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• "Find all tiles connected to this one" project

  - by Omega

  Remember MS Paint? The bucket tool? If you used it and clicked on a pixel, all pixels connected to this pixel that are the same are affected. The theory is, I suppose, to check if there is any pixel adjacent to the selected one. If such pixel is the same type as the selected one, check for more adjacent pixels in this one, and so on. I want to implement something similar in VB.NET. Basically I have a 2D array map which represents the map. Let's assume there are only two types of tile: 0 and 1. Now, I got pretty much everything ready: I got my 2d map and I can tell which tile is clicked and tell what array indexes are the ones that represent such tile. Now for the "painting" process. Whenever I think about it, I can't figure a convenient way to execute such iteration. Can someone help me choosing a correct design/way/tip to achieve this?

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• "pseudo-atomic" operations in C++

  - by dan

  So I'm aware that nothing is atomic in C++. But I'm trying to figure out if there are any "pseudo-atomic" assumptions I can make. The reason is that I want to avoid using mutexes in some simple situations where I only need very weak guarantees. 1) Suppose I have globally defined volatile bool b, which initially I set true. Then I launch a thread which executes a loop while(b) doSomething(); Meanwhile, in another thread, I execute b=true. Can I assume that the first thread will continue to execute? In other words, if b starts out as true, and the first thread checks the value of b at the same time as the second thread assigns b=true, can I assume that the first thread will read the value of b as true? Or is it possible that at some intermediate point of the assignment b=true, the value of b might be read as false? 2) Now suppose that b is initially false. Then the first thread executes bool b1=b; bool b2=b; if(b1 && !b2) bad(); while the second thread executes b=true. Can I assume that bad() never gets called? 3) What about an int or other builtin types: suppose I have volatile int i, which is initially (say) 7, and then I assign i=7. Can I assume that, at any time during this operation, from any thread, the value of i will be equal to 7? 4) I have volatile int i=7, and then I execute i++ from some thread, and all other threads only read the value of i. Can I assume that i never has any value, in any thread, except for either 7 or 8? 5) I have volatile int i, from one thread I execute i=7, and from another I execute i=8. Afterwards, is i guaranteed to be either 7 or 8 (or whatever two values I have chosen to assign)?

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• Switching Between Cards in a CardLayout using getParent()

  - by plutoisaplanet

  Hey everyone, I am writing an application where I am using the CardLayout to swap between two panels that are placed right on top of one another. There's a JPanel called Top, and it's layout is the CardLayout. Inside this JPanel is a JPanel called CMatch. Whenever the user clicks the submit button in the CMatch panel, I want a new JPanel added to Top that is custom built based on what the user types in, and it will be shown instead of the original CMatch panel. All of this done using the CardLayout. These are all different classes in different files, however (the panel Top with CardLayout, the panel CMatch that is inside the Top panel, and the custom built panel). So i tried using the following to add the new panel to the Top panel and then have it shown: (this code takes place in the CMatch class): private void submitButtionActionPerformed(ActionEvent e) { CardLayout cl = (CardLayout)(this.getParent().getLayout()); cl.addLayoutComponent(new CChoice(), "college_choices"); cl.show(this.getParent(), "college_choices"); } However, this didn't work. So i was wondering, what am I doing wrong? Any advice is greatly appreciated, thanks!

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• Prevent coersion to a single type in unlist() or c(); passing arguments to wrapper functions

  - by Leo Alekseyev

  Is there a simple way to flatten a list while retaining the original types of list constituents?.. Is there a way to programmatically construct a heterogeneous list?.. For instance, I want to create a simple wrapper for functions like png(filename,width,height) that would take device name, file name, and a list of options. The naive approach would be something like my.wrapper <- function(dev,name,opts) { do.call(dev,c(filename=name,opts)) } or similar code with unlist(list(...)). This doesn't work because opts gets coerced to character, and the resulting call is e.g. png(filename,width="500",height="500"). If there's no straightforward way to create heterogeneous lists like that, is there a standard idiomatic way to splice arguments into functions without naming them explicitly (e.g. do.call(dev,list(filename=name,width=opts["width"]))? -- Edit -- Gavin Simpson answered both questions below in his discussion about constructing wrapper functions. Let me give a summary of the answer to the title question: It is possible to construct a heterogeneous list with c() provided the arguments to c() are lists. To wit: > foo <- c("a","b"); bar <- 1:3 > c(foo,bar) [1] "a" "b" "1" "2" "3" > c(list(foo),list(bar)) [[1]] [1] "a" "b" [[2]] [1] 1 2 3 > c(as.list(foo),as.list(bar)) ## this creates a flattened heterogeneous list [[1]] [1] "a" [[2]] [1] "b" [[3]] [1] 1 [[4]] [1] 2 [[5]] [1] 3

