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  • HELP!! Ruby & RoR Resources?

    - by aaroninfidel
    Hello, I've been a PHP Developer for a few years now and I've recently been interested in learning Ruby & Rails but I've found a lot of the resources I've found seem to be dated and not for Rails 2.0 or Ruby 1.8.6 etc... can anyone point me in the right direction? I'm running OSX 10.6 with the default ruby & rails installation. Thanks!

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  • How to connect remote EJB module from application client

    - by Zeck
    Hi guys, I have a EJB module in remote Glassfish server and application client in my computer. I want to connect from the application client to the remote EJB. Here is the my EJB interface: @Remote public interface BookEJBRemote { public String getTitle(); } Here is the my ejb: @Stateless public class BookEJB implements BookEJBRemote { @Override public String getTitle() { return "Twenty Thousand Leagues Under the Sea"; } } I have several questions : Can I use Dependency Injection in the remote application client to connect to the ejb? If so what can i do to achieve this. Do i need to configure in the sun-ejb-jar.xml and sun-application-client.xml? In other words, if i use DI like @EJB MyEJBRemote ejb; How application client container know what ejb to be injected? Where should i specify the information? How can i run the application client? I tried to run package-appclient in the glassfish server to get appclient.jar and copy it to my computer. Then i type appclient.jar -client myAppClient.jar . It didn't work. How do i point the target server? if i cannot use DI in the client then i guess i have to use JNDI lookup. Do i need to configure jndi name in sun-ejb-jar.xml or in the sun-application-client.xml? No matter how i try i never manage to run application client ? Can you guys put some working example? And thank you for every advises and examples?

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  • "Nearly divisible"

    - by bobobobo
    I want to check if a floating point value is "nearly" a multiple of 32. E.g. 64.1 is "nearly" divisible by 32, and so is 63.9. Right now I'm doing this: #define NEARLY_DIVISIBLE 0.1f float offset = fmodf( val, 32.0f ) ; if( offset < NEARLY_DIVISIBLE ) { // its near from above } // if it was 63.9, then the remainder would be large, so add some then and check again else if( fmodf( val + 2*NEARLY_DIVISIBLE, 32.0f ) < NEARLY_DIVISIBLE ) { // its near from below } Got a better way to do this?

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  • What is your strategy to avoid dynamic typing errors in Python (NoneType has not attribute x)?

    - by Koen Bok
    Python is one of my favorite languages, but I really have a love/hate relationship with it's dynamicness. Apart from the advantages, it often results in me forgetting to check a type, trying to call an attribute and getting the NoneType (or any other) has no attribute x error. A lot of them are pretty harmless but if not handled correctly they can bring down your entire app/process/etc. Over time I got better predicting where these could pop up and adding explicit type checking, but because I'm only human I miss one occasionally and then some end-user finds it. So I'm interested in your strategy to avoid these. Do you use type-checking decorators? Maybe special object wrappers? Please share...

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  • Code Analysis - Treat as Error

    - by Brian Schmitt
    Looking to enable the "Enable code Analysis on Build" feature in Visual Studio. Obviously the Rules are a best practice, and I am working with an existing code base that currently fails many of the rules. I am looking for input as to which rules are the most egregious and should be treated as an Error.

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  • Exception design: Custom exceptions reading data from file?

    - by User
    I have a method that reads data from a comma separated text file and constructs a list of entity objects, let's say customers. So it reads for example, Name Age Weight Then I take these data objects and pass them to a business layer that saves them to a database. Now the data in this file might be invalid, so I'm trying to figure out the best error handling design. For example, the text file might have character data in the Age field. Now my question is, should I throw an exception such as InvalidAgeException from the method reading the file data? And suppose there is length restriction on the Name field, so if the length is greater than max characters do I throw a NameTooLongException or just an InvalidNameException, or do I just accept it and wait until the business layer gets a hold of it and throw exceptions from there? (If you can point me to a good resource that would be good too)

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  • What's the pythonic way of declaring variables?

    - by the_drow
    Usually declaring variables on assignment is considered a best practice in VBScript or JavaScript , for example, although it is allowed. Why does Python force you to create the variable only when you use it? Since Python is case sensitive can't it cause bugs because you misspelled a variable's name? How would you avoid such a situation?

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  • Common programming mistakes for Scala developers to avoid

    - by jelovirt
    In the spirit of Common programming mistakes for Java developers to avoid? Common programming mistakes for JavaScript developers to avoid? Common programming mistakes for .NET developers to avoid? Common programming mistakes for Haskell developers to avoid? Common programming mistakes for Python developers to avoid? Common Programming Mistakes for Ruby Developers to Avoid Common programming mistakes for PHP developers to avoid? what are some common mistakes made by Scala developers, and how can we avoid them? Also, as the biggest group of new Scala developers come from Java, what specific pitfalls they have to be aware of? For example, one often cited problem Java programmers moving to Scala make is use a procedural approach when a functional one would be more suitable in Scala. What other mistakes e.g. in API design newcomers should try to avoid.

