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  • Should I use custom exceptions to control the flow of application?

    - by bonefisher
    Is it a good practise to use custom business exceptions (e.g. BusinessRuleViolationException) to control the flow of user-errors/user-incorrect-inputs??? The classic approach: I have a web service, where I have 2 methods, one is the 'checker' (UsernameAlreadyExists()) and the other one is 'creator' (CreateUsername())... So if I want to create a username, I have to do 2 roundtrips to webservice, 1.check, 2.if check is OK, create. What about using UsernameAlreadyExistsException? So I call only the 2. web service method (CrateUsername()), which contains the check and if not successfull, it throws the UsernameAlreadyExistsException. So the end goal is to have only one round trip to web service and the checking can be contained also in other web service methods (so I avoid calling the UsernameAlreadyExists() all the times..). Furthermore I can use this kind of business error handling with other web service calls completely avoiding the checking prior the call.

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  • VB6 Serial port programming

    - by commodus86
    I'm not much experienced in VB6 serial port programming. I need to control another circuit through serial port. (I have heard that pin 4 and pin 7 are used for that purpose. If these pins are incorrect please tell me what pins are used for such purposes) My requirement is to set those pins to high or low and read their levels(high or low) through VB6 program. How to do the task?? Thanx,

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  • Suggestions: Anti-Pattern counter-examples

    - by Tom W
    It doesn't seem that this exact question has been asked before, so I'll fire away: Most of us are familiar with the concept of an anti-pattern. However, avoiding implementation of anti-patterns can in principle swing too far the other way and cause problems itself. As an example, "Design by Committee" has a counter-example that I'd call "Design by Maverick" - wherein the design of an important feature is handed off to an individual to do what they think best, with the intention of reviewing their work later and deciding whether it should be finalised or go through another iteration. This takes much longer in practice as the rest of the team are occupied by other things, and can end up with a feature that's useful to nobody, particularly if the Maverick is not themselves an experienced end-user. Does anyone have any more examples of anti-pattern counter-examples?

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  • Any reason not to always log stack traces?

    - by Chris Knight
    Encountered a frustrating problem in our application today which came down to an ArrayIndexOutOfBounds exception being thrown. The exception's type was just about all that was logged which is fairly useless (but, oh dear legacy app, we still love you, mostly). I've redeployed the application with a change which logs the stack trace on exception handling (and immediately found the root cause of the problem) and wondered why no one else did this before. Do you generally log the stack trace and is there any reason you wouldn't do this? Bonus points if you can explain (why, not how) the rationale behind having to jump hoops in java to get a string representation of a stack trace!

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  • What are some good programming challenge websites?

    - by Martin
    I used to be a member of +Ma's Reversing, and later became a member of Caesum's Electrica. Recently I've played Bright Shadows. Are there other good sites for a challenge? Question reopened; not a duplicate. Similar, yes, but slightly different. Related: http://stackoverflow.com/questions/24692/where-can-you-find-funeducational-programming-challenges

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  • How to release a simple program

    - by Zenya
    What is the best practice for releasing a simple software? Suppose I created a very small simple and useful program or a tool and would like to share it with everyone by uploading it to my web-site. Do I need a license and which one? (I read http://www.gnu.org/ and http://www.fsf.org/ but still cannot decide - there are too many of them.) Do I need to put somewhere a copyright and what is the basic principles of creating "Copyright" string? How can I make a user, who is going to download and install my program, to believe that my program doesn't contain viruses or a malicious code?

