feat(take): Added take() method for single-use values

KrishnaPG · KrishnaPG · commit 7c3be0d8fd7d · 2019-11-27T08:05:39.000+05:30
Closes #159
diff --git a/_src/lib/node_cache.coffee b/_src/lib/node_cache.coffee
@@ -287,6 +287,26 @@ module.exports = class NodeCache extends EventEmitter
 
 		return delCount
 
+	# ## take
+	#
+	# get the cached value and remove the key from the cache.
+	# Equivalent to calling `get(key)` + `del(key)`.
+	# Useful for implementing `single use` mechanism such as OTP, where once a value is read it will become obsolete.
+	#
+	# **Parameters:**
+	#
+	# * `key` ( String | Number ): cache key
+	#
+	# **Example:**
+	#
+	#	myCache.take "myKey", ( err, val )
+	#
+	take: ( key )=>
+		_ret = @get(key)
+		if (_ret) 
+			@del(key)
+		return _ret
+
 	# ## ttl
 	#
 	# reset or redefine the ttl of a key. `ttl` = 0 means infinite lifetime.
diff --git a/_src/test/mocha_test.coffee b/_src/test/mocha_test.coffee
@@ -70,6 +70,7 @@ describe "`#{pkg.name}@#{pkg.version}` on `node@#{process.version}`", () ->
 					b:
 						x: 2
 						y: 3
+				otp: randomString 10
 			return
 
 		it "set key", () ->
@@ -103,6 +104,50 @@ describe "`#{pkg.name}@#{pkg.version}` on `node@#{process.version}`", () ->
 			0.should.eql count
 			return
 
+		it "take key", () ->
+			# make sure we are starting fresh
+			res = localCache.has("otp")
+			res.should.eql false
+
+			# taking a non-exitent value should be fine
+			res = localCache.take("otp")
+			should.not.exist(res)
+
+			# check if otp insertion suceeded
+			res = localCache.set "otp", state.otp, 0
+			true.should.eql res
+
+			# are we able to check the presence of the key?
+			res = localCache.has("otp")
+			res.should.eql true
+
+			# not once, but twice?
+			# This proves that keys can be accessed as many times as required, but 
+			# not the value. The `take()` method makes the values as single-read, not the keys.
+			res = localCache.has("otp")
+			res.should.eql true
+
+			# take the value
+			otp = localCache.take("otp")
+			otp.should.eql state.otp
+
+			# key should not be present anymore once the value is read
+			res = localCache.has("otp")
+			res.should.eql false
+
+			# and, re-insertions are not probhitied
+			res = localCache.set "otp", "some other value"
+			true.should.eql res
+
+			# should be able take the value again
+			otp = localCache.take("otp")
+			otp.should.eql "some other value"
+
+			# key should not be present anymore, again
+			res = localCache.has("otp")
+			res.should.eql false					
+			return
+
 		it "update key (and get it to check if the update worked)", () ->
 			res = localCache.set state.key, state.value2, 0
 			true.should.eql res
diff --git a/package.json b/package.json
@@ -51,7 +51,7 @@
     "node": ">= 0.4.6"
   },
   "scripts": {
-    "test": "COFFEECOV_INIT_ALL=false mocha --require coffee-script/register --require coffee-coverage/register-istanbul _src/test/mocha_test.coffee -R spec && tsc",
+    "test": "mocha --require coffee-script/register --require coffee-coverage/register-istanbul _src/test/mocha_test.coffee -R spec && tsc",
     "build": "grunt build"
   },
   "dependencies": {