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  • How to handle input and parameter validation between layers?

    - by developr
    If I have a 3 layer web forms application that takes user input, I know I can validate that input using validation controls in the presentation layer. Should I also validate in the business and data layers as well to protect against SQL injection and also issues? What validations should go in each layer? Another example would be passing a ID to return a record. Should the data layer ensure that the id is valid or should that happen in BLL / UI?

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  • Java operator overloading

    - by nimcap
    Not using operators makes my code obscure. (aNumber / aNother) * count is better than aNumber.divideBy(aNother).times(count) After 6 months of not writing a single comment I had to write a comment to the simple operation above. Usually I refactor until I don't need comment. And this made me realize that it is easier to read and perceive math symbols and numbers than their written forms. For example TWENTY_THOUSAND_THIRTEEN.plus(FORTY_TWO.times(TWO_HUNDERED_SIXTY_ONE)) is more obscure than 20013 + 42*261 So do you know a way to get rid of obscurity while not using operator overloading in Java? Update: I did not think my exaggeration on comments would cause such trouble to me. I am admitting that I needed to write comment a couple of times in 6 months. But not more than 10 lines in total. Sorry for that. Update 2: Another example: budget.plus(bonusCoefficient.times(points)) is more obscure than budget + bonusCoefficient * points I have to stop and think on the first one, at first sight it looks like clutter of words, on the other hand, I get the meaning at first look for the second one, it is very clear and neat. I know this cannot be achieved in Java but I wanted to hear some ideas about my alternatives.

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  • Java 'Prototype' pattern - new vs clone vs class.newInstance

    - by Guillaume
    In my project there are some 'Prototype' factories that create instances by cloning a final private instance. The author of those factories says that this pattern provides better performance than calling 'new' operator. Using google to get some clues about that, I've found nothing really relevant about that. Here is a small excerpt found in a javdoc from an unknown project javdoc from an unknown project Sadly, clone() is rather slower than calling new. However it is a lot faster than calling java.lang.Class.newInstance(), and somewhat faster than rolling our own "cloner" method. For me it's looking like an old best practice of the java 1.1 time. Does someone know more about this ? Is this a good practice to use that with 'modern' jvm ?

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  • Can per-user randomized salts be replaced with iterative hashing?

    - by Chas Emerick
    In the process of building what I'd like to hope is a properly-architected authentication mechanism, I've come across a lot of materials that specify that: user passwords must be salted the salt used should be sufficiently random and generated per-user ...therefore, the salt must be stored with the user record in order to support verification of the user password I wholeheartedly agree with the first and second points, but it seems like there's an easy workaround for the latter. Instead of doing the equivalent of (pseudocode here): salt = random(); hashedPassword = hash(salt . password); storeUserRecord(username, hashedPassword, salt); Why not use the hash of the username as the salt? This yields a domain of salts that is well-distributed, (roughly) random, and each individual salt is as complex as your salt function provides for. Even better, you don't have to store the salt in the database -- just regenerate it at authentication-time. More pseudocode: salt = hash(username); hashedPassword = hash(salt . password); storeUserRecord(username, hashedPassword); (Of course, hash in the examples above should be something reasonable, like SHA-512, or some other strong hash.) This seems reasonable to me given what (little) I know of crypto, but the fact that it's a simplification over widely-recommended practice makes me wonder whether there's some obvious reason I've gone astray that I'm not aware of.

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  • Is there a way to avoid spaghetti code over the years?

    - by Yoni Roit
    I've had several programming jobs. Each one with 20-50 developers, project going on for 3-5 years. Every time it's the same. Some programmers are bright, some are average. Everyone has their CS degree, everyone read design patterns. Intentions are good, people are trying hard to write good code but still after a couple of years the code turns into spaghetti. Changes in module A suddenly break module B. There are always these parts of code that no one can understand except for the person who wrote it. Changing infrastructure is impossible and backwards compatibility issues prevent good features to get in. Half of the time you just want to rewrite everything from scratch. And people more experienced than me treat this as normal. Is it? Does it have to be? What can I do to avoid this or should I accept it as a fact of life? Edit: Guys, I am impressed with the amount and quality of responses here. This site and its community rock!

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  • When should I implement IDisposable?

    - by Bobby
    What is the best practice for when to implement IDisposable? Is the best rule of thumb to implement it if you have one managed object in the class, or does it depend if the object was created in the class or just passed in? Should I also do it for classes with no managed objects at all?

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  • To be effective on your home projects is it better using the same technologies used at work?

