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  • Using boost::iterator

    - by Neil G
    I wrote a sparse vector class (see #1, #2.) I would like to provide two kinds of iterators: The first set, the regular iterators, can point any element, whether set or unset. If they are read from, they return either the set value or value_type(), if they are written to, they create the element and return the lvalue reference. Thus, they are: Random Access Traversal Iterator and Readable and Writable Iterator The second set, the sparse iterators, iterate over only the set elements. Since they don't need to lazily create elements that are written to, they are: Random Access Traversal Iterator and Readable and Writable and Lvalue Iterator I also need const versions of both, which are not writable. I can fill in the blanks, but not sure how to use boost::iterator_adaptor to start out. Here's what I have so far: template<typename T> class sparse_vector { public: typedef size_t size_type; typedef T value_type; private: typedef T& true_reference; typedef const T* const_pointer; typedef sparse_vector<T> self_type; struct ElementType { ElementType(size_type i, T const& t): index(i), value(t) {} ElementType(size_type i, T&& t): index(i), value(t) {} ElementType(size_type i): index(i) {} ElementType(ElementType const&) = default; size_type index; value_type value; }; typedef vector<ElementType> array_type; public: typedef T* pointer; typedef T& reference; typedef const T& const_reference; private: size_type size_; mutable typename array_type::size_type sorted_filled_; mutable array_type data_; // lots of code for various algorithms... public: class sparse_iterator : public boost::iterator_adaptor< sparse_iterator // Derived , array_type::iterator // Base (the internal array) (this paramater does not compile! -- says expected a type, got 'std::vector::iterator'???) , boost::use_default // Value , boost::random_access_traversal_tag? // CategoryOrTraversal > class iterator_proxy { ??? }; class iterator : public boost::iterator_facade< iterator // Derived , ????? // Base , ????? // Value , boost::?????? // CategoryOrTraversal > { }; };

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  • Linux: shell builtin string matching

    - by gmatt
    I am trying to become more familiar with using the builtin string matching stuff available in shells in linux. I came across this guys posting, and he showed an example a="abc|def" echo ${a#*|} # will yield "def" echo ${a%|*} # will yield "abc" I tried it out and it does what its advertised to do, but I don't understand what the $,{},#,*,| are doing, I tried looking for some reference online or in the manuals but I couldn't find anything. Can anyone explain to me what's going on here?

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  • Where in an Eclipse workspace is the list of projects stored?

    - by Kris Pruden
    I use eclipse with "external" projects - i.e. projects created from existing source. Poking around in the workspace files, I cannot find any reference to these projects. My question is: how does eclipse keep track of these projects? I'd like to be able to add such a project to the workspace automatically (by generating .project and .classpath files)..

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  • Unique_ptr compiler errors

    - by Godric Seer
    I am designing and entity-component system for a project, and C++ memory management is giving me a few issues. I just want to make sure my design is legitimate. So to start I have an Entity class which stores a vector of Components: class Entity { private: std::vector<std::unique_ptr<Component> > components; public: Entity() { }; void AddComponent(Component* component) { this -> components.push_back(std::unique_ptr<Component>(component)); } ~Entity(); }; Which if I am not mistaken means that when the destructor is called (even the default, compiler created one), the destructor for the Entity, will call ~components, which will call ~std::unique_ptr for each element in the vector, and lead to the destruction of each Component, which is what I want. The component class has virtual methods, but the important part is its constructor: Component::Component(Entity parent) { parent.addComponent(this) // I am not sure if this would work like I expect // Other things here } As long as passing this to the method works, this also does what I want. My confusion is in the factory. What I want to do is something along the lines of: std::shared_ptr<Entity> createEntity() { std::shared_ptr<Entity> entityPtr(new Entity()); new Component(*parent); // Initialize more, and other types of Components return entityPtr; } Now, I believe that this setup will leave the ownership of the Component in the hands of its Parent Entity, which is what I want. First a small question, do I need to pass the entity into the Component constructor by reference or pointer or something? If I understand C++, it would pass by value, which means it gets copied, and the copied entity would die at the end of the constructor. The second, and main question is that code based on this sample will not compile. The complete error is too large to print here, however I think I know somewhat of what is going on. The compiler's error says I can't delete an incomplete type. My Component class has a purely virtual destructor with an implementation: inline Component::~Component() { }; at the end of the header. However since the whole point is that Component is actually an interface. I know from here that a complete type is required for unique_ptr destruction. The question is, how do I work around this? For reference I am using gcc 4.4.6.