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• Vector Usage in MPI(C++)

  - by lsk1985

  I am new to MPI programming,stiil learning , i was successful till creating the Derived data-types by defining the structures . Now i want to include Vector in my structure and want to send the data across the Process. for ex: struct Structure{ //Constructor Structure(): X(nodes),mass(nodes),ac(nodes) { //code to calculate the mass and accelerations } //Destructor Structure() {} //Variables double radius; double volume; vector<double> mass; vector<double> area; //and some other variables //Methods to calculate some physical properties Now using MPI i want to sent the data in the structure across the processes. Is it possible for me to create the MPI_type_struct vectors included and send the data? I tried reading through forums, but i am not able to get the clear picture from the responses given there. Hope i would be able to get a clear idea or approach to send the data PS: i can send the data individually , but its an overhead of sending the data using may MPI_Send/Recieve if we consider the domain very large(say 10000*10000)

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• Memory allocation patterns in C++

  - by Mahatma

  I am confused about the memory allocation in C++ in terms of the memory areas such as Const data area, Stack, Heap, Freestore, Heap and Global/Static area. I would like to understand the memory allocation pattern in the following snippet. Can anyone help me to understand this. If there any thing more apart from the variable types mentioned in the example to help understand the concept better please alter the example. class FooBar { int n; //Stored in stack? public: int pubVar; //stored in stack? void foo(int param) //param stored in stack { int *pp = new int; //int is allocated on heap. n = param; static int nStat; //Stored in static area of memory int nLoc; //stored in stack? string str = "mystring"; //stored in stack? .. if(CONDITION) { static int nSIf; //stored in static area of memory int loopvar; //stored in stack .. } } } int main(int) { Foobar bar; //bar stored in stack? or a part of it? Foobar *pBar; //pBar is stored in stack pBar = new Foobar(); //the object is created in heap? What part of the object is stored on heap } EDIT: What confuses me is, if pBar = new Foobar(); stores the object on the heap, how come int nLoc; and int pubVar;, that are components of the object stored on stack? Sounds contradictory to me. Shouldn't the lifetime of pubvar and pBar be the same?

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• Accessing both stored procedure output parameters AND the result set in Entity Framework?

  - by MS.

  Is there any way of accessing both a result set and output parameters from a stored procedure added in as a function import in an Entity Framework model? I am finding that if I set the return type to "None" such that the designer generated code ends up calling base.ExecuteFunction(...) that I can access the output parameters fine after calling the function (but of course not the result set). Conversely if I set the return type in the designer to a collection of complex types then the designer generated code calls base.ExecuteFunction<T>(...) and the result set is returned as ObjectResult<T> but then the value property for the ObjectParameter instances is NULL rather than containing the proper value that I can see being passed back in Profiler. I speculate the second method is perhaps calling a DataReader and not closing it. Is this a known issue? Any work arounds or alternative approaches? Edit My code currently looks like public IEnumerable<FooBar> GetFooBars( int? param1, string param2, DateTime from, DateTime to, out DateTime? createdDate, out DateTime? deletedDate) { var createdDateParam = new ObjectParameter("CreatedDate", typeof(DateTime)); var deletedDateParam = new ObjectParameter("DeletedDate", typeof(DateTime)); var fooBars = MyContext.GetFooBars(param1, param2, from, to, createdDateParam, deletedDateParam); createdDate = (DateTime?)(createdDateParam.Value == DBNull.Value ? null : createdDateParam.Value); deletedDate = (DateTime?)(deletedDateParam.Value == DBNull.Value ? null : deletedDateParam.Value); return fooBars; }

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• Using MPI_Type_Vector and MPI_Gather, in C.