    - by systempuntoout
    To be more productive and effective, is it better to start developing an home project using the same technologies used at work? I'm not talking about a simple hello world web page but an home project with all bells and whistles that one day, maybe, you could sell on internet. This dilemma is often subject of flames between me and a friend. He thinks that if you want to make a great home-made project you need to use the same technologies used daily at work staying in the same scope too; for example, a c++ computer game programmer should develope an home-made c++ game. I'm pretty sure that developing using the same technologies used at work can be more productive at beginning, but surely less exciting and stimulating of working with other languages\ides\libraries out of your daily job. What's your opinion about that?

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  • How convince other developers not to ignore Exceptions?

    - by Mnementh
    Recently I encountered a bug in an application I took over from another developer. I debugged for the reason and over an hour later I realized, that the problem wasn't the code producing the exception, but some code executed before this returning wrong data. If I dived into this, I encountered the following: try { ... } catch (XYException e){} If the Exception would have been propagated (a change I did), I would have found the reason for the bugs in a few minutes, as the stacktrace had pointed me to the problem. So how can I convince other developers to never catch and ignore exceptions in this way?

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  • How does this code break the Law of Demeter?

    - by Dave Jarvis
    The following code breaks the Law of Demeter: public class Student extends Person { private Grades grades; public Student() { } /** Must never return null; throw an appropriately named exception, instead. */ private synchronized Grades getGrades() throws GradesException { if( this.grades == null ) { this.grades = createGrades(); } return this.grades; } /** Create a new instance of grades for this student. */ protected Grades createGrades() throws GradesException { // Reads the grades from the database, if needed. // return new Grades(); } /** Answers if this student was graded by a teacher with the given name. */ public boolean isTeacher( int year, String name ) throws GradesException, TeacherException { // The method only knows about Teacher instances. // return getTeacher( year ).nameEquals( name ); } private Grades getGradesForYear( int year ) throws GradesException { // The method only knows about Grades instances. // return getGrades().getForYear( year ); } private Teacher getTeacher( int year ) throws GradesException, TeacherException { // This method knows about Grades and Teacher instances. A mistake? // return getGradesForYear( year ).getTeacher(); } } public class Teacher extends Person { public Teacher() { } /** * This method will take into consideration first name, * last name, middle initial, case sensitivity, and * eventually it could answer true to wild cards and * regular expressions. */ public boolean nameEquals( String name ) { return getName().equalsIgnoreCase( name ); } /** Never returns null. */ private synchronized String getName() { if( this.name == null ) { this.name == ""; } return this.name; } } Questions How is the LoD broken? Where is the code breaking the LoD? How should the code be written to uphold the LoD?

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  • Newbie T-SQL dynamic stored procedure -- how can I improve it?

    - by Andy Jones
    I'm new to T-SQL; all my experience is in a completely different database environment (Openedge). I've learned enough to write the procedure below -- but also enough to know that I don't know enough! This routine will have to go into a live environment soon, and it works, but I'm quite certain there are a number of c**k-ups and gotchas in it that I know nothing about. The routine copies data from table A to table B, replacing the data in table B. The tables could be in any database. I plan to call this routine multiple times from another stored procedure. Permissions aren't a problem: the routine will be run by the dba as a timed job. Could I have your suggestions as to how to make it fit best-practice? To bullet-proof it? ALTER PROCEDURE [dbo].[copyTable2Table] @sdb varchar(30), @stable varchar(30), @tdb varchar(30), @ttable varchar(30), @raiseerror bit = 1, @debug bit = 0 as begin set nocount on declare @source varchar(65) declare @target varchar(65) declare @dropstmt varchar(100) declare @insstmt varchar(100) declare @ErrMsg nvarchar(4000) declare @ErrSeverity int set @source = '[' + @sdb + '].[dbo].[' + @stable + ']' set @target = '[' + @tdb + '].[dbo].[' + @ttable + ']' set @dropStmt = 'drop table ' + @target set @insStmt = 'select * into ' + @target + ' from ' + @source set @errMsg = '' set @errSeverity = 0 if @debug = 1 print('Drop:' + @dropStmt + ' Insert:' + @insStmt) -- drop the target table, copy the source table to the target begin try begin transaction exec(@dropStmt) exec(@insStmt) commit end try begin catch if @@trancount > 0 rollback select @errMsg = error_message(), @errSeverity = error_severity() end catch -- update the log table insert into HHG_system.dbo.copyaudit (copytime, copyuser, source, target, errmsg, errseverity) values( getdate(), user_name(user_id()), @source, @target, @errMsg, @errSeverity) if @debug = 1 print ( 'Message:' + @errMsg + ' Severity:' + convert(Char, @errSeverity) ) -- handle errors, return value if @errMsg <> '' begin if @raiseError = 1 raiserror(@errMsg, @errSeverity, 1) return 1 end return 0 END Thanks!

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