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  • CQRS - Should a Command try to create a "complex" master-detail entity?

    - by Simon Crabtree
    I've been reading Greg Young and Udi Dahan's thoughts on Command Query Responsibilty Separation and a lot of what I read strikes a chord with me. My domain (we track vehicles which are doing deliveries) has the concept of a Route which contains one or more Stops. I need my customers to be able to set these up in our system by calling a webservice, and then be able to retrieve information about a Route and how the vehicle is progressing. In the past I would have "cut-down" DTO classes which closely resemble my domain classes, and the customer would create a RouteDto with an array of StopDto(s), and call our CreateRoute webmethod, passing in the RouteDto. When they query our system by calling the GetRouteDetails method, I would return exactly the same objects to them. One of the appealing aspects of CQRS is that the RouteDto might have all manner of properties that the customer wants to query, but have no business setting when they create a Route. So I create a separate CreateRouteRequest class which is passed in when calling the CreateRoute "command", and a Route DTO class which gets returned as a query result. class Route{ string Reference; List<Stop> Stops; } But I need my customer to provide me with Route AND Stop details when they create a route. As I see it I could either... Give my CreateRouteRequest class a Stops(s) property which is an array of "something" representing the data they need to provide about each stop - but what do I call this class? It's not a Stop as that's what I'm calling the list of DTO inside my Route DTO, but I don't like "CreateStopRequest". I also wonder if I'm stuck in a CRUD mindset here thinking in terms of master-detail information and asking the customer to think like that too. class CreateRouteRequest{ string Reference; ... List<CreateStopRequest> Stops; } or They call CreateRoute, and then make a number of calls to an AddStopToRoute method. This feels a bit more "behavioural" but I'm going to lose the ability to treat creating a route including its stops as a single atomic command. If they create a Route and then try to add a Stop which fails due to some validation problem they're going to have a partially correct Route. The fact that I can't come up with a good name for the list of "StopCreationData" objects I'd be working with in option 1, makes me wonder if there's something I'm missing.

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  • Spring annotation mvc - request and response

    - by Eqbal
    I am using annotation based mvc and I am trying to get access to request and response objects using this method declaration in my controller. @RequestMapping(method=RequestMethod.GET) public String checkRequest(Model model, HttpServletRequest request, HttpServletResponse response) But I get an error saying GET method not supported. I need the request and response to pass it to another API call.

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  • Could not load file or assembly or one of its dependencies

    - by kp
    I changed some names of namespaces, assemblies in one of existing project (C# and ASP.NET). But when I try to debug it; I get this error. Could not load file or assembly 'HR' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040). I have replaced DFI with HR in the code.

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  • Speeding up templates in GAE-Py by aggregating RPC calls

    - by Sudhir Jonathan
    Here's my problem: class City(Model): name = StringProperty() class Author(Model): name = StringProperty() city = ReferenceProperty(City) class Post(Model): author = ReferenceProperty(Author) content = StringProperty() The code isn't important... its this django template: {% for post in posts %} <div>{{post.content}}</div> <div>by {{post.author.name}} from {{post.author.city.name}}</div> {% endfor %} Now lets say I get the first 100 posts using Post.all().fetch(limit=100), and pass this list to the template - what happens? It makes 200 more datastore gets - 100 to get each author, 100 to get each author's city. This is perfectly understandable, actually, since the post only has a reference to the author, and the author only has a reference to the city. The __get__ accessor on the post.author and author.city objects transparently do a get and pull the data back (See this question). Some ways around this are Use Post.author.get_value_for_datastore(post) to collect the author keys (see the link above), and then do a batch get to get them all - the trouble here is that we need to re-construct a template data object... something which needs extra code and maintenance for each model and handler. Write an accessor, say cached_author, that checks memcache for the author first and returns that - the problem here is that post.cached_author is going to be called 100 times, which could probably mean 100 memcache calls. Hold a static key to object map (and refresh it maybe once in five minutes) if the data doesn't have to be very up to date. The cached_author accessor can then just refer to this map. All these ideas need extra code and maintenance, and they're not very transparent. What if we could do @prefetch def render_template(path, data) template.render(path, data) Turns out we can... hooks and Guido's instrumentation module both prove it. If the @prefetch method wraps a template render by capturing which keys are requested we can (atleast to one level of depth) capture which keys are being requested, return mock objects, and do a batch get on them. This could be repeated for all depth levels, till no new keys are being requested. The final render could intercept the gets and return the objects from a map. This would change a total of 200 gets into 3, transparently and without any extra code. Not to mention greatly cut down the need for memcache and help in situations where memcache can't be used. Trouble is I don't know how to do it (yet). Before I start trying, has anyone else done this? Or does anyone want to help? Or do you see a massive flaw in the plan?

