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I want to build a solitaire game in C++ for my project.
Here's what I have come up with: Card class Properties/members: Suit,Rank,Color(All of these can be enums) Actions/Functions: Flip card, compare card, print card Rules Class: Would contain the rules of the game and also validate each user action/command to check if it is allowed. Commands Class: I am thinking this need not necessarily be a class. Could be an enum as well. A base class CardPile. Have more classes derived from CardPile such as DealPile, Temporary Pile, DestinationPile, TablePile. What I am not clear about is the relationships between classes.
Thanks!
You need a representation of a card which will hold the card's value and suit.
You will also need a data structure to represent a "stack" of cards.
From there, building the GUI shouldn't be that challenging. This is a very easy project, and you seem to have the right idea.
Consider, instead of doing a bunch of up-front design, focusing on creating things that work. What will your program need to do?
It'll need to shuffle, so design a way to represent 52 cards and shuffle them. It's pretty easy to implement, but it's a good starting point.
Then you'll need to lay out the cards. So come up with a way to lay out the cards and put the rest in the draw pile.
And so forth. Instead of analyzing objects, focus on behaviors. Create objects only as needed in order to support the behaviors of your program. That will help you avoid getting lost in the analysis and excess code and ensure that you have a program that actually does some useful things.
(What if you need to turn in your design before doing anything? Not a problem; do your thinking the way I've described above. The implementation will be left for later, but even just thinking out how routines like the above will work will be more valuable than designing a bunch of objects without knowing what you'll do with them.)
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About six months ago I put on a full-stack developer hat at my job and started working on a tool comprised of a GUI and a database. The client has requested that the tool be written in Python, so I've been working with the company PyQt license to create the interface.
This is the first tool of this kind I've ever created and it's going quite well, but a question that keeps nagging at me as I subclass PyQt's various GUI elements is: "Where should I implement this?"
For example, one of the tool's functions involves giving a user a form to fill out (which is a subclassed GUI element) and then submitting the completed form to be stored in one of the database's tables -- pretty standard stuff. The user fills out the form and upon pressing the "submit" button, the form's fields are validated to ensure they adhere to certain constraints and then a stored procedure is called in the database to submit the form's data. Let's call that function submit().
Obviously there are a myriad of ways to structure the code but the 3 big ones I've been toying with are:
Implement submit() directly in the form's class body as one of its methods
Create functions outside the class and have the class itself call them
Create a "handler" class that receives the form's fields in a signal emitted upon clicking the "submit" button
My question is this: which of them, if any, is the "best" way to do this? When I say "best" I mean which is the most "OOP-ish" in terms of accepted conventions, as well as which of them would be easiest for the programmer who comes after me to read and maintain.
Thanks in advance :)
Think of the different parts of your application as systems, each with their own responsibility. For example, the UI system, the database system, and the system(s) in between that implement the business rules. In each system, have a different version of your business objects that matches the abstraction of the system; for example, a user entry form in the UI system, a user table in the database system, a user model in the business system.
Then, as per your option 3, establish communication between the different systems via messages and signals. You would have to decide on some sort of protocol for the data payload being passed around so that you do not leak abstraction between systems. Data transfer objects are a good way to do that, but you could also send bytes or some textual representation such as JSON.
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I'm starting project number 8,192. Like most of my projects, they are either throw-away projects or projects that get canceled either from boredom, time or lack of usefulness.
But there is a project that has been on the back-burners for a long time that I really want to finish. In my perfect world mind, it should take 3 months for first release.
Anyway, one of my biggest issues is taking a large project (or even a small to medium one) and break it down into manageable pieces. My error is to always jump right on the terminal, open Textmate and start coding. This almost always fails. I get lost in feature creep, learning newer methods, framework wars, etc. Then, two months have gone by and nothing to show for it.
So I was thinking if BDD (such as Cucumber) might be a solution to this? Could it be used to scope out the larger pieces, then the smaller pieces until I have a feature list that is most of the project. At that point, I just start coding the pieces right?
What are your suggestions on tackling this problem that I'm sure other developers share.
BTW, I'm using Rails 3 (sometimes Padrino).
Thanks
On which track? BDD doesn't define the track--it communicates the track.
BDD may be the only requirements you have (or need), but that doesn't address the issue of feeping creaturisms unless you have the discipline not to implement anything for which no spec exists.
Uncaptured features don't get implemented, period. If a feature is added, it gets a scope, and is prioritized with the rest of the features. It may usurp something less-desirable, it may not.
The product owner (you in this case) must decide how much can be implemented in the time allotted, and which features should be implemented. Still boils down to discipline, however, you just have a tool that (helps) make sure what you implemented is what you actually wanted.
It doesn't, however, make sure that what you get is only what you originally wanted--it won't make sure nothing else is implemented on top of the specs you bothered to implement.
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I recently had my code reviewed by a senior developer in my company. He criticized my design for using too many classes. I am interested to hear your reactions.
