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• What elegant method callback design should be used ?

  - by ereOn

  Hi, I'm surprised this question wasn't asked before on SO (well, at least I couldn't find it). Have you ever designed a method-callback pattern (something like a "pointer" to a class method) in C++ and, if so, how did you do it ? I know a method is just a regular function with some hidden this parameter to serve as a context and I have a pretty simple design in mind. However, since things are often more complex than they seem to, I wonder how our C++ gurus would implement this, preferably in an elegant and standard way. All suggestions are welcome !

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• How to handle recursive parent/child problems like this?

  - by lsdude

  In web dev I come across these problems a lot. For example, we have a giant list of URLs that are in this format: /businesses /businesses/food /businesses/food/wendys /businesses/food/wendys/chili /businesses/food/wendys/fries /businesses/food/wendys/chicken-nuggets /businesses/pharmacy/cvs /businesses/pharmacy/cvs/toothpaste /businesses/pharmacy/cvs/toothpaste/brand ... and then we need to output each one, where the parent category is in h1 tags, the child is in h2 tags, and the children of that are in h3 tags. I can handle this but I feel my code is messy. I'm sure there is a design pattern I can use? Langs are ruby/php usually. how would you handle this?

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• What's the fastest way to compare two objects in PHP?

  - by johnnietheblack

  Let's say I have an object - a User object in this case - and I'd like to be able to track changes to with a separate class. The User object should not have to change it's behavior in any way for this to happen. Therefore, my separate class creates a "clean" copy of it, stores it somewhere locally, and then later can compare the User object to the original version to see if anything changed during its lifespan. Is there a function, a pattern, or anything that can quickly compare the two versions of the User object? Option 1 Maybe I could serialize each version, and directly compare, or hash them and compare? Option 2 Maybe I should simply create a ReflectionClass, run through each of the properties of the class and see if the two versions have the same property values? Option 3 Maybe there is a simple native function like objects_are_equal($object1,$object2);? What's the fastest way to do this?

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• When should I use adorners?

  - by Francesco

  Hi all! WPF is great because there are many things to achieve own goals. By example, for what I understand, adorners can add some controls to a UI element, but I think that the same behavior can be achieved through a custom control that contains the additional element. So, my question is: when should I prefer adorners to a more complex (but I think, more flexible) custom control? Please consider that I'm extensively using MVVM pattern and I would like to bind commands to the additional element. Particularly, I'm designing a diagram designer application and I would like to add connection points to my shapes. Thank you

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• Using Remote Web Page to Initialize iPhone App

  - by Chris_K

  My iPhone app relies on a vendor's XML feed to provide data. But that feed is not locked down. The vendor could change the format of the XML at any time, although so far they've promised not to. Since I might want to tell my app to use a different URL for its data source, I'd like to set up a single "Command Central" Web page, on my own server, to direct the app to the correct data source. In other words, each time my app starts, in the background and unseen by the user, it would visit "http://www.myserver.com/iphoneapp_data_sources.xml" to retrieve the URL for retrieving data from my vendor. That way, if my vendor suddenly changes the exact URL or the XML feed that the app needs, I can update that Web page and ensure that all installations of the app are using the correct XML feed. Does anyone have any advice or examples showing this kind of approach? It seems as if this must be a common problem, but so far I haven't found a well-established design pattern that fits it.

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• Optimizing NSNumber numberWithInt:

  - by Riviera

  I am profiling an iPhone app and I noticed a strange pattern. In a certain block of code that's called quite frequently... [item setQuadrant:[NSNumber numberWithInt:a]]; [item setIndex:[NSNumber numberWithInt:b]]; [item setTimestamp:[NSNumber numberWithInt:c]]; [item setState:[NSNumber numberWithInt:d]]; [item setCompletionPercentage:[NSNumber numberWithInt:e]]; [item setId_:[NSNumber numberWithInt:f]]; ...the first call to [NSNumber numberWithInt:] takes an inordinate amount of time, in the order of 10-15x that of the remaining calls. I've verified that the results are consistent if I shuffle the lines (the first line is always the slow one, by the same ratio). Is there something going on that I'm not aware of? Perhaps this happens because this block is inside a try/catch?

