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  • vim "autoindent" // pattern

    - by anon
    My terminal is 160 characters wide. I use VIM. Is there a way to tell vim: when you see "//", autoindent it to start @ width 80? (And haave it also affected when I highlight a region and hit =) Thanks!

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  • Pattern for limiting number of simultaneous asynchronous calls

    - by hitch
    I need to retrieve multiple objects from an external system. The external system supports multiple simultaneous requests (i.e. threads), but it is possible to flood the external system - therefore I want to be able to retrieve multiple objects asynchronously, but I want to be able to throttle the number of simultaneous async requests. i.e. I need to retrieve 100 items, but don't want to be retrieving more than 25 of them at once. When each request of the 25 completes, I want to trigger another retrieval, and once they are all complete I want to return all of the results in the order they were requested (i.e. there is no point returning the results until the entire call is returned). Are there any recommended patterns for this sort of thing? Would something like this be appropriate (pseudocode, obviously)? private List<externalSystemObjects> returnedObjects = new List<externalSystemObjects>; public List<externalSystemObjects> GetObjects(List<string> ids) { int callCount = 0; int maxCallCount = 25; WaitHandle[] handles; foreach(id in itemIds to get) { if(callCount < maxCallCount) { WaitHandle handle = executeCall(id, callback); addWaitHandleToWaitArray(handle) } else { int returnedCallId = WaitHandle.WaitAny(handles); removeReturnedCallFromWaitHandles(handles); } } WaitHandle.WaitAll(handles); return returnedObjects; } public void callback(object result) { returnedObjects.Add(result); }

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  • Pattern for managing reference count and object life

    - by Gopalakrishnan Subramani
    We have a serial port which is connected to hundreds of physical devices on the same wire. We have protocols like Modbus and Hart to handle the request and response between the application and devices. The question is related to managing the reference count of the channel. When no device is using the channel, the channel should be closed. public class SerialPortChannel { int refCount = 0; public void AddReference() { refCount++; } public void ReleaseReference() { refCount--; if (refCount <= 0) this.ReleasePort(); //This close the serial port } } For each device connected, we create a object for the device like device = new Device(); device.Attach(channel); //this calls channel.AddReference() When the device disconnect, device.Detach(channel); //this calls channel.ReleaseReference() I am not convinced by the reference count model. Are there any better way to handle this problem in .NET World?

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  • Manipulating collections & the ViewModel pattern

    - by Kragen
    I'm relatively new to WPF, and I'm having trouble with what I'm fairly certain is a relatively simple problem. I have my underlying data object, a Person: class Person { public string Surname {get; set; } public string Firstname {get; set; } public List<Address> Addresses {get; } } And I wish to display and edit this object in my WPF app. To this end I've created a ViewModel that I bind to in my xaml: class PersonViewModel { public string Fullname {get; } public ObservableCollection<AddressViewModel> Addresses {get; } } This is fine, except when it comes to manipulating my Address collection, where I can't work out what I should be doing: Should I add methods AddAddress, RemoveAddress etc... to my PersonViewModel class for manipulating my collection with instances of AddressViewModel Should I just add instances of AddressViewModel to my Addresses observable collection Both of the above seem a bit messy - is there a better way of dealing with collections?

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  • Working with arrays of lists pattern in java

    - by Mad Wombat
    I am writing a card game in java where I need to spread cards from a deck into several columns until I have fixed amount of cards left. This is how I do this. public class Column extends ArrayList {} List deck = Cards.createNewDeck(); Column[] columns = new Column[10]; int c = 0; while (deck.size() 50) { if (c == 10) { c = 0; } if (columns[c] == null) { columns[c] = new Column(); } columns[c].add(Cards.dealTopCard(deck)); c += 1; } This somehow seems clunky. Is there a more readable/comprehensive way of doing the same thing?