  - by Goloneg

  Hi, I am trying to multiply square matrices in parallele with MPI. I use a MPI_Type_vector to send square submatrixes (arrays of float) to the processes, so they can calculate subproducts. Then, for the next iterations, these submatrices are send to neighbours processes as MPI_Type_contiguous (the whole submatrix is sent). This part is working as expected, and local results are corrects. Then, I use MPI_Gather with the contiguous types to send all local results back to the root process. The problem is, the final matrix is build (obviously, by this method) line by line instead of submatrix by submatrix. I wrote an ugly procedure rearranging the final matrix, but I would like to know if there is a direct way of performing the "inverse" operation of sending MPI_Type_vectors (i.e., sending an array of values and directly arranging it in a subarray form in the receiving array). An example, to try and clarify my long text : A[16] and B[16] are 4x4 matrices to be multiplied ; C[16] will contain the result ; 4 processes are used (Pi with i from 0 to 3) : Pi gets two 2x2 submatrices : subAi[4] and subBi[4] ; their product is stored locally in subCi[4]. For instance, P0 gets : subA0[4] containing A[0], A[1], A[4] and A[5] ; subB0[4] containing B[0], B[1], B[4] and B[5]. After everything is calculed, root process gathers all subCi[4]. Then C[16] contains : [ subC0[0], subC0[1], subC0[2], subC0[3], subC1[0], subC1[1], subC1[2], subC1[3], subC2[0], subC2[1], subC2[2], subC2[3], subC3[0], subC3[1], subC3[2], subC3[3]] and I would like it to be : [ subC0[0], subC0[1], subC1[0], subC1[1], subC0[2], subC0[3], subC1[2], subC1[3], subC2[0], subC2[1], subC3[0], subC3[1], subC2[2], subC2[3], subC3[2], subC3[3]] without further operation. Does someone know a way ? Thanks for your advices.

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• Nginx Rails app can't deploy

  - by user3596718

  I have an issue with my rails application running with passenger and nginx hosted in Ubuntu 12.04. In the nginx.conf file below, my "example.com" (Regular HTML) and "redmine.example.com" (Rails app) are working perfectly, but my "crete.example.com" (Another Rails app) is showing "502 bad gateway". I have them both hosted in /var/data with the same permissions and ownerships, also tried different ports, I can't think of something else to try. worker_processes 1; events { worker_connections 1024; } http { passenger_root /usr/lib/ruby/vendor_ruby/phusion_passenger/locations.ini; include mime.types; default_type application/octet-stream; sendfile on; keepalive_timeout 65; server{ listen 80; server_name example.com; root /opt/nginx/html; } server{ server_name redmine.example.com; root /var/data/redmine/public; passenger_enabled on; location ~ ^/<SUBURI>(/.*|$){ alias /var/data/redmine/public$1; passenger_base_uri /redmine; passenger_app_root /var/data/redmine; passenger_document_root /var/data/redmine/public; passenger_enabled on;} } server{ server_name crete.example.com; root /var/data/crete/public; passenger_enabled on; location ~ ^/<SUBURI>(/.*|$){ alias /var/data/crete/public$1; passenger_base_uri /crete; passenger_app_root /var/data/crete; passenger_document_root /var/data/crete/public; passenger_enabled on;} } } This are my Ruby and Rails versions: ruby 2.0.0p451 (2014-02-24 revision 45167) [x86_64-linux] Rails 4.1.0 My nginx error.log 2014/05/02 12:29:50 [error] 3343#0: *4 upstream prematurely closed connection while reading response header from upstream, client: xxx.xx.xx.xx, server: crete.example.com, request: "GET / HTTP/1.1", upstream: "passenger:/tmp/passenger.1.0.3 323/generation-0/request:", host: "crete.example.com" Any other conf file you might need to solve this don't hesitate to ask.

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• MDX: Filtering a member set by a measure's table values

