This section of our beginning python training class always stumps students.  Firstly, because they need to know the difference between a function and a method.  Secondly, they need to understand object oriented programming concepts.  Thirdly, they need to realize that python has three types of methods.  Then they need to know how to use each method, which means they need to know the purpose of each method type.  Then they have to understand mutable versus non-mutable types.  The list goes on.  As part of our python tutorial, I hope to shed some light on this confusing topic.

To begin, the difference between a function and a method in python is that a method is defined within a class.  Here is an illustration:

#function

	def greeting():
	                print "Hello, I hope you're having a great day!"

	class HSGPrinter(object):
	                #method
	                def greeting(self): 
	                                print "Hello, I hope you're having a great day!"

As should be obvious, the second definition of greeting is encapsulated within the HSGPrinter class and is , therefore, refered to as a method.

The astute reader will notice that the greeting method contains one parameter named self.  For those who know C++ , Java or C#, self is equivalent to this i.e. it is a reference to the invoking object:

Have you ever played a game on your iPhone and wondered how to share it with your friends? Of course, not everyone has iPhones, and they aren’t always watching the leaderboards on the Gaming app, provided by Apple. Well, guess what? You don’t have to take a whole other camera to take a picture of your iPhone to create a photo of that particular score you have achieved. All you have to do is simultaneously press the “Home Button” and the “Lock Button” on your iPhone. After that, your iPhone should consequently flash to white, as if it were snapping its shutter, and taking a picture. Afterwards, you should be able to find the picture in your Photo Albums and share it with your friends.                                                                                        

But, taking screenshots of your iPhone doesn’t always have to deal with your game scores, you can take screenshots of almost any happening on your phone and share it with people! Have you ever had a memorable texting conversation with your friend, where you mistyped something, and the conversation went haywire? Sharing it becomes easy by using this feature. Want to show how odd a website looks on your iPhone compared to looking at it on your computer, and give it to their support to fix it? Take a screenshot of it! The possibilities of this feature are endless, and can become timeless with a simple picture.

A business rule is the basic unit of rule processing in a Business Rule Management System (BRMS) and, as such, requires a fundamental understanding. Rules consist of a set of actions and a set of conditions whereby actions are the consequences of each condition statement being satisfied or true. With rare exception, conditions test the property values of objects taken from an object model which itself is gleaned from a Data Dictionary and UML diagrams. See my article on Data Dictionaries for a better understanding on this subject matter.

A simple rule takes the form:

if condition(s)

then actions.

An alternative form includes an else statement where alternate actions are executed in the event that the conditions in the if statement are not satisfied:

if condition(s)

then actions

else alternate_actions

It is not considered a best prectice to write rules via nested if-then-else statements as they tend to be difficult to understand, hard to maintain and even harder to extend as the depth of these statements increases; in other words, adding if statements within a then clause makes it especially hard to determine which if statement was executed when looking at a bucket of rules. Moreoever, how can we determine whether the if or the else statement was satisfied without having to read the rule itself. Rules such as these are often organized into simple rule statements and provided with a name so that when reviewing rule execution logs one can determine which rule fired and not worry about whether the if or else statement was satisfied. Another limitation of this type of rule processing is that it does not take full advantage of rule inferencing and may have a negative performance impact on the Rete engine execution. Take a class with HSG and find out why.

Rule Conditions