Learning by Teaching

Docendo discimus or Learning by Teaching, is one of good method to improve yourself (or at least, myself).

Learning by teaching gives you better experience, knowledge and skills, and can be very useful, compared to learning by yourself or from other. It is because in order to teach someone, you will need to know the answer from the problem beforehand, or at least has an expertise in the case. Also, teaching requires you to be able to explain the method correctly and presenting the knowledge. In other words, converting Tacit Knowledge to Explicit Knowledge. Not other than that, you must proof your knowledge and defend it from any disagreements.

Has an Expertise in the Case

You cannot teach or giving knowledge if you do not has an expertise in the case. Some exceptions may be for seniority or positional power, but it is another topic. It means that if you already can teach, you already has some level of expertise in the case. It is a good indicator to measure yourself.

If you need to teach, answering question or giving knowledge, it means that you need to know the field and becoming an expert at that field too. It forces you to learn. Even when teaching or after that (evaluation) you can still learning from your teaching. It is a very good improvement.

Able to Explain

Sherlock Holmes said once in his book Study in Scarlet, It was easier to know it than to explain why I know it. If you were asked to prove that two and two made four, you might find some difficulty, and yet you are quite sure of the fact. It is not an easy thing to explain something that you know and most of the time, it is easier for you to understand it yourself.

That is one of good reason why learning by explaining is better than learning by yourself. If you already can teach or explaining the knowledge, it means that you already have the knowledge in a good level. If you do not know the knowledge itself, how can you explain it?

Defend from any Disagreement

Disagreement may comes from other source. The worst type of disagreement by comes from those who has better expertise in the fields (someone that has been respected as masters, such as Martin Fowler for OOP design). In order to prove that your knowledge is correct (or at least acceptable), you must have some ability to protect it from any disagreements. (well in this case, I don't want to mention the worst type of agreement in an organization, that is disagreement from people who has the power, and the disagreement comes from their taste themselves)

Some published books are good to be referenced as sources. Because if you cannot explain the knowledge well, or cannot defend it, you can use the reference as your shield. Published book is good because it is well written, mostly easy to understand and accepted by most people. Moreover, it is written by experts in the fields, improving the correctness (as described in the first point here). The authors itself, is already at a level that is able to defend their statements from disagreements.

Don't worry if you find that your statements cannot be protected. It means that you still need to learn. Moreover, you can learn from the disagreement as the starting point, and begin research from it. At the moment you know the facts that can be used to defend it, you begin to make statements again, and the process iterated itself. It only means that whether your statement can be protected or not, it has learning process in it, and it is good.

Conclusion

Learning by teaching is a good thing to do to improve yourself. Most of the time, you need to do some other types of learning before teaching, so it only leads to some process of learning.

Programming Idealism, Avoiding Hungarian Notation

Hungarian Notation

From wikipedia, hungarian notation is an identifier naming convention in computer programming, in which the name of a variable or function indicates its type or intended use. There are two types of Hungarian notation: Systems Hungarian notation and Apps Hungarian notation.
System Hungarian is intended to emphasize the variable's type. It is extremely useful in interpret / dynamic language such as javascript or php, and useless at all in static programming language. Especially in compiled oop language such as Java and C#, where data contract and type casting is the major problem, it has no benefit at all.
Apps Hungarian is intended to describe the functionality of given variable, regardless of it's type. As Joel Spoolsky has been explained in his article, there are some variable that is prone to error, even though already has compiled-type checking. One of his example is between unsafe and safe string (encoded html tags for example), in which the type is same but serve different purpose.
The article is posted at 2005. It means it already there for more than 7 years around. Given current ability of compiler and programming language, what can we do to improve the design?

Problem

There lies one and only one problem in Joel's solution, that is the code can still pass compilation phase. As stated by Mark Seeman in his article, faster feedback means less costs to correct errors. Ideally, it is the best when we can get all the system's error during compilation phase, but it mostly impossible for some reasons (such as parsing error or business rule error, in which cannot be caught by compiler). In short, you need to create compile error as much as possible to catch wrong code, rather than getting run time exceptions.