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• What is the purpose of this delegate usage?

  - by Kev

  Whilst poking around some code in .NET Reflector in an app I don't have the source code for I found this: if (DeleteDisks) { using (List<XenRef<VDI>>.Enumerator enumerator3 = list.GetEnumerator()) { MethodInvoker invoker2 = null; XenRef<VDI> vdiRef; while (enumerator3.MoveNext()) { vdiRef = enumerator3.Current; if (invoker2 == null) { // // Why do this? // invoker2 = delegate { VDI.destroy(session, vdiRef.opaque_ref); }; } bestEffort(ref caught, invoker2); } } } if (caught != null) { throw caught; } private static void bestEffort(ref Exception caught, MethodInvoker func) { try { func(); } catch (Exception exception) { log.Error(exception, exception); if (caught == null) { caught = exception; } } } Why not call VDI.destroy() directly. Is this just a way of wrapping the same pattern of try { do something } catch { log error } if it's used a lot?

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• Extract dates from filename

  - by Newbie

  I have a situation where I need to extract dates from the file names whose general pattern is [filename_]YYYYMMDD[.fileExtension] e.g. "xxx_20100326.xls" or x2v_20100326.csv The below program does the work //Number of charecter in the substring is set to 8 //since the length of YYYYMMDD is 8 public static string ExtractDatesFromFileNames(string fileName) { return fileName.Substring(fileName.IndexOf("_") + 1, 8); } Is there any better option of achieving the same? I am basically looking for standard practice. I am using C#3.0 and dotnet framework 3.5 Edit: I have like the solution and the way of answerig of LC. I have used his program like string regExPattern = "^(?:.*_)?([0-9]{4})([0-9]{2})([0-9]{2})(?:\\..*)?$"; string result = Regex.Match(fileName, @regExPattern).Groups[1].Value; The input to the function is : "x2v_20100326.csv" But the output is: 2010 instead of 20100326(which is the expected one). Can anyone please help.

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• PHP: get contents of a remote webpage that require authentication?

  - by powerboy

  I receive many emails whose contents are of the same pattern, e.g. Name: XXX Phone: XXX Bio: XXX ...... I want to write a PHP script to parse these emails and save the data into a database. I tried to use file_get_contents() to get the contents of these emails. The problem is that, it requires authentication to access to my emails. Even though I have signed into my email account on the server (localhost actually), file_get_contents() still return the webpage that prompts me to sign in. So how to access the contents of my emails with a PHP script? EDIT: it is a gmail account.

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• Div horizontal aligning, one fixed, one adaptive

  - by Dorian McHensie

  Hello everyone. I would like to create a vertical splitted site structure using two divs: My intention is to have d2 next to d1 in a horizontal align structure (same line). What i get is not this. In fact using that code, d2 does not take the remaining space, but collapses to the min width. if I use WRONG because d2 goes down and takes all the space (but both divs are in different lines). HOW TO REACH MY OBJECTIVE? Is there a design pattern for this problem???? Thanks.

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• Insert A Line At The Beginnig Of A File

  - by thebourneid

  I'm trying to insert/add a line 'COMMENT DUMMY' at the beginnig of a file as a first row if /PATTERN/ not found. I know how to do this with OPEN CLOSE function. Probably after reading the file it should look something like this: open F, ">", $fn or die "could not open file: $!"; ; print F "COMMENT DUMMY\n", @array; close F; But I have a need to implement this with the use of the Tie::File function and don't know how. use strict; use warnings; use Tie::File; my $fn = 'test.txt'; tie my @lines, 'Tie::File', $fn or die "could not tie file: $!"; untie @lines;

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• Joomla forwarding code to the View...is this the correct way to do it?

