create Facade page and link to main Readme

README.md

@@ -28,7 +28,7 @@ A curated collection of idiomatic design & application patterns for Go language.
 | [Bridge](/structural/bridge.md) | Decouples an interface from its implementation so that the two can vary independently | ✘ |
 | [Composite](/structural/composite.md) | Encapsulates and provides access to a number of different objects | ✘ |
 | [Decorator](/structural/decorator.md) | Adds behavior to an object, statically or dynamically | ✔ |
-| [Facade](/structural/facade.md) | Uses one type as an API to a number of others | ✘ |
+| [Facade](/structural/facade.md) | Uses one type as an API to a number of others | ✔ |
 | [Flyweight](/structural/flyweight.md) | Reuses existing instances of objects with similar/identical state to minimize resource usage | ✘ |
 | [Proxy](/structural/proxy.md) | Provides a surrogate for an object to control it's actions | ✔ |
 

structural/facade.md

@@ -0,0 +1,75 @@
+# Facade Pattern
+
+[Façade pattern](https://en.wikipedia.org/wiki/Facade_pattern) provides a simplified interface to a complex subsystem.
+
+## Implementation
+
+`LogDecorate` decorates a function with the signature `func(int) int` that
+manipulates integers and adds input/output logging capabilities.
+
+```go
+// Subsystem1 represents a complex subsystem
+type Subsystem1 struct{}
+
+func (s *Subsystem1) Operation1() {
+    fmt.Println("Subsystem1: Operation1")
+}
+
+// Subsystem2 represents another complex subsystem
+type Subsystem2 struct{}
+
+func (s *Subsystem2) Operation2() {
+    fmt.Println("Subsystem2: Operation2")
+}
+
+// Subsystem3 represents yet another complex subsystem
+type Subsystem3 struct{}
+
+func (s *Subsystem3) Operation3() {
+    fmt.Println("Subsystem3: Operation3")
+}
+
+// Facade provides a simplified interface to the complex subsystems
+type Facade struct {
+    subsystem1 *Subsystem1
+    subsystem2 *Subsystem2
+    subsystem3 *Subsystem3
+}
+
+func NewFacade() *Facade {
+    return &Facade{
+        subsystem1: &Subsystem1{},
+        subsystem2: &Subsystem2{},
+        subsystem3: &Subsystem3{},
+    }
+}
+
+func (f *Facade) OperationA() {
+    fmt.Println("Facade: OperationA")
+    f.subsystem1.Operation1()
+    f.subsystem2.Operation2()
+}
+
+func (f *Facade) OperationB() {
+    fmt.Println("Facade: OperationB")
+    f.subsystem2.Operation2()
+    f.subsystem3.Operation3()
+}
+```
+
+## Usage
+
+```go
+func main() {
+    facade := NewFacade()
+    facade.OperationA()
+    facade.OperationB()
+}
+```
+
+1. _Subsystem1_, _Subsystem2_, and _Subsystem3_ represent complex subsystems with their own operations.
+1. The _Facade_ struct provides a simplified interface to these subsystems.
+1. The _NewFacade_ function initializes the subsystems and returns a new instance of the Facade.
+1. The _Facade_ struct has methods _OperationA_ and _OperationB_ that internally call the operations of the subsystems, providing a simplified interface to the client
+
+This way, the client code can interact with the Facade instead of dealing with the complexities of the subsystems directly