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• Why is Javascript's Math.floor the slowest way to calculate floor in Javascript?

  - by z5h

  I'm generally not a fan of microbenchmarks. But this one has a very interesting result. http://ernestdelgado.com/archive/benchmark-on-the-floor/ It suggests that Math.floor is the SLOWEST way to calculate floor in Javascript. ~~n, n|n, n&n all being faster. This seems pretty shocking as I would expect that people implementing Javascript in today's modern browsers would be some pretty smart people. Does floor do something important that the other methods fail to do? Is there any reason to use it?

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• Style of if: to nest or not to nest

  - by Marco

  A colleague of mine and me had a discussion about the following best-practice issue. Most functions/methods start with some parameter checking. I advocate the following style, which avoids nesting. if (parameter one is ugly) return ERROR; if (parameter two is nonsense || it is raining) return ERROR; // do the useful stuff return result; He, who comes from a more functional/logic programming background, prefers the following, because it reduces the number of exit points from the function. if (parameter one is ok) { if (parameter two is ok && the sun is shining) { // do the useful stuff return result } } return ERROR; Which one would you prefer and why?

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• Is this an UITableView -beginUpdates documentation error?

  - by mystify

  I can't wrap my head around what they tried to say here in the docs for -beginUpdate: Call this method if you want subsequent insertions, deletion, and selection operations (for example, cellForRowAtIndexPath: and indexPathsForVisibleRows) to be animated simultaneously. Let's see... cellForRowAtIndexPath: and indexPathsForVisibleRows are both GETTER methods. They do not update anything and do not change anything. So why should I call -beginUpdates before calling these? And what's animated regarding these? Well, nothing, huh? Just want to make sure this is really an error in the docs and I didn't miss something.

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• Log with timestamps that have millisecond accuracy & resolution in Windows C++

  - by Psychic

  I'm aware that for timing accuracy, functions like timeGetTime, timeBeginPeriod, QueryPerformanceCounter etc are great, giving both good resolution & accuracy, but only based on time-since-boot, with no direct link to clock time. However, I don't want to time events as such. I want to be able to produce an exact timestamp (local time) so that I can display it in a log file, eg 31-12-2010 12:38:35.345, for each entry made. (I need the millisecond accuracy) The standard Windows time functions, like GetLocalTime, whilst they give millisecond values, don't have millisecond resolution, depending on the OS running. I'm using XP, so I can't expect much better than about a 15ms resolution. What I need is a way to get the best of both worlds, without creating a large overhead to get the required output. Overly large methods/calculations would mean that the logger would start to eat up too much time during its operation. What would be the best/simplest way to do this?

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• Please recommend good books for telemetry / SCADA system design & programming

  - by Mawg

  I am looking at several projects, all with roughly the same fucntionality. Some instruments collect some data (or control some functionality). They commmunicate by Internet (Etehrnet/wifi/GPRS/sasatellite) with a databse server which stores the measurements and provides a browser based means of qeurying the data, prodcuing reports, etc (and possibly also allows control of the remote equipment). Can anyone recommend a good book describing an approach to developing such a software architecture, keeping it generic, which tools, languages. test methods, etc to use? (note to self: ask a similar question about possible existing frameworks)

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• Checking if an object has been released before sending a message to it

  - by Tom Irving

  I've only recently noticed a crash in one of my apps when an object tried to message its delegate and the delegate had already been released. At the moment, just before calling any delegate methods, I run this check: if (delegate && [delegate respondsToSelector:...]){ [delegate ...]; } But obviously this doesn't account for if the delegate isn't nil, but has been deallocated. Besides setting the object's delegate to nil in the delegate's dealloc method, is there a way to check if the delegate has already been released just incase I no longer have a reference to the object.

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• Using Routing helpers in a Rake task

  - by trobrock

  I have a rake task that sends out the next 'x' invitations to join a beta it uses this code: desc "This will send out the next batch of invites for the beta" task :send_invites => :environment do limit = ENV['limit'] c = 0 invitation = Invitation.all(:conditions => { :sent_at => nil, :sender_id => nil }, :limit => limit).each do |i| Mailer.deliver_invitation(i, register_url(i.token)) c.increment! end puts "Sent #{c} invitations." end I need to pass in the 'register_url' to the Mailer in order for the link to show up in the email, but since this is running from a rake task and not from a request it does not have a access to the helper methods. What is the best way of achieving this?

