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• Any Practical Alternative to the Signals + Slots model for GUI Programming?

  - by IntermediateHacker

  The majority of GUI Toolkits nowadays use the Signals + Slots model. It was Qt and GTK+, if I am not wrong, who pioneered it. You know, the widgets or graphical objects (sometimes even ones that aren't displayed) send signals to the main-loop handler. The main-loop handler then calls the events, callbacks or slots assigned for that widget / graphical object. There are usually default (and in most cases virtual) event-handlers already provided by the toolkit for handling all pre-defined signals, therefore, unlike previous designs where the developer had to write the entire main-loop and handler for each and every message himself (think WINAPI), the developer only has to worry about the signals he needs to implement new functionality on. Now this design is being used in most modern toolkits as far as I know. There are Qt, GTK+, FLTK etc. There is Java Swing. C# even has a language feature for it ( events and delegates ), and Windows Forms has been developed on this design. In fact, over the last decade, this design for GUI programming has become a kind of an unwritten standard. Since it increases productivity and provides greater abstraction. However, my question is: Is there any alternative design, that is parallel or practical for modern GUI programming? i.e Is the Signals + Slots design, the only practical one in town? Is it feasible to do GUI Programming with any other design? Are any modern (preferably successful and popular) GUI toolkits built on an alternative design?

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• Basis of definitions

  - by Yttrill

  Let us suppose we have a set of functions which characterise something: in the OO world methods characterising a type. In mathematics these are propositions and we have two kinds: axioms and lemmas. Axioms are assumptions, lemmas are easily derived from them. In C++ axioms are pure virtual functions. Here's the problem: there's more than one way to axiomatise a system. Given a set of propositions or methods, a subset of the propositions which is necessary and sufficient to derive all the others is called a basis. So too, for methods or functions, we have a desired set which must be defined, and typically every one has one or more definitions in terms of the others, and we require the programmer to provide instance definitions which are sufficient to allow all the others to be defined, and, if there is an overspecification, then it is consistent. Let me give an example (in Felix, Haskell code would be similar): class Eq[t] { virtual fun ==(x:t,y:t):bool => eq(x,y); virtual fun eq(x:t, y:t)=> x == y; virtual fun != (x:t,y:t):bool => not (x == y); axiom reflex(x:t): x == x; axiom sym(x:t, y:t): (x == y) == (y == x); axiom trans(x:t, y:t, z:t): implies(x == y and y == z, x == z); } Here it is clear: the programmer must define either == or eq or both. If both are defined, the definitions must be equivalent. Failing to define one doesn't cause a compiler error, it causes an infinite loop at run time. Defining both inequivalently doesn't cause an error either, it is just inconsistent. Note the axioms specified constrain the semantics of any definition. Given a definition of == either directly or via a definition of eq, then != is defined automatically, although the programmer might replace the default with something more efficient, clearly such an overspecification has to be consistent. Please note, == could also be defined in terms of !=, but we didn't do that. A characterisation of a partial or total order is more complex. It is much more demanding since there is a combinatorial explosion of possible bases. There is an reason to desire overspecification: performance. There also another reason: choice and convenience. So here, there are several questions: one is how to check semantics are obeyed and I am not looking for an answer here (way too hard!). The other question is: How can we specify, and check, that an instance provides at least a basis? And a much harder question: how can we provide several default definitions which depend on the basis chosen?

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• handling a GET error properly

  - by Andrew Heath

  I have a website that takes two primary get strings: ?type=GAME&id=SomeGameID ?type=SCENARIO&id=SomeScenarioID for reasons unknown, I have recently begun receiving requests for erroneous get strings from both Yandex and Baidu. They are always in the form of: ?type=GAME&id=SomeScenarioID None of my users are triggering these errors, so I am (sort of) confident that this is not due to an HTML template error somewhere on my part. There is also no HTTP_REFER showing up in the $_SERVER array, so I'm guessing these are direct requests from bad dbase data on their part. I see two options for dealing with these bad requests, and would like to know which is recommended... or if there are other, better options I have not thought of: simply 404 the request, since it is incorrect redirect the request to ?type=SCENARIO&id=SomeScenarioID because the scenario IDs are always valid, the breakage is due to asking for the wrong type.

