It's a pretty popular and well known phrase that you should "only catch/throw exceptions which are exceptional". However, how is an "exceptional" exception determined?
For example, a bad password is very routine in logging into a service, so this is not exceptional. Statistics for a web app would probably show something like one bad login attempt for every 5 attempts (from no specific user). Likewise, with attempting to go to a checkout with a basket in an online store, this could be very commmon (especially for new users). However, a file not found could go either way. I usually work along the lines that if a method is missing something to do its work, throw an exception, but then it gets a little confusing here. In some cases, a file not found could be common (e.g. a file share used by many users with no tight controls), compared to a very locked down production environment missing a file, which would be exceptional.
Is this the right way to deduce between whether an exception is exceptional or not? I can easily filter things like no network connection etc as exceptional, but some cases are hard to judge. Is it subjective?
Thanks
I think it's pretty subjective, honestly, so I prefer to avoid that method of figuring out when I should use exceptions.
Instead, I prefer to consider three things:
Is it likely that I might want to let the call stack unwind more than one level?
Is there another way? (Return null or an error code, etc.) If so, do I have even the slightest performance concern?
If neither of those lead to a clear decision, which is easier to read by someone who has to maintain the code?
If #1 is true, and I don't have a MAJOR performance concern, I will probably opt to use exceptions because it will speed up my development time not to have to code return codes (and manually code the logic to have them propagate up the call stack if needed). When you use exceptions, call stack unwinding is free of charge for development time.
If #2 is true, and either I'm not going more than one frame (maybe two?) up the call stack or I have a serious performance concern (in a tight loop, for example), then I'll try really hard to find another way that doesn't involve exceptions.
Exceptions are only a tool for programmers in a language which supports them. I don't believe they have to have any intrinsic value as to what is "exceptional" or not. Instead, I say use them when they are the best tool for the job.
Almost everywhere I worked I met lots of people who didn't care that they produced massive amounts of boilerplate code.
For me this is one of the worst things ever, it leads to errors, it is boring and it increases the noise.
Worst example may be even Microsofts unwillingness to give us a better syntax for this annoying "INotifyPropertyChanged" - stuff. You can't use automatically generated properties, you have to create a big redundancy (replicating the property name in the call to "OnPropertyChanged" or whatever your raiser method is called).
Some people go as far as to accept that most programs in many programming languages consist of mostly the same repeated code (noise), not interesting stuff (signal). See MSDN - examples for example, there is so much unneeded, repeated code all over the place (the horrible "INotifyPropertyChanged" - pattern that ruins all the flow being only the tip of the iceberg).
However, when I raise this issue and propose solutions like AOP (PostSharp.NET) or using delegates (for the non - C# - folks: anonymous functions, often realized using a lambda operator), all I get is "we don't care".
Anyone else here troubled by the insane amount of noise introduced by boilerplate code and who wants to think about ways to push solutions to the boilerplate - issue?
For what it's worth, I'm completely on your side.
The boilerplate folks argue that the repetitive, redundant code is "automatic" or "consistent" and therefore doesn't contribute to code complexity. Often when a language forces developers to create boilerplate, the industry creates IDEs and other crutches to automate the process. Then, when the apparent cost of producing that boilerplate code approaches zero, people think it doesn't cost anything.
They're wrong: Boilerplate code contributes to code bulk, and anyone maintaining code has to dig through the irrelevant code to get at the important parts. Also, since auto-generated code can and often does get edited, it can hide bugs introduced by typos, incomplete renaming or other accidents. The cost of boilerplate code is not in its creation but in its maintenance - which many projects try to ignore completely.
In the '80s, I saw trade mags plastered with ads for memory leak debuggers for C++, and it was an obvious sign to me that memory management in C++ is seriously broken. Now, in the vicinity of Java and C#, I see a proliferation of code generating assists, and that indicates to me that those languages have issues that would be better solved elsewhere.
Scala has issues of its own, but I love what they've done with properties and auto-initializing constructors.
Just kill'em. No, really, if someone writes boilerplate code and doesn't care to improve it, I doubt we may call him professional. It often happens that management wants to see tasks done fast and only thing that's left is to push out some write-only boilerplate code just to make them happy. If your management encourages such approach - change your job.
I've just found myself in situation where I needed to handle exception I'll probably never get, so out of curiosity, let's do a small poll.
Do you validate the presence of resources in your programs? I mean, those resources which are installed with your program, like icons, images and similar. Generally, if those are missing, either your install didn't do its job, or the user randomly deleted files in your app.