  - by oyvinro

  I have some numbers in a fact table, and have generated a measure which use the SUM aggregator to summarize the numbers. But the problem is that I only want to sum the numbers that are higher than, say 10. I tried using a generic expression in the measure definition, and that works of course, but the problem is that I need to be able to dynamically set that value, because it's not always 10, meaning users should be able to select it themselves. More specifically, my current MDX looks like this: WITH SET [Email Measures] AS '{[Measures].[Number Of Answered Cases], [Measures].[Max Expedition Time First In Case], [Measures].[Avg Expedition Times First In Case], [Measures].[Number Of Incoming Email Requests], [Measures].[Avg Number Of Emails In Cases], [Measures].[Avg Expedition Times Total],[Measures].[Number Of Answered Incoming Emails]}' SET [Organizations] AS '{[Organization.Id].[860]}' SET [Operators] AS '{[Operator.Id].[3379],[Operator.Id].[3181]}' SET [Email Accounts] AS '{[Email Account.Id].[6]}' MEMBER [Time.Date].[Date Period] AS Aggregate ({[Time.Date].[2008].[11].[11] :[Time.Date].[2009].[1].[2] }) MEMBER [Email.Type].[Email Types] AS Aggregate ({[Email.Type].[0]}) SELECT {[Email Measures]} ON columns, [Operators] ON rows FROM [Email_Fact] WHERE ( [Time.Date].[Date Period] ) Now, the member in question is the calculated member [Avg Expedition Times Total]. This member takes in two measures; [Sum Expedition Times] and [Nr of Expedition Times] and splits one on the other to get the average, all this presently works. However, I want [Sum Expedition Times] to only summarize values over or under a parameter of my/the user's wish. How do I filter the numbers [Sum Expedition Times] iterates through, rather than filtering on the sum that the measure gives me in the end?

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• C++ traits question

  - by duli

  I have a templated class template <typename Data> class C { ..... } In most situations, I depend on the compiler to let me substitute types for Data. I call methods foo(), goo() on objects of type Data, so what I substitute needs to provide that. I now need to substitute int and string for my Data type. I do not want to specialize because the class is already too big and would require specializing each method (with only small code change). My options (please tell me if there are more) 1) I can provide wrapper classes around int and string which implement the methods foo(), goo() etc 2) provide a traits class traits that calls foo() or goo() on objects of classes that provide foo(),goo() (these are my present substitutable classes) and specialize these classes for int and string. Questions 1) what are the relative merits of 1 vs 2? 2) My traits classes will have static methods. Can a traits class have non-static methods as well? I see most traits classes define constants in the STL. 3) Do I make the traits classes global or should I pass them in as a template parameter for class C?

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• Are there any other ways to iterate through the attributes of a custom class, excluding the in-built ones?

  - by Ricardo Altamirano

  Is there another way to iterate through only the attributes of a custom class that are not in-built (e.g. __dict__, __module__, etc.)? For example, in this code: class Terrain: WATER = -1 GRASS = 0 HILL = 1 MOUNTAIN = 2 I can iterate through all of these attributes like this: for key, value in Terrain.__dict__.items(): print("{: <11}".format(key), " --> ", value) which outputs: MOUNTAIN --> 2 __module__ --> __main__ WATER --> -1 HILL --> 1 __dict__ --> <attribute '__dict__' of 'Terrain' objects> GRASS --> 0 __weakref__ --> <attribute '__weakref__' of 'Terrain' objects> __doc__ --> None If I just want the integer arguments (a rudimentary version of an enumerated type), I can use this: for key, value in Terrain.__dict__.items(): if type(value) is int: # type(value) == int print("{: <11}".format(key), " --> ", value) this gives the expected result: MOUNTAIN --> 2 WATER --> -1 HILL --> 1 GRASS --> 0 Is it possible to iterate through only the non-in-built attributes of a custom class independent of type, e.g. if the attributes are not all integral. Presumably I could expand the conditional to include more types, but I want to know if there are other ways I'm missing.

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• Best practice when removing entity regarding mappedBy collections?

  - by Daniel Bleisteiner

  I'm still kind of undecided which is the best practice to handle em.remove(entity) with this entity being in several collections mapped using mappedBy in JPA. Consider an entity like a Property that references three other entities: a Descriptor, a BusinessObject and a Level entity. The mapping is defined using @ManyToOne in the Property entity and using @OneToMany(mappedBy...) in the other three objects. That inverse mapping is defined because there are some situations where I need to access those collections. Whenever I remove a Property using em.remove(prop) this element is not automatically removed from managed entities of the other three types. If I don't care about that and the following page load (webapp) doesn't reload those entities the Property is still found and some decisions might be taken that are no longer true. The inverse mappings may become quite large and though I don't want to use something like descriptor.getProperties().remove(prop) because it will load all those properties that might have been lazy loaded until then. So my currently preferred way is to refresh the entity if it is managed: if (em.contains(descriptor)) em.refresh(descriptor) - which unloads a possibly loaded collection and triggers a reload upon the next access. Is there another feasible way to handle all those mappedBy collections of already loaded entites?