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• Dealing with state problems in functional programming

  - by Andrew Martin

  I've learned how to program primarily from an OOP standpoint (like most of us, I'm sure), but I've spent a lot of time trying to learn how to solve problems the functional way. I have a good grasp on how to solve calculational problems with FP, but when it comes to more complicated problems I always find myself reverting to needing mutable objects. For example, if I'm writing a particle simulator, I will want particle "objects" with a mutable position to update. How are inherently "stateful" problems typically solved using functional programming techniques?

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• When to start thinking about scalability?

  - by Rits

  I'm having a funny but also terrible problem. I'm about to launch a new (iPhone) app. It's a turn-based multiplayer game running on my own custom backend. But I'm afraid to launch. For some reason, I think it might become something big and that its popularity will kill my poor lonely single server + MySQL database. On one hand I'm thinking that if it's growing, I'd better be prepared and have a scalable infrastructure already in place. On the other hand I just feel like getting it out into the world and see what happens. I often read stuff like "premature optimization is the root of all evil" or people saying that you should just build your killer game now, with the tools at hand, and worry about other stuff like scalability later. I'd love to hear some opinions on this from experts or people with experience with this. Thanks!

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• How can I quantify the amount of technical debt that exists in a project?

  - by Erik Dietrich

  Does anyone know if there is some kind of tool to put a number on technical debt of a code base, as a kind of code metric? If not, is anyone aware of an algorithm or set of heuristics for it? If neither of those things exists so far, I'd be interested in ideas for how to get started with such a thing. That is, how can I quantify the technical debt incurred by a method, a class, a namespace, an assembly, etc. I'm most interested in analyzing and assessing a C# code base, but please feel free to chime in for other languages as well, particularly if the concepts are language transcendent.

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• Help needed on a UI/Developer Interview

  - by AJ Seth

  I have a phone interview with a major Internet company and it is a mostly front-end developer position. If anyone has experience with UI/developer interviews and can give some advice/questions asked etc. that'll be great. Additionally, what resources can be read and reviewed for the following: Designing for performance, scalability and availability Internet and OS security fundamentals EDIT: Now I am told that the interview I am told will be mostly on coding, Data Structures, design questions etc. Anyone?

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• How to motivate team for knowledge sharing sessions

  - by ring bearer

  I work in a team with wide range of expertise and experience. I have been trying to introduce weekly knowledge sharing sessions. Sessions of 30-60 min length where everybody gets a chance to present something and talk about it. This will contribute in improving presentational and language skills. However, the team is not motivated towards this, either the attendance is too low or none. How to get a team work towards such an idea?

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• Where can you find your first customers as a freelancer?

  - by Adam Smith

  I want to start doing freelance work, but no matter how I look at it, it seems like the best way to get customers and to have work most of the time, you have to already be in the freelancing game. Most freelancers I've talked to have had the same customers over the years or got new customers because their satisfied clients referred them. What I'd like to know from the successful people here that work as freelancers is how do you start doing business when you haven't yet set foot in freelancing? I want to start small, creating websites that won't require me to hire other people other than maybe a designer I already know. (I'd like to create desktop applications as well, but I think I should keep that for later when I'm more experienced) . I thought about localized Google ads or visiting companies and meeting the people in charge there, but I wouldn't know which kind of businesses to look for or if it's even a good way to approach this. Anyone care to share their personal startup experiences / advice that can help future freelancers?

