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  • Can the Singleton be replaced by Factory?

    - by lostiniceland
    Hello Everyone There are already quite some posts about the Singleton-Pattern around, but I would like to start another one on this topic since I would like to know if the Factory-Pattern would be the right approach to remove this "anti-pattern". In the past I used the singleton quite a lot, also did my fellow collegues since it is so easy to use. For example, the Eclipse IDE or better its workbench-model makes heavy usage of singletons as well. It was due to some posts about E4 (the next big Eclipse version) that made me start to rethink the singleton. The bottom line was that due to this singletons the dependecies in Eclipse 3.x are tightly coupled. Lets assume I want to get rid of all singletons completely and instead use factories. My thoughts were as follows: hide complexity less coupling I have control over how many instances are created (just store the reference I a private field of the factory) mock the factory for testing (with Dependency Injection) when it is behind an interface In some cases the factories can make more than one singleton obsolete (depending on business logic/component composition) Does this make sense? If not, please give good reasons for why you think so. An alternative solution is also appreciated. Thanks Marc

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  • Are GUIDs the ultimate ID?

    - by mafutrct
    I noticed some people don't bother having the usual incremented number as ID but instead simply generate a GUID. The advantages include: Quick and easy No need to keep track of previous IDs Guaranteed to be unique even across machines without knowledge of each other Some disadvantages are: Possibly performance bottleneck Uses a large number of bytes My understanding is that using a GUID is beneficial in most cases, except if optimization for time or space is an issue. Did I miss something? Or do you agree with this idea?

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  • JavaScript Resource Management Design Pattern

    - by Adam
    As a web developer, a common problem I find myself tackling is waiting for something to load before doing something else. In particular, I often hide (using either display: none; or visibility: hidden; depending on the situation) elements while waiting for a background image or a CSS file to load. Consider this example from Last.FM. They overlay a semi-transparant PNG over each album art image so that it looks like it's inside a jewel-case. They let it load when it loads, so depending on your internet speed, you may see the art image by itself (without the overlay) temporarily. In this case, the album art looks fine without the jewel-case effect. But in similar situations, I have found that I don't want the user to see the site's design mangled as resources incrementally load. So, in rare cases I have hidden everything from the user until the whole kit and kaboodle has loaded. But this is often a pain to write out, and may force the user to wait for a pretty long time to see anything (besides "loading..." text). I can think of (and have used on occasion) some obvious solutions/compromises: Use some inline CSS so that as certain parts of the DOM load and render, they will immediately have the correct size/position/etc. Immediately render the navigation part of the site, so that if the user wanted to use the current page purely to get somewhere else, they don't have to wait for the rest to load. Load pixelated images first as placeholders for layout while lazy-loading higher quality images as replacements. Something quirky like using a cute animated gif to distract the user during a "loading..." phase. Show useful information as a reference while loading the full UI. (Something akin to Gmail Inbox Preview, etc.) (Sorry if my question was basically just asked and answered...) Despite all of these ideas, I still find myself hoping there are better ways of doing some of these things. So I guess what I'm looking for is some inspiration and/or any creative ways of dealing with this problem that you guys may have seen out in the wild.

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  • Binning a numeric variable in R

    - by McPeterson
    I have a vector X that contains positive numbers that I want to bin/discretize. For this vector, I want the numbers [0, 10) to show up just as they exist in the vector, but numbers [10,∞) to be 10+. I'm using: x <- c(0,1,3,4,2,4,2,5,43,432,34,2,34,2,342,3,4,2) binned.x <- as.factor(ifelse(x > 10,"10+",x)) but this feels klugey to me. Does anyone know a better solution or a different approach? mcpeterson

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  • Best Practice With JFrame Constructors?

