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  • Rails - How to use modal form to add object in one model, then reflect that change on main page?

    - by Jim
    I'm working on a Rails app and I've come across a situation where I'm unsure of the cleanest way to proceed. I posted a question on SO with code samples and such - it has received no answers, and the more I think about the problem, the more I think I might be approaching this the wrong way. (See the SO question at http://stackoverflow.com/questions/9521319/how-to-reference-form-when-rendering-partial-from-js-erb-file) So, in more of a generic architecture type question: Right now I have a form where a user can add a new recipe. The form also allows the user to select ingredients (it uses a collection_select which contains Ingredient.all). The catch is - I'd like the user to be able to add a new ingredient on the fly, without leaving the recipe form. Using a hidden div and some jQuery/AJAX, I have a link the user can click to popup a modal form containing ingredients/new.html.erb which is a simple form. When that form is submitted, I call ingredients/create.js.erb to validate the ingredient was saved and hide the modal div. Now I am back to my recipe form, but my collection_select hasn't updated. It seems I have a few choices here: try and re-render the collection_select portion of the form so it grabs a new list of ingredients. This was the method I was attempting when I wrote the SO question. The problem I run into is the partial I use for the collection_select needs the parent form passed in, and when I try and render from the JS file I don't know how to pass it the form object. Reload the recipe form. This works (the collection_select now contains the new ingredient), but the user loses any progress they made on the recipe form. I would need a way to persist the form data - I thought about manually passing the values back and forth, but that is sloppy and there has to be a better way... Try and manually insert the tags using jQuery - this would be simple, but because I'm allowing for multiple ingredients to be added, I can't be certain what ID to target. Now, I can't be the only person to have this issue - so is there an easier way I'm missing? I like option 2 above, but I don't know if there's an easy way to grab the entire params hash as if I had submitted the main recipes form. Hopefully someone can point me in the right direction so I can find an answer to this... If this doesn't make any sense at all, let me know - I can post code samples if you want, but most of the pertinent code is up on the SO question. Thanks!

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  • Pushing complete notifications to client

    - by ton.yeung
    So with cqrs, we accept that consistency is eventual. However, that doesn't mean that the user has to continually poll, or that eventual means an update has to take more then 500ms to sync. For the sake of UX, we want to at least give the illusion of consistency, or if not possible, be as transparent as possible. With that in mind, I have this setup: angularjs web client, consumes webapi restful services, sends commands to nservicebus command handlers, saves to neventstore, dispatches events to nservicebus event handlers, sends message to signalr hub, sends notifications to angularjs web client so with that setup, theoretically some initiates a request the server validates the request sends out the necessary commands In the mean time the client gets a 200 response updates the view: working on it gets message sometime later: done, here's the updated data Here's where things get interesting, each command could spawn multiple events. Not sure if this is a serious no, no, or not, but that's how it is currently. For example, a new customer spawns CustomerIDCreated, CustomerNameUpdated, CustomerAddressUpdated, etc... Which event handler needs to notify the client? Should all of them in a progress bar style update?

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  • Programming Language, Turing Completeness and Turing Machine

