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  • NSMagedObjectContext, threads and NSFechedResultsController

    - by tmpz
    Dear iphone developers, Core Data newbie speaking here. In my application I have two NSManagedObjectContext that refer to that same NSPersistentStorageController. One ManagedObjectContext (c1) is in the main thread --created when I create a NSFetchedResultsController -- and the second ManagedObjectContext (c2) created in a second thread, running in the background, detached from the main thread. In the background thread I pull some data off a website and insert the entities created for the pulled data in the thread's ManagedObjectContext (c2). In the meanwhile, the main thread sits doing nothing and displaying a UITableView whose data do be display should be provided by the NSFetchedResultsController. When the background thread has finished pulling the data and inserting entities in c2, c2 saves, and the background thread notifies the main thread that the processing has finished before it exiting. As a matter of fact, the entities that I have inserted in c2 are know by c1 because it can ask it about one particular entity with [c1 existingObjectWithID:ObjectID error:&error]; I would expect at this point, if I call on my tableview reloadData to see some rows showing up with the data I pulled from the web in the background thread thanks to the NSFetchedResults controller which should react to the modifications of its ManagedObjectContext (c1). But nothing is happening! Only if I restart the application I see what I have previously pulled from the web! Where am I doing things wrong? Thank you in advance!

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  • PHP: Adding arrays together

    - by Svish
    Could someone help me explain this? I have two snippets of code, one works as I expect, but the other does not. This works $a = array('a' => 1, 'b' => 2); $b = array('c' => 3); $c = $a + $b; print_r($c); // Output Array ( [a] => 1 [b] => 2 [c] => 3 ) This does not $a = array('a', 'b'); $b = array('c'); $c = $a + $b; print_r($c); // Output Array ( [a] => 1 [b] => 2 ) What is going on here?? Why doesn't the second version also add the two arrays together? What have I misunderstood? What should I be doing instead? Or is it a bug in PHP?

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  • How can I call a function in a parent movieclip from an externally-loaded child?

    - by Doug Wolfgram
    I have a swf file that is my 'shell' program that contains many functions. This shell program loads child movies. In the root timeline of the child movie, I have the following code: function putresponse(q,r) { trace (r); _root.debug(r); } _root.debug("foo"); Debug is a function that writes some text to the screen. When I run this locally, the putresponse function gets called and the trace happens. When I run it remotely (inside the shell) the first debug happens immediately on load (as you'd expect) but then later when putresponse is called, the debug(r) is not executed. The external clip is at the same url as the shell so I don't think it is a security issue. Also, as I said, the debug("foo") works fine. This one really has me perplexed. Can anyone shed some light as to why I can't call the debug from _root when called from a function rather than on the first-level timeline? EDIT: The call to putresponse is coming form two layers deep in local (within the child MC) MCs. The actual call is: _parent._parent.putrepsonse(q,r);

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  • Mobile site not rendering mobile within iframe

    - by user2788371
    I'm launching a mobile version of an existing corporate web application that currently loads in an iframe for corporate authentication purposes. When accessing the web app's direct link from a mobile device, it displays beautifully. The problem is that when accessing through the iframe, the site doesn't seem to scale correctly and it looks more like I'm accessing the desktop version of the site. Any suggestions on how make the site within the iframe recognize the mobile device's width and adjust appropriately? I've tried setting the viewport within the HTML and CSS of the site being loaded and even then I'm not getting the change I expect on my iPhone. I haven't had the opportunity to test an Android yet but within our company, iOS is the most important. Some of snippets of code I have tried are listed below. I've also tried 480px and device-width (which I believe I can't access because the iframe is a different domain). Unfortunately, modifying the iframe page and settings are not an option. Also, Javascript cannot be used as a solution for other reasons. Within HTML of web app site: <meta name="viewport" content="width=320px, initial-scale=1.0, user-scalable=no" /> Within CSS of web app site: @viewport { width: 320px; } The above CSS does not seem to render even when not used in device specific @media code.

