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• Software cost estimation

  - by David Conde

  I've seen on my work place (a University) most students making the software estimation cost of their final diploma work using COCOMO. My guessing is that this way of estimating costs is somewhat old (COCOMO dates of 1981), hence my question: How do you estimate costs in your software? I've seen things like : Cost = ( HoursOfWork + EstimatedIddle ) * HourlyRate That's not what I want, I'm looking for a properly (scientifically) defined cost model EDIT I've found some related questions on SO: What are some of the software cost estimation methods and models? How do you estimate the cost of developing software requirements?

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• Evolution of mainstream programming languages: simplicity versus complexity.

  - by Giorgio

  I had posted this question on http://stackoverflow.com but I was suggested that it may be more appropriate to post it on this forum. I did a quick search on this site and it seems to me that this question has not been asked yet. Please give me a hint if the topic has been raised already by someone else. Update I have rephrased this question, removed personal opinions and made it shorter. I hope in this way it is better suited for this forum. By looking at the recent development of Java (Java 7) and C++ (C++0x) I see that new features are added to these languages. For sure this makes it easier to use certain programming idioms, adding to the productivity of developers. On the other hand, there might be the following risks A language becomes too big, complex, and difficult to understand. It lacks coherence in the design, e.g. if it mixes different paradigms like object-orientation and functional programming, which might not fit well together. Questions: what is more important to you as a developer: to have a rich language that captures a large collection of programming idioms or to have a small language that aims at coherence and simplicity (of course, with a good deal of libraries and tools accompanying it)? Or is it possible to have both? With respect to these issues: How do you judge the current evolutions of main-stream programming languages like Java or C++? Are they becoming too complex, less intuitive? Do they have enough features? Do they need more? Are they still easy enough to understand and use?

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• I'm a CS student, and honestly, I don't understand Knuth's books

  - by Raymond Ho

  I stumbled upon this quote from Bill Gates: "You should definitely send me a resume if you can read the whole thing." He was talking about The Art of Programming books. So I was pretty curious and want to read it all. But honestly, I don't understand it. I'm really not that intellectual. So this should be the reason why I can't understand it, but I am eager to learn. I'm currently reading Volume 1 about fundamental algorithms. Are there any books out there that are friendly for novices/slow people like me, which would help to build up my knowledge so that I can read Knuth's book with ease in the future?

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• What are the preferred documentation tools for the major programming languages?

  - by Dave Peck

  I'm interested in compiling a list of major programming languages and their preferred documentation toolsets. To scope this a bit: The exact structure of the answer may vary from language to language, but there appear to be two aspects common to all languages: (1) in-code syntax for documentation, and (2) documentation generators that make use of said syntax. There are also cases where generators are used independent of code. For example, tutorial-style documentation is common in the Python world and is often disconnected from underlying code. Many languages have multiple commonly-used documentation strategies and tool chains, and I'd love to capture this. Finally, there are cross-language tools like Doxygen that also have some traction and would be worth noting here. Here are some obvious target languages to start with: Python, Ruby, Java, C#, PHP, Objective-C, C/C++, Haskell, Erlang, Scala, Clojure If this question catches on, I'll try and keep this section updated with the most recent list. Thanks!

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• Monitoring C++ applications

