse ¶
OrElse returns the float64 value or a default value if the value is not present
type Int ¶
type Int struct {
// contains filtered or unexported fields
}
Int is an optional int
type Int16 ¶
type Int16 struct {
// contains filtered or unexported fields
}
Int16 is an optional int16
func (*Int16) OrElse ¶
OrElse returns the int16 value or a default value if the value is not present
type Int32 ¶
type Int32 struct {
// contains filtered or unexported fields
}
Int32 is an optional int32
func (*Int32) OrElse ¶
OrElse returns the int32 value or a default value if the value is not present
type Int64 ¶
type Int64 struct {
// contains filtered or unexported fields
}
Int64 is an optional int64
func (*Int64) OrElse ¶
OrElse returns the int64 value or a default value if the value is not present
type Int8 ¶
type Int8 struct {
// contains filtered or unexported fields
}
Int8 is an optional int8
type Rune ¶
type Rune struct {
// contains filtered or unexported fields
}
Rune is an optional rune
type String ¶
type String struct {
// contains filtered or unexported fields
}
String is an optional string
func (*String) OrElse ¶
OrElse returns the string value or a default value if the value is not present
type Uint ¶
type Uint struct {
// contains filtered or unexported fields
}
Uint is an optional uint
type Uint16 ¶
type Uint16 struct {
// contains filtered or unexported fields
}
Uint16 is an optional uint16
func (*Uint16) OrElse ¶
OrElse returns the uint16 value or a default value if the value is not present
type Uint32 ¶
type Uint32 struct {
// contains filtered or unexported fields
}
Uint32 is an optional uint32
func (*Uint32) OrElse ¶
OrElse returns the uint32 value or a default value if the value is not present
type Uint64 ¶
type Uint64 struct {
// contains filtered or unexported fields
}
Uint64 is an optional uint64
func (*Uint64) OrElse ¶
OrElse returns the uint64 value or a default value if the value is not present
type Uint8 ¶
type Uint8 struct {
// contains filtered or unexported fields
}
Uint8 is an optional uint8
func (*Uint8) OrElse ¶
OrElse returns the uint8 value or a default value if the value is not present
type Uintptr ¶
type Uintptr struct {
// contains filtered or unexported fields
}
Uintptr is an optional uintptr
func (*Uintptr) OrElse ¶
OrElse returns the uintptr value or a default value if the value is not present
Source Files
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Directories
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| Path | Synopsis |
|---|---|
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cmd
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optional
Optional is a tool that generates 'optional' type wrappers around a given type T. Typically this process would be run using go generate, like this: //go:generate optional -type=Foo running this command optional -type=Foo in the same directory will create the file optional_foo.go containing a definition of type OptionalFoo struct { ...
|
Optional is a tool that generates 'optional' type wrappers around a given type T. Typically this process would be run using go generate, like this: //go:generate optional -type=Foo running this command optional -type=Foo in the same directory will create the file optional_foo.go containing a definition of type OptionalFoo struct { ... |