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  • In Lua, can I easily select the Nth result without custom functions?

    - by romkyns
    Suppose I am inserting a string into a table as follows: table.insert(tbl, mystring) and that mystring is generated by replacing all occurrences of "a" with "b" in input: mystring = string.gsub(input, "a", "b") The obvious way to combine the two into one statement doesn't work, because gsub returns two results: table.insert(tbl, string.gsub(input, "a", "b")) -- error! -- (second result of gsub is passed into table.insert) which, I suppose, is the price paid for supporting multiple return values. The question is, is there a standard, built-in way to select just the first return value? When I found select I thought that was exactly what it did, but alas, it actually selects all results from N onwards, and so doesn't help in this scenario. Now I know I can define my own select as follows: function select1(n, ...) return arg[n] end table.insert(tbl, select1(1, string.gsub(input, "a", "b"))) but this doesn't look right, since I'd expect a built-in way of doing this. So, am I missing some built-in construct? If not, do Lua developers tend to use a separate variable to extract the correct argument or write their own select1 functions?

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  • Should I be backing up a webapp's data to another host continuously ?

    - by user196289
    I have webapp in development. I need to plan for what happens if the host goes down. I will lose some very recent session status (which I can live with) and everything else should be persistently stored in the database. If I am starting up again after an outage, can I expect a good host to reconstruct the database to within minutes of where I was up to ? Or seconds ? Or should I build in a background process to continually mirror the database elsewhere ? What is normal / sensible ? Obviously a good host will have RAID and other redundancy so the likelihood of total loss should be low, and if they have periodic backups I should lose only very recent stuff but this is presumably likely to be designed with almost static web content in mind, and my site is transactional with new data being filed continuously (with a customer expectation that I don't ever lose it). Any suggestions / advice ? Are there off the shelf frameworks for doing this ? (I'm primarily working in Java) And should I just plan to save the data or should I plan to have an alternative usable host implementation ready to launch in case the host doesn't come back up in a suitable timeframe ?

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  • java threads don't see shared boolean changes

    - by andymur
    Here the code class Aux implements Runnable { private Boolean isOn = false; private String statusMessage; private final Object lock; public Aux(String message, Object lock) { this.lock = lock; this.statusMessage = message; } @Override public void run() { for (;;) { synchronized (lock) { if (isOn && "left".equals(this.statusMessage)) { isOn = false; System.out.println(statusMessage); } else if (!isOn && "right".equals(this.statusMessage)) { isOn = true; System.out.println(statusMessage); } if ("left".equals(this.statusMessage)) { System.out.println("left " + isOn); } } } } } public class Question { public static void main(String [] args) { Object lock = new Object(); new Thread(new Aux("left", lock)).start(); new Thread(new Aux("right", lock)).start(); } } In this code I expect to see: left, right, left right and so on, but when Thread with "left" message changes isOn to false, Thread with "right" message don't see it and I get ("right true" and "left false" console messages), left thread don't get isOn in true, but right Thread can't change it cause it always see old isOn value (true). When i add volatile modifier to isOn nothing changes, but if I change isOn to some class with boolean field and change this field then threads are see changes and it works fine Thanks in advance.

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  • MVC2 AJAX - determining UpdateTargetId based on the returned data

    - by DanielJW
    The scenario: I'm creating a login form for an MVC2 application. How i'm doing it: The form submits to an MVC2 action which validates the username/password. If it fails validation the action returns the form (a partial view) for the user to try again. If it passes validation the action returns the page the user was visiting before they logged in (a view). What i want to happen: 1 - when the form is submitted and the user validates successfully, The returned result should replace the current page (like what happens if you don't set an UpdateTargetId). 2 - When the form is submitted and the user fails validation, the returned result should replace the form (like what happens if you set the UpdateTargetID to the form's containing element). The problem: I can make both of those things work, but not at the same time. I can either have it always replace the current page, or always just replace the contents of the UpdateTargetId element. But I need it to be able to do either depending on whether the user successfully validated or not. What I need The ideal solution would be to be able to examine the result of the ajax request and determine whether to use the UpdateTargetId (replacing just the form) or not (replacing the whole page). I expect it would involve some work with jquery (assuming it's possible) but i'm not really that great with jquery yet to figure out how to do it myself. If it can't be done this way I'm also open to other methods/solutions for making it work in a similar fashion. Thanks in advance ..