If you do validate the presence, what do you do when the files are not there?
Of course, for web apps, you'll have nice 404 page or broken link, but what about the rest? Fail early, yes, but leave handling failures to your compiler, or what?
In Python, many folks rely on simple exception handling for this kind of thing. We might wrap an application in a Big-Old-Try-Block that reports "serious problems" for unhandleable exceptions like this and tries to clean up and exit gracefully.
It's hardly worth checking deeply in advance.
If it's even possible for the user to get to some super delicate and precious part of the application and the app dies undoing hours (or years) of work, then you should rethink that use case to create a more robust scenario where a crash is not so destructive.
Graceful Degradation:
... but no, in a lot of cases it doesn't really matter if resources are missing, that's violating the structural integrity of the program. In the case in my picture above, it's a video game where resources are loaded over the net, and sometimes (I think?) the server doesn't supply the textures needed so they are displayed as pink and black checkers. In that case it makes a bit of sense.
As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.
Closed 11 years ago.
Locked. This question and its answers are locked because the question is off-topic but has historical significance. It is not currently accepting new answers or interactions.
As we program, we all develop practices and patterns that we use and rely on. However, over time, as our understanding, maturity, and even technology usage changes, we come to realize that some practices that we once thought were great are not (or no longer apply).
An example of a practice I once used quite often, but have in recent years changed, is the use of the Singleton object pattern.
Through my own experience and long debates with colleagues, I've come to realize that singletons are not always desirable - they can make testing more difficult (by inhibiting techniques like mocking) and can create undesirable coupling between parts of a system. Instead, I now use object factories (typically with a IoC container) that hide the nature and existence of singletons from parts of the system that don't care - or need to know. Instead, they rely on a factory (or service locator) to acquire access to such objects.
My questions to the community, in the spirit of self-improvement, are:
What programming patterns or practices have you reconsidered recently, and now try to avoid?
What did you decide to replace them with?
//Coming out of university, we were taught to ensure we always had an abundance
//of commenting around our code. But applying that to the real world, made it
//clear that over-commenting not only has the potential to confuse/complicate
//things but can make the code hard to follow. Now I spend more time on
//improving the simplicity and readability of the code and inserting fewer yet
//relevant comments, instead of spending that time writing overly-descriptive
//commentaries all throughout the code.
Single return points.
I once preferred a single return point for each method, because with that I could ensure that any cleanup needed by the routine was not overlooked.
Since then, I've moved to much smaller routines - so the likelihood of overlooking cleanup is reduced and in fact the need for cleanup is reduced - and find that early returns reduce the apparent complexity (the nesting level) of the code. Artifacts of the single return point - keeping "result" variables around, keeping flag variables, conditional clauses for not-already-done situations - make the code appear much more complex than it actually is, make it harder to read and maintain. Early exits, and smaller methods, are the way to go.
Trying to code things perfectly on the first try.
Trying to create perfect OO model before coding.
Designing everything for flexibility and future improvements.
In one word overengineering.
Hungarian notation (both Forms and Systems).
I used to prefix everything. strSomeString or txtFoo.
Now I use someString and textBoxFoo. It's far more readable and easier for someone new to come along and pick up. As an added bonus, it's trivial to keep it consistant -- camelCase the control and append a useful/descriptive name. Forms Hungarian has the drawback of not always being consistent and Systems Hungarian doesn't really gain you much. Chunking all your variables together isn't really that useful -- especially with modern IDE's.
The "perfect" architecture
I came up with THE architecture a couple of years ago. Pushed myself technically as far as I could so there were 100% loosely coupled layers, extensive use of delegates, and lightweight objects. It was technical heaven.
And it was crap. The technical purity of the architecture just slowed my dev team down aiming for perfection over results and I almost achieved complete failure.
We now have much simpler less technically perfect architecture and our delivery rate has skyrocketed.
The use of caffine. It once kept me awake and in a glorious programming mood, where the code flew from my fingers with feverous fluidity. Now it does nothing, and if I don't have it I get a headache.
Commenting out code. I used to think that code was precious and that you can't just delete those beautiful gems that you crafted. I now delete any commented-out code I come across unless there's a TODO or NOTE attached because it's too perilous to leave it in. To wit, I've come across old classes with huge commented-out portions and it really confused me why they were there: were they recently commented out? is this a dev environment change? why does it do this unrelated block?