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• .htaccess trickery multi-language website

  - by user1658741

  I have a website right now that uses two languages (french and english) The way it works right now is that if someone goes to mysite.com/folder/file.php for example, file.php is simply a script that figures out which language to use, get's it's own path and filename(file.php) and serves up mysite.com/en/folder/file.php (if the language is english). However what shows up in the URL is still mysite.com/folder/file.php. For any folder and any file the same script is used. If I want to add a new file I have to add the file to the folder the user types into the browser as well to the en and fr folders. Could I do some .htaccess trickery so that whatever URL is typed, one .php file gets open that checks the language and what folder/file was requested and then serves up the correct language file? here's the php file that is served up for any files in the URL. <?php // Get current document path which is mirrored in the language folders $docpath = $_SERVER['PHP_SELF']; // Get current document name (Used when switching languages so that the same current page is shown when language is changed) $docname = GetDocName(); //call up lang.php which handles display of appropriate language webpage. //lang.php uses $docpath and $docname to give out the proper $langfile. //$docpath/$docname is mirrored in the /lang/en and /lang/fr folders $langfile = GetDocRoot()."/lang/lang.php"; include("$langfile"); //Call up the proper language file to display function GetDocRoot() { $temp = getenv("SCRIPT_NAME"); $localpath=realpath(basename(getenv("SCRIPT_NAME"))); $localpath=str_replace("\\","/",$localpath); $docroot=substr($localpath,0, strpos($localpath,$temp)); return $docroot; } function GetDocName() { $currentFile = $_SERVER["SCRIPT_NAME"]; $parts = Explode('/', $currentFile); $dn = $parts[count($parts) - 1]; return $dn; } ?>

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• Is there a Java data structure that is effectively an ArrayList with double indicies and built-in in

  - by Bob Cross

  I am looking for a pre-built Java data structure with the following characteristics: It should look something like an ArrayList but should allow indexing via double-precision rather than integers. Note that this means that it's likely that you'll see indicies that don't line up with the original data points (i.e., asking for the value that corresponds to key "1.5"). As a consequence, the value returned will likely be interpolated. For example, if the key is 1.5, the value returned could be the average of the value at key 1.0 and the value at key 2.0. The keys will be sorted but the values are not ensured to be monotonically increasing. In fact, there's no assurance that the first derivative of the values will be continuous (making it a poor fit for certain types of splines). Freely available code only, please. For clarity, I know how to write such a thing. In fact, we already have an implementation of this and some related data structures in legacy code that I want to replace due to some performance and coding issues. What I'm trying to avoid is spending a lot of time rolling my own solution when there might already be such a thing in the JDK, Apache Commons or another standard library. Frankly, that's exactly the approach that got this legacy code into the situation that it's in right now.... Is there such a thing out there in a freely available library?

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• Alternative to Altova's MissionKit

  - by nomad311

  Anyone know of any good alternatives (other than those listed below which really are only good at specific XML development tasks)? The Why (if you're interested): I've been doing XML development on and off for years now, but someone brought XMLSpy to my attention recently, and it is awesome - the price isn't. Lately I've been using a combination of: Notepad++ (modifying XML) EditX (validating/debugging XML) Eclipse (designing schemas) and MS Visual Studio (validating schemas) ...based on which makes the task(s) easiest. But, I've just found out that we will be using XSL transformations to generate XML in the future. I've never used mission kit before, but I'm just short of positive XMLSpy replaces all the above mentioned tool for XML development. And if their XSL tools are anywhere near the caliber of XMLSpy ...simply put I need it. I don't believe that I can convince the budgeting types to buy licenses for MissionKit at $1000 each (won't stop me from trying). In the mean while some research on alternatives won't hurt, but a few Google queries has only revealed that not many people pay for Altova's (overpriced?) software as there are mostly links to P2P sites for downloading a more free-like version of MissionKit.