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  • Integration test for H1 text failing when it should be passing (Rspec and Capybara)

    - by rebec
    Below you can see my test for what happens when a user tries to access the page to edit a profile photo that they don't own. I've used the same test on the NEW action, where it worked fine, but it surprised me by failing when I copied it down to the EDIT action tests. I've used save_and_open_page to test what Capybara's seeing (as you can see below); the resulting page definitely has an h1 with the specified text in it. No spelling errors, and case is all the same as in the test. I've tried using both have_css and have_selector. Both fail. I'm still learning Ruby, Rails, Rspec and especially Capybara (was using webrat previously and recently switched over), and wonder if I'm misconceiving of something that's making me expect this to pass when it doesn't. Any thoughts? Thanks! describe "EDIT" do let(:user) { FactoryGirl.create(:user) } let(:different_user) { FactoryGirl.create(:user) } let(:admin_user) { FactoryGirl.create(:user, role: "admin") } let(:profile_photo1) { FactoryGirl.create(:profile_photo, user: user) } subject { page } context "when signed in as any member" do before { login different_user visit edit_user_profile_photo_path(:id => profile_photo1, :user_id => profile_photo1.user_id) save_and_open_page } # It should deny access with an Unauthorised/Forbidden message. it { should have_css('h1', text: "Unauthorised/Forbidden.") } end

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  • Using "as bool?" instead of "object something = ViewState["hi"]"

    - by Programmin Tool
    So I'm going through old code (2.0) and I came across this: object isReviewingValue = ViewState["IsReviewing"]; if (isReviewingValue is bool) { return (bool)isReviewingValue; } My first thought was to us the "as" keyword to avoid the unneeded (bool)isReviewingValue; But "as" only works with non value types. No problem, I just went ahead and did this: bool? isReviewingValue= ViewState["IsReviewing"] as bool?; if (isReviewingValue.HasValue) { return isReviewingValue.Value; } Question is: Besides looking a bit more readable, is this in fact better? EDIT: So this is getting more interesting. I decided to test it using a simple stopwatch and turns out that the second is much faster... Which after reading some of the responses here I didn't expect at all. I was thinking for sure my way was much slower. Tell me what I did wrong: public Stopwatch AsRun() { Stopwatch watch = new Stopwatch(); watch.Start(); for (Int32 loopCounter = 0; loopCounter < 10000; loopCounter++) { Boolean? test = true as Boolean?; if (test.HasValue) { Boolean something = test.Value; } } watch.Stop(); return watch; } public Stopwatch ObjectIsRun() { Stopwatch watch = new Stopwatch(); watch.Start(); for (Int32 loopCounter = 0; loopCounter < 10000; loopCounter++) { Object test = true; if (test is Boolean) { Boolean something = (Boolean)test; } } watch.Stop(); return watch; } Every time I run these methods against each other, the AsRun is twice as fast.

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  • Possible to push a hash value only if it is unique?

    - by Structure
    In the example code below, assuming that the value $keyvalue is constantly changing, I am attempting to use a single line (or something similarly contained) to test and see if the current $keyvalue already exists. If it does, then do nothing. If it does not, then push it. This line would reside within a while statement which is why it needs to be contained within a few lines. Preserving order does not matter as long as there are no duplicate values. my $key = "numbers"; my $keyvalue = 1; my %hash = ($key => '1'); push (@{$hash{$key}}, $keyvalue) unless exists $hash{$key}; I am not getting any errors with use strict; use warnings;, but at the same time this is not working. In the example above, I would expect that since the default value is 1 that the $keyvalue would not be pushed as it is also 1. Perhaps I have gotten myself all turned around... Are there adjustments to get this to work or any alternatives that can be used instead to accomplish the same thing?