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• Navigating from VB.NET code to C# code problem

  - by user181218

  Hi, There seemes to be a consistent problem with the following situation: Say you have a VS2008 solution, consisting of a (say console) application written in vb.net, and a class library written in c#. The application references the class library project. This, of course, complies and works well. However, when you right-click (in the vb.net application code) a function prototype/object type defined in the class library, and select "Go to definition", the object browser opens providing you with the the list of methods available for the class the class library consists of. BAD. However, if you try to do the same when both the application and cl are in c#, this works just fine and you navigate driectly to the relevant function/class.GOOD. Known issue? Solvable?

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• Fast parsing of PHP in C#

  - by Jessica Shea

  Hello there, I've got a requirement for parsing PHP files in C#. We essentially require some of the devs in another country to upload PHP files and once uploaded we need to check the php files and get a list of all the methods and classes/functions etc. I thought of using a regex but I can't workout if a function belongs to a class etc, so I was wondering if theres already something 'out there' that will parse out PHP files and spit out its functions (I'm trying to avoid writing a full blow AST implementation). Does anyone have any idea? I looked at Coco/R but I couldn't find a PHP grammar file. I'm using .NET 2.0 and C#.

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• linq "let" translation

  - by luke

  I understand that when the C# compiler sees a linq query comprehension, it basically does a straight translation to the corresponding Linq Extension methods and lambdas. i.e. from x in list select x.property gets translated to: list.Select(x => x.property) my question is what do let clauses get translated to. for example how would this get translated by the compiler. from x in list let v = SomeComplexExpressionDependingOnx select v (p.s. i know this could be reduced to just select SomeComplexExpressionDependingOnx but i want to know how this is done in general) Thanks!

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• Reference Value Parameter VS Return value which one is good?

  - by CodeYun

  When we want to modify some value in one object we may use two different methods, just want to know which one is better or there is no big different between them. void SomeMethod() { UserInfo newUser = New UserInfo(); ModifyUserInfo(newUser); //Modify UserInfo after calling void method GetUserInfo } void ModifyUserInfo(UseerInfo userInfo) { userInfo.UserName = "User Name"; ..... } void SomeMethod() { UserInfo newUser = New UserInfo(); //Assign new userinfo explicitly newUser = GetUserInfo(newUser); } UserInfo ModifyUserInfo(UseerInfo userInfo) { userInfo.UserName = "User Name"; ..... return userInfo; }

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• Visual Studio - easy way to bring up type definition as source code

  - by Igor Zevaka

  Oftentimes I want to bring up a system class in a source view, so that I can browse the properties and methods exposed by the class in a source view. Below is the screenshot of what I mean: Usually I do this by selecting the class name and pressing F12 (or right clickGo To Definition). However, if I haven't got it anywhere ready, i have type it up and then do Go To Definition. Most of the time I have to delete what I typed later on. Is there a way to bring up this view without having to type the class name? The VS2010 Navigate To dialog doesn't support this.

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• Scroll Gestures not Passed to IScrollInfo implementing panel in Windows Phone 7 CTP

  - by user50088

  I am using a custom panel as a ItemsPanel for a ItemsControl in a with a custom template that provides for a scroll viewer. (See Xaml below.) So long as my panel does not implement IScrollInfo, scrolling works in this scenerio. I implement IScrollInfo and update my viewport and extent sizes in measure override. The scroll bar shows the correct relative size, and if I call the IScrollInfo methods directly, scrolling works as expected. However, the drag and flick gestures no longer scroll the content. Putting a breakpoint on the input of every IScrollInfo method shows that drag and pick are not calling the interface. Removing the IScrollInfo interface declaration restores the scroll on drag and flick behavior. Is there a simple way to restore the flick and pan gestures to ItemControls with panels that implement IScrollInfo?

