Category Archives: Week 5

Strategy Pattern Design Article

This article shows the “intent” of the strategy design pattern and how to successfully use it when refactoring code which is our current class topic. According to the article the strategy pattern (a behavioral design pattern in CS helps define a group of algorithms in separate classes which will effectively use each other’s objects.

One of the larger issues addressed by using the strategy pattern helps keep the main class from growing into a more complex mess. The strategy pattern allows for a developer to take/extract a class that has different functions and funnel them into a new class which is what this pattern refers to as a strategy.

Interfaces are commonly used with the strategy pattern in order to communicate with the other “strategies” that you previously extracted from the main class. The use of interfaces in the strategy pattern also allows your code to switch between algorithms at run time by using sub objects that perform their own tasks.

I chose this article as I feel it gives readers like myself a good general understanding of how to use and implement the strategy pattern. The article effectively shows you when you should or should not use the strategy pattern along with the pros and cons of using it. Similarities between the strategy pattern and other patterns it also outlined in the article which helps you tell the patterns apart and when you should use one pattern over another.

This article from refactoring guru has helped me to better understand the strategy pattern as a whole and helped me gain a somewhat smaller but still important understanding of some aspects of other design patterns (for example command and state). There are also examples of the strategy pattern being used in different coding languages found under the “Relations with Other Patterns” section.  I plan to use the information in this article to help me understand the Strategy pattern more in current and future assignments as well as in my professional career whenever I may need to refactor code through the different design patterns.

Overall I believe the general understanding of the strategy pattern gained from this article can help myself and any other student that may be having trouble with the topic or even someone who is just curious and would like to learn more about design patterns as their are articles on the other design patterns on the same website that can be accessed easily through links near the end of the page.

From the blog CS@Worcester – Dylan Brown Computer Science by dylanbrowncs and used with permission of the author. All other rights reserved by the author.

Software Construction Log #2 – Learning about Containerization and Virtualization

            In my experience, the concept of virtualization is currently synonymous with the creation of virtual machines that are used to emulate hardware and operating systems that, for one reason or another, are not readily available during the process of software development. For example, during my studies I have needed to use programs that were not available on Windows operating systems or to study an operating system for which a physical unit may not be readily available. Whatever the case may be, virtualization is not a new concept, and it is widely utilized in software development. It is important to note that virtualization is not exclusive to virtual machines, as it has a broader range that includes any concept related to the abstraction of a system’s physical components into virtual components.

            Among others, one concept of virtualization is containerization, with which most of us are familiar through Docker. Conversely, containerization refers to the containment of applications, their dependencies, and their required operating system into a singular package, also called container (hence, the name) that can be deployed and used on any operating system. By design, containers are meant to be a portable and lightweight way of testing and deploying applications, at least when compared to virtual machines. However, it is important to note that singular instances of containers cannot be modified, whereas it is possible to customize and modify virtual machines. Despite the caveats or benefits of virtual machines and containers, both are equally important during development.

          As I mentioned before, I have used virtual machines during my studies to create and use servers that I had no immediate physical access to, so the concept of virtual machines is not entirely foreign to me. However, I have little experience by comparison when it comes to Docker and using containers for software development, so I believe it is important for me to understand their differences so that I can know how to properly utilize them. As I was researching more regarding the concepts of virtualization and containerization, I came across the post titled What’s the Diff: VMs vs Containers on BackBlaze.Com, in which Roderick Bauer defines what virtual machines and containers are in detail, how they are different based on their structure on a server, as well as listing their benefits and best uses. Though Bauer does not directly state their caveats, by looking at the differences of both virtualization and containerization I can better understand when either approach could be more suitable depending on the needs during development.

            Moreover, what this post also helped me understand better is that neither option is mutually exclusive; it is possible (and sometimes, even preferable) to utilize both virtualization and containerization during development, rather than being limited to either option, so long as doing so does contribute to improving development.

Direct link to the resource referenced in the post:

Recommended materials/resources reviewed related to virtualization, virtual machines, and Docker/containerization:
7) (Definition of Virtualization)

From the blog CS@Worcester – CompSci Log by sohoda and used with permission of the author. All other rights reserved by the author.