  - by Scott A

  We're implementing a new centralized monitoring solution (Zenoss). Incorporating servers, networking, and Java programs is straightforward with SNMP and JMX. The question, however, is what are the best practices for monitoring and managing custom C++ applications in large, heterogenous (Solaris x86, RHEL Linux, Windows) environments? Possibilities I see are: Net SNMP Advantages single, central daemon on each server well-known standard easy integration into monitoring solutions we run Net SNMP daemons on our servers already Disadvantages: complex implementation (MIBs, Net SNMP library) new technology to introduce for the C++ developers rsyslog Advantages single, central daemon on each server well-known standard unknown integration into monitoring solutions (I know they can do alerts based on text, but how well would it work for sending telemetry like memory usage, queue depths, thread capacity, etc) simple implementation Disadvantages: possible integration issues somewhat new technology for C++ developers possible porting issues if we switch monitoring vendors probably involves coming up with an ad-hoc communication protocol (or using RFC5424 structured data; I don't know if Zenoss supports that without custom Zenpack coding) Embedded JMX (embed a JVM and use JNI) Advantages consistent management interface for both Java and C++ well-known standard easy integration into monitoring solutions somewhat simple implementation (we already do this today for other purposes) Disadvantages: complexity (JNI, thunking layer between native C++ and Java, basically writing the management code twice) possible stability problems requires a JVM in each process, using considerably more memory JMX is new technology for C++ developers each process has it's own JMX port (we run a lot of processes on each machine) Local JMX daemon, processes connect to it Advantages single, central daemon on each server consistent management interface for both Java and C++ well-known standard easy integration into monitoring solutions Disadvantages: complexity (basically writing the management code twice) need to find or write such a daemon need a protocol between the JMX daemon and the C++ process JMX is new technology for C++ developers CodeMesh JunC++ion Advantages consistent management interface for both Java and C++ well-known standard easy integration into monitoring solutions single, central daemon on each server when run in shared JVM mode somewhat simple implementation (requires code generation) Disadvantages: complexity (code generation, requires a GUI and several rounds of tweaking to produce the proxied code) possible JNI stability problems requires a JVM in each process, using considerably more memory (in embedded mode) Does not support Solaris x86 (deal breaker) Even if it did support Solaris x86, there are possible compiler compatibility issues (we use an odd combination of STLPort and Forte on Solaris each process has it's own JMX port when run in embedded mode (we run a lot of processes on each machine) possibly precludes a shared JMX server for non-C++ processes (?) Is there some reasonably standardized, simple solution I'm missing? Given no other reasonable solutions, which of these solutions is typically used for custom C++ programs? My gut feel is that Net SNMP is how people do this, but I'd like other's input and experience before I make a decision.

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• How do I hire testers by giving them a buggy app for testing their efficiency?

  - by Jay

  My boss wants to recruit testers based on their testing efficiency (number of bugs identified). So, he's shortlisted 5 people and I need to give them an app full of bugs and see how they fare in reporting obvious bugs, and hidden bugs. I know.... it kind of sounds weird. I guess, this is just like the coding world, where you hire a programmer by assessing his/her programming ability (which is a little easier). Once hired, these testers would be testing a java swing app, so their familiarity of testing frameworks/tools is not really required. So, my question here is - How do I go about finding buggy apps (web/non-web), preferably java ones, that I can have the shortlisted testers have a go at? How would you go about this task if your boss asks you to do so? I am kind of clueless at this point - I googled a bit, thought about finding new apps on sourceforge with lots of bugs, but both approaches didn't work for me.

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• API design and versioning using EJB

  - by broschb

  I have an API that is EJB based (i.e. there are remote interfaces defined) that most of the clients use. As the client base grows there are issues with updates to the API and forcing clients to have to update to the latest version and interface definition. I would like to possibly look at having a couple versions of the API deployed at a time (i.e. have multiple EAR files deployed with different versions of the API) to support not forcing the clients to update as frequently. I am not concerned about the actual deployment of this, but instead am looking for thoughts and experiences that others have on using EJB's as an API client. How do you support updating versions, are clients required to update? Does anyone run multiple versions in a production environment? Are there pro's cons? Any other experiences or thoughts on this approach, and having an EJB centric API?

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• Which is the most practical way to add functionality to this piece of code?