The Proposed Design

Using Joel's example for safe and unsafe string, we need to create a design where we can handle safe and unsafe string which can give compile error. By using C# syntax, as usual for oop language, first I define some classes. The class is for unsafe string.

public class DecodedHtmlString
{
    public DecodedHtmlString(string decodedString)
    {
        this.decodedString = decodedString;
    }

    private string decodedString;
    public override string ToString()
    {
        return decodedString;
    }
}

Simple enough. It gives no benefit but gives you a self-documenting data type. The class represent a html string in a decoded way, and no encoding happen here. Next, for the safe (encoded string).

public class EncodedHtmlString
{
    public EncodedHtmlString(DecodedHtmlString decodedString)
    {
        this.encodedString = System.Web.HttpUtility.HtmlEncode(decodedString.ToString());
    }

    private string encodedString;
    public override string ToString()
    {
        return encodedString;
    }
}

Again, a self explaining class accepting encoded string from a decoded string. Now we want to make both of the classes communicate each other. We have several options such as type casting or static parsing, which is easy enough in C# that I won't explain. In here I will do constructor injection and To type casting instead. For the DecodedHtmlString, we add a constructor and ToEncodedHtmlString method:

    public DecodedHtmlString(EncodedHtmlString encodedString)
    {
        this.decodedString = System.Web.HttpUtility.HtmlDecode(encodedString.ToString());
    }
    public EncodedHtmlString ToEncodedHtmlString()
    {
        return new EncodedHtmlString(this);
    }

And for the EncodedHtmlString side:

    public static EncodedHtmlString FromEncodedString(string encodedString)
    {
        EncodedHtmlString result = new EncodedHtmlString();
        result.encodedString = encodedString;
    }
    public DecodedHtmlString ToDecodedHtmlString()
    {
        return new DecodedHtmlString(this);
    }

Consumer

Let's see from consumer point of view:

string unsafeString = Request.Forms["CUSTOM_INPUT"]; // input from form
string safeString = System.Web.HttpUtility.HtmlEncode(unsafeString); // encoded safe string for reference
DecodedHtmlString decoded;
EncodedHtmlString encoded;

// initial creation
decoded = new DecodedHtmlString(unsafeString); // correct
encoded = EncodedHtmlString.FromEncodedString(safeString); //correct

// type casting
encoded = decoded.ToEncodedHtmlString(); // correct
encoded = new EncodedHtmlString(decoded); // also correct
decoded = encoded.ToDecodedHtmlString(); // correct
decoded = new DecodedHtmlString(encoded); // also correct

// wrong initial creation
decoded = new DecodedHtmlString(safeString); // wrong
encoded = EncodedHtmlString.FromEncodedString(unsafeString); //wrong

// to primitive
unsafeString = decoded.ToString(); // correct
safeString = encoded.ToString(); // correct

// wrong to primitive
unsafeString = encoded.ToString(); // wrong
safeString = decoded.ToString(); // wrong

We got 4 possible wrong code, that is from primitive and to primitive parameter assignment, and for other scenarios it is correct. Now let's see whether we can exploit the data type validation with parameter accepting data type.

public void WriteToDatabase(EncodedHtmlString encoded)
{
    string encodedString = encoded.ToString();
    // doing with encodedString
}

WriteToDatabase(unsafeString); // compile error
WriteToDatabase(safeString); // compile error
WriteToDatabase(decoded); // compile error
WriteToDatabase(encoded); // correct

Now we got 3 compile error and one correct code. If you favor to get a compile error, it is an improvement since now you can protect myself from 3 possible parameter assignment errors. And if you carefully using the two data types instead of passing from primitive string, it will be fine. The only two things that can pass the compile error is when casting to primitive, or from primitive.

But hey, isn't most of the operation (at least safe and unsafe string) is using primitive type? If we take account Response.Write and Database operations, it is very clear that most of the critical operation is using primitive type. (even for url, etc). Moreover, we add 2 more classes for this design.

Conclusion

We can get the design where we will receive compile error instead of run time error or buggy code. However, we still cannot get one hundred percent buggy-code free with this design, and most of the operations are error-prone here. Additionally, it introduces two dependent classes as well, making it more tight coupling.

In the end, it is still the framework's support that do the decide. If the framework support the Encoded and Decoded datatype by default, and suggesting you to use the datatype instead of primitives, maybe it is worth it. However, with current framework design, it is very unlikely for this design to give decent benefit.