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• Logging errors caused by exceptions deep in the application

  - by Kaleb Pederson

  What are best-practices for logging deep within an application's source? Is it bad practice to have multiple event log entries for a single error? For example, let's say that I have an ETL system whose transform step involves: a transformer, pipeline, processing algorithm, and processing engine. In brief, the transformer takes in an input file, parses out records, and sends the records through the pipeline. The pipeline aggregates the results of the processing algorithm (which could do serial or parallel processing). The processing algorithm sends each record through one or more processing engines. So, I have at least four levels: Transformer - Pipeline - Algorithm - Engine. My code might then look something like the following: class Transformer { void Process(InputSource input) { try { var inRecords = _parser.Parse(input.Stream); var outRecords = _pipeline.Transform(inRecords); } catch (Exception ex) { var inner = new ProcessException(input, ex); _logger.Error("Unable to parse source " + input.Name, inner); throw inner; } } } class Pipeline { IEnumerable<Result> Transform(IEnumerable<Record> records) { // NOTE: no try/catch as I have no useful information to provide // at this point in the process var results = _algorithm.Process(records); // examine and do useful things with results return results; } } class Algorithm { IEnumerable<Result> Process(IEnumerable<Record> records) { var results = new List<Result>(); foreach (var engine in Engines) { foreach (var record in records) { try { engine.Process(record); } catch (Exception ex) { var inner = new EngineProcessingException(engine, record, ex); _logger.Error("Engine {0} unable to parse record {1}", engine, record); throw inner; } } } } } class Engine { Result Process(Record record) { for (int i=0; i<record.SubRecords.Count; ++i) { try { Validate(record.subRecords[i]); } catch (Exception ex) { var inner = new RecordValidationException(record, i, ex); _logger.Error( "Validation of subrecord {0} failed for record {1}", i, record ); } } } } There's a few important things to notice: A single error at the deepest level causes three log entries (ugly? DOS?) Thrown exceptions contain all important and useful information Logging only happens when failure to do so would cause loss of useful information at a lower level. Thoughts and concerns: I don't like having so many log entries for each error I don't want to lose important, useful data; the exceptions contain all the important but the stacktrace is typically the only thing displayed besides the message. I can log at different levels (e.g., warning, informational) The higher level classes should be completely unaware of the structure of the lower-level exceptions (which may change as the different implementations are replaced). The information available at higher levels should not be passed to the lower levels. So, to restate the main questions: What are best-practices for logging deep within an application's source? Is it bad practice to have multiple event log entries for a single error?

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• What is the equivalent word for "compile" in an interpreted language?

  - by user46874

  (I was encouraged to ask this question here.) In C, we say: GCC compiles foo.c. For interpreters (such as Lua), what is the equivalent verb? The Lua interpreter ____ foo.lua. When I write instructions for users of my Lua script, I often say: Run the interpreter on foo.lua. I think this can be said more succinctly: Interpret (or Translate) foo.lua. but that sounds awkward for some reason (perhaps because I'm unsure of its correctness). I can't really say compile because users may confuse it with the usage of the Lua compiler when I actually mean the Lua interpreter.

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• Looking for a light weight note program.

  - by Erin

  This might belongs on superuser but for me it's part of programming so i will ask it here. I find I use notepad to keep chunks of data that are important but not important enough to keep in my head. The one problem with this is I end up with a lot of files on my desktop that I don't know what they are for, or I don't save the file and my computer gets rebooted for some reason. So that big ramble leads to the question. I am looking for a note taking system that is light weight and easy to manage. I would rather it not be a huge application like onenote but if that is what you are using and is is working well for you could you explain how you are doing it? Thanks Erin.

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• What is a good use case for scala?

  - by Usman Ismail

  In a current project we have setup the build so that we could mix Java and Scala. I would like to use more Scala in our code base to make the code more readable and concise. In the process also learn the language by handing over real features. So I plan to use Scala for some classes to showcase its benefits and convince other devs to look into using Scala too. For a rest based web server or a program in general what kind of code structures lend themselves to Scala's functional programming style.