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• Anonymous types based in Interface

  - by Bhaskar

  Can I create anonymous implementations of an interface , in a way similar to the way delegate() { // type impl here , but not implementing any interface} Something on the lines of new IInterface() { // interface methods impl here } The situations where I see them to be useful are for specifying method parameters which are interface types, and where creating a class type is too much code. For example , consider like this : public void RunTest() { Cleanup(delegate() { return "hello from anonymous type"; }); } private void Cleanup(GetString obj) { Console.WriteLine("str from delegate " + obj()); } delegate string GetString(); how would this be achieved if in the above code , the method Cleanup had an interface as a parameter , without writing a class definition ? ( I think Java allows expressions like new Interface() ... )

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• Designing constructors around type erasure in Java

  - by Internet Friend

  Yesterday, I was designing a Java class which I wanted to be initalized with Lists of various generic types: TheClass(List<String> list) { ... } TheClass(List<OtherType> list) { ... } This will not compile, as the constructors have the same erasure. I just went with factory methods differentiated by their names instead: public static TheClass createWithStrings(List<String> list) public static TheClass createWithOtherTypes(List<OtherType> list) This is less than optimal, as there isn't a single obvious location where all the different options for creating instances are available. I tried to search for better design ideas, but found surprisingly few results. What other patterns exist for designing around this problem?

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• How to keep the popup menu of a JComboBox open on populating it ?

  - by Stormshadow

  I have a JComboBox on my Panel. One of the popup menu items is 'More' and when I click that I fetch more menu items and add them to the existing list. After this, I wish to keep the popup menu open so that the user realizes that more items have been fetched however, the popup closes. The event handler code I am using is as follows public void actionPerformed(ActionEvent e) { if (e.getSource() == myCombo) { JComboBox selectedBox = (JComboBox) e.getSource(); String item = (String) selectedBox.getSelectedItem(); if (item.toLowerCase().equals("more")) { fetchItems(selectedBox); } selectedBox.showPopup(); selectedBox.setPopupVisible(true); } } private void fetchItems(JComboBox box) { box.removeAllItems(); /* code to fetch items and store them in the Set<String> items */ for (String s : items) { box.addItem(s); } } I do not understand why the showPopup() and setPopupVisible() methods are not functioning as expected.

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• Looking for a C# code parser

  - by Blindy

  I'm looking for a set of classes (preferably in the .net framework) that will parse C# code and return a list of functions with parameters, classes with their methods, properties etc. Ideally it would provide all that's needed to build my own intellisense. I have a feeling something like this should be in the .net framework, given all the reflection stuff they offer, but if not then an open source alternative is good enough. What I'm trying to build is basically something like Snippet Compiler, but with a twist. I'm trying to figure out how to get the code dom first. I tried googling for this but I'm not sure what the correct term for this is so I came up empty.

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• does a switch idiom make sense in this case?

  - by the ungoverned

  I'm writing a parser/handler for a network protocol; the protocol is predefined and I am writing an adapter, in python. In the process of decoding the incoming messages, I've been considering using the idiom I've seen suggested elsewhere for "switch" in python: use a hash table whose keys are the field you want to match on (a string in this case) and whose values are callable expressions: self.switchTab = { 'N': self.handleN, 'M': self.handleM, ... } Where self.handleN, etc., are methods on the current class. The actual switch looks like this: self.switchTab[selector]() According to some profiling I've done with cProfile (and Python 2.5.2) this is actually a little bit faster than a chain of if..elif... statements. My question is, do folks think this is a reasonable choice? I can't imagine that re-framing this in terms of objects and polymorphism would be as fast, and I think the code looks reasonably clear to a reader.

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• What are the pro and cons of having localization files vs hard coded variables in source code?

  - by corgrath

  Definitions: Files: Having the localization phrases stored in a physical file that gets read at application start-up and the phrases are stored in the memory to be accessed via util-methods. The phrases are stored in key-value format. One file per language. Variables: The localization texts are stored as hard code variables in the application's source code. The variables are complex data types and depending on the current language, the appropriate phrase is returned. Background: The application is a Java Servlet and the developers use Eclipse as their primary IDE. Some brief pro and cons: Since Eclipse is use, tracking and finding unused localizations are easier when they are saved as variables, compared to having them in a file. However the application's source code becomes bigger and bloated. What are the pro and cons of having localization text in files versus hard coded varibles in source code? What do you do and why?

