From bbb60799f88be20dff04d45a0bd9d02254e00a6d Mon Sep 17 00:00:00 2001
From: joeduffy <joeduffy@acm.org>
Date: Tue, 17 Jan 2017 15:58:11 -0800
Subject: [PATCH] Add a Require family of functions to pkg/util/contract

---
 pkg/util/contract/require.go | 30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)
 create mode 100644 pkg/util/contract/require.go

diff --git a/pkg/util/contract/require.go b/pkg/util/contract/require.go
new file mode 100644
index 000000000..f5985a8d7
--- /dev/null
+++ b/pkg/util/contract/require.go
@@ -0,0 +1,30 @@
+// Copyright 2016 Marapongo, Inc. All rights reserved.
+
+package contract
+
+import (
+	"fmt"
+)
+
+const requireMsg = "A precondition has failed for %v"
+
+// Require checks a precondition condition pertaining to a function parameter, and Fails if it is false.
+func Require(cond bool, param string) {
+	if !cond {
+		failfast(fmt.Sprintf(requireMsg, param))
+	}
+}
+
+// RequireM checks a precondition condition pertaining to a function parameter, and FailMs if it is false.
+func RequireM(cond bool, param string, msg string) {
+	if !cond {
+		failfast(fmt.Sprintf("%v: %v", fmt.Sprintf(requireMsg, param), msg))
+	}
+}
+
+// RequireMF checks a precondition condition pertaining to a function parameter, and FailMFs if it is false.
+func RequireMF(cond bool, param string, msg string, args ...interface{}) {
+	if !cond {
+		failfast(fmt.Sprintf("%v: %v", fmt.Sprintf(requireMsg, param), fmt.Sprintf(msg, args...)))
+	}
+}