    - by Amumu
    A programming language is said to be Turing Completeness if it can successfully simulate a universal TM. Let's take functional programming language for example. In functional programming, function has highest priority over anything. You can pass functions around like any primitives or objects. This is called first class function. In functional programming, your function does not produce side effect i.e. output strings onto screen, change the state of variables outside of its scope. Each function has a copy of its own objects if the objects are passed from the outside, and the copied objects are returned once the function finishes its job. Each function written purely in functional style is completely independent to anything outside of it. Thus, the complexity of the overall system is reduced. This is referred as referential transparency. In functional programming, each function can have its local variables kept its values even after the function exits. This is done by the garbage collector. The value can be reused the next time the function is called again. This is called memoization. A function usually should solve only one thing. It should model only one algorithm to answer a problem. Do you think that a function in a functional language with above properties simulate a Turing Machines? Functions (= algorithms = Turing Machines) are able to be passed around as input and returned as output. TM also accepts and simulate other TMs Memoization models the set of states of a Turing Machine. The memorized variables can be used to determine states of a TM (i.e. which lines to execute, what behavior should it take in a give state ...). Also, you can use memoization to simulate your internal tape storage. In language like C/C++, when a function exits, you lose all of its internal data (unless you store it elsewhere outside of its scope). The set of symbols are the set of all strings in a programming language, which is the higher level and human-readable version of machine code (opcode) Start state is the beginning of the function. However, with memoization, start state can be determined by memoization or if you want, switch/if-else statement in imperative programming language. But then, you can't Final accepting state when the function returns a value, or rejects if an exception happens. Thus, the function (= algorithm = TM) is decidable. Otherwise, it's undecidable. I'm not sure about this. What do you think? Is my thinking true on all of this? The reason I bring function in functional programming because I think it's closer to the idea of TM. What experience with other programming languages do you have which make you feel the idea of TM and the ideas of Computer Science in general? Can you specify how you think?

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  • How to get better at solving Dynamic programming problems

    - by newbie
    I recently came across this question: "You are given a boolean expression consisting of a string of the symbols 'true', 'false', 'and', 'or', and 'xor'. Count the number of ways to parenthesize the expression such that it will evaluate to true. For example, there is only 1 way to parenthesize 'true and false xor true' such that it evaluates to true." I knew it is a dynamic programming problem so i tried to come up with a solution on my own which is as follows. Suppose we have a expression as A.B.C.....D where '.' represents any of the operations and, or, xor and the capital letters represent true or false. Lets say the number of ways for this expression of size K to produce a true is N. when a new boolean value E is added to this expression there are 2 ways to parenthesize this new expression 1. ((A.B.C.....D).E) ie. with all possible parenthesizations of A.B.C.....D we add E at the end. 2. (A.B.C.(D.E)) ie. evaluate D.E first and then find the number of ways this expression of size K can produce true. suppose T[K] is the number of ways the expression with size K produces true then T[k]=val1+val2+val3 where val1,val2,val3 are calculated as follows. 1)when E is grouped with D. i)It does not change the value of D ii)it inverses the value of D in the first case val1=T[K]=N.( As this reduces to the initial A.B.C....D expression ). In the second case re-evaluate dp[K] with value of D reversed and that is val1. 2)when E is grouped with the whole expression. //val2 contains the number of 'true' E will produce with expressions which gave 'true' among all parenthesized instances of A.B.C.......D i) if true.E = true then val2 = N ii) if true.E = false then val2 = 0 //val3 contains the number of 'true' E will produce with expressions which gave 'false' among all parenthesized instances of A.B.C.......D iii) if false.E=true then val3=( 2^(K-2) - N ) = M ie. number of ways the expression with size K produces a false [ 2^(K-2) is the number of ways to parenthesize an expression of size K ]. iv) if false.E=false then val3 = 0 This is the basic idea i had in mind but when i checked for its solution http://people.csail.mit.edu/bdean/6.046/dp/dp_9.swf the approach there was completely different. Can someone tell me what am I doing wrong and how can i get better at solving DP so that I can come up with solutions like the one given above myself. Thanks in advance.

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  • Can someone provide a short code example of compiler bootstrapping?

