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Search found 5705 results on 229 pages for 'observer pattern'.

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  • some confusions to singleton pattern in PHP

    - by SpawnCxy
    Hi all, In my team I've been told to write resource class like this style: class MemcacheService { private static $instance = null; private function __construct() { } public static function getInstance($fortest = false) { if (self::$instance == null) { self::$instance = new Memcached(); if ($fortest) { self::$instance->addServer(MEMTEST_HOST, MEMTEST_PORT); } else { self::$instance->addServer(MEM_HOST, MEM_PORT); } } return self::$instance; } } But I think in PHP resource handles will be released and initialized again every time after a request over. That means MemcacheService::getInstance() is totally equal new Memcached() which cannot be called singleton pattern at all. Please correct me if I'm wrong. Regards

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  • Search for a pattern in a list of strings - Python

    - by Holtz
    I have a list of strings containing filenames such as, file_names = ['filei.txt','filej.txt','filek.txt','file2i.txt','file2j.txt','file2k.txt','file3i.txt','file3j.txt','file3k.txt'] I then remove the .txt extension using: extension = os.path.commonprefix([n[::-1] for n in file_names])[::-1] file_names_strip = [n[:-len(extension)] for n in file_names] And then return the last character of each string in the list file_names_strip: h = [n[-1:] for n in file_names_strip] Which gives h = ['i', 'j', 'k', 'i', 'j', 'k', 'i', 'j', 'k'] How can i test for a pattern of strings in h? So if i,j,k occur sequentially it would return True and False if not. I need to know this because not all file names are formatted like they are in file_names. So: test_ijk_pattern(h) = True no_pattern = ['1','2','3','1','2','3','1','2','3'] test_ijk_pattern(no_pattern) = False

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  • db2 sql pattern matching

    - by Jitesh
    I have a table in db2 which has the following fields int xyz; string myId; string myName; Example dataset xyz | myid | myname -------------------------------- 1 | ABC.123.456 | ABC 2 | PRQS.12.34 | PQRS 3 | ZZZ.3.2.2 | blah I want to extract the rows where myName matches the character upto "." in the myId field. So from the above 3 rows, I want the firs 2 rows since myName is present in myId before "." How can I do this in the query, can I do some kind of pattern matching inside the query?

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  • Need help understanding the MVC design pattern

    - by Doron Sinai
    Hi, I am trying to find a ood example of MVC design pattern in java. This is what i understood from reading about it, please correct me if I am wrong: I have the Model part which is the logic behind the program, let's say if we have a phonebook, so adding and removing contact from the Array will be the model. The Gui is the view and it contains buttons that upon clicking them, the model is changing. What I am trying to undersand what is the controller part, is it the ActionListeners? how to you seperate those modules in practice. thank you

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  • creational pattern for instances depending on multiple subclass instances

    - by markusw
    I have a problem, for that I was not able to identify a suitable design pattern. I want to create instances depending on a given type that has been passed to a factory method. What I am doing until now is the following: T create(SuperType x) { if (x instanceof SubType1) { // do some stuff and return a new SubType extends T } else if (x instanceof SubType2) { // do some stuff and return a new SubType extends T } else if ... } else { throw new UnSupportedOperationException("nothing defined for " + x); } } It seems not to be best pratice for me. Has anybody an idea how to solve this in a better way?

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  • Self-Configuring Classes W/ Command Line Args: Pattern or Anti-Pattern?

    - by dsimcha
    I've got a program where a lot of classes have really complicated configuration requirements. I've adopted the pattern of decentralizing the configuration and allowing each class to take and parse the command line/configuration file arguments in its c'tor and do whatever it needs with them. (These are very coarse-grained classes that are only instantiated a few times, so there is absolutely no performance issue here.) This avoids having to do shotgun surgery to plumb new options I add through all the levels they need to be passed through. It also avoids having to specify each configuration option in multiple places (where it's parsed and where it's used). What are some advantages/disadvantages of this style of programming? It seems to reduce separation of concerns in that every class is now doing configuration stuff, and to make programs less self-documenting because what parameters a class takes becomes less explicit. OTOH, it seems to increase encapsulation in that it makes each class more self-contained because no other part of the program needs to know exactly what configuration parameters a class might need.