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  • Facebook API - Detect if session is active OR NOT active

    - by Tom Doe
    I'm sure I'm simply overlooking something in the Facebook API docs. Basically, after I've loaded the FB Graph, I need to know if the session is active... I cannot simply assume they're logged out and simply re-render if they're logged in once the 'auth.statusChange' event is triggered. I need to know right off the bat. Below is the code that I've used. Most importantly the FB.getLoginStatus/getAuthResponse/getAccessToken don't work like I'd expect; essentially where it indicates, when invoked, whether they're logged in or out. (function(d) { // Create fb-root var fb_root = document.createElement('div'); fb_root.id = "fb-root"; document.getElementsByTagName('body')[0].appendChild( fb_root ); // Load FB Async var js, id = 'facebook-jssdk', ref = d.getElementsByTagName('script')[0]; if (d.getElementById(id)) {return;} js = d.createElement('script'); js.id = id; js.async = true; js.src = "//connect.facebook.net/en_US/all.js"; ref.parentNode.insertBefore(js, ref); // App config-data var config = { appId : XXXX, cookie: true, status: true, frictionlessRequests: true }; window.fbAsyncInit = function() { // This won't work. // I can't assume they're logged out and rely on this to tell me they're logged in. FB.Event.subscribe('auth.statusChange', function(response) {}); // Init FB.init(config); // These do not inidicate if the user is logged out :( FB.getLoginStatus(function(response) { }); FB.getAuthResponse(function(response) { }); FB.getAccessToken(function(response) { }); }; }(document)); Any help is much appreciated. :)

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  • AutoMapper strings to enum descriptions

    - by 6footunder
    Given the requirement: Take an object graph, set all enum type properties based on the processed value of a second string property. Convention dictates that the name of the source string property will be that of the enum property with a postfix of "Raw". By processed we mean we'll need to strip specified characters e.t.c. I've looked at custom formatters, value resolvers and type converters, none of which seems like a solution for this? We want to use AutoMapper as opposed to our own reflection routine for two reasons, a) it's used extensively throughout the rest of the project and b) it gives you recursive traversal ootb. -- Example -- Given the (simple) structure below, and this: var tmp = new SimpleClass { CountryRaw = "United States", Person = new Person { GenderRaw="Male" } }; var tmp2 = new SimpleClass(); Mapper.Map(tmp, tmp2); we'd expect tmp2's MappedCountry enum to be Country.UnitedStates and the Person property to have a gender of Gender.Male. public class SimpleClass1 { public string CountryRaw {get;set;} public Country MappedCountry {get;set;} public Person Person {get;set;} } public class Person { public string GenderRaw {get;set;} public Gender Gender {get;set;} public string Surname {get;set;} } public enum Country { UnitedStates = 1, NewZealand = 2 } public enum Gender { Male, Female, Unknown } Thanks

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  • Need for J2me source code

    - by tikamchandrakar
    For J2me It strikes me as odd that you need an extra "api key" and so on. But actually, what I really want is NOT create an extra facebook application that needs to be registered on Facebook. I don't want to create any extra configuration effords necessary for the user of my application to undergo. All my user should need is his well-known login data for facebook. Everything else should be completely transparent to him. So, I thought maybe would u can do the login process, creating a request to the REST server via http. I know this would provide me with an XML. I hope that the this API will somehow automatically transform that XML into an intuitive object model that represents the facebook user data of the respective user. So, I would expect something like userData = new FacebookData(new FacebookConnection("user_name", "password")). Done. If you get, what I mean. No api key. No secret key. Just the well-known login data. Practically, the equivalent to thunderbird webmail, which allows you to access your MSN hotmail account via Thunderbird. Thunderbird webmail will automatically converts the htmls obtained from a hotmail browser login into the data structure usually passed on to a mail client. Hope you get what I mean. I was expecting the equilalent for the your API.

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  • Why doesn't my <div> float around another floated <div> while other elements do?

