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  • Using MVP, how to create a view from another view, linked with the same model object

    - by Dinaiz
    Background We use the Model-View-Presenter design pattern along with the abstract factory pattern and the "signal/slot" pattern in our application, to fullfill 2 main requirements Enhance testability (very lightweight GUI, every action can be simulated in unit tests) Make the "view" totally independant from the rest, so we can change the actual view implementation, without changing anything else In order to do so our code is divided in 4 layers : Core : which holds the model Presenter : which manages interactions between the view interfaces (see bellow) and the core View Interfaces : they define the signals and slots for a View, but not the implementation Views : the actual implementation of the views When the presenter creates or deals with views, it uses an abstract factory and only knows about the view interfaces. It does the signal/slot binding between views interfaces. It doesn't care about the actual implementation. In the "views" layer, we have a concrete factory which deals with implementations. The signal/slot mechanism is implemented using a custom framework built upon boost::function. Really, what we have is something like that : http://martinfowler.com/eaaDev/PassiveScreen.html Everything works fine. The problem However, there's a problem I don't know how to solve. Let's take for example a very simple drag and drop example. I have two ContainersViews (ContainerView1, ContainerView2). ContainerView1 has an ItemView1. I drag the ItemView1 from ContainerView1 to ContainerView2. ContainerView2 must create an ItemView2, of a different type, but which "points" to the same model object as ItemView1. So the ContainerView2 gets a callback called for the drop action with ItemView1 as a parameter. It calls ContainerPresenterB passing it ItemViewB In this case we are only dealing with views. In MVP-PV, views aren't supposed to know anything about the presenter nor the model, right ? How can I create the ItemView2 from the ItemView1, not knowing which model object is ItemView1 representing ? I thought about adding an "itemId" to every view, this id being the id of the core object the view represents. So in pseudo code, ContainerPresenter2 would do something like itemView2=abstractWidgetFactory.createItemView2(); this.add(itemView2,itemView1.getCoreObjectId()) I don't get too much into details. That just work. The problem I have here is that those itemIds are just like pointers. And pointers can be dangling. Imagine that by mistake, I delete itemView1, and this deletes coreObject1. The itemView2 will have a coreObjectId which represents an invalid coreObject. Isn't there a more elegant and "bulletproof" solution ? Even though I never did ObjectiveC or macOSX programming, I couldn't help but notice that our framework is very similar to Cocoa framework. How do they deal with this kind of problem ? Couldn't find more in-depth information about that on google. If someone could shed some light on this. I hope this question isn't too confusing ...

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  • Fetching Data from Multiple Tables using Joins

    Applying normalization to relational databases tends to promote better accuracy of queries, but it also leads to queries that take a little more work to develop, as the data may be spread amongst several tables. In today's article, we'll learn how to fetch data from multiple tables by using joins.

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  • What is the right way to do this HTML: header with icon linked

    - by Hell Awaits
    I know how to make these examples look and behave the same. But I would like to know which is the right way to build a HTML structure. <a><img><h1></h1></a> - looks wrong because an inline element is inside of a block element <a><img></a><h1><a></a></h1> - the same a-element is defined twice. Also I'm not sure about markup inside headers Any other solutions ?

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  • Never update systems tables directly - a study in Agent job scheduling

    It is often recommended that system tables should not be updated directly. Presenting a case in point built around nightly job configuration in order to demonstrate the possible issues with updating system tables directly. What can SQL Monitor 3.2 monitor?Whatever you think is most important. Use custom metrics to monitor and alert on data that's most important for your environment. Find out more.

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  • Path tables or real time searching for AI?

    - by SirYakalot
    What is the more common practice in commercial games; path lookup tables or real time searches? I've read that in many games path lookup tables are pre-calculated and baked into each map, so to speak, then steering behaviour is used to handle dynamic obstacles. or is it better practice to use optimised hierarchical A* searches? I understand the pro's and cons of each, I'm just curious as to what is most often used in the industry.