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  • What software design pattern is best for the following scenario (C#)

    - by askjdh
    I have a gps device that records data e.g. datetime, latitude, longitude I have an sdk that reads the data from the device. The way the data is read: A command packet (basically a combination of int values in a struct) is sent to the device. The device responds with the data in fixed size chunks e.g. 64bytes Depending on the command issued I will get back differect data structs e.g. sending command 1 to the device returns a struct like struct x { id int, name char[20] } command 2 returns a collection of the following structs (basically it boils down to an array of the structs - y[12]) struct y { date datetime, lat decimal, lon decimal } I would then want to convert the struct to a class and save the data to a database. What would be the best way to encapsulate the entire process, preferably using some established design pattern? Many thanks M

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  • Dashboard pattern: HorizontalScrollView with pagination or ScrollView?

    - by Macarse
    I am starting a new application and I am willing to use the Dashboard pattern. For example: The Google IO app uses it: My issue is that the amount of buttons will be more than six. I'm not sure if I should use vertical or horizontal scrolling. Vertical scrolling could be done with a ScrollView or a GridView but I am not sure which would be the easier way to implement the horizontal version. I was thinking of using an HorizontalScrollView but it doesn't have pagination. It should feel similar to the tweetdeck app. How would you implement it?

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  • regex pattern to match only strings that don't contain spaces PHP

    - by Jamex
    Hi, I want to match the word/pattern that is contained in the variable, but only match against the words that don't have white spaces. Please give suggestions. $var = 'look'; $array = ('look', 'greatlook', 'lookgreat', 'look great', 'badlook', 'look bad', 'look ', ' look'); matches words: look, greatlook, lookgreat, badlook non matches: look great, bad look, look (trailing space(s)), (space(s)) look. The syntax of the below functions are OK, but it matches everything $match = preg_grep ("/$var/", $array); $match = preg_grep ("/^$var/", $array); (match words with 'look' at the start) but when I include the [^\s], it gives an error $match = preg_grep ("/$var[^\s]/", $array); Parse error: syntax error, unexpected '^', expecting T_STRING or T_VARIABLE TIA

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  • Design pattern for extending Android's activities?

    - by Carl
    While programming on Android, I end up writing a parent activity which is extended by several others. A bit like ListActivity. My parent activity extends Activity. if I intend to use a Map or a List, I can't use my parent activity as superclass - the child activity can only extend one activity obviously. As such I end up writing my parent activities with the same logic for Activity, ListActivity, MapActivity and so forth. What am I looking for is some sort of trait functionality/design pattern which would help in this case. Any suggestions?

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  • Xcode iphone sdk - Searching in UITableView, different pattern matching

    - by Lorenzo
    Hi everyone, I'm coding a UITableView with a UISearchBar to search between a list of cities (loaded in the uitableview) Here is my code for searhing: - (void) searchTableView { NSString *searchText = searchBar.text; NSMutableArray *searchArray = [[NSMutableArray alloc] init]; for (NSDictionary *dictionary in listOfItems) { NSArray *array = [dictionary objectForKey:@"Cities"]; [searchArray addObjectsFromArray:array]; } for (NSString *sTemp in searchArray) { NSRange titleResultsRange = [sTemp rangeOfString:searchText options:NSCaseInsensitiveSearch]; if (titleResultsRange.length > 0) [copyListOfItems addObject:sTemp]; } [searchArray release]; searchArray = nil;} And with this everything works fine, but i need to do something a bit different. I need to search only between items that match pattern Word* and not * Word *. For example if I search "roma", this need to match just with "Roma" or "Romania" and not with "Castelli di Roma". Is that possible with this searchbar? How can i modify this? Thanks

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  • ClearCase UCM Mainline Configuration Management Pattern Question

    - by cogmios
    A configuration management pattern question (using Rational ClearCase UCM) When I use the mainline approach I create new releases by: - create release 1 from mainline - on a certain moment baseline release 1, deliver release 1 to mainline - create release 2 from mainline - on a certain moment baseline release 2, deliver release 2 to mainline - create release 3 from mainline - etc... Works very nice because the pathname is /main/release 3/latest instead of /main/release 1/release 2/release 3/latest etc... However... when in release 1 are new elements that have to be propagated to later releases I can not use the mainline since the mainline is already on e.g. release 4. The only thing I can do is deliver/merge from release 1 directly to release 2. The bad thing is that the pathname then becomes /main/release 1/release 2/latest for that files (and possibly later releases). That is I think not in line with the mainline approach. What am I doing wrong?