  - by Adam Arold

  I'm writing an open source library which handles hexagonal grids. It mainly revolves around the HexagonalGrid and the Hexagon class. There is a HexagonalGridBuilder class which builds the grid which contains Hexagon objects. What I'm trying to achieve is to enable the user to add arbitrary data to each Hexagon. The interface looks like this: public interface Hexagon extends Serializable { // ... other methods not important in this context <T> void setSatelliteData(T data); <T> T getSatelliteData(); } So far so good. I'm writing another class however named HexagonalGridCalculator which adds some fancy pieces of computation to the library like calculating the shortest path between two Hexagons or calculating the line of sight around a Hexagon. My problem is that for those I need the user to supply some data for the Hexagon objects like the cost of passing through a Hexagon, or a boolean flag indicating whether the object is transparent/passable or not. My question is how should I implement this? My first idea was to write an interface like this: public interface HexagonData { void setTransparent(boolean isTransparent); void setPassable(boolean isPassable); void setPassageCost(int cost); } and make the user implement it but then it came to my mind that if I add any other functionality later all code will break for those who are using the old interface. So my next idea is to add annotations like @PassageCost, @IsTransparent and @IsPassable which can be added to fields and when I'm doing the computation I can look for the annotations in the satelliteData supplied by the user. This looks flexible enough if I take into account the possibility of later changes but it uses reflection. I have no benchmark of the costs of using annotations so I'm a bit in the dark here. I think that in 90-95% of the cases the efficiency is not important since most users wont't use a grid where this is significant but I can imagine someone trying to create a grid with a size of 5.000.000.000 X 5.000.000.000. So which path should I start walking on? Or are there some better alternatives? Note: These ideas are not implemented yet so I did not pay too much attention to good names.

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• What does the Spring framework do? Should I use it? Why or why not?

  - by sangfroid

  So, I'm starting a brand-new project in Java, and am considering using Spring. Why am I considering Spring? Because lots of people tell me I should use Spring! Seriously, any time I've tried to get people to explain what exactly Spring is or what it does, they can never give me a straight answer. I've checked the intros on the SpringSource site, and they're either really complicated or really tutorial-focused, and none of them give me a good idea of why I should be using it, or how it will make my life easier. Sometimes people throw around the term "dependency injection", which just confuses me even more, because I think I have a different understanding of what that term means. Anyway, here's a little about my background and my app : Been developing in Java for a while, doing back-end web development. Yes, I do a ton of unit testing. To facilitate this, I typically make (at least) two versions of a method : one that uses instance variables, and one that only uses variables that are passed in to the method. The one that uses instance variables calls the other one, supplying the instance variables. When it comes time to unit test, I use Mockito to mock up the objects and then make calls to the method that doesn't use instance variables. This is what I've always understood "dependency injection" to be. My app is pretty simple, from a CS perspective. Small project, 1-2 developers to start with. Mostly CRUD-type operations with a a bunch of search thrown in. Basically a bunch of RESTful web services, plus a web front-end and then eventually some mobile clients. I'm thinking of doing the front-end in straight HTML/CSS/JS/JQuery, so no real plans to use JSP. Using Hibernate as an ORM, and Jersey to implement the webservices. I've already started coding, and am really eager to get a demo out there that I can shop around and see if anyone wants to invest. So obviously time is of the essence. I understand Spring has quite the learning curve, plus it looks like it necessitates a whole bunch of XML configuration, which I typically try to avoid like the plague. But if it can make my life easier and (especially) if make it can make development and testing faster, I'm willing to bite the bullet and learn Spring. So please. Educate me. Should I use Spring? Why or why not?

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• How to update dependency during runtime in my .NET application?

  - by Louis Rhys

  I have a server-client application. Sometimes the server is updated which requires some DLLs in the client to be updated as well (The DLLs are the dependencies of the main executable). For now, we have to close the client, manually deploy the DLLs, and then start the client again. This is kind of an inconvenience because the client is an automated application, so normally it doesn't need any user intervention. Is it possible for this to be done automatically without restart or user intervention? Like, the client would download the latest DLL, and replace the current one?

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• Metaphor for task synchronization [closed]

  - by nkint

  I'm looking for a metaphor. A friend of mine taught me to use metaphors from nature, everyday life, math, and use them to design my projects. They can help in creating a better design or better understanding or the problem, and they are cool. Now I'm working on a project with hardware and micro-controllers in C. For convenience, I have decided to use multiple micro-controllers as co-processor units for real-time (the slaves) and a master. This has saved me a lot of headache: I can code the main logic in the master without paying too much attention to super optimizing everything; I don't care if I need some blocking-call; I don't worry about serial communication with the computer. I just send messages to the slaves and they are super fast super in real time. I like my design and it seems to work well. So here are the important concepts that I'm trying capture in the metaphor: hierarchy of processing Not using one big brain but rather several small, distributed brain units using distributed power or resources I'm looking for a good metaphor for this concept of having one unit synchronize the work of all the others. Preferably, the metaphor would come from nature, biology, or zoology.

