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  • How to map inheritance with property returned other inheritance?

    - by dario-g
    Hi I have abstract class Vehicle and two classes that derive from: Car and ForkLift. public abstract class Vehicle { public EngineBase Engine { get; set; } } public class Car : Vehicle { public GasEngine Engine { get; set; } } public class ForkLift : Vehicle { public ElectricEngine Engine { get; set; } } and Engine clasess: public abstract class Engine { } public class GasEngine : Engine { } public class ElectricEngine : Engine { } Engines are mapped with "table per class hierarchy". With Vehicles I want to use the same pattern. How to map Engine class and derived with that Engine property?

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  • Prevent Erroneous Property Assignment

    - by Gordon
    Porting android applications to iphone applications always gives me the following pattern that I accidentally create: - (void) myFunc:(id)prop { self.property = property; } Which instead should be: - (void) myFunc:(id)prop { self.property = prop; } This always causes my program to quietly break because property gets reset to its existing value rather than being set to the new value, 'prop'. I cannot name the parameter 'prop' to 'property' since the compile complains that the parameter masks the instance variables visibility. Is there a good way to avoid this situation? There are no compiler warnings. Is there a way to make xcode prevent this? I cannot see very many situations where you would set a property to the value of its underlying instance variable (maybe to trigger a KVO binding?), but I don't see myself doing that in majority of cases. I understand the above code is synthetic and should be done with @synthesize, but I am just using it as a simplified example to illustrate my point.

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  • Is it considered bad practice to have ViewModel objects hold the Dispatcher?

    - by stiank81
    My WPF application is structured using the MVVM pattern. The ViewModels will communicate asynchronously with a server, and when the requested data is returned a callback in the ViewModel is triggered, and it will do something with this data. This will run on a thread which is not the UI Thread. Sometimes these callbacks involve work that needs to be done on the UI thread, so I need the Dispatcher. This might be things such as: Adding data to an ObservableCollection Trigger Prism commands that will set something to be displayed in the GUI Creating WPF objects of some kind. I try to avoid the latter, but the two first points here I find to be reasonable things for ViewModels to do. So; is it okay to have ViewModels hold the Dispatcher to be able to Invoke commands for the UI thread? Or is this considered bad practice? And why?

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  • Javascript object encapsulation that tracks changes

    - by Raynos
    Is it possible to create an object container where changes can be tracked Said object is a complex nested object of data. (compliant with JSON). The wrapper allows you to get the object, and save changes, without specifically stating what the changes are Does there exist a design pattern for this kind of encapsulation Deep cloning is not an option since I'm trying to write a wrapper like this to avoid doing just that. The solution of serialization should only be considered if there are no other solutions. An example of use would be var foo = state.get(); // change state state.update(); // or state.save(); client.tell(state.recentChange()); A jsfiddle snippet might help : http://jsfiddle.net/Raynos/kzKEp/ It seems like implementing an internal hash to keep track of changes is the best option. [Edit] To clarify this is actaully done on node.js on the server. The only thing that changes is that the solution can be specific to the V8 implementation.

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  • Disposing a Bitmap through its Finalizer

    - by devoured elysium
    I have a complex program in which I have to first create, then use wrappers around bitmaps and send them across a lot of different classes. The problem in the end is deciding which classes should dispose the bitmaps. Most of the time the end classes don't know if they can indeed dispose the bitmap as the same bitmap can be used in several places. Also, I can't just copy the bitmaps because this is a kind of resource intensive algorithm and doing it would be dead slow. I looked up on reflector for Image/Bitmap's implementations and they seem to use the Dispose Pattern. So, even if I don't call Dispose(), the CLR will eventually call it some other time. Is it too bad if I just let the bitmaps be as they are, and let the finalizer take care of them?

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  • Using MySQL as a job queue

    - by user237815
    I'd like to use MySQL as a job queue. Multiple machines will be producing and consuming jobs. Jobs need to be scheduled; some may run every hour, some every day, etc. It seems fairly straightforward: for each job, have a "nextFireTime" column, and have worker machines search for the job with the nextFireTime, change the status of the record to "inProcess", and then update the nextFireTime when the job ends. The problem comes in when a worker dies silently. It won't be able to update the nextFireTime or set the status back to "idle". Unfortunately, jobs can be long-running, so a reaper thread that looks for jobs that have been inProcess too long isn't an option. There's no timeout value that would work. Can anyone suggest a design pattern that would properly handle unreliable worker machines?

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  • c# EnumerateFiles wildcard returning non matches?