    - by David Barry
    In both my Java classes, and the books we used in them laying out a GUI with code heavily involved the constructor of the JFrame. The standard technique in the books seems to be to initialize all components and add them to the JFrame in the constructor, and add anonymous event handlers to handle events where needed, and this is what has been advocated in my class. This seems to be pretty easy to understand, and easy to work with when creating a very simple GUI, but seems to quickly get ugly and cumbersome when making anything other than a very simple gui. Here is a small code sample of what I'm describing: public class FooFrame extends JFrame { JLabel inputLabel; JTextField inputField; JButton fooBtn; JPanel fooPanel; public FooFrame() { super("Foo"); fooPanel = new JPanel(); fooPanel.setLayout(new FlowLayout()); inputLabel = new JLabel("Input stuff"); fooPanel.add(inputLabel); inputField = new JTextField(20); fooPanel.add(inputField); fooBtn = new JButton("Do Foo"); fooBtn.addActionListener(new ActionListener() { public void actionPerformed(ActionEvent e) { //handle event } }); fooPanel.add(fooBtn); add(fooPanel, BorderLayout.CENTER); } } Is this type of use of the constructor the best way to code a Swing application in java? If so, what techniques can I use to make sure this type of constructor is organized and maintainable? If not, what is the recommended way to approach putting together a JFrame in java?

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  • Best practice for handling ConnectionDroppedHandler in OCS Server Application

    - by Paul Nearney
    Hi all, In general, it seems that the majority of times that ConnectionDroppedHandler would get called in an OCS server application is for expected reasons e.g. server application has been unregistered, server is shutting down, etc. Are there any unexpected situations in which ConnectionDroppedHandler can be called? Basically, i'm wondering whether it will ever be necessary to log an error to the event log from this event handler. Many thanks, Paul

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  • Views performance in MySQL

    - by Gianluca Bargelli
    I am currently writing my truly first PHP Application and i would like to know how to project/design/implement MySQL Views properly; In my particular case User data is spread across several tables (as a consequence of Database Normalization) and i was thinking to use a View to group data into one large table: CREATE VIEW `Users_Merged` ( name, surname, email, phone, role ) AS ( SELECT name, surname, email, phone, 'Customer' FROM `Customer` ) UNION ( SELECT name, surname, email, tel, 'Admin' FROM `Administrator` ) UNION ( SELECT name, surname, email, tel, 'Manager' FROM `manager` ); This way i can use the View's data from the PHP app easily but i don't really know how much this can affect performance. For example: SELECT * from `Users_Merged` WHERE role = 'Admin'; Is the right way to filter view's data or should i filter BEFORE creating the view itself? (I need this to have a list of users and the functionality to filter them by role).

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  • ASP.NET MVC Paging for a search form

    - by James Alexander
    I've read several different posts on paging w/ in MVC but none describe a scenario where I have something like a search form and then want to display the results of the search criteria (with paging) beneath the form once the user clicks submit. My problem is that, the paging solution I'm using will create <a href="..."> links that will pass the desired page like so: http://mysite.com/search/2/ and while that's all fine and dandy, I don't have the results of the query being sent to the db in memory or anything so I need to query the DB again. If the results are handled by the POST controller action for /Search and the first page of the data is rendered as such, how do I get the same results (based on the form criteria specified by the user) when the user clicks to move to page 2? Some javascript voodoo? Leverage Session State? Make my GET controller action have the same variables expected by the search criteria (but optional), when the GET action is called, instantiate a FormCollection instance, populate it and pass it to the POST action method (there-by satisfying DRY)? Can someone point me in the right direction for this scenario or provide examples that have been implemented in the past? Thanks!

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  • Best Practice Guide: Swing

    - by wishi_
    Hi! Does anybody know Swing related GUI guidelines - specifically on how to design Swing apps and which components I should use? I'm not looking for an official standard, but pragmatic tips I can use to set a good standard for my projects. I haven't used too much of Swing by myself. Surely clicking a GUI with a GUI designer isn't a big deal. However I'd like to get some insights from people who have experience with Swing and know what to avoid. Swing lately (in Java 6- 10) got decent changes. So there isn't too much specific standardization out there currently.

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  • Obj-c categories in static library

    - by Vladimir
    Can you guide me how to properly link static library to iphone project. I use staic library project added to app project as direct dependency (target - general - direct dependecies) and all works OK, but categories. A category defined in static library is not working in app. So my question is how to add static library with some categories into other project? And in general, what is best practice to use in app project code from other projects?

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  • Could any help me in resource of how to build framework with api like facebook ?

