From c58a2063660ecbc21f854600129d81660d2ece14 Mon Sep 17 00:00:00 2001
From: Tamer Tas <contact@tmrts.com>
Date: Tue, 15 Dec 2015 00:31:23 +0200
Subject: [PATCH] Add template design pattern

---
 README.md   | 50 +++++++++++++++++++++++++++++++++++++++++++++++++-
 template.go | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+), 1 deletion(-)
 create mode 100644 template.go

diff --git a/README.md b/README.md
index 8f3937a..36acac4 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,50 @@
 # awesome-go-patterns
- A curated list of Go desing patterns
+ A collection of Go design patterns/idioms
+ 
+Current Patterns:
+
+__Creational Patterns__:
+
+| Pattern | Description |
+|:-------:| ----------- |
+| [abstract_factory](abstract_factory.go) | use a generic function with specific factories |
+| [borg](borg.go) | a singleton with shared-state among instances |
+| [builder](builder.go) | instead of using multiple constructors, builder object receives parameters and returns constructed objects |
+| [factory_method](factory_method.go) | delegate a specialized function/method to create instances |
+| [lazy_evaluation](lazy_evaluation.go) | lazily-evaluated property pattern in Go |
+| [pool](pool.go) | preinstantiate and maintain a group of instances of the same type |
+| [prototype](prototype.go) | use a factory and clones of a prototype for new instances (if instantiation is expensive) |
+
+__Structural Patterns__:
+
+| Pattern | Description |
+|:-------:| ----------- |
+| [3-tier](3-tier.go) | data<->business logic<->presentation separation (strict relationships) |
+| [adapter](adapter.go) | adapt one interface to another using a white-list |
+| [bridge](bridge.go) | a client-provider middleman to soften interface changes |
+| [composite](composite.go) | encapsulate and provide access to a number of different objects |
+| [decorator](decorator.go) | wrap functionality with other functionality in order to affect outputs |
+| [facade](facade.go) | use one class as an API to a number of others |
+| [flyweight](flyweight.go) | transparently reuse existing instances of objects with similar/identical state |
+| [front_controller](front_controller.go) | single handler requests coming to the application |
+| [mvc](mvc.go) | model<->view<->controller (non-strict relationships) |
+| [proxy](proxy.go) | an object funnels operations to something else |
+
+__Behavioral Patterns__:
+
+| Pattern | Description |
+|:-------:| ----------- |
+| [chain](chain.go) | apply a chain of successive handlers to try and process the data |
+| [catalog](catalog.go) | general methods will call different specialized methods based on construction parameter |
+| [chaining_method](chaining_method.go) | continue callback next object method |
+| [command](command.go) | bundle a command and arguments to call later |
+| [mediator](mediator.go) | an object that knows how to connect other objects and act as a proxy |
+| [memento](memento.go) | generate an opaque token that can be used to go back to a previous state |
+| [observer](observer.go) | provide a callback for notification of events/changes to data |
+| [publish_subscribe](publish_subscribe.go) | a source syndicates events/data to 0+ registered listeners |
+| [registry](registry.go) | keep track of all subclasses of a given class |
+| [specification](specification.go) |  business rules can be recombined by chaining the business rules together using boolean logic |
+| [state](state.go) | logic is organized into a discrete number of potential states and the next state that can be transitioned to |
+| [strategy](strategy.go) | selectable operations over the same data |
+| [template](template.go) | an object imposes a structure but takes pluggable components |
+| [visitor](visitor.go) | invoke a callback for all items of a collection |
diff --git a/template.go b/template.go
new file mode 100644
index 0000000..d9563ea
--- /dev/null
+++ b/template.go
@@ -0,0 +1,48 @@
+// In Template pattern, an abstract struct exposes defined way(s)/template(s)
+// to execute its methods. This pattern comes under behavior pattern category.
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+type Operator interface {
+	Apply(int, int) int
+}
+
+type Operation struct {
+	Operator Operator
+}
+
+func (o *Operation) Operate(leftValue, rightValue int) int {
+	return o.Operator.Apply(leftValue, rightValue)
+}
+
+type Multiplication struct{}
+
+func (_ Multiplication) Apply(lval, rval int) int {
+	return lval * rval
+}
+
+type Pow struct{}
+
+func (_ Pow) Apply(lval, rval int) int {
+	return int(math.Pow(float64(lval), float64(rval)))
+}
+
+func main() {
+	mult := Operation{
+		Operator: Multiplication{},
+	}
+
+	// Outputs 15
+	fmt.Println(mult.Operate(3, 5))
+
+	pow := Operation{
+		Operator: Pow{},
+	}
+
+	// Outputs 243
+	fmt.Println(pow.Operate(3, 5))
+}