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• Formal definition for term "pure OO language"?

  - by Yauhen Yakimovich

  I can't think of a better place among SO siblings to pose such a question. Originally I wanted to ask "Is python a pure OO language?" but considering troubles and some sort of discomfort people experience while trying to define the term I decided to start with obtaining a clear definition for the term itself. It would be rather fair to start with correspondence by Dr. Alan Kay, who has coined the term (note the inspiration in biological analogy to cells or other living objects). There are following ways to approach the task: Give a comparative analysis by listing programming languages that exhibits certain properties unique and sufficient to define the term (although Smalltalk and Java are passing examples but IMO this way seems neither really complete or nor fruitful) Give a formal definition (or close to it, e.g. in more academic or mathematical style). Give a philosophical definition that would totally rely on semantical context of concrete language or a priori programming experience (there must be some chance of successful explanation by the community). My current version: "If a certain programing (formal) language that can (grammatically) differentiate between operations and operands as well as infer about the type of each operand whether this type is an object (in sense of OOP) or not then we call such a language an OO-language as long as there is at least one type in this language which is an object. Finally, if all types of the language are also objects we define such language to be pure OO-language." Would appreciate any possible improvement of it. As you can see I just made the definition dependent on the term "object" (often fully referenced as class of objects).

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• Language parsing to find important words

  - by Matt Huggins

  I'm looking for some input and theory on how to approach a lexical topic. Let's say I have a collection of strings, which may just be one sentence or potentially multiple sentences. I'd like to parse these strings to and rip out the most important words, perhaps with a score that denotes how likely the word is to be important. Let's look at a few examples of what I mean. Example #1: "I really want a Keurig, but I can't afford one!" This is a very basic example, just one sentence. As a human, I can easily see that "Keurig" is the most important word here. Also, "afford" is relatively important, though it's clearly not the primary point of the sentence. The word "I" appears twice, but it is not important at all since it doesn't really tell us any information. I might expect to see a hash of word/scores something like this: "Keurig" => 0.9 "afford" => 0.4 "want" => 0.2 "really" => 0.1 etc... Example #2: "Just had one of the best swimming practices of my life. Hopefully I can maintain my times come the competition. If only I had remembered to take of my non-waterproof watch." This example has multiple sentences, so there will be more important words throughout. Without repeating the point exercise from example #1, I would probably expect to see two or three really important words come out of this: "swimming" (or "swimming practice"), "competition", & "watch" (or "waterproof watch" or "non-waterproof watch" depending on how the hyphen is handled). Given a couple examples like this, how would you go about doing something similar? Are there any existing (open source) libraries or algorithms in programming that already do this?

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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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• What is a business problem?

  - by Juha Untinen

  Can you give an example or two of what a business problem is? I hear this word thrown around a lot, but even after searching, I cannot find a clear answer. Especially when it comes to software development. Are any of these classified as a business problem? Convert invoice from format A to format B Send data from Company A database to Company B database Create a program for time reporting Make the financial software retrieve data faster Generate a weekly data transfer volume statistic Or is a business problem something else?

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• Is it customary to write Java domain objects / data transfer objects with public member variables on mobile platforms?

  - by Sean Mickey

  We performed a code review recently of mobile application Java code that was developed by an outside contractor and noticed that all of the domain objects / data transfer objects are written in this style: public class Category { public String name; public int id; public String description; public int parentId; } public class EmergencyContact { public long id; public RelationshipType relationshipType; public String medicalProviderType; public Contact contact; public String otherPhone; public String notes; public PersonName personName; } Of course, these members are then accessed directly everywhere else in the code. When we asked about this, the developers told us that this is a customary performance enhancement design pattern that is used on mobile platforms, because mobile devices are resource-limited environments. It doesn't seem to make sense; accessing private members via public getters/setters doesn't seem like it could add much overhead. And the added benefits of encapsulation seem to outweigh the benefits of this coding style. Is this generally true? Is this something that is normally done on mobile platforms for the reasons given above? All feedback welcome and appreciated -

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• Do you start migrating your Swing project to JavaFX

  - by Yan Cheng CHEOK

  I have a 4 years old project which is written in Swing + SwingX. Currently, it is still alive and still kicking. However, as more GUI related feature requests coming in (For instance, a sortable tree table), I start to feel the difficulty in fulling the requests. This is true especially there isn't active development going around SwingX project. Also, I hardly can find any good, yet being actively maintained/ developed/ evolving GUI Java framework. I was wondering, any of Swing developers feel the same thing? Have you start to migrate your Swing project to a much more active developed GUI framework like JavaFX?

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• Why does XCode convert PNGs to CgBI format?

