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  • Naming a class that processes orders

    - by p.campbell
    I'm in the midst of refactoring a project. I've recently read Clean Code, and want to heed some of the advice within, with particular interest in Single Responsibility Principle (SRP). Currently, there's a class called OrderProcessor in the context of a manufacturing product order system. This class is currently performs the following routine every n minutes: check database for newly submitted + unprocessed orders (via a Data Layer class already, phew!) gather all the details of the orders mark them as in-process iterate through each to: perform some integrity checking call a web service on a 3rd party system to place the order check status return value of the web service for success/fail email somebody if web service returns fail constantly log to a text file on each operation or possible fail point I've started by breaking out this class into new classes like: OrderService - poor name. This is the one that wakes up every n minutes OrderGatherer - calls the DL to get the order from the database OrderIterator (? seems too forced or poorly named) - OrderPlacer - calls web service to place the order EmailSender Logger I'm struggling to find good names for each class, and implementing SRP in a reasonable way. How could this class be separated into new class with discrete responsibilities?

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  • How do you save/export changes made in Firebug?

    - by blunders
    Using Firebug to edit CSS, how do I save/export changes made to the CSS? TOOLS: Firefox, Firebug MAJOR UPDATE: If you know of a way to lock the forward/back/refresh on a FireFox tab, please let me know. Otherwise, I've given up on using FireBug/FireDiff as an IDE for CSS, it's nice, but lol... press backspace at the wrong time and ALL your work is gone... funny. So, really like the browser highlighting to CSS/HTML in Firebug. Know any good CSS editors that do this? Really had hope FireBug would work, but for now only see it as being good for ad-hoc inspection and test; meaning using it for what it's made for. UPDATES: @Lèse majesté: Just as an update, "Web Developer add-on" does let you edit CSS, but it does not let you edit/save CSS changes made by Firebug. Meaning you use Firebug to ID and maybe test changes, but it does not let you save the changes from Firebug. Here's a "how to" covering how to use them together: FF + FB + WD @Lèse majesté: Still playing around with FireDiff. It works okay, found one bug already (although I'm just working around it), and there's no "how to" I've been able to find, so I'm just trying every feature and clicking around... (for example, to export a diff you must be over the last item in the list, right click, and select as "Save Diff". The ".diff" is just a text file, no idea why at this point the ext is .diff.

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  • How to verify the Liskov substitution principle in an inheritance hierarchy?

    - by Songo
    Inspired by this answer: Liskov Substitution Principle requires that Preconditions cannot be strengthened in a subtype. Postconditions cannot be weakened in a subtype. Invariants of the supertype must be preserved in a subtype. History constraint (the "history rule"). Objects are regarded as being modifiable only through their methods (encapsulation). Since subtypes may introduce methods that are not present in the supertype, the introduction of these methods may allow state changes in the subtype that are not permissible in the supertype. The history constraint prohibits this. I was hoping if someone would post a class hierarchy that violates these 4 points and how to solve them accordingly. I'm looking for an elaborate explanation for educational purposes on how to identify each of the 4 points in the hierarchy and the best way to fix it. Note: I was hoping to post a code sample for people to work on, but the question itself is about how to identify the faulty hierarchies :)

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  • Designing exceptions for conversion failures

    - by Mr.C64
    Suppose there are some methods to convert from "X" to "Y" and vice versa; the conversion may fail in some cases, and exceptions are used to signal conversion errors in those cases. Which would be the best option for defining exception classes in this context? A single XYConversionException class, with an attribute (e.g. an enum) specifying the direction of the conversion (e.g. ConversionFromXToY, ConversionFromYToX). A XYConversionException class, with two derived classes ConversionFromXToYException and ConversionFromYToXException. ConversionFromXToYException and ConversionFromYToXException classes without a common base class.

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  • Is it a good approach to rely on 3rd party software ( not library )?

    - by gunbuster363
    We have program using a call to a winzip program or 7zip commandline tool to zip some files. Once I accidentally uninstall winzip on my computer and making one of our program( created by the programmer already left ) crashed. So we cannot uninstall the winzip program. Now I've come to a point which I need to decide a external tool for gzip in windows or I make a java program which I can call to gzip the file. Obviously a external tool such as 7z is convenient and we can avoid some extra coding with java. On the contrary, if 7z is uninstalled accidentally, our program will crash. What do you think?