Seriously consider not commenting out code and just deleting it instead. If you need it, it's still in source control. YAGNI though.
The overuse / abuse of #region directives. It's just a little thing, but in C#, I previously would use #region directives all over the place, to organize my classes. For example, I'd group all class properties together in a region.
Now I look back at old code and mostly just get annoyed by them. I don't think it really makes things clearer most of the time, and sometimes they just plain slow you down.
So I have now changed my mind and feel that well laid out classes are mostly cleaner without region directives.
Waterfall development in general, and in specific, the practice of writing complete and comprehensive functional and design specifications that are somehow expected to be canonical and then expecting an implementation of those to be correct and acceptable. I've seen it replaced with Scrum, and good riddance to it, I say. The simple fact is that the changing nature of customer needs and desires makes any fixed specification effectively useless; the only way to really properly approach the problem is with an iterative approach. Not that Scrum is a silver bullet, of course; I've seen it misused and abused many, many times. But it beats waterfall.
Never crashing.
It seems like such a good idea, doesn't it? Users don't like programs that crash, so let's write programs that don't crash, and users should like the program, right? That's how I started out.
Nowadays, I'm more inclined to think that if it doesn't work, it shouldn't pretend it's working. Fail as soon as you can, with a good error message. If you don't, your program is going to crash even harder just a few instructions later, but with some nondescript null-pointer error that'll take you an hour to debug.
My favorite "don't crash" pattern is this:
public User readUserFromDb(int id){
User u = null;
try {
ResultSet rs = connection.execute("SELECT * FROM user WHERE id = " + id);
if (rs.moveNext()){
u = new User();
u.setFirstName(rs.get("fname"));
u.setSurname(rs.get("sname"));
// etc
}
} catch (Exception e) {
log.info(e);
}
if (u == null){
u = new User();
u.setFirstName("error communicating with database");
u.setSurname("error communicating with database");
// etc
}
u.setId(id);
return u;
}
Now, instead of asking your users to copy/paste the error message and sending it to you, you'll have to dive into the logs trying to find the log entry. (And since they entered an invalid user ID, there'll be no log entry.)
I thought it made sense to apply design patterns whenever I recognised them.
Little did I know that I was actually copying styles from foreign programming languages, while the language I was working with allowed for far more elegant or easier solutions.
Using multiple (very) different languages opened my eyes and made me realise that I don't have to mis-apply other people's solutions to problems that aren't mine. Now I shudder when I see the factory pattern applied in a language like Ruby.
Obsessive testing. I used to be a rabid proponent of test-first development. For some projects it makes a lot of sense, but I've come to realize that it is not only unfeasible, but rather detrimental to many projects to slavishly adhere to a doctrine of writing unit tests for every single piece of functionality.
Really, slavishly adhering to anything can be detrimental.
This is a small thing, but: Caring about where the braces go (on the same line or next line?), suggested maximum line lengths of code, naming conventions for variables, and other elements of style. I've found that everyone seems to care more about this than I do, so I just go with the flow of whoever I'm working with nowadays.
Edit: The exception to this being, of course, when I'm the one who cares the most (or is the one in a position to set the style for a group). In that case, I do what I want!
(Note that this is not the same as having no consistent style. I think a consistent style in a codebase is very important for readability.)
Perhaps the most important "programming practice" I have since changed my mind about, is the idea that my code is better than everyone else's. This is common for programmers (especially newbies).
Utility libraries. I used to carry around an assembly with a variety of helper methods and classes with the theory that I could use them somewhere else someday.
In reality, I just created a huge namespace with a lot of poorly organized bits of functionality.
Now, I just leave them in the project I created them in. In all probability I'm not going to need it, and if I do, I can always refactor them into something reusable later. Sometimes I will flag them with a //TODO for possible extraction into a common assembly.
Designing more than I coded.
After a while, it turns into analysis paralysis.
The use of a DataSet to perform business logic. This binds the code too tightly to the database, also the DataSet is usually created from SQL which makes things even more fragile. If the SQL or the Database changes it tends to trickle to everything the DataSet touches.
Performing any business logic inside an object constructor. With inheritance and the ability to create overloaded constructors tend to make maintenance difficult.
Abbreviating variable/method/table/... Names
I used to do this all of the time, even when working in languages with no enforced limits on lengths of names (well they were probably 255 or something). One of the side-effects were a lot of comments littered throughout the code explaining the (non-standard) abbreviations. And of course, if the names were changed for any reason...