  - by Gdeglin

  According to the research done here http://imageoptim.com/tweetbot.html, Xcode's conversion of PNGs to the proprietary Apple CgBI format does not create a noticeable performance improvement. Their claim is that the conversion only reduces PNG loading speed by 1 nanosecond. If this is true, why does apple bother with the CgBI format at all? Has anyone else benchmarked loading CgBI images vs regular PNG images on iOS devices to see if they perform differently?

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• How to fill certain application design learning "gaps"?

  - by e4rthdog

  In life it doesnt matter if you do one thing for 15 years. You will end up waking one day and asking stuff that are equal to "how do i walk?" :) My specific question is that as a new entrant to C# and OOP i am stepping into many little "details" that need to be addressed. Written a lot of code in VB.NET / cobol / simple php e.t.c surely does not help much into the OOP world... So , even after reading entry level books for C# and watching some videos i recently found out about the "factory model design" for applications. I would appreciate if any of you guys recomment some reading on application design architecture for further reading...

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• Explanation of the definition of interface inheritance as described in GoF book

  - by Geek

  I am reading the first chapter of the Gof book. Section 1.6 discusses about class vs interface inheritance: Class versus Interface Inheritance It's important to understand the difference between an object's class and its type. An object's class defines how the object is implemented.The class defines the object's internal state and the implementation of its operations.In contrast,an object's type only refers to its interface--the set of requests on which it can respond. An object can have many types, and objects of different classes can have the same type. Of course, there's a close relationship between class and type. Because a class defines the operations an object can perform, it also defines the object's type . When we say that an object is an instance of a class, we imply that the object supports the interface defined by the class. Languages like c++ and Eiffel use classes to specify both an object's type and its implementation. Smalltalk programs do not declare the types of variables; consequently,the compiler does not check that the types of objects assigned to a variable are subtypes of the variable's type. Sending a message requires checking that the class of the receiver implements the message, but it doesn't require checking that the receiver is an instance of a particular class. It's also important to understand the difference between class inheritance and interface inheritance (or subtyping). Class inheritance defines an object's implementation in terms of another object's implementation. In short, it's a mechanism for code and representation sharing. In contrast,interface inheritance(or subtyping) describes when an object can be used in place of another. I am familiar with the Java and JavaScript programming language and not really familiar with either C++ or Smalltalk or Eiffel as mentioned here. So I am trying to map the concepts discussed here to Java's way of doing classes, inheritance and interfaces. This is how I think of of these concepts in Java: In Java a class is always a blueprint for the objects it produces and what interface(as in "set of all possible requests that the object can respond to") an object of that class possess is defined during compilation stage only because the class of the object would have implemented those interfaces. The requests that an object of that class can respond to is the set of all the methods that are in the class(including those implemented for the interfaces that this class implements). My specific questions are: Am I right in saying that Java's way is more similar to C++ as described in the third paragraph. I do not understand what is meant by interface inheritance in the last paragraph. In Java interface inheritance is one interface extending from another interface. But I think the word interface has some other overloaded meaning here. Can some one provide an example in Java of what is meant by interface inheritance here so that I understand it better?

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• Class Design for special business rules

  - by Samuel Front

  I'm developing an application that allows people to place custom manufacturing orders. However, while most require similar paperwork, some of them have custom paperwork that only they require. My current class design has a Manufacturer class, of which of one of the member variables is an array of RequiredSubmission objects. However, there are two issues that I am somewhat concerned about. First, some manufacturers are willing to accept either a standard form or their own custom form. I'm thinking of storing this in the RequiredSubmission object, with an array of alternate forms that are a valid substitute. I'm not sure that this is ideal, however. The major issue, however, is that some manufacturers have deadline cycles. For example, forms A, B and C have to be delivered by January 1, while payment must be rendered by January 10. If you miss those, you'll have to wait until the next cycle. I'm not exactly sure how I can get this to work with my existing classes—how can I say "this set of dates all belong to the same cycle, with date A for form A, date B for form B, etc." I would greatly appreciate any insights on how to best design these classes.

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• Working with CPU cycles in Gameboy Advance

  - by Preston Sexton

  I am working on an GBA emulator and stuck at implementing CPU cycles. I just know the basic knowledge about it, each instruction of ARM and THUMB mode as each different set of cycles for each instructions. Currently I am simply saying every ARM instructions cost 4 cycles and THUMB instructions cost 2 cycles. But how do you implement it like the CPU documentation says? Does instruction cycles vary depending on which section of the memory it's currently accessing to? http://nocash.emubase.de/gbatek.htm#cpuinstructioncycletimes According to the above specification, it says different memory areas have different waitstates but I don't know what it exactly mean. Furthermore, what are Non-sequential cycle, Sequential cycle, Internal Cycle, Coprocessor Cycle for? I saw in some GBA source code that they are using PC to figure out how many cycles each instruction takes to complete, but how are they doing it?