Decision Table – Based Testing

For the fourth assignment in software testing, we had to create a decision table testing. A decision table is a black-box test technique that visually presents combinations of inputs and outputs, where inputs are conditions or cases, and outputs are actions or effects. A full decision table contains all combinations of conditions and actions. Additionally, it shows the causes and effects. Therefore, this technique is also called a cause-effect table. A well-created decision table can help to sort out the right response of the system, depending on the input data, as it should include all conditions. It simplifies designing the logic and thus improves the development and testing of our product. 

The decision table works on input conditions and actions. We create a Table in which the top rows are input conditions, and in the same vein, the bottom rows are resulting actions. Similarly, the columns correspond to unique combinations of these conditions.

Advantages of Decision Table Testing

The system behavior is different for different input, both equivalent partitioning, and boundary value analysis won’t help, but decision table can be used.

It can be easily interpreted and is used for development and business as well.

Help to make effective combinations and better coverage for testing.

Any complex business conditions can be easily turned into decision tables.

In a case we are going for 100% coverage typically when the input combinations are low, this technique can ensure the coverage.

Disadvantages of Decision Table Testing

The number of inputs increases the table will become more complex.


From the blog CS@Worcester – Tech, Guaranteed by mshkurti and used with permission of the author. All other rights reserved by the author.

Dig Deeper

For this week I want to talk about the Dig Deeper apprenticeship pattern. This is a pattern that everyone in computer science understand it well and doesn’t need to many words. The main point of this pattern is that no matter what tool you decide to explore, learn to dig deep into it. Acquire the depths of knowledge to the point that you know why things are the way they are.

In today’s world there are so many tools that is so hard to keep track with. I’m sure anyone can learn a tool or language if they have enough time to explore and understand it. If that’s not the case then you only ever learn the parts of a technology that you need to get your portion of the system working, and you depend on other members of the team to learn the other parts. So, with what you end up is a superficial knowledge of a thousand tools and you’re not even aware of how little you know until something or someone puts you to the test.

Another thing that I like, and I don’t like at the same time is depend on other members of the team to learn other parts. There are serious students or coworkers who will do their job but also, we have the other side of coin. There are people who don’t take it seriously, so you end up doing all the work by yourself or have misunderstanding. Solution to this is to hope you have time to learn and explore more of the tool and finger crossed to have someone driven to learn new things working with you.

Another advantage of digging deep into a technology is that you can actually explain what’s going on beneath the surface of the systems you work on. The book explains how in interviews, this understanding will distinguish you from other candidates who can’t describe the software they’ve helped build in a meaningful way because all they understand is one little portion. Once you’re part of a team, it’s the application of this pattern that separates out those who are making random piles of rubble. So, you don’t have to fake it till you make it. If you invest your free time to learn something new you going to add more points to yourself.

Apprenticeship Patterns by Dave Hoover; Adewale Oshineye

From the blog CS@Worcester – Tech, Guaranteed by mshkurti and used with permission of the author. All other rights reserved by the author.

Record What You Learn – Apprenticeship Pattern

In this post I will be discussing the apprenticeship pattern, “Record What You Learn” written by Adewale Oshineye and Dave Hoover in the book Apprenticeship Patterns: Guidance for the Aspiring Software Craftsman, 2009. This pattern is design towards people who end up learning the same lessons over and over again or going through the same experiences or failures but can never get the details or reasons to stick.

The solution suggested is to create a blog, notebook, or wiki that you can treat as a journal and record important things that you learn. This is not to write down and forget about. Throughout your career you should return to this journal to review it and make new connections in your memory. When reviewing you should update what is written as more knowledge and experience is accumulated over time. The authors even suggest creating two blogs, one a public record and one a private. This allows you to share the lessons you have learned and also get feedback on what you have written with the public record and be able to be brutally honest with yourself in the private record. Internal and external feedback allows you to have an honest and accurate self-assessment. The main goal of this pattern is to keep a journal of your path to mastery so that you can reflect on and learn in the future.

I found this particular apprenticeship pattern interesting because this morning I was thinking about starting a notebook in which I can keep any important lessons as well as important details. This way I would be able to look back on it frequently and grow as a developer. This could include important concepts, design patterns or failures that I can learn from as I move forward. This book has provided a useful structure in which I can follow and also has inspired me to follow through with it since I have said I was going to do it a few times already but never have. Also, it has given the idea of two journals in which one can be private and one public. Maybe also different journals for different topics such as one for design patterns, one for lessons learned, one for important topics, etc.

Hoover, D. H., & Oshineye, A. (2010). Apprenticeship patterns: Guidance for the aspiring software craftsman. Sebastopol, CA: O’Reilly.

