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• How to deal this situation

  - by user198725878

  I would like to ask you some guidance here. Once I finished my graduation I join a company for Ruby On Rails. They trained me and put into project for ROR. I have spent 1 year of ROR development. I have done basic things in the given project. Then my company got a project for QT, learned and worked for nearly 7 months. Then my company put into me in iOS development. For the past 1 1/2 years, I have been working in the iOS development till date. Also my main worry is, changing the technology I am working makes me not having in depth knowledge on anything. I mean I can't make myself as expert in any language. What is your opinion? Now my company is going to put me into the cross-platform mobile application development. I am worried now, will this affect my growth path by leaving native development? I am ready to learn Android. As I left web development before 2 year ago, I am finding some odds with me. Should look for iOS job change now? Please let me know your advices.

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• Which things instantly ring alarm bells when looking at code? [closed]

  - by FinnNk

  I attended a software craftsmanship event a couple of weeks ago and one of the comments made was "I'm sure we all recognize bad code when we see it" and everyone nodded sagely without further discussion. This sort of thing always worries me as there's that truism that everyone thinks they're an above average driver. Although I think I can recognize bad code I'd love to learn more about what other people consider to be code smells as it's rarely discussed in detail on people's blogs and only in a handful of books. In particular I think it'd be interesting to hear about anything that's a code smell in one language but not another. I'll start off with an easy one: Code in source control that has a high proportion of commented out code - why is it there? was it meant to be deleted? is it a half finished piece of work? maybe it shouldn't have been commented out and was only done when someone was testing something out? Personally I find this sort of thing really annoying even if it's just the odd line here and there, but when you see large blocks interspersed with the rest of the code it's totally unacceptable. It's also usually an indication that the rest of the code is likely to be of dubious quality as well.

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• How to plan/manage multi-platform (mobile) products?

  - by PhD

  Say I've to develop an app that runs on iOS, Android and Windows 8 Mobile. Now all three platforms are technically in different program languages. The only 'reuse' that I can see is that of the boxes-and-lines drawings (UML :) charts and nothing else. So how do companies/programmers manage the variation of the same product across different platforms especially since the implementation languages differ? It's 'easier' in the desktop world IMO given the plethora of languages and cross-platform libraries to make your life easier. Not so in the mobile world. More so, product line management principles don't seem to be all that applicable - what is same and variant doesn't really matter - the application is the same (conceptually) and the implementation is variant. Some difficulties that come to mind: Bug Fixing: Applications maybe designed in a similar manner but the bug identification and fixing would be radically different. A bug on iOS may/may-not be existent for that on Android. Or a bug fix approach on one platform may not be the same on another (unless it's a semantic bug like a!=b instead of a==b which would require the same 'approach' to fixing in essence Enhancements: Making a change on one platform would be radically different than on another Code-Design Divergence: They way the code is written/organized, the class structures etc., could be very different given the different implementation environments - leading to further reuse of the (above) UML models. There are of course many others - just keeping the development in sync and making sure all applications are up to the same version with the same set of features etc. Seems the effort is 3x that of a single application. So how exactly does one manage this nightmarish situation? Some thoughts: Split application to client/server to minimize the effect to client side only (not always doable) Use frameworks like Unity-3D that could take care of the cross-platform problem (mostly applicable to games and probably not to other applications etc.) Any other ways of managing a platform line? What are some proven approaches to managing/taming the effects?

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• decent use-case for goto in c?

  - by Robz

  I really hesitate to ask this, because I don't want to "solicit debate, arguments, polling, or extended discussion" but I'm new to C and want to gain more insight into common patterns used in the language. I recently heard some distaste for the goto command, but I've also recently found a decent use-case for it. Code like this: error = function_that_could_fail_1(); if (!error) { error = function_that_could_fail_2(); if (!error) { error = function_that_could_fail_3(); ...to the n-th tab level! } else { // deal with error, clean up, and return error code } } else { // deal with error, clean up, and return error code } If the clean-up part is all very similar, could be written a little prettier (my opinion?) like this: error = function_that_could_fail_1(); if(error) { goto cleanup; } error = function_that_could_fail_2(); if(error) { goto cleanup; } error = function_that_could_fail_3(); if(error) { goto cleanup; } ... cleanup: // deal with error if it exists, clean up // return error code Is this a common or acceptable use-case of goto in C? Is there a different/better way to do this?