  - by jax

  Here are some sample methods from my Controller class. Now when the user clicks the New button $task=add is sent to the Controller and the add() method is called. As you can see it does not really do anything, it just creates a url and forwards it off to the correct view. Is this the correct way of doing things in the MVC pattern? /** * New button was pressed */ function add() { $link = JRoute::_('index.php?option=com_myapp&c=apps&view=editapp&cid[]=', false); $this->setRedirect($link); } /** * Edit button was pressed - just use the first selection for editing */ function edit() { $cid = JRequest::getVar( 'cid', array(0), '', 'array' ); $id = $cid[0]; $link = JRoute::_("index.php?option=com_myapp&c=apps&view=editapp&cid[]=$id", false); $this->setRedirect($link); }

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• Avoid Circular Reference in Swing GUI

  - by drhorrible

  Maybe it's not worth worrying about in this scenario, but lets say you have two classes, a JFrame with all its components, and a server-like class that handles requests from remote clients. The user is able to start and stop server objects through the GUI, and is shown various events that happen to each server object. Whether or not I use an explicit pattern (like MVC), it seems like the JFrame needs a reference to the server class (to call start and stop) and the server needs a reference to the JFrame (to notify of it of certain events). Is this a problem, or am I looking at this situation in the wrong way?

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• Keeping historic of modification in a database.

  - by mada

  Hi, Im a j2ee developper & we are using hibernatne mapping with a postgres databasae. We have to keep track of any changes occurs in the databse , in others words alls previous & current value of any field should be saved & field can be various types (bytea, int, char...) With a simple table it is easy but we a graph of objets things are more difficult So we have , speaking in a UML point of view, a graph of objects to store in the database with every changes & the user. Any idea or pattern how to do that ? Thanks in advance.

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• Teacher confused about MVC?

  - by Gideon

  I have an assignment to create a game in java using MVC as a pattern. The thing is that stuff I read about MVC aren't really what the teacher is telling me. What I read is that the Model are the information objects, they are manipulated by the controllers. So in a game the controller mutates the placement of the objects and check if there is any collision etc. What my teacher told me is that I should put everything that is universal to the platform in the models and the controllers should only tell the model which input is given. That means the game loop will be in a model class, but also collision checks etc. So what I get from his story is that the View is the screen, the Controller is the unput handeler, and the Model is the rest. Can someone point me in the right direction?

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• Automating builds from subversion tags

  - by Ajaxx

  I'm trying to automate the build process for engineering group. As part of that automation, I'm trying to get to a point where the act of applying a specific tag that adheres to a pattern will kick off an automated process that will do the following: Check out source code Create a build script from a template Build the project I'm pretty certain I could do this with a post-hook in subversion, but I'm trying to figure out a way to do this with something other than a subversion hook. Would it make sense to monitor the tags directory in the subversion repository to kick off my workflow? Are there any decent tools that help with this (.NET would be great if possible). Am I better off just writing an engine to do this? My preferences: Existing product that does all or part of this If development work needs to occur, .NET is preferable Works with Windows (we've got a Linux based repo, but builds all occur on windows)

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• Text replace with regex in SQL Server

  - by Thiyaneshwaran S

  Currently I have a SQL server column of type nvarchar(max) which has text that starts with <span class="escape_<<digits>>"></span> The only thing that varies in the pattern is the <<digits>> in the class name. The common part is <span class="myclass_ and the closing </span> Some sample values are <span class="myclass_12"></span> <span class="myclass_234"></span> <span class="myclass_4546"></span> These span text are present only at the beginning of the column. Any such matching span in the middle should not be removed or matched. Whats the SQL Server query with regex to remove all these occurances of span?

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• Design guide-lines for writing a Typed SQL Statement API ?

  - by this. __curious_geek

  Last night I came up to sometihng intersting while designing my new project that brought me to ask this qustion here. My project is supposed to follow Table Gateway pattern using tradional ADO.Net datasets for data access. I don't want to write plain queries in my data-access classes. So I came up with an idea of writing a parser kindaa api that exposes objects and methods to generate queries on the move based on my domain objects. Later I want this api to hook up to my Business objects and provide Typed SQL generator api right on the business object instances. Any idea or references how can I do this ? This seems very wide to start with that I'm compelled take your opinions here. Does there anything already exists that can do this ?