From the blog CS@Worcester – Austins CS Site by Austin Engel and used with permission of the author. All other rights reserved by the author.

Your First Language

I always feel that if you are better at the first language, the easier it is to learn the next one.

I learned Java in my sophomore year, and then I went to learn C, which felt easy. Because the logic of computer language is interchangeable. For example, if you learn English well, you will find some similarities between French and Spanish. Although French and Spanish maybe your second language, you will learn them much faster than non-proficient English learners. I think this applies to computer language learning as well.

Each language gives you the opportunity to use different patterns to solve problems. In the process of moving beyond your first language, you should look for opportunities to learn languages that approach problems in very different ways. Apprentices who are comfortable with object-oriented languages should explore Functional’s programming language. Students of dynamic typing should delve into static typing. Apprentices comfortable with server-side programming should take a look at user interface design.

You should not be “married” to any particular technology but should have a broad enough technical background and experience base to be able to choose the right solution for a particular situation.

Many people say Java is good because it is suitable for many kinds of software programming. Some people also say that C++ is good because its language is more advanced than Java; there are also people who have learned that learning C++ to learn Java or very simple. I personally hate to talk about what language is best, every use situation has a language that works best for it. Or if you have learned your first language well, mastering it is also a good option. But there are certain situations where C really has the best solution than Java, so we write our software in C. At this point, there is no need to stubbornly think that I am good at Java and I have to use the language I am good at to solve this problem. 

The spirit of craftsmanship is that you strive for the best in what you are good at, but in certain situations, we can’t stick to the rules. Modern society is a utilitarian society, we need to maintain the spirit of artisans while learning to adapt to the society.

From the blog haorusong by and used with permission of the author. All other rights reserved by the author.

Expose Your Ignorance

The book Apprenticeship Patterns by Dave Hoover and Adewale Oshineye covers multiple patterns important to being an apprentice. One of these patterns is called “Expose Your Ignorance” and centers around the issue of not knowing enough about a topic kind of important to the task at hand. Many people’s first instinct is to feign competence in order to avoid worrying their peers and suffer through embarrassment. The pattern instead suggests that people admit their shortcomings and ask questions. It might be hard to do but the benefits far outweigh the risks like learning important information sooner rather than later for example. Doing this has the added benefit of developing the learning ability through enforcing a “not knowing” mentality which just means to approach a situation if you were a novice. This mentality pushes an individual to broaden their horizons rather than becoming an expert on a single subject in a specific context. It also allows one to form strong relationships since this will be showing others your learning ability and flexibility.

I’ve had trouble “Exposing My Ignorance” for most of my life since again, most people’s first instinct is to feign competence. And of course, that wouldn’t work out since people would get mad at me for not knowing something and I’d end up barely learning anything. But I would still keep up this behavior until either late high school or early college mainly because there were some people in my life that would get mad at me for even asking questions. The reason why I broke out of that habit is because as I got older, I realized that there was so much I had no clue of doing. So, I started asking questions without caring what other people thought because I wanted to learn. For example, I wanted to learn to do my laundry so I just asked my mom to teach me and now I still do my own laundry. The same principle applies to software development; If you either don’t know something or aren’t confident in your knowledge on a subject, ask questions since there’s no real harm in doing so.

From the blog CS@Worcester – Rainiery's Blog by rainiery and used with permission of the author. All other rights reserved by the author.

Concrete Skills

Concrete skills are something I feel as though I have an abundance, and simultaneously, a lack of. I guess this depends on what kind of skills are being referenced. If data structures, algorithms, or Leetcode is in question, I have some confidence. Not only are these topics I enjoy, but I also have solid knowledge in these areas. When it comes to automating tasks, or something more applicable to my current capstone situation, such as getting a strong grip on Docker and how each part of the project can be integrated with it, I feel… less qualified. 

The problem is, I think I can get to the technical knowledge I have, but only via the technical knowledge I am lacking. These barriers become apparent when working on a large project like the capstone. I look at the backend components, and I feel solid, even with little JavaScript experience. But picking up Vue.js makes me feel like I’m swimming in circles. There’s no point in making a backend without a frontend to support it, and I know this, but I’m not happy to confront it as it means abandoning my comfort zone for some crazy new frontend world.