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  • Grails pattern to reuse template on error

    - by bsreekanth
    Hello, I have a gsp template, where the data for create view is passed through the controller. def create = { def bookInstance = new Book() bookInstance .properties = params def map = getDefaultValues() render(template: "create", model: [bookInstance : bookInstance , title: map.title, somelist: somelist ....]) the gsp template <g:select optionKey="id" from="${somelist}" name="somelist.id" value="${bookInstance ?.somelist?.id}" noSelection="['null': '']"></g:select> now, in the save method, if there is an error, it returns currently populated and validated instance (default scaffold implementation) render(template: "create", model: [bookInstance : bookInstance ]) But the fields in the gsp (error page rendered from save action) is empty. I could see the reason as it looks the value in "${somelist}" , but it is not used in save method. Do i just need to check for null in the gsp and use whichever map is available, or any better method (passing all the map in the save method is not an option) .. thanks in advance..

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  • Design Pattern for error handling in ASP.NET 3.5 site

    - by Kevin
    I am relatively new to ASP.NET programming, and web programming in general. We have a site we recently ported from .NET 1.1 to 3.5. Currently we have two methods of error handling: either catching the error during data load on a page and displaying the formatted error in a label on the page, or redirecting to a generic error page. Both of these are somewhat annoying, as right now I'm trying to redesign how our errors are displayed. We are soon moving to Master pages, and I'm wondering if there is a way to "build in" an error handling control. What I mean by this is using a ASP.NET user control I've designed that simply gets passed the error string returned from the server. If an error occurs, the page would not display the content, and instead display the error control. This provides us with the ability to retain the current banner/navigation during an error (which we don't get with the generic error page), as well as keeping me from having to add the control to every aspx page we have (which I have to do with using the label-per-page system). Does something like this make sense? Ultimately I just want to have the error control added to a single page, and all other pages have access to it directly. Is this something Master pages help with? Thanks!

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  • GWT and Mock the view in MVP pattern

    - by Yannick Eurin
    Hello, i dunno if the question is already ask, but i couldn't find it... i'm searching a way to mock my view in order to test my presenter ? i try to use mockito for the view, and set it in the presenter, but in result in presenter, when i call presenter.getDisplay() (the getter for the view) all of my widget is null ? as i believe it's normal mockito will not mock the widget. i'm 100% sure i mistaken something but i couldnt find it. thanks for your enlightement :)

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  • JavaScript Resource Management Design Pattern

    - by Adam
    As a web developer, a common problem I find myself tackling is waiting for something to load before doing something else. In particular, I often hide (using either display: none; or visibility: hidden; depending on the situation) elements while waiting for a background image or a CSS file to load. Consider this example from Last.FM. They overlay a semi-transparant PNG over each album art image so that it looks like it's inside a jewel-case. They let it load when it loads, so depending on your internet speed, you may see the art image by itself (without the overlay) temporarily. In this case, the album art looks fine without the jewel-case effect. But in similar situations, I have found that I don't want the user to see the site's design mangled as resources incrementally load. So, in rare cases I have hidden everything from the user until the whole kit and kaboodle has loaded. But this is often a pain to write out, and may force the user to wait for a pretty long time to see anything (besides "loading..." text). I can think of (and have used on occasion) some obvious solutions/compromises: Use some inline CSS so that as certain parts of the DOM load and render, they will immediately have the correct size/position/etc. Immediately render the navigation part of the site, so that if the user wanted to use the current page purely to get somewhere else, they don't have to wait for the rest to load. Load pixelated images first as placeholders for layout while lazy-loading higher quality images as replacements. Something quirky like using a cute animated gif to distract the user during a "loading..." phase. Show useful information as a reference while loading the full UI. (Something akin to Gmail Inbox Preview, etc.) (Sorry if my question was basically just asked and answered...) Despite all of these ideas, I still find myself hoping there are better ways of doing some of these things. So I guess what I'm looking for is some inspiration and/or any creative ways of dealing with this problem that you guys may have seen out in the wild.

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  • what pattern to use for multi-argument method?

