Search Results

Search found 14485 results on 580 pages for 'general technology'.

Page 497/580 | < Previous Page | 493 494 495 496 497 498 499 500 501 502 503 504  | Next Page >

• What programming technique not done by you, was ahead of its time?

  - by Ferds

  There are developers who understand a technology and produce a solution months or years ahead of its time. I worked with a guy who designed an system using C# beta which would monitor different system components on several servers. He used SQL Server that would pick up these system monitoring components (via reflection) and would instantiate them via an NT Service. The simplicity in this design, was that another developer (me), who understood part of a system, would produce a component that could monitor it, as he had the specialized knowledge of that part of the system. I would derive from the monitor base class (to start, stop and log info), install on the monitoring server GAC and then add an entry to the components table in sql server. Then the main engine would pick up this component and do its magic. I understood parts of it, but couldn't work out by derive from a base class, why add to the GAC etc. This was 6 years ago and it took me months to realize what he achieved. What programming technique not done by you was ahead of its time? EDIT : Techniques that you have seen at work or journals/blogs - I don't mean historically over years.

  Read the article

• How to decide between using PLINQ and LINQ at runtime?

  - by Hamish Grubijan

  Or decide between a parallel and a sequential operation in general. It is hard to know without testing whether parallel or sequential implementation is best due to overhead. Obviously it will take some time to train "the decider" which method to use. I would say that this method cannot be perfect, so it is probabilistic in nature. The x,y,z do influence "the decider". I think a very naive implementation would be to give both 1/2 chance at the beginning and then start favoring them according to past performance. This disregards x,y,z, however. I suspect that this question would be better answered by academics than practitioners. Anyhow, please share your heuristic, your experience if any, your tips on this. Sample code: public interface IComputer { decimal Compute(decimal x, decimal y, decimal z); } public class SequentialComputer : IComputer { public decimal Compute( ... // sequential implementation } public class ParallelComputer : IComputer { public decimal Compute( ... // parallel implementation } public class HybridComputer : IComputer { private SequentialComputer sc; private ParallelComputer pc; private TheDecider td; // Helps to decide between the two. public HybridComputer() { sc = new SequentialComputer(); pc = new ParallelComputer(); td = TheDecider(); } public decimal Compute(decimal x, decimal y, decimal z) { decimal result; decimal time; if (td.PickOneOfTwo() == 0) { // Time this and save result into time. result = sc.Compute(...); } else { // Time this and save result into time. result = pc.Compute(); } td.Train(time); return result; } }

  Read the article

• What should I do with an over-bloated select-box/drop-down

  - by Tristan Havelick

  All web developers run into this problem when the amount of data in their project grows, and I have yet to see a definitive, intuitive best practice for solving it. When you start a project, you often create forms with tags to help pick related objects for one-to-many relationships. For instance, I might have a system with Neighbors and each Neighbor belongs to a Neighborhood. In version 1 of the application I create an edit user form that has a drop down for selecting users, that simply lists the 5 possible neighborhoods in my geographically limited application. In the beginning, this works great. So long as I have maybe 100 records or less, my select box will load quickly, and be fairly easy to use. However, lets say my application takes off and goes national. Instead of 5 neighborhoods I have 10,000. Suddenly my little drop-down takes forever to load, and once it loads, its hard to find your neighborhood in the massive alphabetically sorted list. Now, in this particular situation, having hierarchical data, and letting users drill down using several dynamically generated drop downs would probably work okay. However, what is the best solution when the objects/records being selected are not hierarchical in nature? In the past, of done this with a popup with a search box, and a list, but this seems clunky and dated. In today's web 2.0 world, what is a good way to find one object amongst many for ones forms? I've considered using an Ajaxifed search box, but this seems to work best for free text, and falls apart a little when the data to be saved is just a reference to another object or record. Feel free to cite specific libraries with generic solutions to this problem, or simply share what you have done in your projects in a more general way

  Read the article

• Why does this Haskell code produce the "infinite type" error?