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  • how to send an array of bytes over a TCP connection (java programming)

    - by Mark Roberts
    Can somebody demonstrate how to send an array of bytes over a TCP connection from a sender program to a receiver program in Java. (I'm new to Java programming, and can't seem to find an example of how to do this that shows both ends of the connection (sender and receiver.) If you know of an existing example, maybe you could post the link. (No need to reinvent the wheel.) P.S. This is NOT homework! :-)

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  • TDD - beginner problems and stumbling blocks

    - by Noufal Ibrahim
    While I've written unit tests for most of the code I've done, I only recently got my hands on a copy of TDD by example by Kent Beck. I have always regretted certain design decisions I made since they prevented the application from being 'testable'. I read through the book and while some of it looks alien, I felt that I could manage it and decided to try it out on my current project which is basically a client/server system where the two pieces communicate via. USB. One on the gadget and the other on the host. The application is in Python. I started off and very soon got entangled in a mess of rewrites and tiny tests which I later figured didn't really test anything. I threw away most of them and and now have a working application for which the tests have all coagulated into just 2. Based on my experiences, I have a few questions which I'd like to ask. I gained some information from http://stackoverflow.com/questions/1146218/new-to-tdd-are-there-sample-applications-with-tests-to-show-how-to-do-tdd but have some specific questions which I'd like answers to/discussion on. Kent Beck uses a list which he adds to and strikes out from to guide the development process. How do you make such a list? I initially had a few items like "server should start up", "server should abort if channel is not available" etc. but they got mixed and finally now, it's just something like "client should be able to connect to server" (which subsumed server startup etc.). How do you handle rewrites? I initially selected a half duplex system based on named pipes so that I could develop the application logic on my own machine and then later add the USB communication part. It them moved to become a socket based thing and then moved from using raw sockets to using the Python SocketServer module. Each time things changed, I found that I had to rewrite considerable parts of the tests which was annoying. I'd figured that the tests would be a somewhat invariable guide during my development. They just felt like more code to handle. I needed a client and a server to communicate through the channel to test either side. I could mock one of the sides to test the other but then the whole channel wouldn't be tested and I worry that I'd miss that. This detracted from the whole red/green/refactor rhythm. Is this just lack of experience or am I doing something wrong? The "Fake it till you make it" left me with a lot of messy code that I later spent a lot of time to refactor and clean up. Is this the way things work? At the end of the session, I now have my client and server running with around 3 or 4 unit tests. It took me around a week to do it. I think I could have done it in a day if I were using the unit tests after code way. I fail to see the gain. I'm looking for comments and advice from people who have implemented large non trivial projects completely (or almost completely) using this methodology. It makes sense to me to follow the way after I have something already running and want to add a new feature but doing it from scratch seems to tiresome and not worth the effort. P.S. : Please let me know if this should be community wiki and I'll mark it like that. Update 0 : All the answers were equally helpful. I picked the one I did because it resonated with my experiences the most. Update 1: Practice Practice Practice!

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  • Allow for modular development while still running in same JVM?

    - by Marcus
    Our current app runs in a single JVM. We are now splitting up the app into separate logical services where each service runs in its own JVM. The split is being done to allow a single service to be modified and deployed without impacting the entire system. This reduces the need to QA the entire system - just need to QA the interaction with the service being changed. For inter service communication we use a combination of REST, an MQ system bus, and database views. What I don't like about this: REST means we have to marshal data to/from XML DB views couple the systems together which defeats the whole concept of separate services MQ / system bus is added complexity There is inevitably some code duplication between services You have set up n JBoss server configurations, we have to do n number of deployments, n number of set up scripts, etc, etc. Is there a better way to structure an internal application to allow modular development and deployment while allowing the app to run in a single JVM (and achieving the associated benefits)?

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  • What's the best practice to "look up" Java Enums?

    - by Marcus
    We have a REST API where clients can supply parameters representing values defined on the server in Java Enums. So we can provide a descriptive error, we add this lookup method to each Enum. Seems like we're just copying code (bad). Is there a better practice? public enum MyEnum { A, B, C, D; public static MyEnum lookup(String id) { try { return MyEnum.valueOf(id); } catch (IllegalArgumentException e) { throw new RuntimeException("Invalid value for my enum blah blah: " + id); } } } Update: The default error message provided by valueOf(..) would be No enum const class a.b.c.MyEnum.BadValue. I would like to provide a more descriptive error from the API.

