68 lines
1.7 KiB
Markdown
68 lines
1.7 KiB
Markdown
# Builder - fluent immutable builders for Go
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[](https://godoc.org/github.com/lann/builder)
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[](https://travis-ci.org/lann/builder)
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Builder was originally written for
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[Squirrel](https://github.com/lann/squirrel), a fluent SQL generator. It
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is probably the best example of Builder in action.
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Builder helps you write **fluent** DSLs for your libraries with method chaining:
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```go
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resp := ReqBuilder.
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Url("http://golang.org").
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Header("User-Agent", "Builder").
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Get()
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```
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Builder uses **immutable** persistent data structures
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([these](https://github.com/mndrix/ps), specifically)
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so that each step in your method chain can be reused:
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```go
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build := WordBuilder.AddLetters("Build")
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builder := build.AddLetters("er")
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building := build.AddLetters("ing")
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```
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Builder makes it easy to **build** structs using the **builder** pattern
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(*surprise!*):
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```go
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import "github.com/lann/builder"
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type Muppet struct {
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Name string
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Friends []string
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}
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type muppetBuilder builder.Builder
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func (b muppetBuilder) Name(name string) muppetBuilder {
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return builder.Set(b, "Name", name).(muppetBuilder)
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}
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func (b muppetBuilder) AddFriend(friend string) muppetBuilder {
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return builder.Append(b, "Friends", friend).(muppetBuilder)
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}
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func (b muppetBuilder) Build() Muppet {
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return builder.GetStruct(b).(Muppet)
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}
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var MuppetBuilder = builder.Register(muppetBuilder{}, Muppet{}).(muppetBuilder)
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```
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```go
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MuppetBuilder.
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Name("Beaker").
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AddFriend("Dr. Honeydew").
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Build()
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=> Muppet{Name:"Beaker", Friends:[]string{"Dr. Honeydew"}}
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```
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## License
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Builder is released under the
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[MIT License](http://www.opensource.org/licenses/MIT).
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