    - by user1848605
    I have a container with background color green. Inside that green <div>, I have a <div> which is black and styled as a box (50px x 50px) - this <div> is floated to the left. Now if I add a <p> to my markup after the grey <div>, I'd expect it to float around the grey <div>. And it does. However, when I substitue with another <div> which is styled as box (set height and width), it doesn't float around anymore, but disappears behind the floating div. Even if I have first paragraphs which are floating around correctly and THEN I add the div (box), the paragraphs stop floating around and appear on another line. HTML: <div id="greencontainer"> <div id="blackbox"></div> <!--this one is float:left;--> <p>A paragraph that floats around the previous div</p> <div id="anotherbox"></div> <!-- if I add another div with set width and height, it disappears behind the floated one, and even prevents the paragraph from floating around.--> </div> CSS: #blackbox { width:50px; height:50px; background-color:black; float:left; } #p { margin:0px; padding:0px; } #anotherbox { width:50px; height:50px; background-color:grey; }

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  • No result when Rally.data.WsapiDataStore lacks permissions

    - by user1195996
    I'm calling Ext.create('Rally.data.WsapiDataStore', params), and looking for results with the load event. I'm requesting a number of objects across programs that the user may or may not have read permission for. This works fine for queries where the user has permissions. But in the case where the user does not have permission and presumably gets zero results back, the load event does not seem to fire at all. I would expect it to fire with the unsuccessful flag or else to return with empty results. Since I don't know that the request has failed, my program waits and waits. How can I tell if a this request fails to return because of security? BTW, looking at the network stats, I believe all my requests get a "200 OK" status back. Here is the method I use to create the various data stores: _createDataStore: function(params) { this.openRequests++; var createParams = { model: params.type, autoLoad: true, // So I can later determine which query type it is, and which program requestType: params.requestType == undefined ? params.type : params.requestType, program: this.program, listeners: { load: this._onDataLoaded, scope: this }, filters: params.filters, pageSize: params.pageSize, fetch: params.fetch, context: { project: this.project, projectScopeUp: false, projectScopeDown: true }, pageSize: 1 // We only need the count }; console.log('_createDataStore', this.program, createParams.requestType); Ext.create('Rally.data.WsapiDataStore', createParams); }, And here is the _onDataLoaded method: _onDataLoaded: function(store, data, successB) { console.log('_onDataLoaded', this.program, successB); ... I only see this function called for those queries for which the account has permissions.

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  • How many hours a day (of the standard 8) do you actually work? [closed]

    - by someone
    Possible Duplicate: How much do you [really] work a day When I started working (not so long ago), I was very conscientious about really working. If I didn't work for 10 minutes at a time, I felt like I was cheating. But as I started to look around me, I realized that I was the only one... and most of my coworkers were spending a big percentage of their time browsing the internet or playing solitaire. I started to slack off a little more than usual... while still basically getting all my work done. But while I do all that's required of me, and usually quickly, I no longer beg for work to fill up my spare time; I'm content to do what I'm told and play around when no one makes sure I'm busy enough. Which means that I'm often bored and underutilized. (Which I was even when I begged for work - people are pretty laid back about the workload and don't seem to realize how much I can get done if pushed to the fullest.) But I was just talking to a friend who graduated with me and also recently started working... and she came to me with the same concerns about slacking. She's working remotely, which means there are often gaps in communication when she can't really get anything done... And she's feeling guilty about it. Which made me rethink the whole thing... So, as workers, how many hours, out of the 8 standard average, are you actually working (honestly)? And, as bosses, how many hours do you expect your workers to work? And from an ethical standpoint, how much free time, or space out time, can workers have during the day without being considered to be "cheating" their office of labor and money?