    - by Sam Underhill
    As a simplified example I am executing the following IEnumerable<string> files = Directory.EnumerateFiles(path, @"2010*.xml", SearchOption.TopDirectoryOnly).ToList(); In my results set I am getting a few files which do no match the file pattern. According to msdn searchPattern wildcard is "Zero or more characters" and not a reg ex. An example is that I am getting a file name back as "2004_someothername.xml". For information there are in excess of 25,000 files in the folder. Does anyone have any idea what is going on?

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  • Question about regex in linux commands.

    - by smwikipedia
    I ran the following command at linux bash: apt-cache search hex.*(view|edit) My intention was to find any software packages whose name/description contains the pattern 'hex.*(view|edit)'. But among the results I got this: kipi-plugins - image manipulation/handling plugins for KIPI aware programs How could this be in the results list? I didn't see any matching string in this result. Is this a bug of the apt-cache search command? Or do I mis-understand how the regex is used by this command? Many thanks.

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  • Allow a new line anywhere in the regex?

    - by Scott Chamberlain
    I am having a find a replace in a bunch of RTF documents, The basic pattern I need is \{(?:\\\*)?\\field\\fldlock\{\\\*\\fldinst ?MERGEFIELD ?((?:\\.*?)?[\w\[\]]+?)(?:\\.*?)?\}(?:\{\\fldrslt\})?\} However I then found out there could potentialy be a newline before each slash, so it turned in to this. \{(?:\s*\\\*)?\s*\\field\s*\\fldlock\s*\{\s*\\\*\s*\\fldinst\s*MERGEFIELD\s*((?:\\.*?)?[\w\[\]]+?(?:\s*\\.*?)?)?\s*\}(?:\s*\{\s*\\fldrslt\s*\})?\s*\} But then I hit this it fails fees totaling $\protect {\field\fldlock{\*\fldinst MERGEFIELD ENTEROUTSTANDINGVETERINARYF EES}}\plain\f0\fs24\prot Is there way have to have it match a new line anywhere in the search too without adding (?:\r?\n)? everywhere? EDIT To clear up confusion on the new lines. I need to keep the newlines in the document, I only want to remove the newlines if they are inside my match, so in the final example I posted it should replace fees totaling $\protect {\field\fldlock{\*\fldinst MERGEFIELD ENTEROUTSTANDINGVETERINARYF EES}}\plain\f0\fs24\prot with fees totaling $\protect ENTEROUTSTANDINGVETERINARYFEES\plain\f0\fs24\prot

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  • Zend_Form: Is this really the way we should be doing things?

    - by Francis Daigle
    OK. I understand how to use Zend_Form and it's implementation of the decorator pattern. My question is, is this the best way to be going about creating forms? Shouldn't a documents forms be left to to the front-end rather than generating forms programmatically? Doesn't this kinda violate the whole idea of keeping things separate? I mean, really, even providing that you have a good understanding of the methodology being employed, does it really save one that much time? I guess what I'm looking for is some guidance as to what might be considered 'best practice'. I'm not saying that Zend_Form doesn't have it's place, I'm just wondering if it should be used in all cases (or not). And this has nothing to do with validation. I'm just thinking that something more akin to using the 'ViewScript' approach might be more appropriate in most cases. Your thoughts?

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  • are Hierarchical SIngletons in Java possible?

    - by Zach H
    I've been toying with an interesting idea (No idea if I'll include it in any code, but it's fun to think about) Let's say we have a program that requires a large number of classes, all of a certain subclass. And those classes all need to be singletons. Now, we could write the singleton pattern for each of those classes, but it seems wasteful to write the same code over and over, and we already have a common base class. It would be really nice to create a getSingleton method of A that when called from a subclass, returns a singleton of the B class (cast to class A for simplicity) class A{ public A getSingleton(){ //Wizardry } } class B extends A{ } A blargh = B.getSingleton() A gish = B.getSingleton() if(A == B) System.out.println("It works!") It seems to me that the way to do this would be to recognize and call B's default constructor (assuming we don't need to pass anything in.) I know a little of the black magic of reflection in Java, but i'm not sure if this can be done. Anyone interested in puzzling over this?

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  • Scala's tuple unwrapping nuance

    - by Paul Milovanov
    I've noticed the following behavior in scala when trying to unwrap tuples into vals: scala> val (A, B, C) = (1, 2, 3) <console>:5: error: not found: value A val (A, B, C) = (1, 2, 3) ^ <console>:5: error: not found: value B val (A, B, C) = (1, 2, 3) ^ <console>:5: error: not found: value C val (A, B, C) = (1, 2, 3) ^ scala> val (u, v, w) = (1, 2, 3) u: Int = 1 v: Int = 2 w: Int = 3 Is that because scala's pattern matching mechanism automatically presumes that all identifiers starting with capitals within patterns are constants, or is that due to some other reason? Thanks!