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• Advantages of Hudson and Sonar over manual process or homegrown scripts.

  - by Tom G

  My coworker and I recently got into a debate over a proposed plan at our workplace. We've more or less finished transitioning our Java codebase into one managed and built with Maven. Now, I'd like for us to integrate with Hudson and Sonar or something similar. My reasons for this are that it'll provide a 'zero-click' build step to provide testers with new experimental builds, that it will let us deploy applications to a server more easily, that tools such as Sonar will provide us with well-needed metrics on code coverage, Javadoc, package dependencies and the like. He thinks that the overhead of getting up to speed with two new frameworks is unacceptable, and that we should simply double down on documentation and create our own scripts for deployment. Since we plan on some aggressive rewrites to pay down the technical debt previous developers incurred (gratuitous use of Java's Serializable interface as a file storage mechanism that has predictably bit us in the ass) he argues that we can document as we go, and that we'll end up changing a large swath of code in the process anyways. I contend that having accurate metrics that Sonar (or fill in your favorite similar tool) provide gives us a good place to start for any refactoring efforts, not to mention general maintenance -- after all, knowing which classes are the most poorly documented, even if it's just a starting point, is better than seat-of-the-pants guessing. Am I wrong, and trying to introduce more overhead than we really need? Some more background: an alumni of our company is working at a Navy research lab now and suggested these two tools in particular as one they've had great success with using. My coworker and I have also had our share of friendly disagreements before -- he's more of the "CLI for all, compiles Gentoo in his spare time and uses Git" and I'm more of a "Give me an intuitive GUI, plays with XNA and is fine with SVN" type, so there's definitely some element of culture clash here.

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• Software Tester to Developer [closed]

  - by Mayu Mayooresan

  Possible Duplicate: How do I become a developer? Its not a question related to programming but related to career. Last 2 and half year I've been working as a Software Tester and i'm seriously considering a track change to programmer. but the problems I think of is.. 1. My age (28) 2. My IT experience with Testing 3. Salary wont match if I change the track as I have to start from scrach. Wot do you think guys?? Please advice me. Is it better to change track or stay in Tester job?? I think I dont seem to like tester job. Please advice. Thanks in advance.

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• How to keep AST for feature access?

  - by greenoldman

  Consider such code (let's say it is C++) Foo::Bar.get().X How one should keep the AST for this -- as "tree" with root at left Foo(Bar(get(X)), or with root at right (((Foo)Bar)get)X? Or maybe as a flat structure (list)? The first one seems more convenient when resolving names, the second when working with it as expression. I set tag parsing but I am asking from semantic analysis POV really (there is no such tag).

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• String patterns that can be used to filter and group files

  - by Louis Rhys

  One of our application filters files in certain directory, extract some data from it and export a document from the extracted data. The algorithm for extracting the data depends on the file, and so far we use regex to select the algorithm to be used, for example .*\.txt will be processed by algorithm A, foo[0-5]\.xml will be processed by algo B, etc. However now we need some files to be processed together. For example, in one case we need two files, foo.*\.xml and bar.*\.xml. Part of the information to be extracted exist in the foo file, and the other part in the bar file. Moreover, we need to make sure the wild card is compatible. For example, if there are 6 files foo1.xml foo23.xml bar1.xml bar9.xml bar23.xml foo4.xml I would expect foo1 and bar1 to be identified as a group, and foo23 and bar23 as another group. bar9 and foo4 has no pair, so they will not be treated. Now, since the filter is configured by user, we need to have a pattern that can express the above requirement. I don't think you can express meaning like above in standard regex. (foo|bar).*\.xml will match all 6 file above and we can't identify which file is paired for a particular file. Is there any standard pattern that can express it? Or any idea how to modify regex to support this, that can be implemented easily?

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• How to import ejb project classes into web project on eclipse?

  - by Jhonnytunes

  I have 3 projects on eclipse, maven ejb project, maven wicket webapp project and a enterprise application project that includes ejb and web I mentioned before, as modules. But my question is, How from my web project can I use classes on the ejb project. Lets say ClassA is on the ejb project and I want to say from web project: ClassA cl = new ClassA. I wont be allowed since web project doesnt have ClassA but ejb project. I want to use ejb project as a Business Logic, JPA part. Also I want to include here some not beans classes that I want to use from the web. Dont know if its possible. The web project goes without Business logic, just the wicket pages calling ejb, and using ther classes. Im new in the EE world. Never made an ear file including a war and ejb jar for deploying it on Glassfish. Thanks in advanced.

