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First off all, I know there are several questions about "Java inline". But they are all about how the compiler or JVM inlines function calls. I'm interested in doing this myself, or create some kind of a View for it. I want to define a function call of a class, and want to see everything inlined. Every method call should get inlined. I'm not sure how to handle instantiation of new objects, but it doesn't matter as much.
The goal is manual optimization, i.e. if a parameter is checked too often against null. Is there a tool to to something like this? I would prefer a GUI, but some kind of command line tool where I can specify a class function and it dumps some text somewhere will suffice, too.
EDIT:
For clearification:
Today I argued to use the NullObjectPattern, because some are defensively overchecking for nulls everywhere. This makes the code unreadable and unclean. I dont like it and wanted to have some kind of a tool, to show them how often they are actually checking the very same parameter again and again for null.
As was said: Don't guess, especially when you don't know what the JIT compiler will do after the code has been running for a while. You can waste infinite time infinitely improving something that accounts for 1% of runtime and only save 1%, or you can spend a short time getting a 10% improvement of something that accounts for 20% of your runtime and save 2%; the latter is by far a better choice.
The way you determine what's worth improving is by properly profiling your code after it has been fully warmed up.
And the way you get a significant improvement generally has more to do with improved algorithms than with microtuning of single instructions.
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for example, in an ArrayList, each item is very big, and the size of the list may be large enough to exceed the size of memory. What is the strategy to expand a list in this situation?
Thanks for all the replies. I have encountered such a problem that receiving a list of object by remote calling, and each object in the list may be quite large while the size of the list may be 10000 or more. I wonder how to store this list into memory during the execution.
List<BigItem> list = queryService.queryForList(params...);
Your question is very generic, but I think it is possible to give a certain "fact based" answer nonetheless:
If your setup is as such that memory becomes a bottleneck; then your application needs to be aware about that fact. In other words: you need to implement measurements within your application.
You have to enable your application to make the decision if "growing" a list (and "loading" those expensive objects for example) is possible, or not.
A simple starting point is described here; but of course, this is really a complicated undertaking. Your code has to constantly monitor its memory usage; and take appropriate steps if you get closer to your limits.
Alternatively, you should to profiling to really understand the memory consumption "behavior" of your application. There is no point in a putting effort into "self-controlling" ... if your application happens to have various memory leaks for example. Or if your code is generating "garbage" on a rate that makes the garbage collector spin constantly.
You see, a lot of aspects come into play here. You should focus on them one by one. Start with understanding your application; then decide if you have to improve its "garbage collection" behavior; or if you have go down the full nine yards and make your application manage itself!
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I am used to programming in static languages like Java, where changing the signature of a method will cause a compilation error for every line of code that calls the method I changed. This makes modifying large projects much more easy, because I can make a change, and then let the compiler tell me about all the places that I need to fix.
When dealing with a large project in a dynamic language like Python or Ruby, how do you make code changes, and still remain confident that you are not going to be surprised with a run-time error in production because of some scenario you forgot about?
I've seen my fair share of NullPointerExceptions and ArrayIndexOutOfBoundsExceptions in Java, so it's not like these things never happen in a static language, I would just think they happen a lot less.
Here are some ideas for providing some level of the protection that you are used to in Java:
As stated in a previous comment, you should definitely provide adequate unit and integration testing to prevent any issues during a refactor. Testing is even more important in a dynamic language than in a statically-typed language. You should check that values are properly passed and handled in each of your functions.
Use PyCharm and search for usages on a method prior to making the update. This is not full-proof, but does find a good amount of method usage to allow for an easier refactor.
Do a global find for the method name in your editor or search program of choice.
Provide exception handling in your functions for cases where the type is incorrect or a value is unset.
Handle args and kwargs passed into your function carefully. Perhaps provide an error or debug log if you receive an unexpected input.
Provide default values for undefined parameters to a function.
Here is an example of providing a default value for a parameter to ensure that it is defined and initialized to None (similar to null) in the function if it is not passed in with a value:
def my_function(my_parameter=None):
# Do something with my_parameter
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Lots of times I see people naming their methods a(), b(), c(), etc. instead of giving them names that describe what the method actually does. What is the point of this?