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  • Various issues linked to my CD drive, when it has a disc in it

    - by Voyagerfan5761
    When I go to the Desktop and click on a media icon (for my flash drive, a CD, whatever it is), the following problems occur, in this approximate sequence: Nautilus will close if it's open. the desktop icons disappear my Window List shows a button that says "Starting File Manager" the icons reappear the button in Window List disappears Because of this problem, I can no longer drag and drop media, nor can I right-click to perform actions such as "Eject" and "Safely Remove Drive". The same symptoms occur if I click a media icon (that is also present on the desktop) in Nautilus' Computer view, though notably not if I click in the places list on the left. I have confirmed that this problem happens only if there is a CD in the drive (Matshita UJDA360). Also, inserting a disc into the CD drive appears to kill all running programs and restart Nautilus (or X; I'm not sure). Applications like Brasero and Rhythmbox will not start while there is a disc in the drive. Removing the disc doesn't result in the list of media updating; it must be forced to update by clicking on one of the desktop icons and going through one of the above-described cycles. It doesn't seem to matter what type of disc is in the drive. This has happened with CD-RWs I burned years ago using Roxio on Windows XP, the Ubuntu disc I installed from (burned with InfraRecorder Portable under Windows XP), and the retail game disc for Star Trek Armada II. The first indication of a problem was Brasero dying when I tried to insert a disc for erasure and rewriting. Since then, I've drafted several different questions on various issues, finally combining them into this one when I realized that having a CD in the drive was the common link. Could this be a simple driver issue? If Ubuntu is dynamically detecting my hardware on boot, can I specify drivers for devices that I know will be a problem if the default files are used? I'm beginning to think that my laptop, an old Dell Inspiron 2650, is just too old or proprietary-driver-hungry (or something, maybe RAM-starved) for Ubuntu and Windows XP to play nicely alongside each other. Or maybe I just need to carefully take my wall-wart machine to a coffee shop for an afternoon so I can download updates and such from the Internet, as I lack a home connection.

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  • organization of DLL linked functions

    - by m25
    So this is a code organization question. I got my basic code working but when I expand it will be terrible. I have a DLL that I don't have a .lib for. Therefore I have to use the whole loadLibrary()/getprocaddress() combo. it works great. But this DLL that i'm referencing at 100+ functions. my current process is (1) typedef a type for the function. or typedef short(_stdcall *type1)(void); then (2) assign a function name that I want to use such as type1 function_1, then (3) I do the whole LoadLibrary, then do something like function_1 = (type1)GetProcAddress(hinstLib, "_mangled_funcName@5"); normally I would like to do all of my function definitions in a header file but because I have to do use the load library function, its not that easy. the code will be a mess. Right now i'm doing (1) and (2) in a header file and was considering making a function in another .cpp file to do the load library and dump all of the (3)'s in there. I considered using a namespace for the functions so I can use them in the main function and not have to pass over to the other function. Any other tips on how to organize this code to where it is readable and organized? My goals are to be able to use function_1 as a regular function in the main code. if I have to a ref::function_1 that would be okay but I would prefer to avoid it. this code for all practical purposes is just plane C at the moment. thanks in advance for any advice!

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  • Algorithms or patterns for a linked question and answer cost calculator

    - by kmc
    I've been asked to build an online calculator in PHP (and the Laravel framework). It will take the answers to a series of questions to estimate the cost of a home extension. For example, a couple of questions may be: What is the lie of your property? Flat, slightly inclined, heavily inclined. (these suggestive values could have specific values in the underlying calculator like, 0 degrees, 5 degrees, 10 degrees. What is your current flooring system? Wooden, or concrete? These would then impact the results of other questions. Once the size of the extension has been input, the lie of the land will affect how much site works will cost, and how much rubbish collection will cost. The second question will impact the cost of the extensions flooring, as stumping and laying floorboards is a different cost to laying foundations and a concrete slab. It will also influence what heating and cooling systems are available in the calculator. So it's VERY interlinked. The answer to any question can influence the options of other questions, and the end result. I'm having trouble figuring out an approach to this that will allow new options and questions to be plugged in at a later stage without having things too coupled. The Observer pattern, or Laravel's events may be handy, but currently the sheer breadth of the calculator has me struggling to gather my thoughts and see a sensible implementation. Are there any patterns or OO approaches that may help? Thanks!