  - by Charlie Flowers

  I am new to Haskell and facing a "cannot construct infinite type" error that I cannot make sense of. In fact, beyond that, I have not been able to find a good explanation of what this error even means, so if you could go beyond my basic question and explain the "infinite type" error, I'd really appreciate it. Here's the code: intersperse :: a -> [[a]] -> [a] -- intersperse '*' ["foo","bar","baz","quux"] -- should produce the following: -- "foo*bar*baz*quux" -- intersperse -99 [ [1,2,3],[4,5,6],[7,8,9]] -- should produce the following: -- [1,2,3,-99,4,5,6,-99,7,8,9] intersperse _ [] = [] intersperse _ [x] = x intersperse s (x:y:xs) = x:s:y:intersperse s xs And here's the error trying to load it into the interpreter: Prelude :load ./chapter.3.ending.real.world.haskell.exercises.hs [1 of 1] Compiling Main ( chapter.3.ending.real.world.haskell.exercises.hs, interpreted ) chapter.3.ending.real.world.haskell.exercises.hs:147:0: Occurs check: cannot construct the infinite type: a = [a] When generalising the type(s) for `intersperse' Failed, modules loaded: none. Thanks. EDIT: Thanks to the responses, I have corrected the code and I also have a general guideline for dealing with the "infinite type" error in Haskell: Corrected code intersperse _ [] = [] intersperse _ [x] = x intersperse s (x:xs) = x ++ s:intersperse s xs What the problem was: My type signature states that the second parameter to intersperse is a list of lists. Therefore, when I pattern matched against "s (x:y:xs)", x and y became lists. And yet I was treating x and y as elements, not lists. Guideline for dealing with the "infinite type" error: Most of the time, when you get this error, you have forgotten the types of the various variables you're dealing with, and you have attempted to use a variable as if it were some other type than what it is. Look carefully at what type everything is versus how you're using it, and this will usually uncover the problem.

  Read the article

• NHibernate many-to-many mapping

  - by Scozzard

  Hi, I am having an issue with many-to-many mapping using NHibernate. Basically I have 2 classes in my object model (Scenario and Skill) mapping to three tables in my database (Scenario, Skill and ScenarioSkill). The ScenarioSkills table just holds the IDs of the SKill and Scenario table (SkillID, ScenarioID). In the object model a Scenario has a couple of general properties and a list of associated skills (IList) that is obtained from the ScenarioSkills table. There is no associated IList of Scenarios for the Skill object. The mapping from Scenario and Skill to ScenarioSkill is a many-to-many relationship: Scenario * --- * ScenarioSkill * --- * Skill I have mapped out the lists as bags as I believe this is the best option to use from what I have read. The mappings are as follows: Within the Scenario class <bag name="Skills" table="ScenarioSkills"> <key column="ScenarioID" foreign-key="FK_ScenarioSkill_ScenarioID"/> <many-to-many class="Domain.Skill, Domain" column="SkillID" /> </bag> And within the Skill class <bag name="Scenarios" table="ScenarioSkills" inverse="true" access="noop" cascade="all"> <key column="SkillID" foreign-key="FK_ScenarioSkill_SkillID" /> <many-to-many class="Domain.Scenario, Domain" column="ScenarioID" /> </bag> Everything works fine, except when I try to delete a skill, it cannot do so as there is a reference constraint on the SkillID column of the ScenarioSkill table. Can anyone help me? I am using NHibernate 2 on an C# asp.net 3.5 web application solution.

  Read the article

• How to get OCI lib to work on red hat machine to work with R Oracle?

  - by Matt Bannert

  I need to get OCI lib working on my rhel 6.3 machine and I am experiencing some trouble with OCI headers files that can't be found. I have installed (using yum install) oracle-instantclient11.2-basic-11.2.0.3.0-1.x86_64.rpm because this official page it's all I need to run OCI. To test the whole thing in general I've installed sqplus64, which worked after I set export LD_LIBRARY_PATH=/usr/lib/oracle/11.2/client64/lib. Unfortunately the headers files couldn't be found after setting LD_LIBRARY_PATH. Actually I am not surprised because there is no include directory in any of these oracle paths. So the question is: Where do I get these missing header files from? Are they actually already there and I just can find them? Btw: I am doing this whole exercise because I want to use ROracle on my R Studio server and this R package depends on the OCI library. Once I am back in R territory the road gets much less bumpier for me. EDIT: this documentation helped me a little further. However, I guess I found some header files now in: "/usr/include/oracle/11.2/client64". But which variable do I have to set to this location?