          The learning pattern on concrete skills puts some much-needed pressure on me. It points out that I can have all the knowledge of theory and all the ability to learn quickly in the world, but if I can’t put real technical skills on a resume, I’ll never make it past the first round of hiring interviews. Rather than trying to find ways around the difficulties I face in everyday software development life, I should highlight my weaknesses and mark them down as learning opportunities.

          There has been a plethora of times in my CS career at which I confront a problem I have been avoiding and the knowledge I gain suddenly seems to apply everywhere. For example, last semester I learned the state design pattern, and because it came with some confusion, I dropped it quickly enough. Now, as I tried to make a Markov chain simulation in Java for my Math Modeling independent study, I realized a state pattern was a perfect fit. It took a couple hours, but I got it down and it feels great not only to have learned and used something new, but to know I have the knowledge to use whenever I need it going forward.

          I think my first focus should be some more surface level skills. As the chapter points out, the question, “If we hire you today, what can you do on Monday morning that will benefit us?” is one of the most important questions of the interview. If my best answer is, “Try really hard to get up to speed,” I’ll be job hunting for a long, long time. My new goal is to collect the skills I don’t know or feel uncomfortable with that are more common and focus my spare time on them. It will make daily life as a developer easier and take me further in my career faster.

From the blog CS@Worcester – Marcos Felipe's CS Blog by mfelipe98 and used with permission of the author. All other rights reserved by the author.

Breaking Out the White Belt (Disambiguation)

As someone who has been a caddy, industrial mechanic, butcher’s assistant, retail manager, letter carrier, web development intern, substitute teacher, and referee over the course of my life, it’s safe to say that I’m no stranger to breaking out the white belt. The chapter sets up the scenario wherein you’re a competent programmer with a narrower-than-desired field of knowledge and although your competency allows you to feel confident in your day-to-day operations, this coziness with your language or technology stack has limited your ability to wrestle with the novel in a meaningful way. The suggested solution is to embrace the unknown and throw away your preconceived notions about what it means to program or write software, actively avoiding the temptation to relate your previous world to the task at hand. The authors call this mindful approach to limiting context “maintaining a not knowing stance”, an ethos that I would argue is truly the heart of science and fundamental for discovering something new. The case here is that we (the readers) are software developers and the personal discovery is the new world of idioms, approaches, and paradigms that we will hopefully be able to synthesize and, upon achieving contextual competence, apply.

The pattern certainly confirms to me what I already know; being humble is an evergreen approach to learning, however the authors chart territory that I do not know in the chapter and that is the premise given at the outset where one hits a level of competence and plateaus there. I’ve not really been able to wrestle with any technology stack or programming language long enough where I feel competent or fluent to meaningfully contribute, let alone act as a guiding beacon for peers. While I may not be ready now to apply what I’ve learned in the pattern, if I imagined myself a competent C++ developer accustomed to the object-oriented programming paradigm, I would then make an attempt to learn a declarative paradigm, perhaps functional programming. Ultimately one’s next foray in software development will tend towards whatever is productive for their endeavors, occupational or personal and should likely reflect the adage of “picking the right tool for the job”.

From the blog CS@Worcester – Cameron Boyle's Computer Science Blog by cboylecsblog and used with permission of the author. All other rights reserved by the author.

Apprenticeship Patterns Blog Post #3

After completing my apprenticeship introduction blog post and two different patter reviews, I am excited to keep reviewing more. For the next pattern from the textbook that I have chosen to review, I chose the “concrete skills” pattern. The book describes a situation in which you are trying to work with a group or at a job in which you do not have a very strong background in yet. This is ofter one of the most inconvenient thing when looking for starter jobs. Most jobs want individuals who have a good background so they know you will be a good fit for the job. The book also supplies us with a great solution to this problem however. Basically, it states that you will have a better chance getting the job if you can prove that what you lack in background work, you make up for in your ability to learn quickly and work hard to learn new things on your free time as well. The more jobs and projects you can accomplish/work on, the better your portfolio and background becomes overtime. Eventually you will find it easier and easier to get where you want to get, and it all starts with your first several projects/jobs. This specific apprenticeship pattern resonated with me primarily because I personally do not have a great background yet and am trying to create a good one. The advice from this section was super powerful, and to be honest, this might be one of the most important concepts discussed in the entire textbook!

From the blog CS@Worcester – Tim Drevitch CS Blog by timdrevitch and used with permission of the author. All other rights reserved by the author.