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  • Design pattern for mouse interaction

    - by mike
    I need some opinions on what is the "ideal" design pattern for a general mouse interaction. Here the simplified problem. I have a small 3d program (QT and openGL) and I use the mouse for interaction. Every interaction is normally not only a single function call, it is mostly performed by up to 3 function calls (initiate, perform, finalize). For example, camera rotation: here the initial function call will deliver the current first mouse position, whereas the performing function calls will update the camera etc. However, for only a couple of interactions, hardcoding these (inside MousePressEvent, MouseReleaseEvent MouseMoveEvent or MouseWheelEvent etc) is not a big deal, but if I think about a more advanced program (e.g 20 or more interactions) then a proper design is needed. Therefore, how would you design such a interactions inside QT. I hope I made my problem clear enough, otherwise don't bother complain :-) Thanks

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  • Design pattern to encapsulate common funtionality among UI controls

    - by Dan
    I'm brainstorming some ideas around a pattern to use for the following scenario. I have some 3rd party controls that I want to add common functionality to. Functionality is added by handling several of the the events and doing certain things when the events fire along with adding some private variables to hold some state info between events. I want to reuse the code and functionality so this is what I'd typically do. Create a class for this functionality and pass in the instance of the control that I want to add the functionality to in the constructor. Then I can add event handlers to the control in the instance of the class. Can anyone think of alternative patterns to use in order to create this kind of reusable functionality.

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  • Store database, good pattern for simultaneous access

    - by dygi
    I am kinda new to database designing so i ask for some advices or some kind of a good pattern. The situation is that, there is one database, few tables and many users. How should i design the database, or / and which types of queries should i use, to make it work, if users can interact with the database simultaneously? I mean, they have access to and can change the same set of data. I was thinking about transactions, but I am not sure, if that is the right / good / the only solution. I will appreciate some google keywords too.

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  • Pattern matching for lambda expressions

    - by alphomega
    21 --Primitive recursion constructor 22 pr :: ([Int] -> Int) -> ([Int] -> Int) -> ([Int] -> Int) 23 pr f g = \xs 0 -> f xs 24 pr f g = \xs (y+1) -> g xs y ((pr f g) xs y) I want the function this function creates to act differently on different inputs, so that it can create a recursive function. As expected, the above code doesn't work. How do I do something like pattern matching, but for the function it creates? Thanks

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  • Regular Expression: Changes HTML Attributes Value to some pattern

    - by brain90
    Dear Engineers, I'm a newbie in RegEx I have thousands html tags, have wrote like this: <input type="text" name="CustomerName" /> <input type="text" name="SalesOrder"/> I need to match every name attribute values and convert them all to be like this: CustomerName -> cust[customer_name] SalesOrder -> cust[sales_order] So the results will be : <input type="text" name="cust[customer_name]" /> <input type="text" name="cust[sales_order]" /> My best try have stuck in this pattern: name=\"[a-zA-Z0-9]*\" - just found name="CustomerName" Please guide me wrote some Regular Expression magics to done this, I'm using Netbeans PDT. Thanks in advance for any pointers!.

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  • MVC design pattern - who loads view initially

    - by enableDeepak
    This query is about MVC design pattern in general and not ASP.net MVC framework I understand in MVC (desktop application): 1. User clicks something in view 2. this is passed on to controller to manage 3. controller makes some changes in Model 4. Model calls method on view which has the logic to refresh UI Questions around these: Q1) Can controller also modify View or Model only updates View? Q2) When screen loads for the first time, there is no Model change. Then, who fetches data from model and populates view? View directly calls Model and populates itself OR controller gets data and passes to view method OR some dummy event is raised at Model which updates View?