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• Troubleshooting multiple GET variables In PHP

  - by V413HAV

  This may be a very simple question but I don't what's the wrong thing am doing here... To explain you clearly, I've set a real simple example below: <ul> <li><a href="test.php?link1=true">Link 1</a></li> <li><a href="test.php?link2=true">Link 2</a></li> <li><a href="test.php?link3=true">Link 3</a></li> </ul> <?php if(isset($_GET['link1'])) { if(($_GET['link1']) == 'true') { echo 'This Is Link 1'; } } if(isset($_GET['link2'])) { if(($_GET['link2']) == 'true') { echo 'This Is Link 2'; } } if(isset($_GET['link3'])) { if(($_GET['link3']) == 'true') { echo 'This Is Link 3'; } } ?> This is a test.php page, here I've set 3 different arguments for $_GET, and show contents accordingly, now everything works perfect, the only thing am not understanding is how to block this kind of url say if user clicks on link 1 the url will be : http://localhost/test.php?link1=true And the Output of this url is This is Link 1 Now if I change this url to : http://localhost/test.php?link3=true&link2=true&link1=true And the Output what I get is This Is Link 1This Is Link 2This Is Link 3 Now this is ok here, but it's very annoying if someone types this and see's forms one below the other, any way I can stop this tampering?

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• Designing a database for a user/points system? (in Django)

  - by AP257

  First of all, sorry if this isn't an appropriate question for StackOverflow. I've tried to make it as generalisable as possible. I want to create a database (MySQL, site running Django) that has users, who can be allocated a certain number of points for various types of action - it's a collaborative game. My requirements are to obtain: the number of points a user has the user's ranking compared to all other users and the overall leaderboard (i.e. all users ranked in order of points) This is what I have so far, in my Django models.py file: class SiteUser(models.Model): name = models.CharField(max_length=250 ) email = models.EmailField(max_length=250 ) date_added = models.DateTimeField(auto_now_add=True) def points_total(self): points_added = PointsAdded.objects.filter(user=self) points_total = 0 for point in points_added: points_total += point.points return points_total class PointsAdded(models.Model): user = models.ForeignKey('SiteUser') action = models.ForeignKey('Action') date_added = models.DateTimeField(auto_now_add=True) def points(self): points = Action.objects.filter(action=self.action) return points class Action(models.Model): points = models.IntegerField() action = models.CharField(max_length=36) However it's rapidly becoming clear to me that it's actually quite complex (in Django query terms at least) to figure out the user's ranking and return the leaderboard of users. At least, I'm finding it tough. Is there a more elegant way to do something like this? This question seems to suggest that I shouldn't even have a separate points table - what do people think? It feels more robust to have separate tables, but I don't have much experience of database design.

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• Overhead of calling tiny functions from a tight inner loop? [C++]

  - by John

  Say you see a loop like this one: for(int i=0; i<thing.getParent().getObjectModel().getElements(SOME_TYPE).count(); ++i) { thing.getData().insert( thing.GetData().Count(), thing.getParent().getObjectModel().getElements(SOME_TYPE)[i].getName() ); } if this was Java I'd probably not think twice. But in performance-critical sections of C++, it makes me want to tinker with it... however I don't know if the compiler is smart enough to make it futile. This is a made up example but all it's doing is inserting strings into a container. Please don't assume any of these are STL types, think in general terms about the following: Is having a messy condition in the for loop going to get evaluated each time, or only once? If those get methods are simply returning references to member variables on the objects, will they be inlined away? Would you expect custom [] operators to get optimized at all? In other words is it worth the time (in performance only, not readability) to convert it to something like: ElementContainer &source = thing.getParent().getObjectModel().getElements(SOME_TYPE); int num = source.count(); Store &destination = thing.getData(); for(int i=0;i<num;++i) { destination.insert(thing.GetData().Count(), source[i].getName(); } Remember, this is a tight loop, called millions of times a second. What I wonder is if all this will shave a couple of cycles per loop or something more substantial? Yes I know the quote about "premature optimisation". And I know that profiling is important. But this is a more general question about modern compilers, Visual Studio in particular.

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• Launching and Intent from file and mime type