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• How to decide whether to implement an operation as Entity operation vs Service operation in Domain Driven Design?

  - by Louis Rhys

  I am reading Evans's Domain Driven Design. The book says that there are entity and there are services. If I were to implement an operation, how to decide whether I should add it as a method on an entity or do it in a service class? e.g. myEntity.DoStuff() or myService.DoStuffOn(myEntity)? Does it depend on whether other entities are involved? If it involves other entities, implement as service operation? But entities can have associations and can traverse it from there too right? Does it depend on stateless or not? But service can also access entities' variable, right? Like in do stuff myService.DoStuffOn, it can have code like if(myEntity.IsX) doSomething(); Which means that it will depend on the state? Or does it depend on complexity? How do you define complex operations?

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• How to build a team of people not working together?

  - by Bernd

  I am in charge of a group of about 30 software development experts and architects. While these people are co-located in the companies organization chart, they do not really feel as a team. This is due to their work enviroment: 1) The people are spread over eight locations, with a max. distance of about 1000km (this is Europe). 2) The people don't work as team but instead get called as single people (and sometimes small groups into projects for as long as the projects run. 3) Travelling is somewhat limited as this requires business reasons. Lot is done via phone. Do you have ideas or suggestions on how I could make these people feeling part of a joint organization where they support others and get supported by others. So that they get to know their peers, build a network, informally exchange information? So that they generally get the feeling of having common ground and derive motivation and job satisfaction?

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• How to remove java.sql.BatchUpdateException in Grails? [closed]

  - by aman.nepid

  I have a domain like this: class BusinessOrganization { static hasMany = [organizationBusinessTypes:OrganizationBusinessType] String name String icon static constraints = { name(blank:false,unique:true) icon(unique:true) } String toString() { return "${name}" } } When I save some data for first time it works fine. But when by the next time it shows this error : Error 500: Internal Server Error URI /nLocatePortal/businessOrganization/save Class java.sql.BatchUpdateException Message Batch entry 0 insert into business_organization (version, icon, name, id) values ('0', '', 'dddd', '2') was aborted. Call getNextException to see the cause. **Around line 24 of grails-app/controllers/com/nlocate/portal/BusinessOrganizationController.groovy** 21: 22: def save() { 23: def businessOrganizationInstance = new BusinessOrganization(params) 24: if (!businessOrganizationInstance.save(flush: true)) { 25: render(view: "create", model: [businessOrganizationInstance: businessOrganizationInstance]) 26: return 27: } Please someone help me why this is happening. I am new to Grails. I have not modified the controllers but still I get this error.

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• An alternative to multiple inheritance when creating an abstraction layer?

  - by sebf

  In my project I am creating an abstraction layer for some APIs. The purpose of the layer is to make multi-platform easier, and also to simplify the APIs to the feature set that I need while also providing some functionality, the implementation of which will be unique to each platform. At the moment, I have implemented it by defining and abstract class, which has methods which creates objects that implement interfaces. The abstract class and these interfaces define the capabilities of my abstraction layer. The implementation of these in my layer should of course be arbitrary from the POV view of my application, but I have done it, for my first API, by creating chains of subclasses which add more specific functionality as the features of the APIs they expose become less generic. An example would probably demonstrate this better: //The interface as seen by the application interface IGenericResource { byte[] GetSomeData(); } interface ISpecificResourceOne : IGenericResource { int SomePropertyOfResourceOne {get;} } interface ISpecificResourceTwo : IGenericResource { string SomePropertyOfResourceTwo {get;} } public abstract class MyLayer { ISpecificResourceOne CreateResourceOne(); ISpecificResourceTwo CreateResourceTwo(); void UseResourceOne(ISpecificResourceOne one); void UseResourceTwo(ISpecificResourceTwo two); } //The layer as created in my library public class LowLevelResource : IGenericResource { byte[] GetSomeData() {} } public class ResourceOne : LowLevelResource, ISpecificResourceOne { int SomePropertyOfResourceOne {get{}} } public class ResourceTwo : ResourceOne, ISpecificResourceTwo { string SomePropertyOfResourceTwo {get {}} } public partial class Implementation : MyLayer { override UseResourceOne(ISpecificResourceOne one) { DoStuff((ResourceOne)one); } } As can be seen, I am essentially trying to have two inheritance chains on the same object, but of course I can't do this so I simulate the second version with interfaces. The thing is though, I don't like using interfaces for this; it seems wrong, in my mind an interface defines a contract, any class that implements that interface should be able to be used where that interface is used but here that is clearly not the case because the interfaces are being used to allow an object from the layer to masquerade as something else, without the application needing to have access to its definition. What technique would allow me to define a comprehensive, intuitive collection of objects for an abstraction layer, while their implementation remains independent? (Language is C#)