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• Controling CRT memory initialization

  - by Ofek Shilon

  Occasionally you meet bugs that are reproducible only in release builds and/or only on some machines. A common (but by no means only) reason is uninitialized variables, that are subject to random behaviour. E.g, an uninitialized BOOL can be TRUE most of the time, on most machines, but randomly be initialized as FALSE. What I wish I would have is a systematic way of flushing out such bugs by modifying the behaviour of the CRT memory initialization. I'm well aware of the MS debug CRT magic numbers - at the very least I'd like to have a trigger to turn 0xCDCDCDCD (the pattern that initializes freshly allocated memory) to zeros. I suspect one would be able to easily smoke out nasty initialization pests this way, even in debug builds. Am I missing an available CRT hook (API, registry key, whatever) that enables this? Anyone has other ideas to get there?

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• Customer provider Password Reset client.

  - by ProfK

  I'm looking for guidence on writing a custom password reset UI, but it must fit the Provider 'Pattern', or degrade silently to built-in defaults. E.g. my Reset Control must collect extra information, and perform differently to the standard Password Recovery Control. It must close as possible use the standard MembershipProvider interface for standard functions, and only use an extended interface for the non-standard stuff. I'd like some reading on issues such as, what must I ask the Membership Provider for, and what must I do myself. What must I tell the provider (service?) about what I do? Etc.

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• Split string into sentences based on periods

  - by rookie

  Hi all, I have written this piece of code that splits a string and stores it in a string array:- String[] sSentence = sResult.split("[a-z]\.\s+"); However, I've added the [a-z] because I wanted to deal with some of the abbreviation problem. But then my result shows up as so:- Furthermore when Everett tried to instruct them in basic mathematics they proved unresponsiv I see that I loose the pattern specified in the split function. Its okay for me to loose the period, but loosing the last letter of the word disturbs its meaning. Could some one help me with this and in addition also could someone help me with dealing with abbreviations? Like because I split the string based on periods, I do not want to loose the abbreviations. Thanks in advance

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• What is the most efficient functional version of the following imperative code?

  - by justin.r.s.

  I'm learning Scala and I want to know the best way of expressing this imperative pattern using Scala's functional programming capabilities. def f(l: List[Int]): Boolean = { for (e <- l) { if (test(e)) return true } } return false } The best I can come up with is along the lines of: l map { e => test(e) } contains true But this is less efficient since it calls test() on each element, whereas the imperative version stops on the first element that satisfies test(). Is there a more idiomatic functional programming technique I can use to the same effect? The imperative version seems awkward in Scala.

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• Inconsistent Routing Results in MVC

  - by HapiDjus

  Seems I'm still missing something to the MVC routing concept. I have a route that follows nearly the same pattern as another route in an area but for what ever reason I get a 404 every time I attempt to run it. I've tried to use Phil Haack's Route Tester DLL and according to that it hits the correct route (matched route comes out to common/itemhistory/{contentid}). When I try to run it for real, it blows up. I'm trying to map a call to a JsonResult by passing a Guid. I've had success with other routes working fine (common is an area in my site). What could I be doing wrong? context.MapRoute( "ItemHistory", "common/itemhistory/{contentid}", new { controller = "common", action = "GetItemHistory" }, new { contentid = @"^(\{){0,1}[0-9a-fA-F]{8}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{4}\-[0-9a-fA-F]{12}(\}){0,1}$" } ); context.MapRoute( "Common_default", "common/{action}", new { controller="common", action = "Index" } );

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• Custom changeable handler when a Service finishes downloading a file

  - by jax

  I have a Service that downloads a file from the internet. What I want is for the response (an InputStream in this case) to be handled by a custom handler that can be switched (like a strategy pattern) but I can't figure out how to do this. So basically the User of the API would be able to plug in different handlers for the response, some would parse XML, others might save files etc. I realise I could pass through the activity context and execute the method from this (given some interface) but I don't want to do this obviously, in case the Activity is closed in the meantime while the file is still downloaded. How might I do this?

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• replace capturing group

  - by Don

  Hi, If I have a regex with a capturing group, e.g. foo(_+f). If I match this against a string and want to replace the first capturing group in all matches with baz so that foo___f blah foo________f is converted to: foobaz blah foobaz There doesn't appear to be any easy way to do this using the standard libraries. If I use Matcher.replaceAll() this will replace all matches of the entire pattern and convert the string to baz blah baz Obviously I can just iterate through the matches, store the start and end index of each capturing group, then go back and replace them, but is there an easier way? Thanks, Don

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