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  • Best way to get distinct values from large table

    - by derivation
    I have a db table with about 10 or so columns, two of which are month and year. The table has about 250k rows now, and we expect it to grow by about 100-150k records a month. A lot of queries involve the month and year column (ex, all records from march 2010), and so we frequently need to get the available month and year combinations (ie do we have records for april 2010?). A coworker thinks that we should have a separate table from our main one that only contains the months and years we have data for. We only add records to our main table once a month, so it would just be a small update on the end of our scripts to add the new entry to this second table. This second table would be queried whenever we need to find the available month/year entries on the first table. This solution feels kludgy to me and a violation of DRY. What do you think is the correct way of solving this problem? Is there a better way than having two tables?

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  • Ignoring a xml Tag in the middle of the file in Regex (with non capturing group ?)

    - by schmirrwurst
    I have an xml with an embeded tag, and I would like to capture everthing but the FType Tags... in python regex. <xml> <EType> <E></E> <F></F> <FType><E1></E1><E2></E2></FType> <FType><E1></E1><E2></E2></FType> <FType><E1></E1><E2></E2></FType> <G></G> </EType> </xml> I tried : (?P<xml>.*(?=<FType>.*<FType>).*) But it give me everything ;-( I Expect : <xml> <EType> <E></E> <F></F> <G></G> </EType> </xml>

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  • What is the difference between _tmain() and main() in C++?

    - by joshcomley
    If I run my C++ application with the following main() method everything is OK: int main(int argc, char *argv[]) { cout << "There are " << argc << " arguments:" << endl; // Loop through each argument and print its number and value for (int i=0; i<argc; i++) cout << i << " " << argv[i] << endl; return 0; } I get what I expect and my arguments are printed out. However, if I use _tmain: int _tmain(int argc, char *argv[]) { cout << "There are " << argc << " arguments:" << endl; // Loop through each argument and print its number and value for (int i=0; i<argc; i++) cout << i << " " << argv[i] << endl; return 0; } It just displays the first character of each argument. What is the difference causing this?

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  • C# keyhook question

    - by user203123
    I copied the following code from http://www.codeproject.com/KB/cs/CSLLKeyboardHook.aspx, public int hookProc(int code, int wParam, ref keyboardHookStruct lParam) { if (code >= 0) { Keys key = (Keys)lParam.vkCode; if (HookedKeys.Contains(key)) { KeyEventArgs kea = new KeyEventArgs(key); if((wParam == WM_KEYDOWN || wParam == WM_SYSKEYDOWN) && (KeyDown != null)) {KeyDown(this, kea) ;} else if ((wParam == WM_KEYUP || wParam == WM_SYSKEYUP) && (KeyUp != null)) {KeyUp(this, kea); } if (kea.Handled) {return 1;} } } lParam.vkCode ++; lParam.scanCode ++; return CallNextHookEx(hhook, code, wParam, ref lParam); } It works fine but when I make a little change: lParam.vkCode ++; or lParam.scanCode ++; right before the return CallNextHookEx(...), the original keys still appears in Notepad. Ex. If I press "a", I expect the letter in Notepad will be "b" but it still "a". It seems like "lParam" doesn't change. Couldn't understand why?

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  • Template specialization to use default type if class member typedef does not exist

    - by Frank
    Hi Everyone, I'm trying to write code that uses a member typedef of a template argument, but want to supply a default type if the template argument does not have that typedef. A simplified example I've tried is this: struct DefaultType { DefaultType() { printf("Default "); } }; struct NonDefaultType { NonDefaultType() { printf("NonDefault "); } }; struct A {}; struct B { typedef NonDefaultType Type; }; template<typename T, typename Enable = void> struct Get_Type { typedef DefaultType Type; }; template<typename T> struct Get_Type< T, typename T::Type > { typedef typename T::Type Type; }; int main() { Get_Type::Type test1; Get_Type::Type test2; } I would expect this to print "Default NonDefault", but instead it prints "Default Default". My expectation is that the second line in main() should match the specialized version of Get_Type, because B::Type exists. However, this does not happen. Can anyone explain what's going on here and how to fix it, or another way to accomplish the same goal? Thank you.