    - by Jatin
    This Turing award lecture by Ken Thompson on topic "Reflections on Trusting Trust" gives good insight about how C compiler was made in C itself. Though I understand the crux, it still hasn't sunk in. So ultimately, once the compiler is written to do lexical analysis, parse trees, syntax analysis, byte code generation etc, a separate machine code is again written to do all that on compiler? Can anyone please explain with a small example of the procedure? Bootstrapping on wiki gives good insights, but only a rough view on it. PS: I am aware of the duplicates on the site, but found them to be an overview which I am already aware

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  • Multiplayer Game Listen Servers: Ensuring Integrity

    - by Ankit Soni
    I'm making a simple multiplayer game of Tic Tac Toe in Python using Bridge (its an RPC service built over a message queue - RabbitMQ) and I'd like to structure it so that the client and the server are just one file. When a user runs the game, he is offered a choice to either create a game or join an existing game. So when a user creates a game, the program will create the game and also join him as a player to the game. This is basically a listen server (as opposed to a dedicated server) - a familiar concept in multiplayer games. I came across a really interesting question while trying to make this - how can I ensure that the player hosting the game doesn't tamper with it (or atleast make it difficult)? The player hosting the game has access to the array used to store the board etc., and these must be stored in the process' virtual memory, so it seems like this is impossible. On the other hand, many multiplayer games use this model for LAN games.

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  • Isolated Unit Tests and Fine Grained Failures

    - by Winston Ewert
    One of the reasons often given to write unit tests which mock out all dependencies and are thus completely isolated is to ensure that when a bug exists, only the unit tests for that bug will fail. (Obviously, an integration tests may fail as well). That way you can readily determine where the bug is. But I don't understand why this is a useful property. If my code were undergoing spontaneous failures, I could see why its useful to readily identify the failure point. But if I have a failing test its either because I just wrote the test or because I just modified the code under test. In either case, I already know which unit contains a bug. What is the useful in ensuring that a test only fails due to bugs in the unit under test? I don't see how it gives me any more precision in identifying the bug than I already had.

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  • Analysing Group & Individual Member Performance -RUP

    - by user23871
    I am writing a report which requires the analysis of performance of each individual team member. This is for a software development project developed using the Unified Process (UP). I was just wondering if there are any existing group & individual appraisal metrics used so I don't have to reinvent the wheel... EDIT This is by no means correct but something like: Individual Contribution (IC) = time spent (individual) / time spent (total) = Performance = ? (should use individual contribution (IC) combined with something to gain a measure of overall performance).... Maybe I am talking complete hash and I know generally its really difficult to analyse performance with numbers but any mathematicians out there that can lend a hand or know a somewhat more accurate method of analysing performance than arbitrary marking (e.g. 8 out 10)

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  • Any legal issue in developing app similar to others?

    - by demotics2002
    There is a game I want to develop for mobile devices e.g. cellphone/tablet. I have been looking for this game and couldn't find it so I decide to just do it on my own. But I'm worried that there will be legal issues. I'm sorry but I do not know what is the process in doing this. I noticed for example the game Bejeweled Blitz. If I develop something similar, do I have to contact the developer and ask for permission if I develop a game with similar rules but use shapes rather than jewels? The original game exists only on Windows for free. If I develop the game, exactly similar rules but different display, am I allowed to sell it? Thanks...

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  • How do I tell the cases when it's worth to use LINQ?

    - by Lijo
    Many things in LINQ can be accomplished without the library. But for some scenarios, LINQ is most appropriate. Examples are: SELECT - http://stackoverflow.com/questions/11883262/wrapping-list-items-inside-div-in-a-repeater SelectMany, Contains - http://stackoverflow.com/questions/11778979/better-code-pattern-for-checking-existence-of-value Enumerable.Range - http://stackoverflow.com/questions/11780128/scalable-c-sharp-code-for-creating-array-from-config-file WHERE http://stackoverflow.com/questions/13171850/trim-string-if-a-string-ends-with-a-specific-word What factors to take into account when deciding between LINQ and regular .Net language elements?

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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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  • What makes for a good JIRA workflow with a software development team?