  - by stonedonkey

  I've reviewed all the similar questions here, but I can't for the life of me figure out what I'm doing wrong. I've written an application that tries to launch various files, sort of a file browser, when a file is clicked it tries to launch the program based on it's associated MIME type or I want it to present the "Choose Application to Launch" dialog. Here's the code I'm using to launch: File file = new File(app.mediaPath() + "/" +_mediaFiles.get(position)); Intent myIntent = new Intent(android.content.Intent.ACTION_VIEW); String extension = android.webkit.MimeTypeMap.getFileExtensionFromUrl(Uri.fromFile(file).toString()); String mimetype = android.webkit.MimeTypeMap.getSingleton().getMimeTypeFromExtension(extension); myIntent.setDataAndType(Uri.fromFile(file),mimetype); startActivity(myIntent); This fails and generates a: android.content.ActivityNotFoundException: No Activity found to handle Intent { act=android.intent.action.VIEW dat=file:///file:/mnt/sdcard/roms/nes/Baseball_simulator.nes } Now if I install OI File Manager for instance, it opens instead of this error being thrown, and then if I click the same file from within in it, it launches the approriate dialogs. I have noticed that the MIME type for that particular file fails, but other mime types like .zip do return values. Am I missing something that when the MIME type is null to call a dialog that lets the user select? I've tried other variations of launching the app, including not setting the mime type and only using .setData with no success. The action I want to happen is, a user clicks a file, if it's associated with an application that app launches, if not, the user gets the "Complete action using" dialog with a list of apps. Thanks for any advice.

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• Is this a good way to generically deserialize objects?

  - by Damien Wildfire

  I have a stream onto which serialized objects representing messages are dumped periodically. The objects are one of a very limited number of types, and other than the actual sequence of bytes that arrives, I have no way of knowing what type of message it is. I would like to simply try to deserialize it as an object of a particular type, and if an exception is thrown, try again with the next type. I have an interface that looks like this: public interface IMessageHandler<T> where T : class, IMessage { T Handle(string message); } // elsewhere: // (These are all xsd.exe-generated classes from an XML schema.) public class AppleMessage : IMessage { ... } public class BananaMessage : IMessage { ... } public class CoconutMessage : IMessage { ... } Then I wrote a GenericHandler<T> that looks like this: public class GenericHandler<T> : IMessageHandler<T> where T: class, IMessage { public class MessageHandler : IMessageHandler { T IMessageHandler.Handle(string message) { T result = default(T); try { // This utility method tries to deserialize the object with an // XmlSerializer as if it were an object of type T. result = Utils.SerializationHelper.Deserialize<T>(message); } catch (InvalidCastException e) { result = default(T); } return result; } } } Two questions: Using my GenericHandler<T> (or something similar to it), I'd now like to populate a collection with handlers that each handle a different type. Then I want to invoke each handler's Handle method on a particular message to see if it can be deserialized. If I get a null result, move onto the next handler; otherwise, the message has been deserialized. Can this be done? Is there a better way to deserialize data of unknown (but restricted) type?

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• Getting the current item number or index when using will_paginate in rails app

  - by Rich

  I have a rails app that stores movies watched, books read, etc. The index page for each type lists paged collections of all its items, using will_paginate to bring back 50 items per page. When I output the items I want to display a number to indicate what item in the total collection it is. The numbering should be reversed as the collection is displayed with most recent first. This might not relate to will_paginate but rather some other method of calculation. I will be using the same ordering in multiple types so it will need to be reusable. As an example, say I have 51 movies. The first item of the first page should display: Fight Club - Watched: 30th Dec 2010 Whilst the last item on the page should display: The Matrix - Watched: 3rd Jan 2010 The paged collection is available as an instance variable e.g. @movies, and @movies.count will display the number of items in the paged collection. So if we're on page 1, movies.count == 50, whilst on page 2 @movies.count == 1. Using Movie.count would give 51. If the page number and page size can be accessed the number could be calculated so how can they be returned? Though I'm hopeful there is something that already exists to handle this calculation!

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• problem with a string's format in c++ while doing tcp communication

  - by james t

  hi, i am building a simple c++ client, i am splitting the info i get from the server to frames, and pass each frame to a function that processes it, i split the frame into lines using Poco::StringTokenizer tokenizer(frame, "\n"); i take the first line of the tokenizer which represents the type of frame StmpCommand command(tokenizer[0]); a StmpCommand is an enum with the different types of messages and the constructor works as follows : StmpCommand(std::string command): commandType_() { bool x=command=="CONNECTED"; std::cout<<x<<std::endl; if ("SUBSCRIBE" == command) commandType_ = SUBSCRIBE; else if ("UNSUBSCRIBE" == command) commandType_ = UNSUBSCRIBE; else if ("SEND" == command) commandType_ = SEND; else if ("BEGIN" == command) commandType_ = BEGIN; else if ("COMMIT" == command) commandType_ = COMMIT; else if ("CONNECT" == command) commandType_ = CONNECT; else if ("MESSAGE" == command) commandType_ = MESSAGE; else if ("RECEIPT" == command) commandType_ = RECEIPT; else if ("CONNECTED" == command) commandType_ = CONNECTED; else if ("DISCONNECT" == command) commandType_ = DISCONNECT; else if ("ERROR" == command) commandType_ = ERROR; else { std::cerr<<"Error in building StmpCommand object, unknown type - "<<command<<std::endl; } } the first frame i am trying to proccess is a CONNECTED frame therefor i try to create a StmpCommand with CONNECTED as the constructor's only argument and for some reason i am getting an : Error in building StmpCommand object, unknown type - CONNECTED i am clearly passing a string containing CONNECTED but i'm guessing there is something else there that isn't allowing the condition else if ("CONNECTED" == command) to hap