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• What are the arguments against parsing the Cthulhu way?

  - by smarmy53

  I have been assigned the task of implementing a Domain Specific Language for a tool that may become quite important for the company. The language is simple but not trivial, it already allows nested loops, string concatenation, etc. and it is practically sure that other constructs will be added as the project advances. I know by experience that writing a lexer/parser by hand -unless the grammar is trivial- is a time consuming and error prone process. So I was left with two options: a parser generator à la yacc or a combinator library like Parsec. The former was good as well but I picked the latter for various reasons, and implemented the solution in a functional language. The result is pretty spectacular to my eyes, the code is very concise, elegant and readable/fluent. I concede it may look a bit weird if you never programmed in anything other than java/c#, but then this would be true of anything not written in java/c#. At some point however, I've been literally attacked by a co-worker. After a quick glance at my screen he declared that the code is uncomprehensible and that I should not reinvent parsing but just use a stack and String.Split like everybody does. He made a lot of noise, and I could not convince him, partially because I've been taken by surprise and had no clear explanation, partially because his opinion was immutable (no pun intended). I even offered to explain him the language, but to no avail. I'm positive the discussion is going to re-surface in front of management, so I'm preparing some solid arguments. These are the first few reasons that come to my mind to avoid a String.Split-based solution: you need lot of ifs to handle special cases and things quickly spiral out of control lots of hardcoded array indexes makes maintenance painful extremely difficult to handle things like a function call as a method argument (ex. add( (add a, b), c) very difficult to provide meaningful error messages in case of syntax errors (very likely to happen) I'm all for simplicity, clarity and avoiding unnecessary smart-cryptic stuff, but I also believe it's a mistake to dumb down every part of the codebase so that even a burger flipper can understand it. It's the same argument I hear for not using interfaces, not adopting separation of concerns, copying-pasting code around, etc. A minimum of technical competence and willingness to learn is required to work on a software project after all. (I won't use this argument as it will probably sound offensive, and starting a war is not going to help anybody) What are your favorite arguments against parsing the Cthulhu way?* *of course if you can convince me he's right I'll be perfectly happy as well

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• Why do some people hate Dart? [closed]

  - by Hassan

  First, I'd like to note that this question is not intended to compare two languages or technologies, but is only asking about criticisms aimed at a language. I've always thought it a good idea to somehow get rid of Javascript. It works, but it's just so messy. I think many will agree with me there. And that's how I interpreted Google's release of Dart. It seems to me like a very good alternative to Javascript. Now, it looks like some are not very happy that Google has released this new language. Take a look at this Wikipedia page to see what I'm talking about. If you don't feel like reading it, I'll tell you now that some seem to think that Dart is similar to Microsoft's VBScript, in that it only works on Microsoft's browsers. This goes against the web's openness. But it's my understanding that Dart can be compiled to Javascript, which will allow it to be run on any modern browser (as the Wikipedia article also states). So my question is: are these criticisms valid? Is there a real fear that Google is trying to control the web's front-end to be more compatible with its browser?

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• how a pure functional programming language manage without assignment statements?

  - by Gnijuohz

  When reading the famous SICP,I found the authors seem rather reluctant to introduce the assignment statement to Scheme in Chapter 3.I read the text and kind of understand why they feel so. As Scheme is the first functional programming language I ever know something about,I am kind of surprised that there are some functional programming languages(not Scheme of course) can do without assignments. Let use the example the book offers,the bank account example.If there is no assignment statement,how can this be done?How to change the balance variable?I ask so because I know there are some so-called pure functional languages out there and according to the Turing complete theory,this must can be done too. I learned C,Java,Python and use assignments a lot in every program I wrote.So it's really an eye-opening experience.I really hope someone can briefly explain how assignments are avoided in those functional programming languages and what profound impact(if any) it has on these languages. The example mentioned above is here: (define (make-withdraw balance) (lambda (amount) (if (>= balance amount) (begin (set! balance (- balance amount)) balance) "Insufficient funds"))) This changed the balance by set!.To me it looks a lot like a class method to change the class member balance. As I said,I am not familiar with functional programming languages,so if I said something wrong about them,feel free to point out.