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  • how to create button in internet explorer?

    - by karikari
    I am developing a simple c++ program inside Microsoft Visual Studio. This program will later be convert to DLL, in order to register it to Internet Explorer. Inside my program, I would like to do like this: if flag=1, toolbar_button = green; else toolbar button = red; I want to create a simple button on the Internet Explorer, and the button can reflects the color that I pass from my c++ program. How can I achieve this?

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  • Access 2007 can I capture the "clicked" field using an OnClick event on a report?

    - by Aaron Quince
    In Access 2007 I want to be able to click on a name field in a report and call a separate report with personal information about the person who's name was clicked to start the event. This would be as an alternative to creating a subreport or including the subreport fields in the main report in the interest of saving space. How do I reference the value of the clicked field for use in a query called with the OnClick event? Thanks for your help.

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  • Why SQL2008 debugger would NOT step into a certain child stored procedure

    - by John Galt
    I'm encountering differences in T-SQL with SQL2008 (vs. SQL2000) that are leading me to dead-ends. I've verified that the technique of sharing #TEMP tables between a caller which CREATES the #TEMP and the child sProc which references it remain valid in SQL2008 See recent SO question. My core problem remains a critical "child" stored procedure that works fine in SQL2000 but fails in SQL2008 (i.e. a FROM clause in the child sProc is coded as: SELECT * FROM #AREAS A) despite #AREAS being created by the calling parent. Rather than post snippets of the code now, here is another symptom that may help you suggest something. I fired up the new debugger in SQL Mgmt Studio: EXEC dbo.AMS1 @S1='06',@C1='037',@StartDate='01/01/2008',@EndDate='07/31/2008',@Type=1,@ACReq = 1,@Output = 0,@NumofLines = 30,@SourceTable = 'P',@LoanPurposeCatg='P' This is a very large sProc and the key snippet that is weird is the following: **create table #Areas ( State char(2) , County char(3) , ZipCode char(5) NULL , CityName varchar(28) NULL , PData varchar(3) NULL , RData varchar(3) NULL , SMSA_CD varchar(10) NULL , TypeCounty varchar(50) , StateAbbr char(2) ) EXECUTE dbo.AMS_I_GetAreasV5 -- this child populates #Areas @SMSA = @SMSA , @S1 = @S1 , @C1 = @C1 , @Z1 = @Z1 , @SourceTable = @SourceTable , @CustomID = @CustomID , @UserName = @UserName , @CityName = @CityName , @Debug=0 EXECUTE dbo.AMS_I_GetAreas_FixAC -- this child cannot reference #Areas @StartDate = @StartDate , @EndDate = @EndDate , @SMSA_CD = @SMSA_CD , @S1 = @S1 , @C1 = @C1 , @Z1 = @Z1 , @CityName = @CityName , @CustomID = @CustomID , @Debug=0 -- continuation of the parent sProc** I can step through the execution of the parent stored procedure. When I get to the first child sproc above, I can either STEP INTO dbo.AMS_I_GetAreasV5 or STEP OVER its execution. When I arrive at the invocation of the 2nd child sProc - dbo.AMS_I_GetAreas_FixAC - I try to STEP INTO it (because that is where the problem statement is) and STEP INTO is ignored (i.e. treated like STEP OVER instead; yet I KNOW I pressed F11 not F10). It WAS executed however, because when control is returned to the statement after the EXECUTE, I click Continue to finish execution and the results windows shows the errors in the dbo.AMS_I_GetAreas_FixAC (i.e. the 2nd child) stored procedure. Is there a way to "pre-load" an sProc with the goal of setting a breakpoint on its entry so that I can pursue execution inside it? In summary, I wonder if the inability to step into a given child sproc might be related to the same inability of this particular child to reference a #temp created by its parent (caller).