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  • Custom User Management for Google App Engine Java

    - by Gopi
    I am using GAE Java for a multi-user application. There are multiple users with different roles. Each user can login, do some operations and logout. The business restricts me from using Google User Service and I need to implement my own for authentication and session management. Can anyone please share with me how should I go about implementing my own user management? I have read its very tricky to implement own user management. Any pointers in terms of best approaches/ design / existing frameworks if any ? I could see some similar posts but they are for python.

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  • Usage of Assert.Inconclusive

    - by Johannes Rudolph
    Hi, Im wondering how someone should use Assert.Inconclusive(). I'm using it if my Unit test would be about to fail for a reason other than what it is for. E.g. i have a method on a class that calculates the sum of an array of ints. On the same class there is also a method to calculate the average of the element. It is implemented by calling sum and dividing it by the length of the array. Writing a Unit test for Sum() is simple. However, when i write a test for Average() and Sum() fails, Average() is likely to fail also. The failure of Average is not explicit about the reason it failed, it failed for a reason other than what it should test for. That's why i would check if Sum() returns the correct result, otherwise i Assert.Inconclusive(). Is this to be considered good practice? What is Assert.Inconclusive intended for? Or should i rather solve the previous example by means of an Isolation Framework?

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  • Is there an existing template for a new C++ Open Source project

    - by esavard
    I want to start a new C++ (Qt) Open Source project and I'm wondering if there is an existing template somewhere for files usually found in an Open Source project but that are not purely source code (README, LICENSE, CHANGELOG, etc.) I could probably find a popular Open Source project for inspiration but if there is some existing generic templates, I will use that instead. Thanks.

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  • Is there a difference between Perl's shift versus assignment from @_ for subroutine parameters?

    - by cowgod
    Let us ignore for a moment Damian Conway's best practice of no more than three positional parameters for any given subroutine. Is there any difference between the two examples below in regards to performance or functionality? Using shift: sub do_something_fantastical { my $foo = shift; my $bar = shift; my $baz = shift; my $qux = shift; my $quux = shift; my $corge = shift; } Using @_: sub do_something_fantastical { my ($foo, $bar, $baz, $qux, $quux, $corge) = @_; } Provided that both examples are the same in terms of performance and functionality, what do people think about one format over the other? Obviously the example using @_ is fewer lines of code, but isn't it more legible to use shift as shown in the other example? Opinions with good reasoning are welcome.

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  • Using explicitly numbered repetition instead of question mark, star and plus

    - by polygenelubricants
    I've seen regex patterns that use explicitly numbered repetition instead of ?, * and +, i.e.: Explicit Shorthand (something){0,1} (something)? (something){1} (something) (something){0,} (something)* (something){1,} (something)+ The questions are: Are these two forms identical? What if you add possessive/reluctant modifiers? If they are identical, which one is more idiomatic? More readable? Simply "better"?

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  • How to Inserting message into View that depends on session value. ASP.NET MVC. Best practice

    - by Andrew Florko
    User have to populate multistep questionnaire web-forms and step messages depend on the option chosen by user at the very beginning. Messages are stored in web.config file. I use asp.net mvc project, strong typed views and keep business logic separated from controller in static class. I don't want to make business logic dependency on web.config. Well, I have to insert message into view that depends on session value. There are at least 2 options how to implement this: View model has property that is populated in controller/businessLogic and rendered in view like <%: Model.HelpMessage1 %>. I have to pass web.config values from controller to businessLogic that makes business logic methods signature too complex. I don't want to make configuration source abstract (in order to let business logic read configuration values from its methods directly) also. Create static helper class that is called from view like <%: ViewHelper.HelpMessage1(Model.Option1) %>. But in this case logic what to show seems to be separated into two classes: business logic & viewHelper. What will you suggest? Thank you in advance!