  Read the article

• C# wrapper for objects

  - by Haggai

  I'm looking for a way to create a generic wrapper for any object. The wrapper object will behave just like the class it wraps, but will be able to have more properties, variable, methods etc., for e.g. object counting, caching etc. Say the wrapper class be called Wrapper, and the class to be wrapped be called Square and has the constructor Square(double edge_len) and the properties/methods EdgeLength and Area, I would like to use it as follows: Wrapper<Square> mySquare = new Wrapper<Square>(2.5); /* or */ new Square(2.5); Console.Write("Edge {0} -> Area {1}", mySquare.EdgeLength, mySquare.Area); Obviously I can create such a wrapper class for each class I want to wrap, but I'm looking for a general solution, i.e. Wrapper<T> which can handle both primitive and compound types (although in my current situation I would be happy with just wrapping my own classes). Suggestions? Thanks.

  Read the article

• Communication with different social networks, strategy pattern?

  - by bclaessens

  Hi For the last few days I've been thinking how I can solve the following programming problem and find the ideal, flexible programming structure. (note: I'm using Flash as my platform technology but that shouldn't matter since I'm just looking for the ideal design pattern). Our Flash website has multiple situations in which it has to communicate with different social networks (Facebook, Netlog and Skyrock). Now, the communication strategy doesn't have to change multiple times over one "run". The strategy should be picked once (at launch time) for that session. The real problem is the way the communication works between each social network and our website. Some networks force us to ask for a token, others force us to use a webservice, yet another forces us to set up its communication through javascript. The problem becomes more complicated when our website has to run in each network's canvas. Which results in even more (different) ways of communicating. To sum up, our website has to work in the following cases: standalone on the campaign website url (user chooses their favourite network) communicate with netlog OR communicate with facebook OR communicate with skyrock run in a netlog canvas and log in automatically (website checks for netlog parameters) run in a facebook canvas and log in automatically (website checks for facebook params) run in a skyrock canvas and log in automatically (website checks for skyrock params) As you can see, our website needs 6 different ways to communicate with a social network. To be honest, the actual significant difference between all communication strategies is the way they have to connect to their individual network (as stated above in my example). Posting an image, make a comment, ... is the same whether it runs standalone or in the canvas url. WARNING: posting an image, posting a comment DOES differ from network to network. Should I use the strategy pattern and make 6 different communication strategies or is there a better way? An example would be great but isn't required ;) Thanks in advance

  Read the article

• How to collect and inject all beans of a given type in Spring XML configuration

  - by GrzegorzOledzki

  One of the strongest accents of the Spring framework is the Dependency Injection concept. I understand one of the advices behind that is to separate general high-level mechanism from low-level details (as announced by Dependency Inversion Principle). Technically, that boils down to having a bean implementation to know as little as possible about a bean being injected as a dependency, e.g. public class PrintOutBean { private LogicBean logicBean; public void action() { System.out.println(logicBean.humanReadableDetails()); } //... } <bean class="PrintOutBean"> <property name="loginBean" ref="ShoppingCartBean"/> </bean> But what if I wanted to a have a high-level mechanism operating on multiple dependent beans? public class MenuManagementBean { private Collection<Option> options; public void printOut() { for (Option option:options) { // do something for option } //... } } I know one solution would be to use @Autowired annotation in the singleton bean, that is... @Autowired private Collection<Option> options; But doesn't it violate the separation principle? Why do I have to specify what dependents to take in the very same place I use them (i.e. MenuManagementBean class in my example)? Is there a way to inject collections of beans in the XML configuration like this (without any annotation in the MMB class)? <bean class="MenuManagementBean"> <property name="options"> <xxx:autowire by-type="MyOptionImpl"/> </property> </bean>

  Read the article

• Performance Comparison of Shell Scripts vs high level interpreted langs (C#/Java/etc.)