    - by Space Cracker
    we will develop a web site that will have some free services and we want to make it as a framework that can any build application over it or can use its api in their site .. Could any lead me in how to start it , what's the better architecture and design pattern help in that , is there any resources discuss or explain how to do like this ? FYI : we are dot net developers but we can learn any other if its urgently needed in such a solution

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  • How to perform a literal match with regex using wildcard

    - by kashif4u
    I am trying to perform literal match with regular expression using wildcard. string utterance = "Show me customer id 19"; string pattern 1 = "*tom*"; string patter 2 = "*customer id [0-9]*"; Desired results: if (Regex.IsMatch(utterance, pattern 1 )) { MATCH NOT FOUND } if (Regex.IsMatch(utterance, pattern 2 )) { MATCH FOUND } I have tried looking for literal match solution/syntax in wildcard but having difficulty. Could you also enlighten me with with an example on possible Pattern Matching Strength algorithm i.e. if code match 90 select? Note: I have table with 100000 records to perform literal matches from user utterances. Thanks in advance.

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  • What is the best approach to binding commands in a ViewModel to elements in the View?

    - by Micah
    Anyone who has tried to implement RoutedCommands in WPF using M-V-VM has undoubtedly run into issues. Commands (non-UI commands that is) should be implemented in the ViewModel. For instance if I needed to save a CustomerViewModel then I would implement that as a command directly on my CustomerViewModel. However if I wanted to pop up a window to show the users addresses I would implement a ShowCustomerAddress command directly in the view since this a UI specific function. How do I define the command bindings in the viewmodel, and use them in the view?

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  • How build my own Application Setting

    - by adisembiring
    I want to build a ApplicationSetting for my application. The ApplicationSetting can be stored in a properties file or in a database table. The settings are stored in key-value pairs. E.g. ftp.host = blade ftp.username = dummy ftp.pass = pass content.row_pagination = 20 content.title = How to train your dragon. I have designed it as follows: Application settings reader: interface IApplicationSettingReader { read(); } DatabaseApplicationSettingReader { dao appSettingDao; AppSettings read() { List<AppSettingEntity> listEntity = appSettingsDao.findAll(); Map<String, String> map = new HaspMap<String, String>(); foreach (AppSettingEntity entity : listEntity) { map.put(entity.getConfigName(), entity.getConfigValue()); } return new AppSettings(map); } } DatabaseApplicationSettingReader { dao appSettingDao; AppSettings read() { //read from some properties file return new AppSettings(map); } } Application settings class: AppSettings { private static AppSettings instance; private Map map; Public AppSettings(Map map) { this.map = map; } public static AppSettings getInstance() { if (instance == null) { throw new RuntimeException("Object not configure yet"); } return instance; } public static configure(IApplicationSettingReader reader) { instance = reader.read(); } public String getFtpSetting(String param) { return map.get("ftp." + param); } public String getContentSetting(String param) { return map.get("content." + param); } } Test class: AppSettingsTest { IApplicationSettingReader reader; @Before public void setUp() throws Exception { reader = new DatabaseApplicationSettingReader(); } @Test public void getContentSetting_should_get_content_title() { AppSettings.configure(reader); Instance settings = AppSettings.getInstance(); String title = settings.getContentSetting("title"); assertNotNull(title); Sysout(title); } } My questions are: Can you give your opinion about my code, is there something wrong? I configure my application setting once, while the application start, I configure the application setting with appropriate reader (DbReader or PropertiesReader), I make it singleton. The problem is, when some user edit the database or file directly to database or file, I can't get the changed values. Now, I want to implement something like ApplicationSettingChangeListener. So if the data changes, I will refresh my application settings. Do you have any suggestions how this can be implemented?

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  • Recommendations for 'C' Project architecture guidelines?

    - by SiegeX
    Now that I got my head wrapped around the 'C' language to a point where I feel proficient enough to write clean code, I'd like to focus my attention on project architecture guidelines. I'm looking for a good resource that coves the following topics: How to create an interface that promotes code maintainability and is extensible for future upgrades. Library creation guidelines. Example, when should I consider using static vs dynamic libraries. How to properly design an ABI to cope with either one. Header files: what to partition out and when. Examples on when to use 1:1 vs 1:many .h to .c Anything you feel I missed but is important when attempting to architect a new C project. Ideally, I'd like to see some example projects ranging from small to large and see how the architecture changes depending on project size, function or customer. What resource(s) would you recommend for such topics?