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• What free expert system can You recommend (with higher functionality then CLIPS)?

  - by Martin

  Hi, I'm trying to find best free expert system, with the highest functionality. I know about CLIPS, but is there another system, for example being able to accept percent of confidence for each rule (fuzzy logic). I need it to know will I be able to do fast a short project using expert system, with highest functionality. But anyways, it's interesting is there an open source program that aims to gather different AI methods (whitch there are plenty of), and use them together. So I would be extremely thankeful for any info about more robust CLIPS, or similar programs. Thanks!

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• How to show a ProgressDialog while changing from a activity to another activity?

  - by AndroidUser99

  i want to show a PD when my activity A starts another activity B. But in that onclick method, my A activity haves to do some work before start B, and B also haves to do some work because it haves to load a lot of data for the UI. I need a PD that is viewed by the user in all the process of the loading data of changin from activity A to B. ¿how can do it? i tryed storing a static ProgressDialog on MyApplication.java, and with these methods: public static void showProgressDialog(Context c) { pd = ProgressDialog.show(c, c.getResources().getString(R.string.app_name), c.getResources().getString(R.string.loading), true, false); } public static void dismissProgressDialog(){ pd.dismiss(); } but it doesn't works, it doesn't shows nothing, i dont know why how to achieve this by a easy way? i know that i can do it with async task, but that is too hard for me, i can't understand the code examples i am finding on this web and google code examples are welcome thanks

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• changing a picker to table view OR having multiple table views on the same view

  - by Brodie4598

  Hello - My iPad app was rejected due to my use of a picker. The picker was used to control a table view. In my view, a picker was displaying a series of items and when one of those items was selected, it used that selection to populate a table with data. (hopefully that makes sense). Now I need to do this without the picker so I need to have the data that was in the picker be represented in a table view. My question, is how do I have multiple tableViews in the same view? I'm guessing I need to have some kind of if statement in the tableview delegate methods, but I'm not quite sure what the if statement needs to be. Or maybe i'm thinking of this the totally wrong way thanks

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• Select a data template by item type programatically in WPF

  - by Michael Stoll

  Hi all, unfortunately the WPF ToolbarTray does not support binding to a collection of ToolbarViewModels (Correct me, if I'm wrong). Thus I want to create the Toolbars programmatically. So there are two tasks, which I don't know how to do: Select the data template based on the item type. Instantiate the data template as toolbar Both should do the same as WPF does, when we use ItemsControl with an enumerable content and empty template. I used reflector to anaylse what WPF does. Task 1 is done by FrameworkElement.FindTemplateResourceInternal, but this is internal, and I couldn't find any public methods to acomplish the task. Of course one could enumerate all resources and match the data template data type property, but this seems sub-optimal. Who know's how to acomplish these tasks?

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• How can I add a field with an array value to my Perl object?

  - by superstar

  What's the difference between these two constructors in perl? 1) sub new { my $class = shift; my $self = {}; $self->{firstName} = undef; $self->{lastName} = undef; $self->{PEERS} = []; bless ($self, $class); return $self; } 2) sub new { my $class = shift; my $self = { _firstName => shift, _lastName => shift, _ssn => shift, }; bless $self, $class; return $self; } I am using the second one so far, but I need to implement the PEERS array in the second one? How do I do it with the second constructor and how can we use get and set methods on those array variables?

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• Is it safe to call a function to intialize a class in a ctor list?

  - by Michael Dorgan

  I have Angle class that I want initialized to a random value. The Angle constructor can accept an int from a random() function. Is it safe to place this call in the ctor list: foo::foo() : Angle(random(0xFFFF)) {...} or do I have to do it in the body of the constructor? foo::foo() { Angle = Angle(random(0xFFFF)); ...} If it matters, the foo class is derived from another class and does have virtual methods. In addition, no exception handling is allowed in our app.

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