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  • Service Layer - how broad should it be, and should it also be on the local application?

    - by BornToCode
    Background: I need to build a desktop application with some operations (CRUD and more) (=winforms), I need to make another application which will re-use some of the functions of the main application (=webforms). I understood that using service layer is the best approach here. If I understood correctly the service should be calling the function on the BL layer (correct me if I'm wrong) The dilemma: In my main winform UI - should I call the functions from the BL, or from the service? (please explain why) Should I create a service for every single function on the BL even if I need some of the functions only in one UI? for example - should I create services for all the CRUD operations, even though I need to re-use only update operation in the webform? YOUR HELP IS MUCH APPRECIATED

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  • share distribution question

    - by facebook-100000781341887
    Hi, I just developed a facebook game(mifia like), but the graphic I make is not good, because it is reference with some existing photo, trace with AI, and coloring it. Therefore, I invite my friend to join me, he is a graphic designer, own a company with his friend (I know both of them), for the share, I expect at least 70% for me, and at most 30% for them (both of them want to join). Therefore, they give me a counter offer, 60% for me and 40% for them, of course, I feel their counter offer is unacceptable because they only build the image in part time, and all the other work just like coding, webhosting...etc, is what I do in full time. Why they said they worth 40% is that they will make a good graphic, they can provide a advertise channel(on local magazine), etc... Actually, I don't think the game need advertisement on local magazine because the game is not target for local... Please give me some comments on this issue(is the share fair? what is the importance of the image of the game, is it worth more than 30%), or can anyone share the experience on this. Thanks in advance.

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  • Truly useful UML diagrams

    - by eversor
    UML has a jungle of Diagrams. Profile Diagrams, Class Diagrams, Package Diagrams... However, (IMH-and-not-too-experienced-O) I quite see that doing each and every diagram is overkill. Therefore, which UML Diagrams are more suitable in a web context, more expecificly a blog (we want to build it from scratchs). I understand that just because I used UML Diagrams does not imply that our code would be great and brilliant... but, it certainly would be better than just unplanified code...

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  • Why do old programming languages continue to be revised?

    - by SunAvatar
    This question is not, "Why do people still use old programming languages?" I understand that quite well. In fact the two programming languages I know best are C and Scheme, both of which date back to the 70s. Recently I was reading about the changes in C99 and C11 versus C89 (which seems to still be the most-used version of C in practice and the version I learned from K&R). Looking around, it seems like every programming language in heavy use gets a new specification at least once per decade or so. Even Fortran is still getting new revisions, despite the fact that most people using it are still using FORTRAN 77. Contrast this with the approach of, say, the typesetting system TeX. In 1989, with the release of TeX 3.0, Donald Knuth declared that TeX was feature-complete and future releases would contain only bug fixes. Even beyond this, he has stated that upon his death, "all remaining bugs will become features" and absolutely no further updates will be made. Others are free to fork TeX and have done so, but the resulting systems are renamed to indicate that they are different from the official TeX. This is not because Knuth thinks TeX is perfect, but because he understands the value of a stable, predictable system that will do the same thing in fifty years that it does now. Why do most programming language designers not follow the same principle? Of course, when a language is relatively new, it makes sense that it will go through a period of rapid change before settling down. And no one can really object to minor changes that don't do much more than codify existing pseudo-standards or correct unintended readings. But when a language still seems to need improvement after ten or twenty years, why not just fork it or start over, rather than try to change what is already in use? If some people really want to do object-oriented programming in Fortran, why not create "Objective Fortran" for that purpose, and leave Fortran itself alone? I suppose one could say that, regardless of future revisions, C89 is already a standard and nothing stops people from continuing to use it. This is sort of true, but connotations do have consequences. GCC will, in pedantic mode, warn about syntax that is either deprecated or has a subtly different meaning in C99, which means C89 programmers can't just totally ignore the new standard. So there must be some benefit in C99 that is sufficient to impose this overhead on everyone who uses the language. This is a real question, not an invitation to argue. Obviously I do have an opinion on this, but at the moment I'm just trying to understand why this isn't just how things are done already. I suppose the question is: What are the (real or perceived) advantages of updating a language standard, as opposed to creating a new language based on the old?