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  • 2 basic but interesting questions about .NET

    - by b-gen-jack-o-neill
    Hi, when I first saw C#, I thought this must be some joke. I was starting with programming in C. But in C# you could just drag and drop objects, and just write event code to them. It was so simple. Now, I still like C the most, becouse I am very attracted to the basic low level operations, and C is just next level of assembler, with few basic routines, so I like it very much. Even more becouse I write little apps for microcontrollers. But yeasterday I wrote very simple control program for my microcontroller based LED cube in asm, and I needed some way to simply create animation sequences to the Cube. So, I remembered C#. I have practically NO C# skills, but still I created simple program to make animation sequences in about hour with GUI, just with help of google and help of the embeded function descriptions in C#. So, to get to the point, is there some other reason then top speed, to use any other language than C#? I mean, it is so effective. I know that Java is a bit of similiar, but I expect C# to be more Windows effective since its directly from Microsoft. The second question is, what is the advantage of compiling into CIL, and than run by CLR, than directly compile it into machine code? I know that portability is one, but since C# is mainly for Windows, wouldn´t it be more powerfull to just compile it directly? Thanks.

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  • for loop vs std::for_each with lambda

    - by Andrey
    Let's consider a template function written in C++11 which iterates over a container. Please exclude from consideration the range loop syntax because it is not yet supported by the compiler I'm working with. template <typename Container> void DoSomething(const Container& i_container) { // Option #1 for (auto it = std::begin(i_container); it != std::end(i_container); ++it) { // do something with *it } // Option #2 std::for_each(std::begin(i_container), std::end(i_container), [] (typename Container::const_reference element) { // do something with element }); } What are pros/cons of for loop vs std::for_each in terms of: a) performance? (I don't expect any difference) b) readability and maintainability? Here I see many disadvantages of for_each. It wouldn't accept a c-style array while the loop would. The declaration of the lambda formal parameter is so verbose, not possible to use auto there. It is not possible to break out of for_each. In pre- C++11 days arguments against for were a need of specifying the type for the iterator (doesn't hold any more) and an easy possibility of mistyping the loop condition (I've never done such mistake in 10 years). As a conclusion, my thoughts about for_each contradict the common opinion. What am I missing here?

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  • Is there a way to update the height of a single UITableViewCell, without recalculating the height for every cell?

    - by Chris Vasselli
    I have a UITableView with a few different sections. One section contains cells that will resize as a user types text into a UITextView. Another section contains cells that render HTML content, for which calculating the height is relatively expensive. Right now when the user types into the UITextView, in order to get the table view to update the height of the cell, I call [self.tableView beginUpdates]; [self.tableView endUpdates]; However, this causes the table to recalculate the height of every cell in the table, when I really only need to update the single cell that was typed into. Not only that, but instead of recalculating the estimated height using tableView:estimatedHeightForRowAtIndexPath:, it calls tableView:heightForRowAtIndexPath: for every cell, even those not being displayed. Is there any way to ask the table view to update just the height of a single cell, without doing all of this unnecessary work? Update I'm still looking for a solution to this. As suggested, I've tried using reloadRowsAtIndexPaths:, but it doesn't look like this will work. Calling reloadRowsAtIndexPaths: with even a single row will still cause heightForRowAtIndexPath: to be called for every row, even though cellForRowAtIndexPath: will only be called for the row you requested. In fact, it looks like any time a row is inserted, deleted, or reloaded, heightForRowAtIndexPath: is called for every row in the table cell. I've also tried putting code in willDisplayCell:forRowAtIndexPath: to calculate the height just before a cell is going to appear. In order for this to work, I would need to force the table view to re-request the height for the row after I do the calculation. Unfortunately, calling [self.tableView beginUpdates]; [self.tableView endUpdates]; from willDisplayCell:forRowAtIndexPath: causes an index out of bounds exception deep in UITableView's internal code. I guess they don't expect us to do this. I can't help but feel like it's a bug in the SDK that in response to [self.tableView endUpdates] it doesn't call estimatedHeightForRowAtIndexPath: for cells that aren't visible, but I'm still trying to find some kind of workaround. Any help is appreciated.

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