    - by Omid S
    I have a method with the following signature: foo (Sample sample, Aliquot aliquot) "foo" needs to alter a Sample object, either the first argument or from the second argument it can extract its Sample. For example: foo (Sample sample, Aliquot aliquot) { Sample out = null; if (sample != null) out = sample else out = aliquot.getSample() return out; } But that is so un-elegant, other than reading the API a developer does not know the reference of the first argument overrides the Sample of the second argument. Now, I could change "foo" to foo (SomeMagicalObject bar) where SomeMagicalObject is a tuple for Sample and Aliquot and holds some logic ... etc. But I am wondering, are there some patterns for this question?

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  • (static initialization order?!) problems with factory pattern

    - by smerlin
    Why does following code raise an exception (in createObjects call to map::at) alternativly the code (and its output) can be viewed here intererestingly the code works as expected if the commented lines are uncommented with both microsoft and gcc compiler (see here), this even works with initMap as ordinary static variable instead of static getter. The only reason for this i can think of is that the order of initialization of the static registerHelper_ object (factory_helper_)and the std::map object (initMap) are wrong, however i cant see how that could happen, because the map object is constructed on first usage and thats in factory_helper_ constructor, so everything should be alright shouldnt it ? I am even more suprised that those doNothing() lines fix the issue, because that call to doNothing() would happen after the critical section (which currently fails) is passed anyway. EDIT: debugging showed, that without the call to factory_helper_.doNothing(), the constructor of factory_helper_ is never called. #include <iostream> #include <string> #include <map> #define FACTORY_CLASS(classtype) \ extern const char classtype##_name_[] = #classtype; \ class classtype : FactoryBase<classtype,classtype##_name_> namespace detail_ { class registerHelperBase { public: registerHelperBase(){} protected: static std::map<std::string, void * (*)(void)>& getInitMap() { static std::map<std::string, void * (*)(void)>* initMap = 0; if(!initMap) initMap= new std::map<std::string, void * (*)(void)>(); return *initMap; } }; template<class TParent, const char* ClassName> class registerHelper_ : registerHelperBase { static registerHelper_ help_; public: //void doNothing(){} registerHelper_(){ getInitMap()[std::string(ClassName)]=&TParent::factory_init_; } }; template<class TParent, const char* ClassName> registerHelper_<TParent,ClassName> registerHelper_<TParent,ClassName>::help_; } class Factory : detail_::registerHelperBase { private: Factory(); public: static void* createObject(const std::string& objclassname) { return getInitMap().at(objclassname)(); } }; template <class TClass, const char* ClassName> class FactoryBase { private: static detail_::registerHelper_<FactoryBase<TClass,ClassName>,ClassName> factory_helper_; static void* factory_init_(){ return new TClass();} public: friend class detail_::registerHelper_<FactoryBase<TClass,ClassName>,ClassName>; FactoryBase(){ //factory_helper_.doNothing(); } virtual ~FactoryBase(){}; }; template <class TClass, const char* ClassName> detail_::registerHelper_<FactoryBase<TClass,ClassName>,ClassName> FactoryBase<TClass,ClassName>::factory_helper_; FACTORY_CLASS(Test) { public: Test(){} }; int main(int argc, char** argv) { try { Test* test = (Test*) Factory::createObject("Test"); } catch(const std::exception& ex) { std::cerr << "caught std::exception: "<< ex.what() << std::endl; } #ifdef _MSC_VER system("pause"); #endif return 0; }

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  • How should the View pull on the Presenter in the MVP pattern

    - by John Leidegren
    I have a ASP.NET Web Forms application and I'm using some dynamic controls in the view which depend on stuff that the presenter exposes. Is it okay for the view in this case to pull on the presenter for that data? Is there anything I should be extra careful about when considering testability and a loosely coupled design. The page in this case has it's own page-life cycle and the presenter doesn't know about this. However, the page-life cycle dictates that somethings must occur at specific moments in the page-life cycle. This smells like trouble... Any known pit falls?