The Ways of Debugging Part 1: Finding the Possible Root Cause

Background

Debugging can be easy for someone, and very hard for the other. After many years of debugging experience, I find that debugging usually consist of 3 big steps, that is:

1. Finding the possible root cause,
2. Prove the possible root cause to find the real root cause, and
3. Fix the real root cause

Additionally, debugging hardware has many similarity with debugging software, in which also has the 3 big steps above.

Finding the Root Cause

Finding the root cause is the very first step in debugging. In my opinion, it is also the most determining step. The total time required for debugging usually be heavily determined by finding the root cause. It is harder to find the root cause rather than fix the system.

In order to find the root cause, the very first requirement is to understand the system you are debugging. I have once need to debug a system in which I do not understand at all, and it takes the time for me to understand the behavior of system first. Only after that then I can finally continue to find the possible root cause.

Moreover, don't be surprised. Sometimes user will actually submit a bug, without steps to reproduce (especially in entrepreneur system, where the user usually know little of software engineering), complaining about a behavior that is already behave as designed. Without any documentation (that's right, no documentation at all!) about how the system behave, I need to find a person who know the system's behavior, to determine whether it is a bug or not. This is, why at most of the time, usually the tester can find the possible root cause easily, because they know well how the system behave.

Understanding the system first can also be very critical for finding some technical flaws. There flaws are such as race conditions, replication issues, different regional setting, different input format, hacks or security flaws, etc. Right, bad system design can be a root cause for bugs, with additional factor like not understanding the system, it will give you a headache.

Another requirement for finding the root cause is having decent technical knowledge about the platform or programming platform the system use. Some platform used by the system such as the database and application, usually has different behavior between each other. Say, for example, java mark the class and method as virtual by default, and in C# you need to specify with the "virtual" keyword.

Conclusion

Understanding the system and having knowledge about the platform will give you significant boost in time needed to find the possible root cause. I have experienced that I have once finding a possible root cause for a bug in system for only several minutes. It is, of course are made possible by the having knowledge of the system.

Much or less, documentation about how the system behave will help newcomers or debugger to find the possible root cause. Not only it will help to find the possible root cause, the handler can instantly know whether the bug raised by user is actually the system's design or not, or they need to configure something in for the user in order to able to do the required action.

Debugging Hardware Problem

Today, I boot the PC. The boot process goes smoothly until the windows trying to load. Suddenly a blue screen appear and the computer restarted.

If you ever have a pc for 3 years or more, you may experience similar situation as well. PC unable to boot, sudden restart in middle of work, or something like that may happen due to hardware failure.

An experienced one already know that hardware problem can be happened in many parts of hardware, such as CPU, RAM, hard disk, VGA, motherboard, power supply, etc. Similar with software debugging, finding a part of hardware which is the root cause can be a trouble. I find the debugging hardware problem is similar with one in software.

During the booting after my PC restarted, I try to run the windows in safe mode. Strangely, it can run well. Some common applications such as office and browser can be run normally, with the minus of good display and network support due to safe mode.

Normally, you cannot even able to boot at all when the CPU or RAM get any trouble. From this point, I believe that the RAM and CPU is still in good shape, eliminating two error possibilities. Troubled power supply normally cannot affort to boot the system too and not causing blue screen error. So, we get another parts eliminated, leaving both motherboard and VGA alone.

Both parts become the "possible root cause" which cause the error. From this forward, I begin to test the "possible root cause" to be proven. This step is meant to prove whether the possibility is actually the real root cause.

Luckily, my possibility is being strengthened by windows error message in safe mode, showing bcc code 116. After simple searching in Google (thanks Google), I can easily found some article mentioning bcc code 116 related to video graphic error. Now only one thing to prove: whether the system will boot up without using the graphic card.

So I start to reach device manager, disabled the display adapter, and begin restarting the PC. The result is, viola! The system successfully loaded. The application runs well, the browser connected to the internet, and nothing has problem except a poor - low resolution display. And a little lag because the rendering are not being done in graphic card anymore.

The suspect left to motherboard or VGA, which I haven't found the cause yet. That is because I do not has spare change for it. But the bigger suspect is VGA, because it is older than the motherboard.

Conclusion

Finding the cause of hardware error is very similar with debugging software. It is started by finding the possible root cause, proving the possibility, and then fixing the problem. Experience and knowledge also help in both cases, to speeding the discovery of possible root causes. And for both cases also, you need to know how the system behave / working, or you will need additional time to find how the system work.