    - by Hari Seldon
    I am migrating my team from a snarl of poorly managed excel documents, individual checklists, and personal emails to manage our application issues and development tasks to a new JIRA project. My team and I are new to JIRA (and issue tracking software in general). My team is skeptical of the transition at best, so I am also trying not to scare them off by introducing something overly complex at the start. I understand one of JIRA's strengths to be the customized workflows that can be created for a project. I've looked over the JIRA documentation and a number of tutorials, and am comfortable with the how in creating workflows, but I need some contextual What to go along with it. What makes a particular workflow work well? What does a poorly designed workflow look like? What are the benefits/drawbacks of a strict workflow with very specific states and transitions to a looser workflow, with fewer, broader defined states and transitions

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  • Two interfaces with identical signatures

    - by corsiKa
    I am attempting to model a card game where cards have two important sets of features: The first is an effect. These are the changes to the game state that happen when you play the card. The interface for effect is as follows: boolean isPlayable(Player p, GameState gs); void play(Player p, GameState gs); And you could consider the card to be playable if and only if you can meet its cost and all its effects are playable. Like so: // in Card class boolean isPlayable(Player p, GameState gs) { if(p.resource < this.cost) return false; for(Effect e : this.effects) { if(!e.isPlayable(p,gs)) return false; } return true; } Okay, so far, pretty simple. The other set of features on the card are abilities. These abilities are changes to the game state that you can activate at-will. When coming up with the interface for these, I realized they needed a method for determining whether they can be activated or not, and a method for implementing the activation. It ends up being boolean isActivatable(Player p, GameState gs); void activate(Player p, GameState gs); And I realize that with the exception of calling it "activate" instead of "play", Ability and Effect have the exact same signature. Is it a bad thing to have multiple interfaces with an identical signature? Should I simply use one, and have two sets of the same interface? As so: Set<Effect> effects; Set<Effect> abilities; If so, what refactoring steps should I take down the road if they become non-identical (as more features are released), particularly if they're divergent (i.e. they both gain something the other shouldn't, as opposed to only one gaining and the other being a complete subset)? I'm particularly concerned that combining them will be non-sustainable as soon as something changes. The fine print: I recognize this question is spawned by game development, but I feel it's the sort of problem that could just as easily creep up in non-game development, particularly when trying to accommodate the business models of multiple clients in one application as happens with just about every project I've ever done with more than one business influence... Also, the snippets used are Java snippets, but this could just as easily apply to a multitude of object oriented languages.

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  • Compiling vs using pre-built binaries performance?

    - by Nick Rosencrantz
    Will performance be better (quicker) if I manually compile the source for a software component for the actual machine that it will be used on, compared to if the source was compiled on another platform perhaps for many different architectures? I got some good results compiling source that I downloaded and I wonder whether this was due to compiling it instead of downloading a pre-compiled binary which is often the case with software updates.

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  • How to structure a set of RESTful URLs

    - by meetamit
    Kind of a REST lightweight here... Wondering which url scheme is more appropriate for a stock market data app (BTW, all queries will be GETs as the client doesn't modify data): Scheme 1 examples: /stocks/ABC/news /indexes/XYZ/news /stocks/ABC/time_series/daily /stocks/ABC/time_series/weekly /groups/ABC/time_series/daily /groups/ABC/time_series/weekly Scheme 2 examples: /news/stock/ABC /news/index/XYZ /time_series/stock/ABC/daily /time_series/stock/ABC/weekly /time_series/index/XYZ/daily /time_series/index/XYZ/weekly Scheme 3 examples: /news/stock/ABC /news/index/XYZ /time_series/daily/stock/ABC /time_series/weekly/stock/ABC /time_series/daily/index/XYZ /time_series/weekly/index/XYZ Scheme 4: Something else??? The point is that for any data being requested, the url needs to encapsulate whether an item is a Stock or an Index. And, with all the RESTful talk about resources I'm confused about whether my primary resource is the stock & index or the time_series & news. Sorry if this is a silly question :/ Thanks!

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  • Make methods that do not depend on instance fields, static?