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• Should data structures be integrated into the language (as in Python) or be provided in the standard library (as in Java)?

  - by Anto

  In Python, and most likely many other programming languages, common data structures can be found as an integrated part of the core language with their own dedicated syntax. If we put LISP's integrated list syntax aside, I can't think of any other languages that I know which provides some kind of data structure above the array as an integrated part of their syntax, though all of them (but C, I guess) seem to provide them in the standard library. From a language design perspective, what are your opinions on having a specific syntax for data structures in the core language? Is it a good idea, and does the purpose of the language (etc.) change how good this could be of a choice? Edit: I'm sorry for (apparently) causing some confusion about which data structures I mean. I talk about the basic and commonly used ones, but still not the most basic ones. This excludes trees (too complex, uncommon), stacks (too seldom used), arrays (too simple) but includes e.g. sets, lists and hashmaps.

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• AngularJS: structuring a web application with multiple ng-apps

  - by mg1075

  The blogosphere has a number of articles on the topic of AngularJS app structuring guidelines such as these (and others): http://www.johnpapa.net/angular-app-structuring-guidelines/ http://codingsmackdown.tv/blog/2013/04/19/angularjs-modules-for-great-justice/ http://danorlando.com/angularjs-architecture-understanding-modules/ http://henriquat.re/modularizing-angularjs/modularizing-angular-applications/modularizing-angular-applications.html However, one scenario I have yet to come across for guidelines and best practices is the case where you have a large web application containing multiple "mini-spa" apps, and the mini-spa apps all share a certain amount of code. I am not referring to the case of trying to have multiple ng-app declarations on the same page; rather, I mean different sections of a large site that have their own, unique ng-app declaration. As Scott Allen writes in his OdeToCode blog: One scenario I haven't found addressed very well is the scenario where multiple apps exist in the same greater web application and require some shared code on the client. Are there any recommended approaches to take, pitfalls to avoid, or good sample structures of this scenario that you can point to?

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• PHP and performance

  - by Naif

  I always hear that PHP is for medium and small websites whereas .NET and Java for enterprise applications. My question is about PHP. Why is PHP not a good option for enterprise web applications? Is it because if the web application becomes bigger then PHP will be slower as it is an interpreted language? I know that corporate world will choose .NET or J2EE because of the integration with their products and because of back end services, etc. However, if we just have PHP for building sites and web applications then how can we use it to perform well with big sites? In short, Is there a relationship between the performance of PHP and the size of the website? What are the factors that make PHP not appropriate option for big sites?

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• Searching for a key in a multi dimensional array and adding it to another array [migrated]

  - by Moha

  Let's say I have two multi dimensional arrays: array1 ( stuff1 = array ( data = 'abc' ) stuff2 = array ( something = '123' data = 'def' ) stuff3 = array ( stuff4 = array ( data = 'ghi' ) ) ) array2 ( stuff1 = array ( ) stuff3 = array ( anything = '456' ) ) What I want is to search the key 'data' in array1 and then insert the key and value to array2 regardless of the depth. So wherever key 'data' exists in array1 it gets added to array2 with the exact depth (and key names) as in array1 AND without modifying any other keys. How can I do this recursively?