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  • Should I close database connections after use in PHP?

    - by Sprottenwels
    I wonder if I should close any unnecessary database connection inside of my PHP scripts. I am aware of the fact that database connections are closed implicitly when the block stops executing and 'manually' closing the connections could kinda bloat the codebase with unnecessary code. But shouldn't I do so in order to make by code as readable and as easy understandable as possible, while also preventing several possible issues during run time? Also, if I would do, would it be enough to unset() my database object?

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  • I need an approach to the problem of preventing inserting duplicate records into the database

    - by Maurice
    Apologies is this question is asked on the incorrect "stack" A webservice that I call returns a list of data. The data from the webservice is updated periodically, so a call to the webservice done in one hour could return the same data as a call done in an hour. Also, the data is returned based on a start and end date. We have multiple users that can run the webservice search, and duplicate data is most likely to be returned (especially for historical data). However I don't want to insert this duplicate data in the database. I've created a db table in which the data is stored (most important columns are) Id int autoincrement PK Date date not null --The date to which the data set belongs. LastUpdate date not null --The date the data set was last updated. UserName varchar(50) --The name of the user doing the search. I use sql server 2008 express with c# 4.0 and visual studio 2010. Entity Framework is used as the ORM. If stored procedures could be avoided in the proposed solution, then that will be a plus. Another way of looking interpreting what I'm asking a solution for is as follows: I have a million unique records in my table. A user does a new search. The search results from the user contains around 300k of the data that is already in the db. An efficient solution to finding an inserting only the unique records is needed.

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  • two-part dice pool mechanic

    - by bythenumbers
    I'm working on a dice mechanic/resolution system based off of the Ghost/Echo (hereafter shortened to G/E) tabletop RPG. Specifically, since G/E can be a little harsh with dealing out consequences and failure, I was hoping to soften the system and add a little more player control, as well as offer the chance for players to evolve their characters into something unique, right from creation. So, here's the mechanic: Players roll 2d12 against the two statistics for their character (each is a number from 2-11, and may be rolled above or below depending on the nature of the action attempted, rolling your stat exactly always fails). Depending on the success for that roll, they add dice to the pool rolled for a modified G/E style action. The acting player gets two dice anyhow, and I am debating offering a bonus die for each success, or a single bonus die for succeeding on both of the statistic-compared rolls. One the size of the dice pool is set, the entire pool is rolled, and the players are allowed to assign rolled dice to a goal and a danger. Assigned results are judged as follows: 1-4 means the attempted goal fails, or the danger comes true. 5-8 is a partial success at the goal, or partially avoiding the danger. 9-12 means the goal is achieved, or the danger avoided. My concerns are twofold: Firstly, that the two-stage action is too complicated, with two rolls to judge separately before anything can happen. Secondly, that the statistics involved go too far in softening the game. I've run some basic simulations, and the approximate statistics follow: 2 dice (up to) 3 dice (up to) 4 dice failure ~33% ~25% ~20% partial ~33% ~35% ~35% success ~33% ~40% ~45% I'd appreciate any advice that addresses my concerns or offers to refine my simulation (right now the first roll is statistically modeled as sign(1d12-1d12), where 0 is a success).

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  • How to fix this navigation issue in my site?

    - by David
    First off I use webs.com for the creation of my site. I have a very basic layout. List of links of the left and content on the right with a heading up top. Now in my list of links every link is an article that I wrote, I have about 25 links going down the left hand side of my site. Problem is when I try out new themes that support horizontal navigation as opposed to vertical navigation I get either a messy overflow of links Or a link called "more" which lists the rest of the articles in a drop down-list across my site. What I wish I had was a simple horizontal navigation like" "home, about, articles" and when the user clicks on articles it would then bring them to a page containing all my articles there. I would prefer it to be in a table like display. That way is not a long list. Anyways any ideas on how I can fix this issue im having? Please let me know if you need more information.

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  • Expiring timed actions a good idea?

