mirror of
https://github.com/crazybber/awesome-patterns.git
synced 2024-11-25 22:36:05 +03:00
62 lines
1.1 KiB
Markdown
62 lines
1.1 KiB
Markdown
# Builder Pattern
|
|
|
|
Builder pattern separates the construction of a complex object from its
|
|
representation so that the same construction process can create different
|
|
representations.
|
|
|
|
In Go, normally a configuration struct is used to achieve the same behavior,
|
|
however passing a struct to the builder method fills the code with boilerplate
|
|
`if cfg.Field != nil {...}` checks.
|
|
|
|
## Implementation
|
|
|
|
```go
|
|
package car
|
|
|
|
type Speed float64
|
|
|
|
const (
|
|
MPH Speed = 1
|
|
KPH = 1.60934
|
|
)
|
|
|
|
type Color string
|
|
|
|
const (
|
|
BlueColor Color = "blue"
|
|
GreenColor = "green"
|
|
RedColor = "red"
|
|
)
|
|
|
|
type Wheels string
|
|
|
|
const (
|
|
SportsWheels Wheels = "sports"
|
|
SteelWheels = "steel"
|
|
)
|
|
|
|
type Builder interface {
|
|
Color(Color) Builder
|
|
Wheels(Wheels) Builder
|
|
TopSpeed(Speed) Builder
|
|
Build() Interface
|
|
}
|
|
|
|
type Interface interface {
|
|
Drive() error
|
|
Stop() error
|
|
}
|
|
```
|
|
|
|
## Usage
|
|
|
|
```go
|
|
assembly := car.NewBuilder().Paint(car.RedColor)
|
|
|
|
familyCar := assembly.Wheels(car.SportsWheels).TopSpeed(50 * car.MPH).Build()
|
|
familyCar.Drive()
|
|
|
|
sportsCar := assembly.Wheels(car.SteelWheels).TopSpeed(150 * car.MPH).Build()
|
|
sportsCar.Drive()
|
|
```
|