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Listing 4 . Object can modify itself at runtime.
class TestClass(object): def addInstanceVar(self,data):self.iVar = data

I am presenting and explaining this program for a couple of different reasons:

  • It will be useful in explaining the method named __init__ in the next program in this module.
  • It will be useful in explaining issues surrounding class variables in a future module.

Add an instance variable to one object and display it

The other difference between the two programs is shown in Listing 5 . Instead of accessing the object directly to add the new instance variable, as was done in Listing 2 , the code in Listing 5 calls the method named addInstanceVar on the object to cause the new instance variable to be added.

Listing 5 . Add an instance variable to one object and display it.
print("Add an instance variable to one object and display it") ref01.addInstanceVar(1234)print(ref01.iVar)

As mentioned earlier, the end result is the same as you will see if you examine the output from the program shown in Listing 11 .

Visualize the code in Listing 10

Once again, I recommend that you create a visualization for the code in Listing 10 and step through the program one instruction at a time. As you do that, pay attention tothe movements of the red and green arrows on the left, the diagram on the right, and the printed material at the bottom. That should help you to betterunderstand how a Python object can modify itself at runtime.

The method named __init__

You learned in the previous program that a method belonging to an object can add an instance variable to an object at runtime.

You also learned in an earlier module that if your class contains a method named __init__ , that method will be executed automatically in conjunction with the instantiation of the object. As I understand it, that isprobably the last thing that happens before the new object's reference is returned to be saved for later use.

A complete listing of a program that I will use to discuss the __init__ method is shown in Listing 11 . The output produced by that program is shown in Figure 7 . As usual, I will explain the program in fragments.

A class with an __init__ method

Listing 6 shows the definition of a class named TestClass that contains a method named __init__ in addition to a method named addInstanceVar as in the previous program.

Listing 6 . A class with an __init__ method.
class TestClass(object): def __init__(self,data):self.iVar01 = datadef addInstanceVar(self,data): self.iVar02 = data

When either of the methods shown in Listing 6 are executed, a new instance variable will be added to the object and initialized with an incoming datavalue. Since the method named __init__ is always executed automatically in conjunction with the instantiation of an object, the initial state of theobject will include an instance variable named iVar01 .

Instantiate and display two objects

The code in Listing 7 instantiates and prints two new objects of the class named TestClass . You can view the output produced by the code in Listing 7 in Figure 7 . There probably won't be any surprises there.

Questions & Answers

what does preconceived mean
sammie Reply
physiological Psychology
Nwosu Reply
How can I develope my cognitive domain
Amanyire Reply
why is communication effective
Dakolo Reply
Communication is effective because it allows individuals to share ideas, thoughts, and information with others.
effective communication can lead to improved outcomes in various settings, including personal relationships, business environments, and educational settings. By communicating effectively, individuals can negotiate effectively, solve problems collaboratively, and work towards common goals.
it starts up serve and return practice/assessments.it helps find voice talking therapy also assessments through relaxed conversation.
miss
Every time someone flushes a toilet in the apartment building, the person begins to jumb back automatically after hearing the flush, before the water temperature changes. Identify the types of learning, if it is classical conditioning identify the NS, UCS, CS and CR. If it is operant conditioning, identify the type of consequence positive reinforcement, negative reinforcement or punishment
Wekolamo Reply
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Wekolamo
because it helps many people around the world to understand how to interact with other people and understand them well, for example at work (job).
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ARC
A child is a member of community not society elucidate ?
JESSY Reply
Isn't practices worldwide, be it psychology, be it science. isn't much just a false belief of control over something the mind cannot truly comprehend?
Simon Reply
compare and contrast skinner's perspective on personality development on freud
namakula Reply
Skinner skipped the whole unconscious phenomenon and rather emphasized on classical conditioning
war
explain how nature and nurture affect the development and later the productivity of an individual.
Amesalu Reply
nature is an hereditary factor while nurture is an environmental factor which constitute an individual personality. so if an individual's parent has a deviant behavior and was also brought up in an deviant environment, observation of the behavior and the inborn trait we make the individual deviant.
Samuel
I am taking this course because I am hoping that I could somehow learn more about my chosen field of interest and due to the fact that being a PsyD really ignites my passion as an individual the more I hope to learn about developing and literally explore the complexity of my critical thinking skills
Zyryn Reply
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Jonathan
and having a good philosophy of the world is like a sandwich and a peanut butter 👍
Jonathan
generally amnesi how long yrs memory loss
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interpersonal relationships
Abdulfatai Reply
What would be the best educational aid(s) for gifted kids/savants?
Heidi Reply
treat them normal, if they want help then give them. that will make everyone happy
Saurabh
What are the treatment for autism?
Magret Reply
hello. autism is a umbrella term. autistic kids have different disorder overlapping. for example. a kid may show symptoms of ADHD and also learning disabilities. before treatment please make sure the kid doesn't have physical disabilities like hearing..vision..speech problem. sometimes these
Jharna
continue.. sometimes due to these physical problems..the diagnosis may be misdiagnosed. treatment for autism. well it depends on the severity. since autistic kids have problems in communicating and adopting to the environment.. it's best to expose the child in situations where the child
Jharna
child interact with other kids under doc supervision. play therapy. speech therapy. Engaging in different activities that activate most parts of the brain.. like drawing..painting. matching color board game. string and beads game. the more you interact with the child the more effective
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Source:  OpenStax, Itse 1359 introduction to scripting languages: python. OpenStax CNX. Jan 22, 2016 Download for free at https://legacy.cnx.org/content/col11713/1.32
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