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  • How Can I Populate Default Form Data with a ManyToMany Field?

    - by b14ck
    Ok, I've been crawling google and Django documentation for over 2 hours now (as well as the IRC channel on freenode), and haven't been able to figure this one out. Basically, I have a model called Room, which is displayed below: class Room(models.Model): """ A `Partyline` room. Rooms on the `Partyline`s are like mini-chatrooms. Each room has a variable amount of `Caller`s, and usually a moderator of some sort. Each `Partyline` has many rooms, and it is common for `Caller`s to join multiple rooms over the duration of their call. """ LIVE = 0 PRIVATE = 1 ONE_ON_ONE = 2 UNCENSORED = 3 BULLETIN_BOARD = 4 CHILL = 5 PHONE_BOOTH = 6 TYPE_CHOICES = ( ('LR', 'Live Room'), ('PR', 'Private Room'), ('UR', 'Uncensored Room'), ) type = models.CharField('Room Type', max_length=2, choices=TYPE_CHOICES) number = models.IntegerField('Room Number') partyline = models.ForeignKey(Partyline) owner = models.ForeignKey(User, blank=True, null=True) bans = models.ManyToManyField(Caller, blank=True, null=True) def __unicode__(self): return "%s - %s %d" % (self.partyline.name, self.type, self.number) I've also got a forms.py which has the following ModelForm to represent my Room model: from django.forms import ModelForm from partyline_portal.rooms.models import Room class RoomForm(ModelForm): class Meta: model = Room I'm creating a view which allows administrators to edit a given Room object. Here's my view (so far): def edit_room(request, id=None): """ Edit various attributes of a specific `Room`. Room owners do not have access to this page. They cannot edit the attributes of the `Room`(s) that they control. """ room = get_object_or_404(Room, id=id) if not room.is_owner(request.user): return HttpResponseForbidden('Forbidden.') if is_user_type(request.user, ['admin']): form_type = RoomForm elif is_user_type(request.user, ['lm']): form_type = LineManagerEditRoomForm elif is_user_type(request.user, ['lo']): form_type = LineOwnerEditRoomForm if request.method == 'POST': form = form_type(request.POST, instance=room) if form.is_valid(): if 'owner' in form.cleaned_data: room.owner = form.cleaned_data['owner'] room.save() else: defaults = {'type': room.type, 'number': room.number, 'partyline': room.partyline.id} if room.owner: defaults['owner'] = room.owner.id if room.bans: defaults['bans'] = room.bans.all() ### this does not work properly! form = form_type(defaults, instance=room) variables = RequestContext(request, {'form': form, 'room': room}) return render_to_response('portal/rooms/edit.html', variables) Now, this view works fine when I view the page. It shows all of the form attributes, and all of the default values are filled in (when users do a GET)... EXCEPT for the default values for the ManyToMany field 'bans'. Basically, if an admins clicks on a Room object to edit, the page they go to will show all of the Rooms default values except for the 'bans'. No matter what I do, I can't find a way to get Django to display the currently 'banned users' for the Room object. Here is the line of code that needs to be changed (from the view): defaults = {'type': room.type, 'number': room.number, 'partyline': room.partyline.id} if room.owner: defaults['owner'] = room.owner.id if room.bans: defaults['bans'] = room.bans.all() ### this does not work properly! There must be some other syntax I have to use to specify the default value for the 'bans' field. I've really been pulling my hair out on this one, and would definitely appreciate some help. Thanks!

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  • Mercurial setup: One central repo or several?

    - by Robert S.
    My company is switching from Subversion to Mercurial. We're using .NET for our product. We have a solution with about a dozen projects that are separate modules with no dependencies on each other. We're using a central repo on a server with push/pull for our integration build. I'm trying to figure out if I should create one central repo with all the projects in it, or if I should create a separate repo for each project. One argument for separate repos is that branching the individual modules would be easier, but an argument for a single repo is easier management and workflow. I'm very new to hg and DVCS, so some guidance is greatly appreciated.