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  • Special scheduling Algorithm (pattern expansion)

    - by tovare
    Question Do you think genetic algorithms worth trying out for the problem below, or will I hit local-minima issues? I think maybe aspects of the problem is great for a generator / fitness-function style setup. (If you've botched a similar project I would love hear from you, and not do something similar) Thank you for any tips on how to structure things and nail this right. The problem I'm searching a good scheduling algorithm to use for the following real-world problem. I have a sequence with 15 slots like this (The digits may vary from 0 to 20) : 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 (And there are in total 10 different sequences of this type) Each sequence needs to expand into an array, where each slot can take 1 position. 1 1 0 0 1 1 1 0 0 0 1 1 1 0 0 1 1 0 0 1 1 1 0 0 0 1 1 1 0 0 0 0 1 1 0 0 0 1 1 1 0 0 0 1 1 0 0 1 1 0 0 0 1 1 1 0 0 0 1 1 The constraints on the matrix is that: [row-wise, i.e. horizontally] The number of ones placed, must either be 11 or 111 [row-wise] The distance between two sequences of 1 needs to be a minimum of 00 The sum of each column should match the original array. The number of rows in the matrix should be optimized. The array then needs to allocate one of 4 different matrixes, which may have different number of rows: A, B, C, D A, B, C and D are real-world departments. The load needs to be placed reasonably fair during the course of a 10-day period, not to interfere with other department goals. Each of the matrix is compared with expansion of 10 different original sequences so you have: A1, A2, A3, A4, A5, A6, A7, A8, A9, A10 B1, B2, B3, B4, B5, B6, B7, B8, B9, B10 C1, C2, C3, C4, C5, C6, C7, C8, C9, C10 D1, D2, D3, D4, D5, D6, D7, D8, D9, D10 Certain spots on these may be reserved (Not sure if I should make it just reserved/not reserved or function-based). The reserved spots might be meetings and other events The sum of each row (for instance all the A's) should be approximately the same within 2%. i.e. sum(A1 through A10) should be approximately the same as (B1 through B10) etc. The number of rows can vary, so you have for instance: A1: 5 rows A2: 5 rows A3: 1 row, where that single row could for instance be: 0 0 1 1 1 0 0 0 0 0 0 0 0 0 0 etc.. Sub problem* I'de be very happy to solve only part of the problem. For instance being able to input: 1 1 2 3 4 2 2 3 4 2 2 3 3 2 3 And get an appropriate array of sequences with 1's and 0's minimized on the number of rows following th constraints above.

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  • Perl pattern matching with zero width assertion

    - by Simone
    Hi everyone, I can't get why this code work: $seq = 'GAGAGAGA'; my $regexp = '(?=((G[UCGA][GA]A)|(U[GA]CG)|(CUUG)))'; # zero width match while ($seq =~ /$regexp/g){ # globally my $pos = pos($seq) + 1; # position of a zero width matching print "$1 position $pos\n"; } I know this is a zero width match and it dosn't put the matched string in $&, but why does it put it in $1? thank you!

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  • Routing in Php and decorator pattern

    - by Joey Salac Hipolito
    I do not know if I am using the term 'routing' correctly, but here is the situation: I created an .htaccess file to 'process' (dunno if my term is right) the url of my application, like this : RewriteEngine On RewriteCond %{REQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^(.+)$ index.php?url=$1 [QSA,L] Now I have this : http://appname/controller/method/parameter http://appname/$url[0]/$url[1]/$url[2] What I did is: setup a default controller, in case it is not specified in the url setup a Controller wrapper I did it like this $target = new $url[0]() $controller = new Controller($target) The problem with that one is that I can't use the methods in the object I passed in the constructor of the Controller: I resolved it like this : class Controller { protected $target; protected $view; public function __construct($target, $view) { $this->target = $target; $this->view = $view; } public function __call($method, $arguments) { if (method_exists($this->target, $method)) { return call_user_func_array(array($this->target, $method), $arguments); } } } This is working fine, the problem occurs in the index where I did the routing, here it is if(isset($url[2])){ if(method_exists($controller, $url[1])){ $controller->$url[1]($url[2]) } } else { if(method_exists($controller, $url[1])){ $controller->$url[1]() } } where $controller = new Controller($target) The problem is that the method doesn't exist, although I can use it directly without checking if method exist, how can I resolve this?