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  • When are child views added to Layout/ViewGroup from XML

    - by JohnTube
    My question is : I want to know when does a xLayout (or ViewGroup in general) add a child view from XML ? And by "when" I mean at what point of code, in what "pass" of the "traversal" of the UI toolkit ? Which method of xLayout or ViewGroup should I override ? I have done my homework : I have watched the "Writing Custom Views For Android" presented (by Adam Powell and Romain Guy) in the last Google I/O and I have read Adam Powell comments on this Google+ post.

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  • Find Control In Datalist

    - by KareemSaad
    When I tried To Find Control n data List As I Mentioned Below Error(Object reference not set to an instance of an object. I cannot know protected void dlCategory_ItemDataBound(object sender, DataListItemEventArgs e) { Label Lb = (Label)e.Item.FindControl("LblCat"); Lb.ForeColor = System.Drawing.Color.Red; } ' onitemcreated="dlSubCategory_ItemCreated" onitemdatabound="dlSubCategory_ItemDataBound" ' class="buttn_txt" '

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  • MVC validation error with strongly typed view

    - by Remnant
    I have a simple form that I would like to validate on form submission. Note I have stripped out the html for ease of viewing <%=Html.TextBox("LastName", "")%> //Lastname entry <%=Html.ValidationMessage("LastName")%> <%=Html.TextBox("FirstName", "")%>//Firstname entry <%=Html.ValidationMessage("FirstName")%> <%=Html.DropDownList("JobRole", Model.JobRoleList)%> //Dropdownlist of job roles <% foreach (var record in Model.Courses) // Checkboxes of different courses for user to select { %> <li><label><input type="checkbox" name="Courses" value="<%=record.CourseName%>" /><%= record.CourseName%></label></li> <% } %> On submission of this form I would like to check that both FirstName and LastName are populated (i.e. non-zero length). In my controller I have: public ActionResult Submit(string FirstName, string LastName) { if (FirstName.Trim().Length == 0) ModelState.AddModelError("FirstName", "You must enter a first name"); if (LastName.Trim().Length == 0) ModelState.AddModelError("LastName", "You must enter a first name"); if (ModelState.IsValid) { //Update database + redirect to action } return View(); //If ModelState not valid, return to View and show error messages } Unfortunately, this code logic produces an error that states that no objects are found for JobRole and Courses. If I remove the dropdownlist and checkboxes then all works fine. The issue appears to be that when I return the View the view is expecting objects for the dropwdownlist and checkboxes (which is sensible as that is what is in my View code) How can I overcome this problem? Things I have considered: In my controller I could create a JobRoleList object and Course object to pass to the View so that it has the objects to render. The issue with this is that it will overwrite any dropdownlist / checkbox selections that the user has already made. In the parameters of my controller method Submit I could aslo capture the JobRoleList object and Course object to pass back to the View. Again, not sure this would capture any items the user has already selected. I have done much googling and reading but I cannot find a good answer. When I look at examples in books or online (e.g. Nerddinner) all the validation examples involve simple forms with TextBox inputs and don't seems to show instances with multiple checkboxes and dropdownlists. Have I missed something obvious here? What would be best practice in this situation? Thanks

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  • MVC-like Autogenerated Pages for Webforms

    - by CccTrash
    I noticed that MVC lets you pass in LINQ to SQL objects to its views and it will autogenerate Create, Update and View Pages based on the LINQtoSQL object. Is there anything for webforms that lets you do this kind of thing? (In a nice way with validators maybe?)

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  • How to handle unknown initializer functions in lua?

    - by oofoe
    I want to load data written in a variant of lua (eyeonScript). However, the data is peppered with references to initialization functions that are not in plain lua: Redden = BrightnessContrast { Inputs = { Red = Input { Value = 0, }, }, } Standard lua gives "attempt to call a nil value" or "unexpected symbol" errors. Is there any way to catch these and pass it to some sort of generic initializer? I want to wind up with a nested table data structure. Thanks!

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