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• Pantheon Not Completely Installed?

  - by Simon

  I have just installed the pantheon shell today, and I have not found any help with this yet. I am not just a random noob, i use a bunch of other shells and i also have a few development applications on my copy of ubuntu. But ever since ive opened up pantheon, i cannot find settings or this thing called the launchpad. (if the launchpad is the app drawer up in the upper left corner, or if its the dock. i have it, if thats not what launchpad is, then i cant access it.) I can only change my wallpaper by going back to unity, gnome, or KDE. There is a system settings in the power menu (upper right), but it only has Language Support, Ubuntu One, Additional Drivers, And Printing. I can still access the full ubuntu settings in GNOME of Unity. But thats it. I installed in the terminal, uninstalled, and reinstalled using the software center. Please Help Me If Any Of You Can! Thanks!!!

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• Move unity launcher to bottom of the screen

  - by argvar

  I have Ubuntu 13.04 DESKTOP version and for some odd reason I'm told that the Unity launcher cannot be moved to the bottom of the screen because of several reasons: 1. Canonical wants it there so it fits with their overall design goals, namely when it comes to touchscreen devices and netbooks. This in my mind totally ignores the fact that most Ubuntu users are DESKTOP users. No matter what Canonicals long term goal is, it surely mustn't be at the expense of needs of their core user base. 2. Most monitors are widescreen, the launcher is more compact where it is. This is not only taking away the users choice, but is also a wrong assessment. Widescreen monitors can sometimes be rotated on a pivot, giving it a portrait aspect. By displaying the Unity launcher on the left side it takes up a lot of space. Many desktop users have multiple monitors, and having the launcher on the left side of each monitor is very awkward. Also, many websites are catered to fit on a half 1920 display, so you can have two browser windows open side-by-side with all content visible. The placement of the Unity launcher takes away the horizontal space meaning there's less room for each browser window, and you'll see the right side of the web pages being occluded. Any suggestion to simply hide the Unity launcher, or "Canonical knows best" or "get used to it" are unwelcome and totally ignores the above points. Linux is about choice. Canonical's stubbornness with the Unity launcher placement is inconsistent with what Linux is about.

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• how to architect this to make it unit testable

  - by SOfanatic

  I'm currently working on a project where I'm receiving an object via web service (WSDL). The overall process is the following: Receive object - add/delete/update parts (or all) of it - and return the object with the changes made. The thing is that sometimes these changes are complicated and there is some logic involved, other databases, other web services, etc. so to facilitate this I'm creating a custom object that mimics the original one but has some enhanced functionality to make some things easier. So I'm trying to have this process: Receive original object - convert/copy it to custom object - add/delete/update - convert/copy it back to original object - return original object. Example: public class Row { public List<Field> Fields { get; set; } public string RowId { get; set; } public Row() { this.Fields = new List<Field>(); } } public class Field { public string Number { get; set; } public string Value { get; set; } } So for example, one of the "actions" to perform on this would be to find all Fields in a Row that match a Value equal to something, and update them with some other value. I have a CustomRow class that represents the Row class, how can I make this class unit testable? Do I have to create an interface ICustomRow to mock it in the unit test? If one of the actions is to sum all of the Values in the Fields that have a Number equal to 10, like this function, how can design the custom class to facilitate unit tests. Sample function: public int Sum(FieldNumber number) { return row.Fields.Where(x => x.FieldNumber.Equals(number)).Sum(x => x.FieldValue); } Am I approaching this the wrong way?

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• Entry level engineer question regarding memory mangement

  - by Ealianis

  It has been a few months since I started my position as an entry level software developer. Now that I am past some learning curves (e.g. the language, jargon, syntax of VB and C#) I'm starting to focus on more esoteric topics, as to write better software. A simple question I presented to a fellow coworker was responded with "I'm focusing on the wrong things." While I respect this coworker I do disagree that this is a "wrong thing" to focus upon. Here was the code (in VB) and followed by the question. Note: The Function GenerateAlert() returns an integer. Dim alertID as Integer = GenerateAlert() _errorDictionary.Add(argErrorID, NewErrorInfo(Now(), alertID)) vs... _errorDictionary.Add(argErrorID, New ErrorInfo(Now(), GenerateAlert())) I originally wrote the ladder and rewrote it with the "Dim alertID" so that someone else might find it easier to read. But here was my concern and question. "Should one write this with the Dim AlertID, it would in fact take up more memory; finite but more, and should this method be called many times could it lead to an issue? How will .NET handle this object AlertID. Outside of .NET should one manually dispose of the object after use (near the end of the sub)." I want to ensure I become a knowledgeable programmer that does not just rely upon garbage collection. Am I over thinking this? Am I focusing on the wrong things?