I was tasked to create a service which produces an xml file as a result of manipulating 3 other xml files. Let's name these aaa.xml, bbb.xml and ccc.xml. The service works in two phases. In phase one it scrubs aaa.xml against bbb.xml. In the second phase, it merges the product of phase one with ccc.xml to produce a final result.
I chose a design with three classes: an XmlService class which used two other classes, a scrubber class and a merger class. I kept the scrubbing and merging classes separate because the both classes were large and featured distinct logic.
I thought my approach was good because it kept my classes small and cohesive. My approach also helped to control the size of my test class.
The senior developer asserted that the scrubbing and merging classes would only be used by the XmlService class, and should therefore be part of it. He felt this would make the XMLService cohesive and this is what being cohesive means according to him. He also feels that breaking up classes this way makes them loose cohesiveness.
The irony is I tried to break these classes to achieve cohesiveness. What do you think? Who is right or wrong? Are we both right? Thank you for your suggestions.
If you follow the single responsibility principle (and based on the tone of your question, I think you do follow it), then the answer is clear:
A class is too big when it does more than one thing; and
A class is too small when it fails to fulfill its purpose.
That's very broad and indeed subjective -- hence the struggle with your colleague. On your side, you can argue:
There's absolutely no problem in creating additional classes -- It's a non-issue, compile-wise and runtime-wise.
The current implementation of the service may suggest that these classes "belong" to it, but that may change.
You can test each functionality separately.
You can apply dependency injection.
You ease the cognitive load of understanding the inner working of the service, because its code is smaller and better organized.
Furthermore, I think your boss has a misguided understanding of cohesion. Think of it as focus: the narrower the focus of your program, the higher the cohesion. If the code on your satellite classes is merged within the service class, the latter becomes less focused (less cohesive). It's generally accepted that higher cohesion is preferred over lower cohesion. Try to enlighten his/her view about it.
Cohesion is a measure of how strongly related is the functionality within a body of code. That said, if merging and scrubbing aren't strongly related, including them both in the same class reduces cohesion.
The Single Responsibility Principle is also worth mentioning here. Creating a class for the sole purpose of scrubbing and another for the sole purpose of merging follows this principle.
I'd say your approach is the better of the two.
What would you name the classes? ScrubXml and MergeXml are nice names. ProcessXML and ScrubAndMergeXml aren't, the first being too general and the second having a conjunction. As long as none of the classes rely at all on the internals of one or the others (i.e., low coupling), you've got a good design there.
Names are very useful in determining cohesion. A cohesive module does one thing, and therefore has a simple specific name. A module that does more than one thing is less cohesive, and needs a more general or more complicated name.
One problem with merging functionality in X into Y if X is only used by Y is the reductio ad absurdam: if your call graph is acyclic, you'll wind up with all your functionality in one class.
As someone who is coming back from the GodClass building fest of several years in duration, and now trying very hard to avoid that mistake in the future; the error of making a 6000 to 10000 line single source unit with a single class, with over 250 methods, 200 data fields, and some methods over 100 lines, the single responsibility principle looks like something worth defending against the predilections of your unenlightened supervisor.
If however, your supervisor and you are disagreeing over a matter of whether 2000 lines of code belong in one class or three, then I think you're both closer to sane, than I was. Maybe it's a matter of scale and perspective. Some object oriented programming aficionados like a certain "Coefficient of Standalone" per class, in direct violation of the generally understood ideas about how to improve cohesion and minimize coupling.
A set of 3 classes that work well together is, objectively, a more object-oriented system, than a single class that does the same thing. one could argue that if you write an application using only one class, that the application is not really object oriented at all.
If the scrubber and merger are not meaningful outside the context of the main class, then I agree with your reviewer, particularly if you've had to expose any implementation details in order to allow this separation. If you're using a language supporting nested private classes or something similar, that might be a reasonable alternative to maintain the logical separation without exposing implementation details to outside consumers of the main class.
This is a very subjective area, and will be different depending on coding and style guidelines, and who approves your code.
That said, if your defense of your design didn't hold up, and your senior team member still insisted on merging your classes, then you have to compromise:
You've already got the logic separated out. Write the one service class and keep the methods separate like other good design, and then write a glue method. Add some comments above each method explaining how they could easily be partitioned to multiple classes if the need arises in the future.
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In short I'm creating a 2D mmorpg and unlike my last "mmo" I started developing I want to make sure that this one will scale well and work well when I want to add new in-game features or modify existing ones.
With my last attempt with an avatar chat within the first few thousand lines of code and just getting basic features added into the game I seen my code quality lowering and my ability to add new features or modify old ones was getting lower too as I added more features in. It turned into one big mess that some how ran, lol.
This time I really need to buckle down and find a design that will allow me to create a game framework that will be easy to add and remove features (aka things like playing mini-games within my world or a mail system or buddy list or a new public area with interactive items).