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• Composite-like pattern and SRP violation

  - by jimmy_keen

  Recently I've noticed myself implementing pattern similar to the one described below. Starting with interface: public interface IUserProvider { User GetUser(UserData data); } GetUser method's pure job is to somehow return user (that would be an operation speaking in composite terms). There might be many implementations of IUserProvider, which all do the same thing - return user basing on input data. It doesn't really matter, as they are only leaves in composite terms and that's fairly simple. Now, my leaves are used by one own them all composite class, which at the moment follows this implementation: public interface IUserProviderComposite : IUserProvider { void RegisterProvider(Predicate<UserData> predicate, IUserProvider provider); } public class UserProviderComposite : IUserProviderComposite { public User GetUser(SomeUserData data) ... public void RegisterProvider(Predicate<UserData> predicate, IUserProvider provider) ... } Idea behind UserProviderComposite is simple. You register providers, and this class acts as a reusable entry-point. When calling GetUser, it will use whatever registered provider matches predicate for requested user data (if that helps, it stores key-value map of predicates and providers internally). Now, what confuses me is whether RegisterProvider method (brings to mind composite's add operation) should be a part of that class. It kind of expands its responsibilities from providing user to also managing providers collection. As far as my understanding goes, this violates Single Responsibility Principle... or am I wrong here? I thought about extracting register part into separate entity and inject it to the composite. As long as it looks decent on paper (in terms of SRP), it feels bit awkward because: I would be essentially injecting Dictionary (or other key-value map) ...or silly wrapper around it, doing nothing more than adding entires This won't be following composite anymore (as add won't be part of composite) What exactly is the presented pattern called? Composite felt natural to compare it with, but I realize it's not exactly the one however nothing else rings any bells. Which approach would you take - stick with SRP or stick with "composite"/pattern? Or is the design here flawed and given the problem this can be done in a better way?

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• Does it help to be core programmer of a product (meant for social good) for getting into a PhD program at a top university?

  - by Maddy.Shik

  Hey i am working upon a product as core developer which will be launched in USA market in few months if successful. Can this factor improve my chances for getting accepted into a PhD program at a top university (say top 20 in US)? Normally good universities like CMU, Standford, MIT, Cornell are more interested in student's profile like research work, undergraduate school, etc. I am now passed out from very good university it's ranked in top 20 of India only. Neither did I do research work till now. But being one of founding member of company and developing product for same, I want to know if this factor can help and to what extent.

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• What to do when a project is too difficult to continue developing?

  - by MaxWell

  As a developer, can you tell your project manager that an application is unworkable? Or, if you're a project manager, how would you need this presented to you in order to be compelled? This isn't about "how to work on a poor project", it's assuming you cannot. I can provide an example of the situation if anyone thinks it's important, but I'm trying to avoid proposed solutions to "plodding through".

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• Experience of Python's “PEP-302 New Import Hooks”

  - by Koichi Sasada

  I'm one of the developers of Ruby (CRuby). We are working on Ruby 2.0 release (planned to release 2012/Feb). Python has "PEP302: New Import Hooks" (2003): This PEP proposes to add a new set of import hooks that offer better customization of the Python import mechanism. Contrary to the current import hook, a new-style hook can be injected into the existing scheme, allowing for a finer grained control of how modules are found and how they are loaded. We are considering introducing a feature similar to PEP302 into Ruby 2.0 (CRuby 2.0). I want to make a proposal which can persuade Matz. Currently, CRuby can load scripts from only file systems in a standard way. If you have any experience or consideration about PEP 302, please share. Example: It's a great spec. No need to change it. It is almost good, but it has this problem... If I could go back to 2003, then I would change the spec to... I'm sorry if such a question is not suitable for here. I posted here because I'm not sure that I can ask this question at python-dev (of course, the list is not for cruby development). This post is moved from http://stackoverflow.com/questions/11188229/experience-of-pythons-pep-302-new-import-hooks.