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• Automated architecture validation

  - by P.Brian.Mackey

  I am aware of the fact that TFS 2010 ultimate edition can create and validate architecture diagrams. For example, I can create a new modeling project add Layer Diagram Add Layer called View Add BL Layer Add DL layer. Then I can validate this architecture as part of the build process when someone tries to check code into TFS. In other words, if the View references the DL then the compilation process will fail and the checkin will not be allowed. For those without an MSDN ultimate license, can FxCop or some 3rd party utility be used to validate architecture in an automated fashion? I prefer a TFS install-able plugin, but a local VS plugin will do.

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• Where to find a mentor?

  - by Fanatic23

  I have been looking around for resources that discuss about mentors, including questions in the stackexchange network. I see that the general response has been to join open source projects and/or check out local user groups if there exists any. Are we sure that joining open source project can get me a mentor? It can grab eyeballs, yes, if the project is exciting enough but a mentor? I am not so sure. What do you guys think? Finally, I'd want my mentor to be in a specific domain as opposed to just being a coding wizard and that makes the search even more difficult. Suggestions?

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• Ways to organize interface and implementation in C++

  - by Felix Dombek

  I've seen that there are several different paradigms in C++ concerning what goes into the header file and what to the cpp file. AFAIK, most people, especially those from a C background, do: foo.h class foo { private: int mem; int bar(); public: foo(); foo(const foo&); foo& operator=(foo); ~foo(); } foo.cpp #include foo.h foo::bar() { return mem; } foo::foo() { mem = 42; } foo::foo(const foo& f) { mem = f.mem; } foo::operator=(foo f) { mem = f.mem; } foo::~foo() {} int main(int argc, char *argv[]) { foo f; } However, my lecturers usually teach C++ to beginners like this: foo.h class foo { private: int mem; int bar() { return mem; } public: foo() { mem = 42; } foo(const foo& f) { mem = f.mem; } foo& operator=(foo f) { mem = f.mem; } ~foo() {} } foo.cpp #include foo.h int main(int argc, char* argv[]) { foo f; } // other global helper functions, DLL exports, and whatnot Originally coming from Java, I have also always stuck to this second way for several reasons, such as that I only have to change something in one place if the interface or method names change, and that I like the different indentation of things in classes when I look at their implementation, and that I find names more readable as foo compared to foo::foo. I want to collect pro's and con's for either way. Maybe there are even still other ways? One disadvantage of my way is of course the need for occasional forward declarations.

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• New vs Clone Git in Eclipse with EGit

  - by Matty F

  I'm not sure I have either my new repo or clone repo workflow, or both, setup correctly. When I create a new project I create a repo on github, can't clone from it as it's empty so I create a new project which goes into my workspace and then the git init runs on the workspace copy. So I end up with everything in workspace\project-name. However, when I clone from github first I need to clone the repo and this goes into my default git directory (C:\git) as git\cloned-project-name, I then need to import this Git repo as a project into my workspace and I end up with workspace\cloned-project-name effectively duplicating the project folder in the git area. I've tried to clone to workspace\cloned-project-name but then it asks to import the git project and if I try to use workspace\cloned-project-name again, it errs. What am I doing wrong? Thanks, Matt.

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• Should programming languages be strict or loose?

  - by Ralph

  In Python and JavaScript, semi-colons are optional. In PHP, quotes around array-keys are optional ($_GET[key] vs $_GET['key']), although if you omit them it will first look for a constant by that name. It also allows 2 different styles for blocks (colon, or brace delimited). I'm creating a programming language now, and I'm trying to decide how strict I should make it. There are a lot of cases where extra characters aren't really necessary and can be unambiguously interpreted due to priorities, but I'm wondering if I should still enforce them or not to encourage good programming habits. What do you think?

