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59 lines
1.0 KiB
Markdown
59 lines
1.0 KiB
Markdown
# Factory Method Pattern
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Factory method creational design pattern allows creating objects without having
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to specify the exact type of the object that will be created.
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## Implementation
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The example implementation shows how to provide a data store with different
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backends such as in-memory, disk storage.
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### Types
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```go
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package data
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import "io"
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type Store interface {
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Open(string) (io.ReadWriteCloser, error)
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}
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```
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### Different Implementations
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```go
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package data
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type StorageType int
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const (
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DiskStorage StorageType = 1 << iota
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TempStorage
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MemoryStorage
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)
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func NewStore(t StorageType) Store {
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switch t {
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case MemoryStorage:
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return newMemoryStorage( /*...*/ )
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case DiskStorage:
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return newDiskStorage( /*...*/ )
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default:
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return newTempStorage( /*...*/ )
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}
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}
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```
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## Usage
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With the factory method, the user can specify the type of storage they want.
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```go
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s, _ := data.NewStore(data.MemoryStorage)
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f, _ := s.Open("file")
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n, _ := f.Write([]byte("data"))
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defer f.Close()
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```
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