    - by Bart van Heukelom
    We have an online game where players sometimes have to wait a while (say 30 minutes) before a process they intiated completes. This encourages them to come back later. An example of this is growing crops in Farmville or basically any action in the Sims Play4Free. Now, however, there is the idea to let these processes expire, so if the player doesn't 'reap' them in time (e.g. within 4 hours) they are aborted. I'm a bit sceptical about this. How will this make players come back more often? Is not the reward of reaping the process enough for that? Can we expect players to fit their daily schedule around our game, maybe even set the alarm clock at night? Won't this just cause players to give up on starting these processes in the first place? I realise this may be too subjective for this site, so I'll end with a concrete question: Do (m)any other online free-to-play games employ this technique?

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  • How were some language communities (eg, Ruby and Python) able to prevent fragmentation while others (eg, Lisp or ML) were not?

    - by chrisaycock
    The term "Lisp" (or "Lisp-like") is an umbrella for lots of different languages, such as Common Lisp, Scheme, and Arc. There is similar fragmentation is other language communities, like in ML. However, Ruby and Python have both managed to avoid this fate, where innovation occurred more on the implementation (like PyPy or YARV) instead of making changes to the language itself. Did the Ruby and Python communities do something special to prevent language fragmentation?

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  • How to make an Actor follow my finger

    - by user48352
    I'm back with another question that may be really simple. I've a texture drawn on my spritebatch and I'm making it move up or down (y-axis only) with Libgdx's Input Handler: touchDown and touchUp. @Override public boolean touchDown(int screenX, int screenY, int pointer, int button) { myWhale.touchDownY = screenY; myWhale.isTouched = true; return true; } @Override public boolean touchUp(int screenX, int screenY, int pointer, int button) { myWhale.isTouched = false; return false; } myWhale is an object from Whale Class where I move my texture position: public void update(float delta) { this.delta = delta; if(isTouched){ dragWhale(); } } public void dragWhale() { if(Gdx.input.getY(0) - touchDownY < 0){ if(Gdx.input.getY(0)<position.y+height/2){ position.y = position.y - velocidad*delta; } } else{ if(Gdx.input.getY(0)>position.y+height/2){ position.y = position.y + velocidad*delta; } } } So the object moves to the center of the position where the person is pressing his/her finger and most of the time it works fine but the object seems to take about half a second to move up or down and sometimes when I press my finger it wont move. Maybe there's another simplier way to do this. I'd highly appreciate if someone points me on the right direction.

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  • How common are circular references? Would reference-counting GC work just fine?

    - by user9521
    How common are circular references? The less common they are, the fewer hard cases you have if you are writing in a language with only reference counting-GC. Are there any cases where it wouldn't work well to make one of the references a "weak" reference so that reference counting still works? It seems like you should be able to have a language only use reference counting and weak references and have things work just fine most of the time, with the goal of efficiency. You could also have tools to help you detect memory leaks caused by circular references. Thoughts, anyone? It seems that Python uses references counting (I don't know if it uses a tracing collector occasionally or not for sure) and I know that Vala uses reference counting with weak references; I know that it's been done before, but how well would it work?

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  • Options for Application Registry

    - by Matt Felzani
    I work for a small software company (about 200 people building 8-10 applications) and I was hoping to get some advice on products that might be out there to manage the information of which clients are using which versions of our products? The most fundamental relationship would be that a "product" has "versions" and a given "version" is used by a "client." Uses would be: Determine which clients use which products Determine which clients are on which versions of a product Determine which clients are exposed to which vulnerabilities because of the version they use Determine which clients cannot move to a new version because of a vulnerability in the new version that they may hit Determine which clients should be approached for an upgrade Any thoughts or product reviews would be greatly appreciated! Thanks in advance.

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  • Preferred lambda syntax?