Not All Architecture is Fit for Your Apps

I had an interesting discussion over stackoverflow with L-Three in this question. I realized that it is quite an interesting situation there, so I think it need to be blogged. I'm not yet experienced enough in Dependency Injection, so my statements may be mistaken though.

In short, he is advising to use a well structured architecture. That architecture is using some several good techniques, like dependency injection and comand-query separation. Ad a moderate programmer, I can say that the structure is good, clean, easy enough to test and extendable. But I don't like it. No, not because the design is good, but I have some conditions where the architecture can't be applied.

Interface Programming: Entity Wrapper to Handle Dynamic Source Object

Background

During working with legacy code, I have found that many people used DataTable/DataSet instead of strongly typed objects. They are using some code like

string id = row["id"].ToString();

instead of

string id = request.Id;

It is becoming a maintenance hell because of several reasons:

• I do not know the data type from database, so I need to debug into database procedure
• I do not know whether the data is nullable or not, again I need to debug into database
• When I need to change the data type, I need to search for every implementation, change it and make sure it does not break 

And last but not least, if I want to make enhancements or modifications, I have been faced with 2 options:

• Keep  the same programming style, using the DataTable, with the risk that you add another more maintenance hell object
• Refactor it, with the risk of breaking is higher

I want to use Dependency Injection (DI) for my further development. Lack of strongly typed entities are of course prevent me from using DI. So I need to change the DataTable to strongly typed object before using the DI implementation.

Design, don't Code Yet

 Why - Risk at Development

As a programmer, sometimes I doubt whether I should wasting time to think and design about the application that I will develop or not. As a single programmer-architect, there are some self-defined projects where I usually start by code first or by design first. Logically, they should have produced the same result, thinking that the developer and the architect is the same person. Practically, I'm surprised that the project started with code first is tend to have more risk and more likely to be stopped than the one by design-first.

So, logic does not apply here? Yes it is. The reason is basically that the developer is human. and they will likely get bored because of several reasons:

• The project does not has exact requirement and scope
• The project does not has exact release strategy
• The project is most likely isn't needed by the user

The project does not has exact requirement and scope

Once, I have tried to create a so-called "ideal-best" application. The application should be able to handle many kind of business process. That application will be free of bug, easily extendable and has good architecture foundation. And the application can work as both transaction handling or event high level management reporting tools.

It sounds like a good plan at the beginning, however with such a big regards I need to drop the development because I got bored during developing it. It has no exact scope, no exact plan about what I must develop, what I must validate, how is the process after doing this and that, etc. The scope is growing and growing each day I think about the application, and the development cannot follow the planning growth. You have not target to accomplish, and caused you to loss interest in the development.

The project does not has exact release strategy

 What I mean about the term of release strategy here is a strategy about how to deliver the application. It consist of release date, the audience and the platform target. It may has more details than that such as how to replace the current running application without breaking, or how to not breaking other applications which is dependent to it; but it's regarding what kind of application that want to be delivered.

Having no release date deadline (target) can affect the development scope, since you will think like "I have unlimited time to develop this" or "I can add this and that feature before delivering the application, since the release date isn't being decided". 

Lack of audience target can also affect the scope, because you will try to create an application that can be used by any level of management (transaction level or event advanced-level ad-hoc reporting).

Lack of platform target can demoralize your development. You will be haunted by thoughts such as "will it works well in firefox, chrome, or IE?" or "will it works in other-windows operating system?". Thoughts like that will drag your development, because you will be bugged by how you will check them each time you make a modification. Don't be bugged by it!

The project is most likely isn't needed by the user

Any project needed by the user should has estimated release date. In terms of user, the faster the deliver date, the better. Sometimes you may think that this kind of application/enhancement will not be needed by the user. It can be because you can do manipulation to the database directly. This kind of thought can demoralize the development, since you don't know exactly how your application can give good benefits to the user. Don't develop any kind of application which won't be needed. Or if it will, don't ever think that the workaround (direct manipulation) can be the replacement of the application.

Conclusion

Always design your application first before do code. No matter how skillful programmer you are, the risk of not having the application designed beforehand is high. It can makes your effort go waste, and you got nothing from it, except wondering why this is happening. If you cannot do the design, as someone who is good at it. Asking experts in each field, for example accountant during finance application design or a headmaster during education application design. It can give you clear vision about what kind of application you want to develop, and the functionality.