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• Handling game logic events by behavior components

  - by chehob

  My question continues on topic discussed here I have tried implementing attribute/behavior design and here is a quick example demonstrating the issue. class HealthAttribute : public ActorAttribute { public: HealthAttribute( float val ) : mValue( val ) { } float Get( void ) const { return mValue; } void Set( float val ) { mValue = val; } private: float mValue; }; class HealthBehavior : public ActorBehavior { public: HealthBehavior( shared_ptr< HealthAttribute > health ) : pHealth( health ) { // Set OnDamage() to listen for game logic event "DamageEvent" } void OnDamage( IEventDataPtr pEventData ) { // Check DamageEvent target entity // ( compare my entity ID with event's target entity ID ) // If not my entity, do nothing // Else, modify health attribute with received DamageEvent data } protected: shared_ptr< HealthAttribute > pHealth; }; My question - is it possible to get rid of this annoying check for game logic events? In the current implementation when some entity must receive damage, game logic just fires off event that contains damage value and the entity id which should receive that damage. And all HealthBehaviors are subscribed to the DamageEvent type, which leads to any entity possesing HealthBehavior call OnDamage() even if he is not the addressee.

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• What is the recommended MongoDB schema for this quiz-engine scenario?

  - by hughesdan

  I'm working on a quiz engine for learning a foreign language. The engine shows users four images simultaneously and then plays an audio file. The user has to match the audio to the correct image. Below is my MongoDB document structure. Each document consists of an image file reference and an array of references to audio files that match that image. To generate a quiz instance I select four documents at random, show the images and then play one audio file from the four documents at random. The next step in my application development is to decide on the best document schema for storing user guesses. There are several requirements to consider: I need to be able to report statistics at a user level. For example, total correct answers, total guesses, mean accuracy, etc) I need to be able to query images based on the user's learning progress. For example, select 4 documents where guess count is 10 and accuracy is <=0.50. The schema needs to be optimized for fast quiz generation. The schema must not cause future scaling issues vis a vis document size. Assume 1mm users who make an average of 1000 guesses. Given all of this as background information, what would be the recommended schema? For example, would you store each guess in the Image document or perhaps in a User document (not shown) or a new document collection created for logging guesses? Would you recommend logging the raw guess data or would you pre-compute statistics by incrementing counters within the relevant document? Schema for Image Collection: _id "505bcc7a45c978be24000005" date 2012-09-21 02:10:02 UTC imageFileName "BD3E134A-C7B3-4405-9004-ED573DF477FE-29879-0000395CF1091601" random 0.26997075392864645 user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioFiles [ 0 { audioFileName "C3669719-9F0A-4EB5-A791-2C00486665ED-30305-000039A3FDA7DCD2" user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioLanguage "English" date 2012-09-22 01:15:04 UTC } 1 { audioFileName "C3669719-9F0A-4EB5-A791-2C00486665ED-30305-000039A3FDA7DCD2" user "2A8761E4-C13A-470E-A759-91432D61B6AF-25982-0000352D853511AF" audioLanguage "Spanish" date 2012-09-22 01:17:04 UTC } ]

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• Learning a new concept - write from scratch or use frameworks?

  - by Stu

  I have recently been trying to learn about MVVM and all of the associated concepts such as repositories, mediators, data access. I made a decision that I would not use any frameworks for this so that I could gain a better understanding of how everything worked. I’m beginning to wonder if that was the best idea because I have hit some problems which I am not able to solve, even with the help of Stack Overflow! Writing from scratch I still feel that you have a much better understanding of something when you have been in the guts of it than if you were at a higher level. The other side of that coin is that you are in the guts of something that you don't fully understand which will lead to bad design decisions. This then makes it hard to get help because you will create unusual scenarios which are less likely to occur when you working within the confines of a framework. I have found that there are plenty of tutorials on the basics of a concept but very few that take you all the way from novice to expert. Maybe I should be looking at a book for this? Using frameworks The biggest motivation for me to use frameworks is that they are much more likely to be used in the workplace than a custom rolled solution. This can be quite a benefit when starting a new job if it's one less thing you have to learn. I feel that there is much better support for a framework than a custom solution which makes sense; many more people are using the framework than the solution that you created. The level of help is much wider as well, from basic questions to really specific, detailed questions. I would be interested to hear other people's views on this. When you are learning something new, should you/do you use frameworks or not? Why? If it's a combination of both, when do you stop one and move on to the other?