    - by Roger Alsing
    I'm playing around a bit with my own C like DSL grammar and would like some oppinions. I've reserved the use of "(...)" for invocations. eg: foo(1,2); My grammar supports "trailing closures" , pretty much like Ruby's blocks that can be passed as the last argument of an invocation. Currently my grammar support trailing closures like this: foo(1,2) { //parameterless closure passed as the last argument to foo } or foo(1,2) [x] { //closure with one argument (x) passed as the last argument to foo print (x); } The reason why I use [args] instead of (args) is that (args) is ambigious: foo(1,2) (x) { } There is no way in this case to tell if foo expects 3 arguments (int,int,closure(x)) or if foo expects 2 arguments and returns a closure with one argument(int,int) - closure(x) So thats pretty much the reason why I use [] as for now. I could change this to something like: foo(1,2) : (x) { } or foo(1,2) (x) -> { } So the actual question is, what do you think looks best? [...] is somewhat wrist unfriendly. let x = [a,b] { } Ideas?

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  • Provide an OnChange event for an internal property which is controlled externally?

    - by NGLN
    For fun and by request I am updating this ImageGrid component, a kind of listbox for images that has a FileNames property of type TStrings. For ease of writing, I have been misusing its FileNames.Objects property for bitmap storage. But since the TStrings type suggests that users of the component could or would want to use the Objects property for custom data, e.g. like TListBox.Items, I am rewriting the component to store the bitmaps elsewhere and leave FileNames.Objects untouched for unknown future usage. Now I am wondering whether to provide an OnChange event. And if so, whether to fire it when one or more FileNames.Objects changes. Trying to answer it myself, I dove in Delphi's own VCL and stumbled on: TMemo: has an OnChange event, but ignores Lines.Objects TListBox: has no OnChange event, but is capable of storing Items.Objects TStringGrid: has no OnChange event, but is capable of storing Objects, Rows.Objects, Cols.Objects So now I am somewhat puzzeled, because I cannot imagine Borland's developers didn't add events for several Objects properties out of ease. Sure, when a user changes a FileNames.Object in my component, he knows he does and could implement appropriate interaction himself. But wouldn't it be convenient when the component does automatically? What would you expect from this component in this regard?

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  • Procedural object generation and unique identification

    - by 2080
    My question relates to procedural content generation and data management of the emerging objects in a database. I assume a networked game, with a server-client model. Unspecified objects in the game world are generated while the game is running with procedural algorithms (for example perlin noise). The players (/clients) can modify the properties of these objects, but have to notify the server of these changes. How could this communication address unique objects, so that both the server and the client know of which object they are speaking? Not only the inner properties of the objects can differ, but also visible, such as the position. When the player wants to select one of these objects the game has to find out the id - does anyone know which methods or algorithms can accomplish that?

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  • Is premature optimization really the root of all evil?

    - by Craig Day
    A colleague of mine today committed a class called ThreadLocalFormat, which basically moved instances of Java Format classes into a thread local, since they are not thread safe and "relatively expensive" to create. I wrote a quick test and calculated that I could create 200,000 instances a second, asked him was he creating that many, to which he answered "nowhere near that many". He's a great programmer and everyone on the team is highly skilled so we have no problem understanding the resulting code, but it was clearly a case of optimizing where there is no real need. He backed the code out at my request. What do you think? Is this a case of "premature optimization" and how bad is it really?

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  • Why don't languages include implication as a logical operator?

    - by Maciej Piechotka
    It might be a strange question, but why there is no implication as a logical operator in many languages (Java, C, C++, Python Haskell - although as last one have user defined operators its trivial to add it)? I find logical implication much clearer to write (particularly in asserts or assert-like expressions) then negation with or: encrypt(buf, key, mode, iv = null) { assert (mode != ECB --> iv != null); assert (mode == ECB || iv != null); assert (implies(mode != ECB, iv != null)); // User-defined function }

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  • Nested Entities and calculation on leaf entity property - SQL or NoSQL approach

    - by Chandu
    I am working on a hobby project called Menu/Recipe Management. This is how my entities and their relations look like. A Nutrient has properties Code and Value An Ingredient has a collection of Nutrients A Recipe has a Collection of Ingredients and occasionally can have a collection of other recipes A Meal has a Collection of Recipes and Ingredients A Menu has a Collection of Meals The relations can be depicted as In one of the pages, for a selected menu I need to display the effective nutrients information calculated based on its constituents (Meals, Recipes, Ingredients and the corresponding nutrients). As of now am using SQL Server to store the data and I am navigating the chain from my C# code, starting from each meal of the menu and then aggregating the nutrient values. I think this is not an efficient way as this calculation is being done every time the page is requested and the constituents change occasionally. I was thinking about a having a background service that maintains a table called MenuNutrients ({MenuId, NutrientId, Value}) and will populate/update this table with the effective nutrients when any of the component (Meal, Recipe, Ingredient) changes. I feel that a GraphDB would be a good fit for this requirement, but my exposure to NoSQL is limited. I want to know what are the alternative solutions/approaches to this requirement of displaying the nutrients of a given menu. Hope my description of the scenario is clear.