  - by dferraro

  Hi all, First - This is not meant to be a 'which is better, ignorant nonionic war thread'... But rather, I generally need help in making an architecture decision / argument to put forward to my boss. Skipping the details - I simply just would love to know and find the results of anyone who has done some performance comparisons of Shell vs [Insert General Purpose Programming Language (interpreted) here), such as C# or Java... Surprisingly, I have spent some time on Google on searching here to not find any of this data. Has anyone ever done these comparisons, in different use-cases; hitting a database like in a XYX # of loops doing different types of SQL (Oracle pref, but MSSQL would do) queries such as any of the CRUD ops - and also not hitting database and just regular 50k loop type comparison doing different types of calculations, and things of that nature? In particular - for right now, I need to a comparison of hitting an Oracle DB from a shell script vs, lets say C# (again, any GPPL thats interpreted would be fine, even the higher level ones like Python). But I also need to know about standard programming calculations / instructions/etc... Before you ask 'why not just write a quick test yourself? The answer is: I've been a Windows developer my whole life/career and have very limited knowledge of Shell scripting - not to mention *nix as a whole.... So asking the question on here from the more experienced guys would be grealty beneficial, not to mention time saving as we are in near perputual deadline crunch as it is ;). Thanks so much in advance,

  Read the article

• Validating parameters according to a fixed reference

  - by James P.

  The following method is for setting the transfer type of an FTP connection. Basically, I'd like to validate the character input (see comments). Is this going overboard? Is there a more elegant approach? How do you approach parameter validation in general? Any comments are welcome. public void setTransferType(Character typeCharacter, Character optionalSecondCharacter) throws NumberFormatException, IOException { // http://www.nsftools.com/tips/RawFTP.htm#TYPE // Syntax: TYPE type-character [second-type-character] // // Sets the type of file to be transferred. type-character can be any // of: // // * A - ASCII text // * E - EBCDIC text // * I - image (binary data) // * L - local format // // For A and E, the second-type-character specifies how the text should // be interpreted. It can be: // // * N - Non-print (not destined for printing). This is the default if // second-type-character is omitted. // * T - Telnet format control (<CR>, <FF>, etc.) // * C - ASA Carriage Control // // For L, the second-type-character specifies the number of bits per // byte on the local system, and may not be omitted. final Set<Character> acceptedTypeCharacters = new HashSet<Character>(Arrays.asList( new Character[] {'A','E','I','L'} )); final Set<Character> acceptedOptionalSecondCharacters = new HashSet<Character>(Arrays.asList( new Character[] {'N','T','C'} )); if( acceptedTypeCharacters.contains(typeCharacter) ) { if( new Character('A').equals( typeCharacter ) || new Character('E').equals( typeCharacter ) ){ if( acceptedOptionalSecondCharacters.contains(optionalSecondCharacter) ) { executeCommand("TYPE " + typeCharacter + " " + optionalSecondCharacter ); } } else { executeCommand("TYPE " + typeCharacter ); } } }

  Read the article

• Firefox extension js object initialization

  - by Michael

  Note: this is about Firefox extension, not a js general question. In Firefox extension project I need my javascript object to be initialized just once per Firefox window. Otherwise each time I open my window a new timers will be engaged, new properties will be used, so everything will start from scratch. hope example below will demystify my question :) var StupidExtension { statusBarValue: "Not Initialized Yet", startup: function () { ... // Show statusBarValue in Status Bar Panel }, initTimerToRetrieveStatusBarValueFromNetwork: function () { ... } } so each time you hit Ctrl+N a new window you will see "Not Initialized Yet" and then new timer will be fired, so after some time it retrieve data from network you will see value also on second window and so on. Ideally would be to have just a single timer function running and updating all status bar panels in all Firefox windows. Of course I can do some caching, like saving the value in prefs or some other storage, then show it from there. But I feel like this is artificial. So the question will be is there "native" technique of making static some parts of the object among all Firefox window instances?