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• I can't program because the code I am using uses old coding styles. Is this normal to programmers? [closed]

  - by Renato Dinhani Conceição

  I'm in my first real job as programmer, but I can't solve any problems because of the coding style used. The code here: Does not have comments Does not have functions (50, 100, 200, 300 or more lines executed in sequence) Uses a lot of if statements with a lot of paths Has variables that make no sense (eg.: cf_cfop, CF_Natop, lnom, r_procod) Uses an old language (Visual FoxPro 8 from 2002), but there are new releases from 2007. I feel like I have gone back to 1970. Is it normal for a programmer familiar with OOP, clean-code, design patterns, etc. to have trouble with coding in this old-fashion way? EDIT: All the answers are very good. For my (un)hope, appears that there are a lot of this kind of code bases around the world. A point mentioned to all answers is refactor the code. Yeah, I really like to do it. In my personal project, I always do this, but... I can't refactor the code. Programmers are only allowed to change the files in the task that they are designed for. Every change in old code must be keep commented in the code (even with Subversion as version control), plus meta informations (date, programmer, task) related to that change (this became a mess, there are code with 3 used lines and 50 old lines commented). I'm thinking that is not only a code problem, but a management of software development problem.

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• How to tackle an experienced C# Programmer?

  - by nandu.com

  I am a noob in c# and asp.net developing. I have spent 6 months in design and another 6 in sql and asp.net programming. I just know the basics of asp.net and C#. I was programming as per the instruction of my tech leads and all good things changed in a day. :( All my tech leads (2+ experienced) left the company complaining about salary. And instead of those, company has recruited a 5+ experienced programmer cum tech lead (who is very strict), he is expecting me to code anything he says. Previous seniors of me, would say 'use ajax for this, use query for this instead of coding' and so on. I will do it exactly. I am not experienced enough to perform it myself. Now I am in a dilemma. I want to stay in the company and learn some more, but this new tech lead is expecting me to learn everything myself (he is telling me to learn jquery, javascript menus, session and chart in .Net, and so on and do things myself without asking him anything...I mean anything) :(((( PLease suggest to me some good tips to handle him. I think all programmers world wide would have faced a similar problem atleast once in the big programming life. So please..help .. 911

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• Testing a codebase with sequential cohesion

  - by iveqy

  I've this really simple program written in C with ncurses that's basically a front-end to sqlite3. I would like to implement TDD to continue the development and have found a nice C unit framework for this. However I'm totally stuck on how to implement it. Take this case for example: A user types a letter 'l' that is captured by ncurses getch(), and then an sqlite3 query is run that for every row calls a callback function. This callback function prints stuff to the screen via ncurses. So the obvious way to fully test this is to simulate a keyboard and a terminal and make sure that the output is the expected. However this sounds too complicated. I was thinking about adding an abstraction layer between the database and the UI so that the callback function will populate a list of entries and that list will later be printed. In that case I would be able to check if that list contains the expected values. However, why would I struggle with a data structure and lists in my program when sqlite3 already does this? For example, if the user wants to see the list sorted in some other way, it would be expensive to throw away the list and repopulate it. I would need to sort the list, but why should I implement sorting when sqlite3 already has that? Using my orginal design I could just do an other query sorted differently. Previously I've only done TDD with command line applications, and there it's really easy to just compare the output with what I'm expected. An other way would be to add CLI interface to the program and wrap a test program around the CLI to test everything. (The way git.git does with it's test-framework). So the question is, how to add testing to a tightly integrated database/UI.