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• Refactoring and Open / Closed principle

  - by Giorgio

  I have recently being reading a web site about clean code development (I do not put a link here because it is not in English). One of the principles advertised by this site is the Open Closed Principle: each software component should be open for extension and closed for modification. E.g., when we have implemented and tested a class, we should only modify it to fix bugs or to add new functionality (e.g. new methods that do not influence the existing ones). The existing functionality and implementation should not be changed. I normally apply this principle by defining an interface I and a corresponding implementation class A. When class A has become stable (implemented and tested), I normally do not modify it too much (possibly, not at all), i.e. If new requirements arrive (e.g. performance, or a totally new implementation of the interface) that require big changes to the code, I write a new implementation B, and keep using A as long as B is not mature. When B is mature, all that is needed is to change how I is instantiated. If the new requirements suggest a change to the interface as well, I define a new interface I' and a new implementation A'. So I, A are frozen and remain the implementation for the production system as long as I' and A' are not stable enough to replace them. So, in view of these observation, I was a bit surprised that the web page then suggested the use of complex refactorings, "... because it is not possible to write code directly in its final form." Isn't there a contradiction / conflict between enforcing the Open / Closed Principle and suggesting the use of complex refactorings as a best practice? Or the idea here is that one can use complex refactorings during the development of a class A, but when that class has been tested successfully it should be frozen?

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• Algorithm to reduce calls to mapping API

  - by aidan

  A random distribution of points lies on a map. This data lies behind an API, and I want to grab the complete set of points within a given bounding box. I can query the API with the bounding box and the API will return the set of points that fall within that box. The problem is that the API will limit the result set to 10 items, with no pagination and no indication if there are more points that have been omitted. So I made a recursive algorithm that takes a bounding box and requests the points that lie within it. If the result set is exactly 10 items, then I split the bounding box into four quadrants and recurse. It works fine but my question is this: if want to minimize the number of API calls, what is the optimal way to split the bounding box? Splitting it into quadrants was just an arbitrary decision. When there are a lot of points on the map, I have to drill down many levels before I start getting meaningful results. So I imagine it might be faster to split the box into, say, 9, 16, or more sections. But if I do that, then I eventually get to a point where a lot of requests are returning 0 results which isn't so efficient. Also, does the size of the limit on the results set affect the answer? (This is all assuming that I have no prior knowledge of nominal point density in the bounding box)

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• Graphically intensive silverlight design

  - by Rick Hodder

  I'm designing a silverlight application for showing sheet music from a midi file. I want to create a horizontally scrolling musical staff. At my job I maintain a winforms application that is a scrolling Gantt chart of airplane schedules, and it basically has a rows collection, and it maps the left-most pixel and right-most pixels of the control to datetimes. Then the paint method loops through what it determines will be the visible rows, and draws a screen that shows the schedule information between the two dates. Would I be correct in assuming that I would need to something similar in silverlight for my sheetmusic, or would it be better to just create a horizontal scrollviewer containing a canvas that I have drawn programmaticially on. Am I headed in the right direction? I havent seen any articles on designing such a custom control: can you point me at any?

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• Start with open source desktop application and move to iPhone/Android app

  - by user92356

  I'm a high schooler and I am competing in an open source software development competition. It must be a desktop application that runs on either Windows or Linux. I have a great idea for the open source desktop app, and I wanted to know if I could take it farther and port it to the iPhone or Android platform and make money (preferably through $.99 cost, not ads) I read somewhere that certain open source licenses allow me to do this... am I correct?

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• What is the role of C++ today?

  - by hades

  Currently I'm an IT student and I'm wondering what is still important in C++ today, what for is it used? I completed basic C++ course in my university but I can't imagine where can I use my knowledge and in which direction should I go learning C++. In other words what should I learn to become a successful C++ programmer? Currently I'm learning Java just because I don't see clearly in which area C++ could be useful today, but I clearly know which kind of work I'll be doing as a Java programmer. But I still hope that C++ isn't dead.

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• Is it bad practice to pass instances through several layers?

  - by Puckl

  In my program design, I often come to the point where I have to pass object instances through several classes. For example, if I have a controller that loads an audio file, and then passes it to a player, and the player passes it to the playerRunnable, which passes it again somewhere else etc. It looks kind of bad, but I don´t know how to avoid it. Or is it OK to do this? EDIT: Maybe the player example is not the best because I could load the file later, but in other cases that does not work.

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