    - by m3th0dman
    Recently I started programming in Groovy for a integration testing framework, for a Java project. I use Intellij IDEA with Groovy plug-in and I am surprised to see as a warning for all the methods that are non-static and do not depend on any instance fields. In Java, however, this is not an issue (at least from IDE's point of view). Should all methods that do not depend onto any instance fields be transformed into static functions? If true, is this specific to Groovy or it is available for OOP in general? And why?

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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 far has a bug pushed you? [closed]

    - by Darknight
    When debugging (hard to find) bugs, I know I've personally gotten so frustrated as to lash out on the keyboard and shout profanities at the monitor. I have repeatability witnessed co-workers throw their computer mouse off the table in anger and frustration. What is the furthest a bastard of bug has ever pushed you? EDIT: Hehehe :D it would seem this bug, er I mean post has pushed the guys to close it... Oh well, very very interesting answers anyway.

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  • android app unable to connect to the hsqldb server

    - by Chinta
    I am trying to connect my android app to the hsql db server. Server runs on computer-1. I can connect to the db server from local machine through java as well as Db-visualizer. I can connect to the db server from another computer(computer-2) using Db-visualizer with comouter-1 ip address. Now trying to connect from my app in Nexus 7 the same way I was connecting from computer-2. I am getting "No Suitable Driver" error. Below is the log. 11-02 12:01:41.235: W/System.err(9803): connection string <jdbc:hsqldb:hsql://192.168.2.6:9001/qBank> 11-02 12:01:41.235: W/System.err(9803): user id string <SA> 11-02 12:01:41.235: W/System.err(9803): password string <> 11-02 12:01:41.235: W/System.err(9803): ERROR: failed to get connection. 11-02 12:01:41.235: W/System.err(9803): java.sql.SQLException: No suitable driver 11-02 12:01:41.235: W/System.err(9803): at java.sql.DriverManager.getConnection(DriverManager.java:186) 11-02 12:01:41.235: W/System.err(9803): at java.sql.DriverManager.getConnection(DriverManager.java:213) 11-02 12:01:41.235: W/System.err(9803): at com.scan.util.GatherData.getConnection(GatherData.java:135)

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  • JUnit Testing in Multithread Application

    - by e2bady
    This is a problem me and my team faces in almost all of the projects. Testing certain parts of the application with JUnit is not easy and you need to start early and to stick to it, but that's not the question I'm asking. The actual problem is that with n-Threads, locking, possible exceptions within the threads and shared objects the task of testing is not as simple as testing the class, but testing them under endless possible situations within threading. To be more precise, let me tell you about the design of one of our applications: When a user makes a request several threads are started that each analyse a part of the data to complete the analysis, these threads run a certain time depending on the size of the chunk of data (which are endless and of uncertain quality) to analyse, or they may fail if the data was insufficient/lacking quality. After each completed its analysis they call upon a handler which decides after each thread terminates if the collected analysis-data is sufficient to deliver an answer to the request. All of these analysers share certain parts of the applications (some parts because the instances are very big and only a certain number can be loaded into memory and those instances are reusable, some parts because they have a standing connection, where connecting takes time, ex.gr. sql connections) so locking is very common (done with reentrant-locks). While the applications runs very efficient and fast, it's not very easy to test it under real-world conditions. What we do right now is test each class and it's predefined conditions, but there are no automated tests for interlocking and synchronization, which in my opionion is not very good for quality insurances. Given this example how would you handle testing the threading, interlocking and synchronization?

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  • How can I discourage the use of Access?