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• The idea of functionN in Scala / Functionaljava

  - by Luke Murphy

  From brain driven development It turns out, that every Function you’ll ever define in Scala, will become an instance of an Implementation which will feature a certain Function Trait. There is a whole bunch of that Function Traits, ranging from Function1 up to Function22. Since Functions are Objects in Scala and Scala is a statically typed language, it has to provide an appropriate type for every Function which comes with a different number of arguments. If you define a Function with two arguments, the compiler picks Function2 as the underlying type. Also, from Michael Froh's blog You need to make FunctionN classes for each number of parameters that you want? Yes, but you define the classes once and then you use them forever, or ideally they're already defined in a library (e.g. Functional Java defines classes F, F2, ..., F8, and the Scala standard library defines classes Function1, ..., Function22) So we have a list of function traits (Scala), and a list of interfaces (Functional-java) to enable us to have first class funtions. I am trying to understand exactly why this is the case. I know, in Java for example, when I write a method say, public int add(int a, int b){ return a + b; } That I cannot go ahead and write add(3,4,5); ( error would be something like : method add cannot be applied to give types ) We simply have to define an interface/trait for functions with different parameters, because of static typing?

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• RESTful applications logic and cross resource operations

  - by Gaz_Edge

  I have an RESTful api that allows my users to receive enquiries about their business e.g. 'I would like to book service x on date y. Is this available?'. The api saves this information as a resource to the following URI users/{userId}/enquiries/{enquiryId} The information shown when this resource is retrieved are the standard sort of things you'd expect from an enquiry - email, first_name, last_name, address, message The api also allows customers to be created for a user. The customer has a login and password and also a profile. The following URIs expose these two resources PUT users/{userId}/customers/{customerId} PUT users/{userId}/customers/{customerId}/profile The problem I am having is that I would like to have the ability to allow users to create a customer from an enquiry. For example, the user is able to offer their service on the date requested and will then want to setup a customer with login details etc to allow them to manage the rest of the process. The obvious answer would be to use a URI like users/{userId}/enquiries/{enquiryId}/convert-to-client The problem with this is is that it somewhat goes against a lot of what I've been reading about how to implement REST (specifically from the book Restful Web Services which suggests that URIs should point to resources not operations on resources). The other option would be to get the client application (i.e. the code that calls the api) to handle some of this application logic. This doesn't quite feel right to me. I have implemented in my design that the client app is fairly dumb. It knows just enough to display the results from the API, and does not contain any application logic. Would be great to hear what others views are on the best way of setting this up Am I wrong to have no application logic in the client app? How would I perform this operation purely in the REST api?

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• Google search question, front page not showing

  - by user5746

  I know this is probably a dumb question but I hope someone can give me some insight; I was ranked on Google first page of search results for "funny st patricks day shirts" but I was third from the bottom and not familiar enough with SEO, so I signed up for "Attracta" to rank higher. Big mistake. Since using Attracta, I've lost the first page and I'm now on the fourth page in that search. What I noticed is that Google is now just showing a sub-page or side page, (a link from my front page, to a page which has only a few designs in it) this is not where I would want customers to land first... but my front page is not showing in that search anymore. Obviously, the title of this side page is not geared toward that search result, so I know that's why I have the pr drop. Why is my front page not ranking over that page, though? Why is it apparently gone from that search, or so far back no one will ever find it? I need to know how to fix this quick if anyone has any advice at all for me. It's the busiest season for my website and the people who were stealing design ideas from me are all ranked higher than my site now. (I can prove this, lol) So, I'm very frustrated by that. I would be very grateful to have any advice at all as to what I can do to fix this. THANKS in advance for any advice you can offer. Catelyn

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• OpenJDK In The News: AMD and Oracle to Collaborate in the OpenJDK Community [..]

  - by $utils.escapeXML($entry.author)