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  • Where to find good examples or Templates for Configuration Management Plans?

    - by Geo
    Documentation is not the favorite area of a developer but an important area to fulfill if you want to have standards in the organization. We are trying to put together a new Configuratio Mgmt Plan to setup Change Controls, Backups strategies and other fun things, like the process from development, staging to production. I will like to have your opinions on good examples or probably a good start for CMP process.

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  • Modelling a manyToMany relationship with attributes

    - by Javi
    Hello, I have a ManyToMany relationship between two classes, for instance class Customer and class Item. A customer can buy several items and an item can be bought by different customers. I need to store extra information in this relationship, for example the day when the item was bought. I wonder how is this usually modelled in JPA, cause I'm not sure how to express this in code. Do I have to create a new class to model all the attributes of the relationship and make a manyToMany relationship between the other classes or is a better way to do this? Thanks

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  • To log in stored procedures?

    - by hgulyan
    If you have a long running SP, do you log somehow it's actions or just wait for this message? "Command(s) completed successfully." I assume, that there can be plenty solutions on this subject, but is there any best practice - a simple solution that is frequently used?

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  • State pattern: Why doesn't the context class implement or inherit the State abstract interface/class

    - by Ricket
    I'm reading about the State pattern. I have only just begun, so of course I begin by reading the entire Wikipedia article on it. I noticed that both of the examples in the article have some base abstract class or Java interface for a generic State's methods/functions. Then there are some states which inherit from the base and implement those methods/functions in different ways. Then there's a Context class which has a private member of type State and which, at any time, can be equal to an instance of one of the implementations. That context class also implements the same methods, and passes them onto the current state instance, and then has an additional method to change the state (or depending on design I understand the change of state could be a reaction to one of the implemented methods). Why doesn't this context class specifically "extend" or "implement" the generic State base class/interface?

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  • trending topics example for a rails app

    - by Gautam
    Hi, I am new to ruby on rails. I want to build an RSS feed aggregator. How do I find out the trending topics from the stream of data[titles] from various RSS feeds. Could you help me how to achieve this?? Looking forward for your help Thanks in advance Gautam

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  • Decorator pattern in C++

    - by AlgoMan
    Can someone give me an example of Decorator pattern in C++ ? I have come across the Java version of it. But C++ i have found it difficult to understand the examples that are given.

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  • Have I taken a wrong path in programming by being excessively worried about code elegance and style?

    - by Ygam
    I am in a major stump right now. I am a BSIT graduate, but I only started actual programming less than a year ago. I observed that I have the following attitude in programming: I tend to be more of a purist, scorning unelegant approaches to solving problems using code I tend to look at anything in a large scale, planning everything before I start coding, either in simple flowcharts or complex UML charts I have a really strong impulse on refactoring my code, even if I miss deadlines or prolong development times I am obsessed with good directory structures, file naming conventions, class, method, and variable naming conventions I tend to always want to study something new, even, as I said, at the cost of missing deadlines I tend to see software development as something to engineer, to architect; that is, seeing how things relate to each other and how blocks of code can interact (I am a huge fan of loose coupling) i.e the OOP thinking I tend to combine OOP and procedural coding whenever I see fit I want my code to execute fast (thus the elegant approaches and refactoring) This bothers me because I see my colleagues doing much better the other way around (aside from the fact that they started programming since our first year in college). By the other way around I mean, they fire up coding, gets the job done much faster because they don't have to really look at how clean their codes are or how elegant their algorithms are, they don't bother with OOP however big their projects are, they mostly use web APIs, piece them together and voila! Working code! CLients are happy, they get paid fast, at the expense of a really unmaintainable or hard-to-read code that lacks structure and conventions, or slow executions of certain actions (which the common reasoning against would be that internet connections are much faster these days, hardware is more powerful). The excuse I often receive is clients don't care about how you write the code, but they do care about how long you deliver it. If it works then all is good. Now, did my "purist" approach to programming may have been the wrong way to start programming? Should I just dump these purist concepts and just code the hell up because I have seen it: clients don't really care how beautifully coded it is?

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