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  • Are there any XML Editors with FTP and file-tree browsing combined?

    - by JW
    Are there any (free preferably) XML Editors combined with FTP and file-tree browsing Project wide find+Replace I.e A bit like what Dreamweaver MX is but with fancier XML capabilities /XSLT /XSD Perhaps even DW does this...im still on an older version. I'd like to keep a smooth flow between find-edit-view-upload any ideas? Background: I have converted most of the html files of my legacy site into XML (which match the directory structure of my 'public docs' folder). Part of a step towards turning it into completely dynamic data via MVC /Front Controller Pattern.

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  • Is there anything wrong with a class with all static methods?

    - by MatthewMartin
    I'm doing code review and came across a class that uses all static methods. The entrance method takes several arguments and then starts calling the other static methods passing along all or some of the arguments the entrance method received. It isn't like a Math class with largely unrelated utility functions. In my own normal programming, I rarely write methods where Resharper pops and says "this could be a static method", when I do, they tend to be mindless utility methods. Is there anything wrong with this pattern? Is this just a matter of personal choice if the state of a class is held in fields and properties or passed around amongst static methods using arguments?

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  • A window that behaves both modally and non-modally

    - by Chris
    I want to create a WPF window that behaves as a modal dialogue box while at the same time facilitating selected operations on certain other windows of the same application. An example of this behaviour can be seen in Adobe Photoshop, which offers several dialogues that allow the user to use an eyedropper tool to make selections from an image while disabling virtually all other application features. I'm guessing that the way forward is to create a non-modal, always-on-top dialogue and programmatically disable those application features that are not applicable to the dialogue. Is there an easy way to achieve this in WPF? Or perhaps there's a design pattern I could adopt.

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  • Caching result of SELECT statement for reuse in multiple queries

    - by Andrew
    I have a reasonably complex query to extract the Id field of the results I am interested in based on parameters entered by the user. After extracting the relevant Ids I am using the resulting set of Ids several times, in separate queries, to extract the actual output record sets I want (by joining to other tables, using aggregate functions, etc). I would like to avoid running the initial query separately for every set of results I want to return. I imagine my situation is a common pattern so I am interested in what the best approach is. The database is in MS SQL Server and I am using .NET 3.5.

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  • Is there an ORM that allows a "plugin" to extend the database?

    - by IP
    So, I've been searching for the answer to this, but I can't find anything I have an Entity Framework Model (MyModel1) - for now, we'll say this contains a "Users" table It's part of a big app, that has a references to an "Addresses" project The addresses project contains an Entity Framework Model (MyModel2), this contains a Users table, and an Addresses table (pointing to the same database. The main app has a control that edits the user, and in that control it has an "addresses" control which actually exists in the "Addresses" project. To make this work, the User control passes the User object down to the addresses control, however, as the User that's been passed belongs to MyModel1 and not MyModel2, another User object has to be loaded up, then it can be used. This isn't ideal as I've had to load up the User twice. Is there a way of say, MyModel2 extending MyModel1, which effectively just adds a relationship to "User". Or is there an ORM that would handle this better? Or even a design pattern that would handle this better?

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  • Linq TakeWhile depending on sum (or aggregate) of elements

    - by martinweser
    I have a list of elements and want to takeWhile the sum (or any aggregation of the elements) satisfy a certain condition. The following code does the job, but i am pretty sure this is not an unusual problem for which a proper pattern should exist. var list = new List<int> { 1, 2, 3, 4, 5, 6, 7 }; int tmp = 0; var listWithSum = from x in list let sum = tmp+=x select new {x, sum}; int MAX = 10; var result = from x in listWithSum where x.sum < MAX select x.x; Does somebody know how to solve the task in nicer way, probably combining TakeWhile and Aggregate into one query? Thx

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  • asp.net web form Cutom Router Handler

    - by jparram
    I am using a custom route handler for a webforms application. I am using routes to determine localization. ie: if the url has es or fr in the route it will load either spanish or french resources. for example: www.someroute/es/checkstuff/checkstuff.aspx will load: www.someroute/checkstuff/checkstuff.aspx with the spanish resources. I am configuring the custom routes in global.asax via: protected void Application_Start(object sender, EventArgs e) { RegisterRoutes(RouteTable.Routes); } public static void RegisterRoutes(RouteCollection routes) { foreach (var value in _customRoutes) { routes.Add(value.RouteName, new Route(value.Route, new CustomRouteHandler(value.ResolvedRoute))); } } where _customroutes is a list of routes. Is there a way to do this with some kind of pattern matching so I can avoid adding a specific route for each page in the application. While I know I could use a t4 template to generate the routes, I guess I am looking for a dynamic way to create the list