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• How much will cost to hire a developer who have to make a SEO software? [closed]

  - by Victor

  Hey guys, I know NOTHING about software developing but I got an amazing idea about a software. The thing is I want to know how much money I would approximately need to hire someone to do it for me. The software is gonna have a lot of features, everything is relative to SEO - link building with Web 2.0 sites, Blog comments, Video Submittion, Bookmarking, RSS, Ping Mode, Forum register and submittion, Proxy mode, ect. The point is to be all automated! I mean all profile creation is going to be automate! There are a lot of softwares but nothing is doing everything that I want. So I would like to build my own software, use it for on my own and of course I'll sell it too! So how much do you think I would need to be able to order such a software?

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• When creating an library published on CodePlex, how "bad" would it be for the unit-test projects to rely on commercial products?

  - by Lasse V. Karlsen

  I have started a project on CodePlex for a WebDAV server implementation for .NET, so that I can host a WebDAV server in my own programs. This is both a learning/research project (WebDAV + server portion) as well as a project I think I can have much fun with, both in terms of making it and using it. However, I see a need to do mocking of types here in order to unit-testing properly. For instance, I will be relying on HttpListener for the web server portion of the WebDAV server, and since this type has no interface, and is sealed, I cannot easily make mocks or stubs out of it. Unless I use something like TypeMock. So if I used TypeMock in the unit-test projects on this library, how bad would this be for potential users? The projects are made in C# 3.5 for .NET 3.5 and 4.0, and the project files was created with Visual Studio 2010 Professional. The actual class libraries you would end up referencing in your software would of course not be encumbered with anything remotely like this, only the unit-test libraries. What's your thoughts on this? As an example, I have in my old code-base, which is private, the ability to just initiate a WebDAV server with just this: var server = new WebDAVServer(); This constructs, and owns, a HttpListener instance internally, and I would like to verify through unit-tests that if I dispose of this server object, the internal listener is disposed of. If, on the other hand, I use the overload where I hand it a listener object, this object should not be disposed of. Short of exposing the internal listener object to the outside world, something I'm a bit loath to do, how can I in a good way ensure that the object was disposed of? With TypeMock I can mock away parts of this object even though it isn't accessed through interfaces. The alternative would be for me to wrap everything in wrapper classes, where I have complete control.

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• Strategy for building an application to replace a large spreadsheet

  - by Dan Walmsley

  I'm working on an application that is going to replace a rather large spreadsheet. The spreadsheet is used to budget purchases and things like that. It is the largest spreadsheet I have ever seen, and it required a lot of manual data entry, so this application is going to automate much of that. But as I'm working on this I've noticed its slow going. And I got to thinking this must be a common thing to do many companies will start with something like a spreadsheet, then when they get too big to maintain that, they will get a custom application built. So is there anything out there ( a framework or similar ) that does this sort of thing, migrating a spreadsheet to a custom application. I've had a quick Google but not really seen the kind of thing that I'm looking for. It's too late for this project, but I thought it would be worth having a look for next time. How do you guys tackle this problem?

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• Can AfferoGPLv3 code be used in GPLv3 code?

  - by Karel Bílek

  Can software with AGPLv3 license be used with GPLv3 project? Can the resulting project be GPLv3, or must it have the special requirements of AGPLv3? I am not very smart from clause 13 of GLPv3 that mentions AGPLv3. Notwithstanding any other provision of this License, you have permission to link or combine any covered work with a work licensed under version 3 of the GNU Affero General Public License into a single combined work, and to convey the resulting work. The terms of this License will continue to apply to the part which is the covered work, but the special requirements of the GNU Affero General Public License, section 13, concerning interaction through a network will apply to the combination as such. Must the resulting, combined work be AGPLv3 or not?

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