  During the JavaOne™ 2012 Strategy Keynote, AMD (NYSE: AMD) announced its participation in OpenJDK™ Project “Sumatra” in collaboration with Oracle and other members of the OpenJDK community to help bring heterogeneous computing capabilities to Java™ for server and cloud environments. The OpenJDK Project “Sumatra” will explore how the Java Virtual Machine (JVM), as well as the Java language and APIs, might be enhanced to allow applications to take advantage of graphics processing unit (GPU) acceleration, either in discrete graphics cards or in high-performance graphics processor cores such as those found in AMD accelerated processing units (APUs).“Affirming our plans to contribute to the OpenJDK Project represents the next step towards bringing heterogeneous computing to millions of Java developers and can potentially lead to future developments of new hardware models, as well as server and cloud programming paradigms,” said Manju Hegde, corporate vice president, Heterogeneous Applications and Developer Solutions at AMD. “AMD has an established track record of collaboration with open-software development communities from OpenCL™ to the Heterogeneous System Architecture (HSA) Foundation, and with this initiative we will help further the development of graphics acceleration within the Java community.”“We expect our work with AMD and other OpenJDK participants in Project “Sumatra” will eventually help provide Java developers with the ability to quickly leverage GPU acceleration for better performance,” said Georges Saab, vice president, Software Development, Java Platform Group at Oracle. "We hope individuals and other organizations interested in this exciting development will follow AMD's lead by joining us in Project “Sumatra."Quotes taken from the first press release from AMD mentioning OpenJDK, titled "AMD and Oracle to Collaborate in the OpenJDK Community to Explore Heterogeneous Computing for Java ".

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• Is there any way to send a column value from outer query to inner sub query? [closed]

  - by chetan

  'Discussions' table schema title description desid replyto upvote downvote views browser used a1 none 1 1 12 - bad topic b2 a1 2 3 14 sql database a3 none 4 5 34 - crome b4 a3 3 4 12 The above table has two types of content types Main Topics and Comments. Unique content identifier 'desid' used to identify that its a main topic or a comment. 'desid' starts with 'a' for Main Topic and for comment 'desid' starts with 'b'. For comment 'replyto' is the 'desid' of main topic to which this comment is associated. I like to find out the list of the top main topics that are arranged on the basis of (upvote+downvote+visits+number of comments to it) addition. The following query gives top topics list in order of (upvote+downvote+visits) select * with highest number of upvote+downvote+views by query "select * from [DB_user1212].[dbo].[discussions] where desid like 'a%' order by (upvote+downvote+visited) desc For (comments+upvote+downvote+views ) I tried select * from [DB_user1212].[dbo].[discussions] where desid like 'a%' order by ((select count(*) from [DB_user1212].[dbo].[discussions] where replyto = desid )+upvote+downvote+visited) desc but it didn't work because its not possible to send desid from outer query to inner subquery. How to solve this? Please note that I want solution in query language only.

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• Inactive JSRs looking for Spec Leads

  - by heathervc

  You may have noticed that some JSRs have a classification of "Inactive" on their JSR page.  The introduction of this term in 2009 was part of an effort to enable and encourage more transparency into the development of JSRs.  You can read more about Inactive JSRs here and also in the JCP FAQ.The following JSR proposals have been Inactive since at least 2009. If you are a JCP Member and are interested in taking over the Specification Lead role for one of these JSRs, please contact the PMO at [email protected] on or before 23 April 2012. With that message, please include the following: the subject line "Spec Lead for JSR ###," where '###' is the JSR number which JCP Member you represent why you wish to take over the Specification lead role Here is the current list of Inactive JSRs for which Members can request to become Specification Leads: JSR 122, JAIN JCAT JSR 161, JAIN ENUM API Specification JSR 182, JPay - Payment API for the Java Platform JSR 210, OSS Service Quality Management API JSR 241, The Groovy Programming Language JSR 251, Pricing API JSR 278, Resource Management API for Java ME JSR 304, Mobile Telephony API v2 JSR 305, Annotations for Software Defect Detection JSR 320, Services Framework

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• Tail-recursive implementation of take-while

  - by Giorgio

  I am trying to write a tail-recursive implementation of the function take-while in Scheme (but this exercise can be done in another language as well). My first attempt was (define (take-while p xs) (if (or (null? xs) (not (p (car xs)))) '() (cons (car xs) (take-while p (cdr xs))))) which works correctly but is not tail-recursive. My next attempt was (define (take-while-tr p xs) (let loop ((acc '()) (ys xs)) (if (or (null? ys) (not (p (car ys)))) (reverse acc) (loop (cons (car ys) acc) (cdr ys))))) which is tail recursive but needs a call to reverse as a last step in order to return the result list in the proper order. I cannot come up with a solution that is tail-recursive, does not use reverse, only uses lists as data structure (using a functional data structure like a Haskell's sequence which allows to append elements is not an option), has complexity linear in the size of the prefix, or at least does not have quadratic complexity (thanks to delnan for pointing this out). Is there an alternative solution satisfying all the properties above? My intuition tells me that it is impossible to accumulate the prefix of a list in a tail-recursive fashion while maintaining the original order between the elements (i.e. without the need of using reverse to adjust the result) but I am not able to prove this. Note The solution using reverse satisfies conditions 1, 3, 4.

