From f01e09337478f246b2b96d15a74c6283e81f09fe Mon Sep 17 00:00:00 2001
From: Steven Degutis <steven.degutis@gmail.com>
Date: Fri, 16 Mar 2012 07:46:12 -0500
Subject: [PATCH] interfaces

---
 about_interfaces.go | 28 ++++++++++++++++++++++++++++
 setup_koans_test.go |  4 ++--
 2 files changed, 30 insertions(+), 2 deletions(-)
 create mode 100644 about_interfaces.go

diff --git a/about_interfaces.go b/about_interfaces.go
new file mode 100644
index 0000000..589caa5
--- /dev/null
+++ b/about_interfaces.go
@@ -0,0 +1,28 @@
+package go_koans
+
+func testInterfaces() {
+  mspaint := &program{3} // mspaint is a kind of *program, which is a valid 'runner'
+  runOnce(mspaint) // runOnce takes an abstract 'runner' type
+
+  assert(mspaint.runTimes == __int__) // conformed interfaces need not be declared, they are inferred
+}
+
+// abstract interface and function that requires it
+
+type runner interface {
+  run()
+}
+
+func runOnce(r runner) {
+  r.run()
+}
+
+// concrete type implementing the interface
+
+type program struct {
+  runTimes int
+}
+
+func (self *program) run() {
+  self.runTimes++
+}
diff --git a/setup_koans_test.go b/setup_koans_test.go
index 328c5af..5b1e977 100644
--- a/setup_koans_test.go
+++ b/setup_koans_test.go
@@ -25,10 +25,10 @@ func TestKoans(t *testing.T) {
   //testEnumeration()
   //testAnonymousFunctions()
   //testVariadicFunctions()
-  testFiles()
+  //testFiles()
+  testInterfaces()
 
   // TODO: ie, gameplan
-  //testInterfaces()
   //testMaps()
   //testStructs()
   //testAllocation()