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  • Pro/con of using Angular directives for complex form validation/ GUI manipulation

    - by tengen
    I am building a new SPA front end to replace an existing enterprise's legacy hodgepodge of systems that are outdated and in need of updating. I am new to angular, and wanted to see if the community could give me some perspective. I'll state my problem, and then ask my question. I have to generate several series of check boxes based on data from a .js include, with data like this: $scope.fieldMappings.investmentObjectiveMap = [ {'id':"CAPITAL PRESERVATION", 'name':"Capital Preservation"}, {'id':"STABLE", 'name':"Moderate"}, {'id':"BALANCED", 'name':"Moderate Growth"}, // etc {'id':"NONE", 'name':"None"} ]; The checkboxes are created using an ng-repeat, like this: <div ng-repeat="investmentObjective in fieldMappings.investmentObjectiveMap"> ... </div> However, I needed the values represented by the checkboxes to map to a different model (not just 2-way-bound to the fieldmappings object). To accomplish this, I created a directive, which accepts a destination array destarray which is eventually mapped to the model. I also know I need to handle some very specific gui controls, such as unchecking "None" if anything else gets checked, or checking "None" if everything else gets unchecked. Also, "None" won't be an option in every group of checkboxes, so the directive needs to be generic enough to accept a validation function that can fiddle with the checked state of the checkbox group's inputs based on what's already clicked, but smart enough not to break if there is no option called "NONE". I started to do that by adding an ng-click which invoked a function in the controller, but in looking around Stack Overflow, I read people saying that its bad to put DOM manipulation code inside your controller - it should go in directives. So do I need another directive? So far: (html): <input my-checkbox-group type="checkbox" fieldobj="investmentObjective" ng-click="validationfunc()" validationfunc="clearOnNone()" destarray="investor.investmentObjective" /> Directive code: .directive("myCheckboxGroup", function () { return { restrict: "A", scope: { destarray: "=", // the source of all the checkbox values fieldobj: "=", // the array the values came from validationfunc: "&" // the function to be called for validation (optional) }, link: function (scope, elem, attrs) { if (scope.destarray.indexOf(scope.fieldobj.id) !== -1) { elem[0].checked = true; } elem.bind('click', function () { var index = scope.destarray.indexOf(scope.fieldobj.id); if (elem[0].checked) { if (index === -1) { scope.destarray.push(scope.fieldobj.id); } } else { if (index !== -1) { scope.destarray.splice(index, 1); } } }); } }; }) .js controller snippet: .controller( 'SuitabilityCtrl', ['$scope', function ( $scope ) { $scope.clearOnNone = function() { // naughty jQuery DOM manipulation code that // looks at checkboxes and checks/unchecks as needed }; The above code is done and works fine, except the naughty jquery code in clearOnNone(), which is why I wrote this question. And here is my question: after ALL this, I think to myself - I could be done already if I just manually handled all this GUI logic and validation junk with jQuery written in my controller. At what point does it become foolish to write these complicated directives that future developers will have to puzzle over more than if I had just written jQuery code that 99% of us would understand with a glance? How do other developers draw the line? I see this all over Stack Overflow. For example, this question seems like it could be answered with a dozen lines of straightforward jQuery, yet he has opted to do it the angular way, with a directive and a partial... it seems like a lot of work for a simple problem. Specifically, I suppose I would like to know: how SHOULD I be writing the code that checks whether "None" has been selected (if it exists as an option in this group of checkboxes), and then check/uncheck the other boxes accordingly? A more complex directive? I can't believe I'm the only developer that is having to implement code that is more complex than needed just to satisfy an opinionated framework.

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