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  • Risking the exception anti-pattern.. with some modifications

    - by Sridhar Iyer
    Lets say that I have a library which runs 24x7 on certain machines. Even if the code is rock solid, a hardware fault can sooner or later trigger an exception. I would like to have some sort of failsafe in position for events like this. One approach would be to write wrapper functions that encapsulate each api a: returnCode=DEFAULT; try { returnCode=libraryAPI1(); } catch(...) { returnCode=BAD; } return returnCode; The caller of the library then restarts the whole thread, reinitializes the module if the returnCode is bad. Things CAN go horribly wrong. E.g. if the try block(or libraryAPI1()) had: func1(); char *x=malloc(1000); func2(); if func2() throws an exception, x will never be freed. On a similar vein, file corruption is a possible outcome. Could you please tell me what other things can possibly go wrong in this scenario?

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  • Using the Proxy pattern with C++ iterators

    - by Billy ONeal
    Hello everyone :) I've got a moderately complex iterator written which wraps the FindXFile apis on Win32. (See previous question) In order to avoid the overhead of constructing an object that essentially duplicates the work of the WIN32_FIND_DATAW structure, I have a proxy object which simply acts as a sort of const reference to the single WIN32_FIND_DATAW which is declared inside the noncopyable innards of the iterator. This is great because Clients do not pay for construction of irrelevant information they will probably not use (most of the time people are only interested in file names), and Clients can get at all the information provided by the FindXFile APIs if they need or want this information. This becomes an issue though because there is only ever a single copy of the object's actual data. Therefore, when the iterator is incrememnted, all of the proxies are invalidated (set to whatever the next file pointed to by the iterator is). I'm concerned if this is a major problem, because I can think of a case where the proxy object would not behave as somebody would expect: std::vector<MyIterator::value_type> files; std::copy(MyIterator("Hello"), MyIterator(), std::back_inserter(files)); because the vector contains nothing but a bunch of invalid proxies at that point. Instead, clients need to do something like: std::vector<std::wstring> filesToSearch; std::transform( DirectoryIterator<FilesOnly>(L"C:\\Windows\\*"), DirectoryIterator<FilesOnly>(), std::back_inserter(filesToSearch), std::mem_fun_ref(&DirectoryIterator<FilesOnly>::value_type::GetFullFileName) ); Seeing this, I can see why somebody might dislike what the standard library designers did with std::vector<bool>. I'm still wondering though: is this a reasonable trade off in order to achieve (1) and (2) above? If not, is there any way to still achieve (1) and (2) without the proxy?

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  • spring security filter-chain regex pattern

    - by lewap
    In my application which uses spring security I want to define two different areas both using their own spring security filter-chain. My question is: is it possible to define two regex expressions as follows: every path starting with /foobar/* every other path not starting with /foobar The important part here is that the second path should also match if somewhere within it, but not in the beginning, it cotains the /foobar/ string. Thanks

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  • RegEx to match a pattern and exclude a part of the string

    - by rojanu
    Hi, I have got some strings to be matched via RegEx. We have a java application which reads the regex from a config file and takes two groups of strings, number of which are specified in the same config. E.g. CustomAction.523274ca945f.dialogLabel=Executing Custom Code... will be matched with (?m)^(?!#)\s*(\S*)\s*=\s*(\S*.*) What I need is to pick the first group "CustomAction.523274ca945f.dialogLabel" and exclude the random string in the middle so I end up with something like "CustomAction.dialogLabel" or "CustomAction..dialogLabel" well any other combination but the random string. Thanks

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  • Decorator Pattern on List<T> for DataGridView

    - by elector
    Hi all, I would like to apply a Decorator on List class and be able to bind it to the WinForms DataGirdView. I would like to know what members of List i need to implement for this new class to be able to bind it to DataGrid. Some of the methods from List I would hide with my decorated class methods and others I would just call _decoratedList.Method(). Is this an option for implementing Decorator on List type? Decorator: public class MyCustomList : List<MyObject> { List<MyObject> _decoratedList; . . . }

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