  Read the article

• Load more function in Javascript

  - by erastusnjuki

  EDIT: This question was initially too general, I think. So What I really need is a very good tutorial on how to implement the Load More function on Safari for iPhone just like the Twitter website(mobile.twitter.com) does. Just a wordpress plugin won't really help. But if the plugin is well explained, like if it is wptouch, home(that also has this function) that can also do. I know that it doesn't really matter that it is being displayed on a mobile device, but the point I am stressing is that if such a function is well explained, then it will be up to me to know how to customize it to suit me. I am using a javascript function to load entries that come from the database dynamically, so that content opens in the same page (like with twitter(tweets feed) and facebook(news feed)). The php/html version(That opens a page in a new tab) is echo '<a href="http://'. $_SERVER['HTTP_HOST'] .'/'.$domain_page.'?form='.$form_id.'&page='.($page+1).'">Load more entries&rsaquo; </a>'; The javascript/ajax version: <div id="call_hv<?php echo md5($_SERVER['REQUEST_URI']); ?>" class="ajax-load-more"> <img id="spinner<?php echo md5($_SERVER['REQUEST_URI']); ?>" class="spin" src="<?php bloginfo('template_directory'); ?>/images/main-ajax-loader.gif" style="display:none" alt="" /> <a class="ajax" href="javascript:$ajax_hv('#spinner<?php echo md5($_SERVER['REQUEST_URI']); ?>').fadeIn(200); $ajax_hv('#ajaxentries_hv<?php echo md5($_SERVER['REQUEST_URI']); ?>').load('form='<? echo $form_id; ?>&page=<?php echo $page+1;?>', {}, function(){ $ajax_hv('#call_hv<?php echo md5($_SERVER['REQUEST_URI']); ?>').fadeOut();})">Load more entries... </a>

  Read the article

• Strict pointer aliasing: is access through a 'volatile' pointer/reference a solution?

  - by doublep

  On the heels of a specific problem, a self-answer and comments to it, I'd like to understand if it is a proper solution, workaround/hack or just plain wrong. Specifically, I rewrote code: T x = ...; if (*reinterpret_cast <int*> (&x) == 0) ... As: T x = ...; if (*reinterpret_cast <volatile int*> (&x) == 0) ... with a volatile qualifier to the pointer. Let's just assume that treating T as int in my situation makes sense. Does this accessing through a volatile reference solve pointer aliasing problem? For a reference, from specification: [ Note: volatile is a hint to the implementation to avoid aggressive optimization involving the object because the value of the object might be changed by means undetectable by an implementation. See 1.9 for detailed semantics. In general, the semantics of volatile are intended to be the same in C++ as they are in C. — end note ] EDIT: The above code did solve my problem at least on GCC 4.5.

  Read the article

• java.awt.Robot.keyPress for continuous keystrokes

  - by Deb

  So, here's my problem. I have a java program which will send keystroke messages to a game (built in Unity), based on how the user interacts with an android phone. (My java program is a listener for the android interaction over wi-fi) Now, in order to do this, I am using java.awt.Robot to send keyPresses to the game window. I have the following code block written in my listener program: if(interacting) { Robot robot = new Robot(); robot.keyPress(VK_A); robot.delay(20); //to simulate the normal keyboard rate } Now the variable interacting will be true as long as the user presses down on the touch screen of the phone, and what I intend to achieve is a continuous chain of keystroke messages being delivered to the game (through the listener). However, this is severely affecting performance, for some reason. I am noticing that the game becomes slow (rapidly dropping frame rates), and even the computer becomes slow, in general. What's going wrong? Should I use a robot.keyRelease(VK_A) after each keyPress? But my game has a different action mapped to the release of a key, and I do not want rapid key presses and releases; what I really want is to simulate continuous keystrokes, in exactly the way it would behave if the user were pressing down the A key on their keyboard manually. Please help.

  Read the article

• Best way to implement plugin framework - are DLLs the only way (C/C++ project)?