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  • C++ Singleton design pattern.

    - by Artem Barger
    Recently I've bumped into realization/implementation of Singleton design pattern for C++. It has looked in the following way (I have adopted it from real life example): // a lot of methods is omitted here class Singleton { public: static Singleton* getInstance( ); ~Singleton( ); private: Singleton( ); static Singleton* instance; }; From this declaration I can deduce that instance field is initiated on the heap, that means there is a memory allocation. That is completely unclear for me is when does exactly memory is going to be deallocated? Or there is a bug and memory leak? It seems like there is a problem in implementation. PS. And main question how to implement it in the right way?

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  • Searching for the right pattern to handle login data

    - by stevebot
    Hi all, I'm working on a controller that handles logins for a Web app. These logins will come from multiple clients but will all contain the same data. However, depending on the client, this data will be interpreted into common entities for our webapp differently. For instance, we have a user code that gets sent in, and in one case we may use the first four digits of the code, and in another case 12 digits of the code to map to a field on a User entity. Instead of handling this all in the controller and having big nasty if blocks of logic, I would like to use a pattern to handle how this information gets ingested into our application. What are your opinions?

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  • command design pattern usage

    - by sagie
    Hi. I've read 3 descriptions of the command design pattern: wikipedia, dofactory and source making. In all of them, the UML shows a relation between the client to the receiver & the concrete command, but no relation to the invoker. But in all 3 examples the client is the one that initiates the invoker and call its Execute method. I think that should be a relation to the invoker as well. Am I missing somthing in here? Maybe even a basic UML knowladge?

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  • commad design pattern usage

    - by sagie
    Hi. I've read 3 descriptions of the command design pattern: wikipedia, dofactory and source making. In all of them, the UML shows a relation between the client to the receiver & the concrete command, but no relation to the invoker. But in all 3 examples the client is the one that initiates the invoker and call its Execute method. I think that should be a relation to the invoker as well. Am I missing somthing in here? Maybe even a basic UML knowladge?

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  • Delete the first line that matches a pattern

    - by gioele
    How can I use sed to delete only the first line that contains a certain pattern? For example, I want to remove the first line matching FAA from this document: 1. foo bar quuz 2. foo FAA bar (this should go) 3. quuz quuz FAA (this should remain) 4. quuz FAA bar (this should also remain) The result should be 1. foo bar quuz 3. quuz quuz FAA (this should remain) 4. quuz FAA bar (this should also remain) A solution for POSIX sed would be greatly appreciated, GNU sed is OK.

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  • What's this UI pattern called?

    - by Bears will eat you
    I'm trying to figure out what this sort of thing is called, and eventually how I can create one in a web browser. It looks like this (screenshot of the first app that came to mind): The specific component/pattern I'm looking for is the two list boxes ("Included Gear" and "Excluded Gear") that represent inclusion/exclusion of items from a set. I'm not really looking for the WPF name (if there is one) but it might be helpful. I am looking for the name of this thingy, if there is one, and if you really want to make my day, you can point me toward a jQuery or YUI way of making one of these dealies in a browser. In case you were wondering, the screenshot is a World of Warcraft gear optimization program. Go figure why it was the first program that came to mind when I was trying to think of an example.

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  • Pattern for unidirectional has_many join?

    - by Kris
    It occurred to me that if I have a has_many join, where the foreign model does not have a belongs_to, and so the join is one way, then I don't actually need a foreign key. We could have a column, category_ids, which stores a marshaled Array of IDs which we can pass to find. So here is an untested example: class page < AR def categories Category.find(self.category_ids) end def categories<<(category) # get id and append to category_ids save! end def category_ids @cat_ids ||= Marshal.load(read_attribute(:category_ids)) rescue [] end def category_ids=(ids) @cat_ids = ids write_attribute(:category_ids, ids) end end page.category_ids = [1,4,12,3] page.categories = Array of Category Is there accepted pattern for this already? Is it common or just not worth the effort?

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