I'm thinking that maybe a component based approach MIGHT be what I'm looking for but I'm really not sure. I have read documents on mmorpg design and 2d game engine architecture but nothing really explained a way of designing a game framework that will basically let me "plug-in" new features into the main game.
Hope someone understands what I mean, any help is appreciated.
If you search for component-based systems within games, you will find something quite different to what you are actually asking for. And how best to do this is far from agreed upon just yet, anyway. So I wouldn't recommend doing that. What you're really talking about is not really anything specific to games, never mind MMOs. It's just the ability to write maintainable code which allows for extension and improvements, which was a problem for business software long before games-as-a-service became so popular and important.
I'd say that addressing this problem comes primarily from two things. Firstly, you need a good specification and a resulting design that makes an attempt to understand future requirements, so that the systems you write now are more easily extended when you come to that. No plug-in architecture can work well without a good idea of what exactly you hope to be plugging in. I'm not saying you need to draw up a 100-page design doc, but at the very least you should be brainstorming your ideas and plans and looking for common ground there, so that when you're coding feature A, you are writing it with Future feature B in mind.
Secondly, you need good software engineering principles which mean that your code is easy to work with and use. eg. Read up on the SOLID principles, and take some time to understand why these 5 ideas are useful. Code that follows those rules is a lot easier to twist to whatever future needs you have.
There is a third way to improve your code, but which isn't going to help you just yet: experience. Your code gets better the more you write and the more you learn about coding. It's possible (well, likely) that with an MMO you are biting off a lot more than you can chew. Even teams of qualified professionals end up with unmaintainable messes of code when attempting projects of that magnitude, so it's no surprise that you would, too. But they have messes of code that they managed to see to completion, and often that's what it's about, not about stopping and redesigning whenever the going gets tough.
Yes, I got what you want...
Basically, you will have to use classic OOP design, the same one that business software coders use...
You will first have to lay out the basic engine, that engine should have a "module loader" or a common OOP-style interface, then you either code modules to be loaded (like, as .dlls) or you code directly within your source code, using that mentioned OOP-style interface, and NEVER, EVER allow a module to depend on each other...
The communication, even inside your code, should be ALWAYS using a interface, never put "public" vars in your modules and use it somewhere else, otherwise you will end with a awfull and messy code.
But if you do it properly, you can do some really cool stuff (I for example, changed the entire game library (API that access video, mouse, keyboard, audio...) of my game, in the middle of development... I just needed to recode one file, that was the one that made the interface between logic, and game library...)
What you're thinking about is exactly what this article describes. It's a lovely way to build games as I have blogged about, and the article is an excellent resource to get your started.
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Stackoverflow users,
How do you keep yourself from creating large classes with large bodied methods. When deadlines are tight, you end up trying to hack things together and it ends up being a mess that needs refactoring.
One way is to start with test driven development and that lends itself to good class design as well as SRP (Single Responsibility Principle).
I also see developers double clicking on controls and typing out line after line in the event method that gets fired.
Any suggestions?
I guess it depends on your internal processes as much as anything.
In my company, we practise peer review, and all code that gets comitted must be 'buddied in' by another developer, who you have to explain your code to.
Time constraints are one thing, but if I review code that has heinously long classes, then I won't agree to the check-in.
It's hard to get used to at first, but at the end of the day, it's better for everyone.
Also, having a senior developer who is a champion for good class design, and is willing and able to give examples, helps tremendously.
Finally, we often do a coding 'show and tell' session where we get to show off our work to our peers, it behooves us not to do this with ugly code!
Use a tool like Resharper and the Extract Method command.
Long classes is one bad code smell of many possible.
Remedying overly large classes by creating lots of small ones may create its own problems. New engineers on your project may find it difficult to follow the flow of the code to work out what happens where. One artifact of this problem can be very tall call stacks, execution nesting through many small classes.
Another suggestion is to do only what is asked. Don't play the "What if" game and try to overdesign a solution. This has the "Keep it simple, stupid" idea behind it.
We're a java and maven shop, and one of the...I guess you could say forensic methods we use are the excellent FindBugs, PMD and javancss plugins. All will give warnings about excessive length in a method, and the cyclomatic complexity calculations can be very eye opening.
The single most important step for me to avoid large classes that often violate SRP was to use a simple dependency injection framework. This freed me from thinking too much about how to wire things together. I only use constructor injection to keep the design free from cycles. Tools like Resharper help to initialize fields from constructor arguments. This combination leads to a near zero overhead for creating and wiring up new classes, and implicitly encourages me to structure behavior in much more detail.
This all works best if data is kept separate from behavior, and your language supports constructs like events that can be used to decouple communication that flows in the downward direction of the dependency graph.
use some static code analysis tools in your automated builds and write/configure/use some rules so that for example someone has to write a justification when he/she breaks it..