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  • What should the Java main method be for a standalone application (for Spring JMS) ?

    - by Brandon
    I am interested in creating a Spring standalone application that will run and wait to receive messages from an ActiveMQ queue using Spring JMS. I have searched a lot of places and cannot find a consistent way of implementing the main method for such a standalone application. There appears to be few examples of Spring standalone applications. I have looked at Tomcat, JBoss, ActiveMQ and other examples from the around the web but I have not come to a conclusion so ... What is the best practice for implementing a main method for a Java application (specifically Spring with JMS) ?

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  • Combine hash values in C#

    - by Chris
    I'm creating a generic object collection class and need to implement a Hash function. I can obviously (and easily!) get the hash values for each object but was looking for the 'correct' way to combine them to avoid any issues. Does just adding, xoring or any basic operation harm the quality of the hash or am I going to have to do something like getting the objects as bytes, combining them and then hashing that? Cheers in advance

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  • best practice for passing many arguments to method ?

    - by Tony
    Occasionally , we have to write methods that receive many many arguments , for example : public void doSomething(Object objA , Object objectB ,Date date1 ,Date date2 ,String str1 ,String str2 ) { } When I encounter this kind of problem , I often encapsulate arguments into a map. Map<Object,Object> params = new HashMap<Object,Object>(); params.put("objA",ObjA) ; ...... public void doSomething(Map<Object,Object> params) { // extracting params Object objA = (Object)params.get("objA"); ...... } This is not a good practice , encapsulate params into a map is totally a waste of efficiency. The good thing is , the clean signature , easy to add other params with fewest modification . what's the best practice for this kind of problem ?

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  • Is it good to subclass a class only to separate some functional parts?

    - by prostynick
    Suppose we have abstract class A (all examples in C#) public abstract class A { private Foo foo; public A() { } public void DoSomethingUsingFoo() { //stuff } public void DoSomethingElseUsingFoo() { //stuff } //a lot of other stuff... } But we are able to split it into two classes A and B: public abstract class A { public A() { } //a lot of stuff... } public abstract class B : A { private Foo foo; public B() : base() { } public void DoSomethingUsingFoo() { //stuff } public void DoSomethingElseUsingFoo() { //stuff } //nothing else or just some overrides of A stuff } That's good, but we are 99.99% sure, that no one will ever subclass A, because functionality in B is very important. Is it still good to have two separate classes only to split some code into two parts and to separate functional elements?

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  • MongoDB query to return only embedded document

    - by Matt
    assume that i have a BlogPost model with zero-to-many embedded Comment documents. can i query for and have MongoDB return only Comment objects matching my query spec? eg, db.blog_posts.find({"comment.submitter": "some_name"}) returns only a list of comments. edit: an example: import pymongo connection = pymongo.Connection() db = connection['dvds'] db['dvds'].insert({'title': "The Hitchhikers Guide to the Galaxy", 'episodes': [{'title': "Episode 1", 'desc': "..."}, {'title': "Episode 2", 'desc': "..."}, {'title': "Episode 3", 'desc': "..."}, {'title': "Episode 4", 'desc': "..."}, {'title': "Episode 5", 'desc': "..."}, {'title': "Episode 6", 'desc': "..."}]}) episode = db['dvds'].find_one({'episodes.title': "Episode 1"}, fields=['episodes']) in this example, episode is: {u'_id': ObjectId('...'), u'episodes': [{u'desc': u'...', u'title': u'Episode 1'}, {u'desc': u'...', u'title': u'Episode 2'}, {u'desc': u'...', u'title': u'Episode 3'}, {u'desc': u'...', u'title': u'Episode 4'}, {u'desc': u'...', u'title': u'Episode 5'}, {u'desc': u'...', u'title': u'Episode 6'}]} but i just want: {u'desc': u'...', u'title': u'Episode 1'}

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