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• OpenGL CPU vs. GPU

  - by Nitrex88

  So I've always been under the impression that doing work on the GPU is always faster than on the CPU. Because of this, in OpenGL, I usually try to do intensive tasks in shaders so they get the speed boost from the GPU. However, now I'm starting to realize that some things simply work better on the CPU and actually perform worse on the GPU (particularly when a geometry shader is involved). For example, in a recent project I did involving procedurally generated terrain, I tried passing a grid of single triangles into a geometry shader, and tesselated each of these triangles into quads with 400 vertices whose height was determined by a noise function. This worked fine, and looked great, but easily maxed out the GPU with only 25 base triangles and caused a very slow framerate. I then discovered that tesselating on the CPU instead, and setting the height (using noise function) in the vertex shader was actually faster! This prompted me to question the benefits of using the GPU as much as possible... So, I was wondering if someone could describe the general pros and cons of using the GPU vs CPU for intensive graphics tasks. I know this mainly comes down to what your trying to achieve, so if necessary, use the above scenario to discuss why the "CPU + vertex shader" was actually faster than doing everything in the geometry shader on the GPU. It's possible my hardware (newest macbook pro) isn't optomized well for the geometry shader (thus causing the slow framerate). Also, I read that the vertex shader is very good with parallelism, and would love a quick explanation of how this may have played a role in speeding up my procedural terrain. Any info/advice about CPU/GPU/shaders would be awesome!

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• Modern.IE VM license

  - by Thomas W.

  Microsoft provides some VMs for testing purposes (advertised on StackOverflow) and I'm trying to understand the license terms. The one I don't really understand is 1.b. You may use the software for testing purposes only. You may not use the software for commercial purposes. My thoughts: a) Testing a website in several browsers on several different virtual machines seems a quite professional approach. I hardly believe many private developers would do that. Of course they should, but which private developer has the time to do so? b) If that's really only available to private developers, what is the offer to companies doing the same thing? I am missing the advertisement for a paid service. My question as a non-native English speaker: Is testing by a company considered as a commercial purpose? Can I use the VMs within a company for testing or not?

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• Should I ditch AJAX in client side web development when I've got a web-socket open?

  - by jt0dd

  I was thinking that maybe I should forget AJAX (HTTP) requests when I've got a web-socket open between client and server, but I decided I should ask here to check if this could be a bad practice for some reason that I'm not thinking of. Once the socket is open, there's less syntax (often meaning simpler error handling) involved in passing information between client and server with Socket.io (just one example of a web-socket). Is there some obvious situation where a web-socket (Socket.io for example) isn't going to be capable of handling a functionality that an AJAX request could do easily?

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• Grid framework for CSS

  - by akp

  I see there are large number of grid frameworks in CSS like 960, heroku grid, etc being used by huge websites. I want to know whether using grid structure is really useful? If yes, then how? One of the biggest problem I saw with grid is having equal heights for elements. If we are using three grids like grid_2, grid_7, grid_3 for 3 vertical panels then it becomes very difficult to have these three panels positioned in a way such that they have equal heights and all of them change height when any of the content exapnds or collapse. This is because elements are floated in grid system and they don't change height along with neighbouring element.

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• Are SQL Injection vulnerabilities in a PHP application acceptable if mod_security is enabled?

  - by Austin Smith

  I've been asked to audit a PHP application. No framework, no router, no model. Pure PHP. Few shared functions. HTML, CSS, and JS all mixed together. I've discovered numerous places where SQL injection would be easily possible. There are other problems with the application (XSS vulnerabilities, rampant inline CSS, code copy-pasted everywhere) but this is the biggest. Sometimes they escape inputs, not using a prepared query or even mysql_real_escape_string(), mind you, but using addslashes(). Often, though, their queries look exactly like this (pasted from their code but with columns and variable names changed): $user = mysql_query("select * from profile where profile_id='".$_REQUEST["profile_id"]."'"); The developers in question claimed that they were unable to hack their application. I tried, and found mod_security to be enabled, resulting in HTTP 406 for some obvious SQL injection attacks. I believe there to be sophisticated workarounds for mod_security, but I don't have time to chase them down. They claim that this is a "conceptual" matter and not a "practical" one since the application can't easily be hacked. Their internal auditor agreed that there were problems, but emphasized the conceptual nature of the issues. They also use this conceptual/practical argument to defend against inline CSS and JS, absence of code organization, XSS vulnerabilities, and massive amounts of repetition. My client (rightly so, perhaps) just wants this to go away so they can launch their product. The site works. You can log in, do what you need to do, and things are visibly functional, if slow. SQL Injection would indeed be hard to do, given mod_security. Further, their talk of "conceptual vs. practical" is rhetorically brilliant, considering that my client doesn't understand web application security. I worry that they've succeeded in making me sound like an angry puritan. In many ways, this is a problem of politics, not technology, but I am at a loss. As a developer, I want to tell them to toss the whole project and start over with a new team, but I face a strong defense from the team that built it and a client who really needs to ship their product. Is my position here too harsh? Even if they fix the SQL Injection and XSS problems can I ever endorse the release of an unmaintainable tangle of spaghetti code?

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