  - by Microkernel

  Introduction: I am currently developing a document classifier software in C/C++ and I will be using Naive-Bayesian model for classification. But I wanted the users to use any algorithm that they want(or I want in the future), hence I went to separate the algorithm part in the architecture as a plugin that will be attached to the main app @ app start-up. Hence any user can write his own algorithm as a plugin and use it with my app. Problem Statement: The way I am intending to develop this is to have each of the algorithms that user wants to use to be made into a DLL file and put into a specific directory. And at the start, my app will search for all the DLLs in that directory and load them. My Questions: (1) What if a malicious code is made as a DLL (and that will have same functions mandated by plugin framework) and put into my plugins directory? In that case, my app will think that its a plugin and picks it and calls its functions, so the malicious code can easily bring down my entire app down (In the worst case could make my app as a malicious code launcher!!!). (2) Is using DLLs the only way available to implement plugin design pattern? (Not only for the fear of malicious plugin, but its a generic question out of curiosity :) ) (3) I think a lot of softwares are written with plugin model for extendability, if so, how do they defend against such attacks? (4) In general what do you think about my decision to use plugin model for extendability (do you think I should look at any other alternatives?) Thank you -MicroKernel :)

  Read the article

• How to DRY on CRUD parts of my Rails app?

  - by kolrie

  I am writing an app which - similarly to many apps out there - is 90% regular CRUD things and 10% "juice", where we need nasty business logic and more flexibility and customization. Regarding this 90%, I was trying to stick to the DRY principle as much as I can. As long as controllers go, I have found resource_controller to really work, and I could get rid of all the controllers on that area, replacing them with a generic one. Now I'd like to know how to get the same with the views. On this app I have an overall, application.html.erb layout and then I must have another layout layer, common for all CRUD views and finally a "core" part: On index.html.erb all I need to generate a simple table with the fields and labels I indicate. For new and edit, also generic form edition, indicating labels and fields (with a possibility of providing custom fields if needed). I am not sure I will need show, but if I do it would be the same as new and edit. What plugins and tools (or even articles and general pointer) would help me to get that done? Thanks, Felipe.

  Read the article

• Web Applications Development: Security practices for Application design

  - by Shyam

  Hi, As I am creating more web applications that are targeted for multiple users, I figured out that I have to start thinking about user management and security. At a glance and in my ideal world, all users belong to a group. Permissions and access is thus defined per group (and inherited by the users of that group). Logically, I have my group of administrators, which are identified with a level "7" (integer) clearance. A group of webusers have for example level "1". This in generally all works great for me, but I need some kind of list that I have to keep in mind how I secure my system, and some general practices. I am not looking for a specific environment; I want to learn the why's and how's. An example is privilege escalation. If someone would be able to "push" themselves inside a group with higher privileges, for example the Administration, how can I prevent this, or what measures should I take to have some sort of precaution? I don't like in that case to walk into a caveat. My question is basically: where can I find a good resource, list, policy, book that explains the security of web applications, the why's, the how's and readable if you don't have any experience in the realm of advanced security? I prefer a free resource, as I believe I couldn't be the first one who thought about this. Thank you for your answers, comments and feedback.

  Read the article

• using yield in C# like I would in Ruby

  - by Sarah Vessels

  Besides just using yield for iterators in Ruby, I also use it to pass control briefly back to the caller before resuming control in the called method. What I want to do in C# is similar. In a test class, I want to get a connection instance, create another variable instance that uses that connection, then pass the variable to the calling method so it can be fiddled with. I then want control to return to the called method so that the connection can be disposed. I guess I'm wanting a block/closure like in Ruby. Here's the general idea: private static MyThing getThing() { using (var connection = new Connection()) { yield return new MyThing(connection); } } [TestMethod] public void MyTest1() { // call getThing(), use yielded MyThing, control returns to getThing() // for disposal } [TestMethod] public void MyTest2() { // call getThing(), use yielded MyThing, control returns to getThing() // for disposal } ... This doesn't work in C#; ReSharper tells me that the body of getThing cannot be an iterator block because MyThing is not an iterator interface type. That's definitely true, but I don't want to iterate through some list. I'm guessing I shouldn't use yield if I'm not working with iterators. Any idea how I can achieve this block/closure thing in C# so I don't have to wrap my code in MyTest1, MyTest2, ... with the code in getThing()'s body?