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• ASP.NET Custom Control - Template Allowing Literal Content

  - by Bob Fincheimer

  I want my User Control to be able to have Literal Content inside of it. For Example: <fc:Text runat="server">Please enter your login information:</fc:Text> Currently the code for my user control is: <ParseChildren(True, "Content")> _ Partial Public Class ctrFormText Inherits FormControl Private _content As ArrayList <PersistenceMode(PersistenceMode.InnerDefaultProperty), _ DesignerSerializationVisibility(DesignerSerializationVisibility.Content), _ TemplateInstance(TemplateInstance.Single)> _ Public Property Content() As ArrayList Get If _content Is Nothing Then Return New ArrayList End If Return _content End Get Set(ByVal value As ArrayList) _content = value End Set End Property Protected Overrides Sub CreateChildControls() If _content IsNot Nothing Then ctrChildren.Controls.Clear() For Each i As Control In _content ctrChildren.Controls.Add(i) Next End If MyBase.CreateChildControls() End Sub End Class And when I put text inside this control (like above) i get this error: Parser Error Message: Literal content ('Please enter your login information to access CKMS:') is not allowed within a 'System.Collections.ArrayList'. This control could have other content than just the text, so making the Content property an attribute will not solve my problem. I found in some places that I need to implement a ControlBuilder Class, along with another class that implements IParserAccessor. Anyway I just want my default "Content" property to have all types of controls allowed in it, both literal and actual controls.

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• Turn based synchronization between threads

  - by Amarus

  I'm trying to find a way to synchronize multiple threads having the following conditions: * There are two types of threads: 1. A single "cyclic" thread executing an infinite loop to do cyclic calculations 2. Multiple short-lived threads not started by the main thread * The cyclic thread has a sleep duration between each cycle/loop iteration * The other threads are allowed execute during the inter-cycle sleep of the cyclic thread: - Any other thread that attempts to execute during an active cycle should be blocked - The cyclic thread will wait until all other threads that are already executing to be finished Here's a basic example of what I was thinking of doing: // Somewhere in the code: ManualResetEvent manualResetEvent = new ManualResetEvent(true); // Allow Externally call CountdownEvent countdownEvent = new CountdownEvent(1); // Can't AddCount a CountdownEvent with CurrentCount = 0 void ExternallyCalled() { manualResetEvent.WaitOne(); // Wait until CyclicCalculations is having its beauty sleep countdownEvent.AddCount(); // Notify CyclicCalculations that it should wait for this method call to finish before starting the next cycle Thread.Sleep(1000); // TODO: Replace with actual method logic countdownEvent.Signal(); // Notify CyclicCalculations that this call is finished } void CyclicCalculations() { while (!stopCyclicCalculations) { manualResetEvent.Reset(); // Block all incoming calls to ExternallyCalled from this point forward countdownEvent.Signal(); // Dirty workaround for the issue with AddCount and CurrentCount = 0 countdownEvent.Wait(); // Wait until all of the already executing calls to ExternallyCalled are finished countdownEvent.Reset(); // Reset the CountdownEvent for next cycle. Thread.Sleep(2000); // TODO: Replace with actual method logic manualResetEvent.Set(); // Unblock all threads executing ExternallyCalled Thread.Sleep(1000); // Inter-cycles delay } } Obviously, this doesn't work. There's no guarantee that there won't be any threads executing ExternallyCalled that are in between manualResetEvent.WaitOne(); and countdownEvent.AddCount(); at the time the main thread gets released by the CountdownEvent. I can't figure out a simple way of doing what I'm after, and almost everything that I've found after a lengthy search is related to producer/consumer synchronization which I can't apply here.

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