Now I much prefer to call things what they really are, with good descriptive names. including standard abbreviations only. No need to include useless comments, and the code is far more readable and understandable.
Wrapping existing Data Access components, like the Enterprise Library, with a custom layer of helper methods.
It doesn't make anybody's life easier
Its more code that can have bugs in it
A lot of people know how to use the EntLib data access components. No one but the local team knows how to use the in house data access solution
I first heard about object-oriented programming while reading about Smalltalk in 1984, but I didn't have access to an o-o language until I used the cfront C++ compiler in 1992. I finally got to use Smalltalk in 1995. I had eagerly anticipated o-o technology, and bought into the idea that it would save software development.
Now, I just see o-o as one technique that has some advantages, but it's just one tool in the toolbox. I do most of my work in Python, and I often write standalone functions that are not class members, and I often collect groups of data in tuples or lists where in the past I would have created a class. I still create classes when the data structure is complicated, or I need behavior associated with the data, but I tend to resist it.
I'm actually interested in doing some work in Clojure when I get the time, which doesn't provide o-o facilities, although it can use Java objects if I understand correctly. I'm not ready to say anything like o-o is dead, but personally I'm not the fan I used to be.
In C#, using _notation for private members. I now think it's ugly.
I then changed to this.notation for private members, but found I was inconsistent in using it, so I dropped that too.
I stopped going by the university recommended method of design before implementation. Working in a chaotic and complex system has forced me to change attitude.
Of course I still do code research, especially when I'm about to touch code I've never touched before, but normally I try to focus on as small implementations as possible to get something going first. This is the primary goal. Then gradually refine the logic and let the design just appear by itself. Programming is an iterative process and works very well with an agile approach and with lots of refactoring.
The code will not look at all what you first thought it would look like. Happens every time :)
I used to be big into design-by-contract. This meant putting a lot of error checking at the beginning of all my functions. Contracts are still important, from the perspective of separation of concerns, but rather than try to enforce what my code shouldn't do, I try to use unit tests to verify what it does do.
I would use static's in a lot of methods/classes as it was more concise. When I started writing tests that practice changed very quickly.
Checked Exceptions
An amazing idea on paper - defines the contract clearly, no room for mistake or forgetting to check for some exception condition. I was sold when I first heard about it.
Of course, it turned to be such a mess in practice. To the point of having libraries today like Spring JDBC, which has hiding legacy checked exceptions as one of its main features.
That anything worthwhile was only coded in one particular language. In my case I believed that C was the best language ever and I never had any reason to code anything in any other language... ever.
I have since come to appreciate many different languages and the benefits/functionality they offer. If I want to code something small - quickly - I would use Python. If I want to work on a large project I would code in C++ or C#. If I want to develop a brain tumour I would code in Perl.
When I needed to do some refactoring, I thought it was faster and cleaner to start straightaway and implement the new design, fixing up the connections until they work. Then I realized it's better to do a series of small refactorings to slowly but reliably progress towards the new design.
Perhaps the biggest thing that has changed in my coding practices, as well as in others, is the acceptance of outside classes and libraries downloaded from the internet as the basis for behaviors and functionality in applications. In school at the time I attended college we were encouraged to figure out how to make things better via our own code and rely upon the language to solve our problems. With the advances in all aspects of user interface and service/data consumption this is no longer a realistic notion.
There are certain things which will never change in a language, and having a library that wraps this code in a simpler transaction and in fewer lines of code that I have to write is a blessing. Connecting to a database will always be the same. Selecting an element within the DOM will not change. Sending an email via a server-side script will never change. Having to write this time and again wastes time that I could be using to improve my core logic in the application.
Initializing all class members.
I used to explicitly initialize every class member with something, usually NULL. I have come to realize that this:
normally means that every variable is initialized twice before ever being read
is silly because in most languages automatically initialize variables to NULL.
actually enforces a slight performance hit in most languages
can bloat code on larger projects
Like you, I also have embraced IoC patterns in reducing coupling between various components of my apps. It makes maintenance and parts-swapping much simpler, as long as I can keep each component as independent as possible. I'm also utilizing more object-relational frameworks such as NHibernate to simplify database management chores.
In a nutshell, I'm using "mini" frameworks to aid in building software more quickly and efficiently. These mini-frameworks save lots of time, and if done right can make an application super simple to maintain down the road. Plug 'n Play for the win!