  Read the article

• Cassandra instead of MySQL for social networking app

  - by Christopher McCann

  I am in the middle of building a new app which will have very similar features to Facebook and although obviously it wont ever have to deal with the likes of 400,000,000 million users it will still be used by a substantial user base and most of them will demand it run very very quickly. I have extensive experience with MySQL but a social app offers complexities which MySQL is not well suited too. I know Facebook, Twitter etc have moved towards Cassandra for a lot of their data but I am not sure how far to go with it. For example would you store such things as user data - username, passwords, addresses etc in Cassandra? Would you store e-mails, comments, status updates etc in Cassandra? I have also read alot that something like neo4j is much better for representing the friend relationships used by social apps as it is a graph database. I am only just starting down the NoSQL route so any guidance is greatly appreciated. Would anyone be able to advise me on this? I hope I am not being too general!

  Read the article

• The use of getters and setters for different programming languages [closed]

  - by leonhart88

  So I know there are a lot of questions on getters and setters in general, but I couldn't find something exactly like my question. I was wondering if people change the use of get/set depending on different languages. I started learning with C++ and was taught to use getters and setters. This is what I understand: In C++ (and Java?), a variable can either be public or private, but we cannot have a mix. For example, I can't have a read-only variable that can still be changed inside the class. It's either all public (can read and change it), or all private (can't read and can only change inside the class). Because of this (and possibly other reasons), we use getters and setters. In MATLAB, I can control the "setaccess" and "getaccess" properties of variables, so that I can make things read-only (can directly access the property, but can't overwrite it). In this case, I don't feel like I need a getter because I can just do class.property. Also, in Python it is considered "Pythonic" to not use getters/setters and to only put things into properties if needed. I don't really understand why its OK to have all public variables in Python, because that's opposite of what I learned when I started with C++. I'm just curious what other people's thoughts are on this. Would you use getters and setters for all languages? Would you only use it for C++/Java and do direct access in MATLAB and Python (which is what I am currently doing)? Is the second option considered bad? For my purposes, I am only referring to simple getters and setters (just return/set the value and do not do anything else). Thanks!

  Read the article

• Using virtualization infrastructure for J2EE application distribution- viable alternative?

  - by Dan

  Our company builds custom J2EE web solutions. At the moment, we use standard J2EE distribution mechanisms (ear/war archives). Application servers are generally administered by our clients' IT departments and since we do not have complete control over the environment, a lot of entropy can be introduced into the solution. For example: latest app. server patch not applied conflicting third party libraries inside the app. server root server runtime and tuning parameters not configured (for example, number of connections in database pool) We are looking into using virtualization infrastructure for J2EE application distribution. Instead of sending the ear/war archive, we’d send image with application server node and our application preinstalled. Some of the benefits are same as using with using virtualization infrastructure in general, namely better use of hardware resources. For us, it reduces the entropy of hosting infrastructure - distributing VM should be less affected by hosting environment. So far, the downside I see can be in application server licenses, here they will have to use dedicated servers for our solution, but this is generally already done that way. Also, there is a complexity with maintaining virtualization infrastructure, but this is often something IT departments have more experience with than with administering and fine-tuning J2EE solutions. Anyone has experience with this model? What are the downsides? Will we not just replace one type of complexity with other?