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  • DTOs Collections mapping Problem

    - by the_knight5000
    I'm working now on a multi-tier project which has layers as following : DAL BLL GUI Layer and Shared DTOs between BLL and GUI layers. I'm facing a problem in mapping the Objects from DAO To DTO, No problem in the simple objects. The problem is in the Objects who have child collections of another objects. ex: Author Category --Categories --Authors the execution goes in an infinite loop of mapping and it get more complex when I want model Self-join tables ex: Safe Safe --TransferSafe(Collection<Safe>) --TransferSafe(Collection<Safe>) the execution goes in an infinite loop of mapping any suggestions about a good solution or a practical mapping pattern?

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  • Should member variables of global objects be made global as well?

    - by David Wong
    I'm developing plugins in Eclipse which mandates the use of singleton pattern for the Plugin class in order to access the runtime plugin. The class holds references to objects such as Configuration and Resources. In Eclipse 3.0 plug-in runtime objects are not globally managed and so are not generically accessible. Rather, each plug-in is free to declare API which exposes the plug-in runtime object (e.g., MyPlugin.getInstance() In order for the other components of my system to access these objects, I have to do the following: MyPlugin.getInstance().getConfig().getValue(MyPlugin.CONFIGKEY_SOMEPARAMETER); , which is overly verbose IMO. Since MyPlugin provides global access, wouldn't it be easier for me to just provide global access to the objects it manages as well? MyConfig.getValue(MyPlugin.CONFIGKEY_SOMEPARAMETER); Any thoughts? (I'm actually asking because I was reading about the whole "Global variable access and singletons are evil" debates)

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  • With vim, how can I use autocmd's for files in subdirectories of a specific path?

    - by René Nyffenegger
    I am trying to figure out how I can define an autocmd that influences all files under a specific path. The autocmd I have tried is something like autocmd BufNewFile,BufRead /specificPath/** imap <buffer> .... Now, I'd expect this autocmd to be used if I edited, say, /foo/bar/specificPath/baz/something/bla.txt, but not if I edited /foo/bar/here/and/there/moreBla.txt If I start vim being in a directory 'above' specificPath, this works as I want it. But it doesn't if I am below that directory. Obviously, the autocmd's pattern is matched against the relative file name, not the absolute one.

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  • Do I need to syncronize thread access to an int

    - by Martin Harris
    I've just written a method that is called by multiple threads simultaneously and I need to keep track of when all the threads have completed, the code uses this pattern: private void RunReport() { _reportsRunning++; try { //code to run the report } finally { _reportsRunning--; } } This is the only place within the code that _reportsRunning's value is changed, and the method takes about a second to run. Occasionally when I have more than six or so threads running reports together the final result for _reportsRunning can get down to -1, if I wrap the calls to _runningReports++ and _runningReports-- in a lock then the behaviour appears to be correct and consistant. So, to the question: When I was learning multithreading in C++ I was taught that you didn't need to synchronize calls to increment and decrement operations because they were always one assembly instruction and therefore it was impossible for the thread to be switched out mid-call. Was I taught correctly, and if so how come that doesn't hold true for C#?

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  • jQuery sanitizing comments and linkifying URLs

    - by iWasRobbed
    In terms of jQuery (or Javascript), what happens behind the scenes when a person posts a comment on Facebook, Twitter, or a blog? For instance, do they sanitize the text first, and then pattern match URL's into an actual link? Are there other items of concern that the client-side should check in addition to doing some checks on the backend? I have found a few regex's for turning URL's into links, but I'm not sure if there are better solutions. I'm trying to wrap my head around the problem, but I'm having a difficult time knowing where to start. Any guidance you can provide is greatly appreciated!

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  • Disable globbing in PHP exec()

    - by wxs
    I have a PHP script which calls another script in order to add IP addresses to a whitelist. I sometimes want to whitelist all addresses, in which case I have it call exec("otherscript *.*.*.*", output, retval); This worked fine, adding the string "*.*.*.*" to the whitelist until I happened to have another file in the directory of the php script that matched that pattern ("foo.1.tar.gz"), at which point the wildcards were expanded, and I ended up with the filename in my whitelist. Is there some way to disable globbing in php's exec? It isn't mentioned in the PHP docs as far as I can tell.

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