    - by Greg Buehler
    Lets pretend that a very large company (revenue numbers with more than 8 figures) is looking to do a refresh on a software system, particularly the dashboard used by employees. This system was originally put together in the early 1990's to handle inventory tracking and storage across a variety of facilities (10+). Since this large company is now in the process of implementing some of these inventory processes with SAP they are in need of a major refresh. The existing system: Microsoft Access project performs dashboard duties Unique shipping/receiving configurations at different facilities require unique forms and queries within the Access project Uses 3rd party libraries referenced by Access to directly interface with at control system (read: motors, conveyors, and counters) Individual SQL Server 2000 instances (some traces of pre-update SQL Server 6.0 documents) at each facility The Issue: This system started as a home brewed inventory tracking scheme with a single internal sponsor who is still in charge of the technical direction. The original sponsor prescribing the desired deliverables that are being called for in the current RFP. The RFP describes a system based around a single Access project. Any suggestion that Access is ill suited for a project of this scope are shot down under the reasoning that "it works for the scope now". Are there any case studies, notices, or statements that can be used to disuade this potential customer from repeating their mistake? Does Microsoft make any statements directly about when it is highly recommended to ditch Access?

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  • What is considered third party code?

    - by Songo
    Inspired by this question Using third-party libraries - always use a wrapper? I wanted to know what people actually consider as third-party libraries. Example from PHP: If I'm building an application using Zend framework, should I treat Zend framework libraries as third party code? Example from C#: If I'm building a desktop application, should I treat all .Net classes as third party code? Example from Java: Should I treat all libraries in the JDK as third party libraries? Some people say that if a library is stable and won't change often then one doesn't need to wrap it. However I fail to see how one would test a class that depends on a third party code without wrapping it.

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  • Should a stack trace be in the error message presented to the user?

    - by Vilx-
    I've got a bit of an argument at my workplace and I'm trying to figure out who is right, and what is the right thing to do. Context: an intranet web application that our customers use for accounting and other ERP stuff. I'm of the opinion that an error message presented to the user (when things crash) should include as much information as possible, including the stack trace. Of course, it has to start with a nice "An Error has occurred, please submit the below information to the developers" in large, friendly letters. My reasoning is that a screenshot of the crashed application will often be the only easily available source of information. Sure, you can try to get a hold of the client's systems administrator(s), attempt to explain where your log files are, etc, but that will probably be slow and painful (talking to the client representatives mostly is). Also, having an immediate and full information is extremely useful in development, where you don't have to go hunting through the log files to find what you need on every exception. (But that could be solved with a configuration switch.) Unfortunately there has been some kind of "Security audit" (no idea how they did that without the sources... but whatever), and they complained about the full exception messages citing them as a security threat. Naturally, the clients (at least one that I know of) has taken this at face value and now demands that the messages be cleaned. I fail to see how a potential attacker could use a stack trace to figure anything out he couldn't have figured out before. Are there any examples, any documented proof of anyone ever doing that? I think that we should fight this foolish idea, but perhaps I'm the fool here, so... Who's right?

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  • GPL - what is distribution?

    - by Martin Beckett
    An interesting point came up on another thread about alleged misappropriation of a GPL project. In this case the enterprise software was used by some large companies who essentially took the code, changed the name, removed the GPL notices and used the result. The point was - if the company did this and only used the software internally then there isn't any distribution and that's perfectly legal under GPL. Modifications by their own employees for internal use would also be allowed. So At what point does it become a distribution? Presumably if they brought in outside contractors under 'work for hire' their modifications would also be internal and so not a distribution. If they hired an external software outfit to do modifications and those changes were only used internally by the company - would those changes be distributed? Does the GPL apply to the client or to the external developers? If the company then give the result to another department, another business unit, another company? What if the other company is a wholly owned subsidiary? ps. yes I know the answer is ask a lawyer. But all the discussion I have seen over GPL2/GPL3 distribution has been about webservices - not about internal use.

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  • Popular programming books which have been translated into Russian

    - by arikfr
    I'm looking for recommendations of popular programming books that have been translated into Russian. I'm talking about books like: Test-Driven Development by Example by Kent Beck Code Complete The Pragmatic Programmer And other books like them. Also, recommendations for books in Russian by other authors but about similar topics (TDD, BDD, general programming methodologies) will be appreciated.

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