  Read the article

• objective-c having issues with an NSDictioary object

  - by Mark

  I have a simple iPhone app that Im learning and I want to have an instance variable called urlLists which is an NSDictionary I have declared it like so: @interface MyViewController : UIViewController <UIPickerViewDataSource, UIPickerViewDelegate>{ IBOutlet UIPickerView *pickerView; NSMutableArray *categories; NSDictionary *urlLists; } @property(retain) NSDictionary *urlLists; @end and in the implementation: @implementation MyViewController @synthesize urlLists; ... - (void)viewDidLoad { [super viewDidLoad]; categories = [[NSMutableArray alloc] init]; [categories addObject:@"Sport"]; [categories addObject:@"Entertainment"]; [categories addObject:@"Technology"]; [categories addObject:@"Political"]; NSArray *objects = [NSArray arrayWithObjects:@"value1", @"value2", @"value3", @"value4", nil]; urlLists = [NSDictionary dictionaryWithObjects:objects forKeys:categories]; for (id key in urlLists) { NSLog(@"key: %@, value: %@", key, [urlLists objectForKey:key]); } } ... @end And, this all works up to here. I have added a UIPicker to my app, and when I select one of the items, I want to Log the one picked and its related entry in my dictionary. -(void) pickerView:(UIPickerView *)thePickerView didSelectRow:(NSInteger)row inComponent:(NSInteger) component { for (id key in self.urlLists) { NSLog(@"key: %@, value: %@", key, [urlLists objectForKey:key]); } } but I get the old EXC_BAD_ACCESS error... I know Im missing something small, but what? Thanks

  Read the article

• How can I solve the Log Pile wooden puzzle with a computer program?

  - by craig1410

  Can anyone suggest how to solve the Log Pile wooden puzzle using a computer program? See here to visualise the puzzle: http://www.puzzlethis.co.uk/products/madcow/the_log_pile.htm The picture only shows some of the pieces. The full set of 10 pieces are configured as follows with 1 representing a peg, -1 representing a hole and 0 representing neither a peg nor a hole. -1,1,0,-1,0 1,0,1,0,0 1,-1,1,0,0 -1,-1,0,0,-1 -1,1,0,1,0 0,1,0,0,1 1,0,-1,0,-1 0,-1,0,1,0 0,0,-1,1,-1 1,0,-1,0,0 The pieces can be interlocked in two layers of 5 pieces each with the top layer at 90 degrees to the bottom layer as shown in the above link. I have already created a solution to this problem myself using Java but I feel that it was a clumsy solution and I am interested to see some more sophisticated solutions. Feel free to either suggest a general approach or to provide a working program in the language of your choice. My approach was to use the numeric notation above to create an array of "Logs". I then used a combination/permutation generator to try all possible arrangements of the Logs until a solution was found where all the intersections equated to zero (ie. Peg to Hole, Hole to Peg or Blank to Blank). I used some speed-ups to detect the first failed intersection for a given permutation and move on to the next permutation. I hope you find this as interesting as I have. Thanks, Craig.

  Read the article

• Reduce durability in MySQL for performance

  - by Paul Prescod

  My site occasionally has fairly predictable bursts of traffic that increase the throughput by 100 times more than normal. For example, we are going to be featured on a television show, and I expect in the hour after the show, I'll get more than 100 times more traffic than normal. My understanding is that MySQL (InnoDB) generally keeps my data in a bunch of different places: RAM Buffers commitlog binary log actual tables All of the above places on my DB slave This is too much "durability" given that I'm on an EC2 node and most of the stuff goes across the same network pipe (file systems are network attached). Plus the drives are just slow. The data is not high value and I'd rather take a small chance of a few minutes of data loss rather than have a high probability of an outage when the crowd arrives. During these traffic bursts I would like to do all of that I/O only if I can afford it. I'd like to just keep as much in RAM as possible (I have a fair chunk of RAM compared to the data size that would be touched over an hour). If buffers get scarce, or the I/O channel is not too overloaded, then sure, I'd like things to go to the commitlog or binary log to be sent to the slave. If, and only if, the I/O channel is not overloaded, I'd like to write back to the actual tables. In other words, I'd like MySQL/InnoDB to use a "write back" cache algorithm rather than a "write through" cache algorithm. Can I convince it to do that? If this is not possible, I am interested in general MySQL write-performance optimization tips. Most of the docs are about optimizing read performance, but when I get a crowd of users, I am creating accounts for all of them, so that's a write-heavy workload.

  Read the article

< Previous Page | 493 494 495 496 497 498 499 500 501 502 503 504  | Next Page >