My guess is that you were reading obfuscated code.
Here's a nice article.
They shouldn't be doing this. It's bad practice.
Either the developer is being lazy, or they are showing a very simple example(still bad practice).
EDIT: (Given the extra detail in your comments)
In that case this is probably done by some automated program. The code the developer is actually working on wouldn't be using these names.
To minimize the load time for .js files, many developers will "compress" them. Compressing also has an option to obfuscate the code, making it more difficult to steal and change by making it difficult to understand. This happens just as you describe, by changing the variable names and function names to "a", "b", "c", etc. This has the side-effect of making the code smaller, since the names are now shorter. An example of a web tool that does this for you is here: http://www.developerfusion.com/tools/compressjavascript/
The code base that you maintain is certainly NOT the one that has been compressed and/or obfuscated.
Nothing. They are just too lazy to follow the standard naming conventions maybe because they are simply doing some quick POC(proof of concept) and they don't want to waste their time in typing some meaningful method name.
But one must always follow the naming conventions in their actual projects where others might be looking/maintaining their code.
This has always been discouraged by every community into programming and probably is a sign of a bad developer.
For more information on why and how do we use coding conventions see this
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I've been running through a lot of code reviews and keep running into a situation where I see conflicting coding standards regarding boolean variables and if statements.
Here is an example of one method(1):
boolean isXTrue = getBooleanValue(DataSetX);
if (isXTrue) {
//do code
}
Here is an example of the other method(2):
if (getBooleanValue(DataSetX)) {
//do code
}
Both do the same thing and function just fine. In some cases, method 1 is a lot more readable since the boolean variable can be named something meaningful, while method 2 saves more lines and unnecessary boolean variable creations.
Maybe I am reading too deep into a simple coding standard, but I'm rather curious that if we use method 1 more often, we could have unnecessary booleans being made.
Sorry if this is a stupid question, but I wanted to get some opinions anyway :)
It's likely that the compiler will optimize both cases so that either way is identical at run time. Of course, that depends on code outside the context that you've provided.
As for the question at large: it's something that you and your coworkers or group need to come to a consensus about. If you're looking for a definite answer about which one to choose, I don't think you're going to get anything convincing other than personal preferences of readability vs line count.
Discuss this with the others that maintain your code base and decide on which should be preferred. Clearly explain why. Then move on to more...err...important issues.
As for my preference? I like option 1. To me, it's more readable, the variable name can be something descriptive like isActive, which makes the code easier to read. Also, inspecting values during debugging is probably easier as you have a definite variable with which to reference prior to its use later in the chain. Again, that's my preference.
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I have just finished a 2D game in Java that I've been working on for a while.
I found that on some computers it runs fine, and on others (which are not particularly slow in general), the game runs a little slower, and with minor interruptions every second or so. Not completely smooth.
Since I am a beginner to making games, and probably since I didn't plan everything about the game in advance, the code of the game is rather long, clumsy and probably inefficient.
I want to improve this in my next projects. So my question is - In general, what would be the main causes for a common 2D game to slow down on a computer?
What should I pay the most attention to, next time, in order to design an efficient game?
Making a small amount of classes? (Even if the classes are small
ones?)
Avoiding repetition of code? (Even small sections of code, such as
short if statements).
Avoiding too many threads running?
Anything else?
Obviously, all of the above are recommended for an efficient program.
But I'd like to know, what in a game's code, could be especially significant for making an efficient application, and what would be less important and will not save significant amounts of memory.
Any advice would be welcome - could be regarding game design, or regarding more specific coding issues.
I don't know if this matters, but please note that I'm talking mainly about real-time games, using a 'game-loop' that constantly updates the game and the dispaly.
The important thing when trying to improve the performance of any program, not just a game, is - don't guess.
If I or anyone says "it's in your collection classes", or "it's in your rendering", or "it's in your memory management", or "it's in your compiler optimization", can you trust it?
Short answer - No - because it's a guess.
It could be true. It could be false. Nobody knows, in your case.
People who say instead of guessing "Use a profiler" are on the right track.
In my opinion there's an even better method, spelled out here.
If you need to know why, I'll explain it further, but the hard part for any programmer is to stop trying to think it out, and let the tool tell you what to look at.