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• POLL: How do you build your interfaces in xcode for iphone/coco-touch applications?

  - by LolaRun

  Hi all, It's been 2 months i'm using xcode and building iphone apps, and i'm finding it really hard to grasp the good design for the applications. I always face problems like you can't put your tabbarcontroller in another custom viewcontroller sort of a thing? or other problems... That 'sometimes' - of course - would work if you did the creation of the views/viewcontrollers programmatically. so I don't know if i should start writing the creation of my objects or use interface builder. This is why i'm asking this poll question, to see what's the most accepted way among other developers. I'm not going to answer my question, so the votes would not increase my reputation and risk my poll being closed soon. I prefer that the first two readers of this question should answer by 'using IB' and the second one 'programmatically' and the rest would vote up or down for these two answers. And don't vote my question either, i just need to know, and maybe someone else wants to know. so the longer this question lives the better. and gaining nothing from it concerning reputation would help that cause. thank you all for your cooperation. and go ahead and answer Peace

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• Performing a Depth First Search iteratively using async/parallel processing?

  - by Prabhu

  Here is a method that does a DFS search and returns a list of all items given a top level item id. How could I modify this to take advantage of parallel processing? Currently, the call to get the sub items is made one by one for each item in the stack. It would be nice if I could get the sub items for multiple items in the stack at the same time, and populate my return list faster. How could I do this (either using async/await or TPL, or anything else) in a thread safe manner? private async Task<IList<Item>> GetItemsAsync(string topItemId) { var items = new List<Item>(); var topItem = await GetItemAsync(topItemId); Stack<Item> stack = new Stack<Item>(); stack.Push(topItem); while (stack.Count > 0) { var item = stack.Pop(); items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } } return items; } I was thinking of something along these lines, but it's not coming together: var tasks = stack.Select(async item => { items.Add(item); var subItems = await GetSubItemsAsync(item.SubId); foreach (var subItem in subItems) { stack.Push(subItem); } }).ToList(); if (tasks.Any()) await Task.WhenAll(tasks); The language I'm using is C#.

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• Why can't non-admin users install software?

  - by fiftyeight

  This is probably something I don't understand since I am used to Windows and am only starting out with Ubuntu. I know that software in linux comes in packages what I don't understand is why can't non-admin users install software. I mean, every application is run by a specific user, and that user will only be able to run that applciation with his privilages, so if he has no admin privileges, the application also won't be able to access unauthorized directories etc. I want most of the time to work on my PC with a non-admin user since it seems more safe to me, most of the time I have no need for admin privileges. and even though I know viruses in linux are uncommon I still think the best practice is to work on the computer in a state that you yourself can't make any changes to important files, that way viruses also can't harm any important files, but I need to install software for programming and web-design etc. and first of all I don't want to switch users all the time. But also it sounds safer to me that everything being done on the PC will be done through the non-admin user. I'll be glad to know what misunderstanding I have here, cause something here doesn't sound right.

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• Question on methods in Object Oriented Programming

  - by mal

  I’m learning Java at the minute (first language), and as a project I’m looking at developing a simple puzzle game. My question relates to the methods within a class. I have my Block type class; it has its many attributes, set methods, get methods and just plain methods. There are quite a few. Then I have my main board class. At the moment it does most of the logic, positioning of sprites collision detection and then draws the sprites etc... As I am learning to program as much as I’m learning to program games I’m curious to know how much code is typically acceptable within a given method. Is there such thing as having too many methods? All my draw functionality happens in one method, should I break this into a few ‘sub’ methods? My thinking is if I find at a later stage that the for loop I’m using to cycle through the array of sprites searching for collisions in the spriteCollision() method is inefficient I code a new method and just replace the old method calls with the new one, leaving the old code intact. Is it bad practice to have a method that contains one if statement, and place the call for that method in the for loop? I’m very much in the early stages of coding/designing and I need all the help I can get! I find it a little intimidating when people are talking about throwing together a prototype in a day too! Can’t wait until I’m that good!

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