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  • How Social Media Marketing and SEO Are Inter-Linked

    Today successful marketer is the one who leverages advantages from both SEO as well as Social Media Marketing (SMM). Social Media (SM) flourishes where people are, and marketers propel there only. Earlier SMM used to be a standalone strategy but with time it was realized that if it is united with marketing efforts it could generate even better results rather than working in isolation.

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  • self referencing tables, good or bad?

    - by NimChimpsky
    Representing geographical locations within an application, the design of the underlying data model suggests two clear options (or maybe more?). One table with a self referencing parent_id column uk - london (london parent id = UK id) or two tables, with a one to many relationship using a foreign key. My preference is for one self-refercing table as it easily allows to extend into as many sub regions as required. IN general do people veer away from self referencing tables, or are they A-OK ?

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  • Utility Queries–Structure of Tables with Identity Column

    - by drsql
    I have been doing a presentation on sequences of late (last planned version of that presentation was last week, but should be able to get the gist of things from the slides and the code posted here on my presentation page), and as part of that, I started writing some queries to interrogate the structure of tables. I started with tables using an identity column for some purpose because they are considerably easier to do than sequences, specifically because the limitations of identity columns make...(read more)

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  • EF Doesn't Like Same Named Tables

    - by Anthony Trudeau
    Originally posted on: http://geekswithblogs.net/tonyt/archive/2013/07/02/153327.aspxIt's another week and another restriction imposed by the Entity Framework (EF). Don't get me wrong. I like EF, but I don't like how it restricts you in different ways. At this point you may be asking yourself the question: how can you have more than one table with the same name?The answer is to have tables in different schemas. I do this to partition the data based on the area of concern. It allows security to be assigned conveniently. A lot of people don't use schemas. I love them. But this article isn't about schemas.In the situation I have two tables:Contact.PersonEmployee.PersonThe first contains the basic, more public information such as the name. The second contains mostly HR specific information. I then mapped these tables to two classes. I stuck to a Table per Class (TPC) mapping, because of problems I've had in the past implementing inheritance with EF. The following code gives you the basic contents of the classes.[Table("Person", Schema = "Employee")]public class Employee {   ...   public int PersonId { get; set; }   [ForeignKey("PersonId")]   public virtual Person Person { get; set; }}[Table("Person", Schema = "Contact")]public class Person {   [Key]   public int Id { get; set; }   ...}This seemingly simple scenario just doesn't work. The problem occurs when you try to add a Person to the DbContext. You get an InvalidOperationException with the following text:The entity types 'Employee' and 'Person' cannot share table 'People' because they are not in the same type hierarchy or do not have a valid one to one foreign key relationship with matching primary keys between them..This is interesting for a couple of reasons. First, there is no People table in my database. Second, I have used the SetInitializer method to stop a database from being created, so it shouldn't be thinking about new tables.The solution to my problem was to change the name of my Employee.Person table. I decided to name it Employee.Employee. It's not ideal, but it gets me past the EF limitation. I hope that this article will help someone else that has the same problem.

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  • applications linked to desktops

    - by ricoamor
    I have just upgraded to Ubuntu 12.04 and I found a weird behaviour in the multi-workspace management. Let's say that I have a couple of terminals opened in one workspace, and that I want to do something else in another workspace. I move to that workspace and then I click on the terminal icon. Immediately I am taken to the initial workspace. This is similar to the multiple workspace behaviour in Os X and it is entirely undesirable. How can I disable the application-workspace association in 12.04? Thanks

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  • Linked List Design

    - by Jim Scott
    The other day in a local .NET group I attend the following question came up: "Is it a valid interview question to ask about Linked Lists when hiring someone for a .NET development position?" Not having a computer sciense degree and being a self taught developer my response was that I did not feel it was appropriate as I in 5 years of developer with .NET had never been exposed to linked lists and did not hear any compeling reason for a use for one. However the person commented that it is a very common interview question so I decided when I left that I would do some reasearch on linked lists and see what I might be missing. I have read a number of posts on stack overflow and various google searches and decided the best way to learn about them was to write my own .NET classes to see how they worked from the inside out. Here is my class structure Single Linked List Constructor public SingleLinkedList(object value) Public Properties public bool IsTail public bool IsHead public object Value public int Index public int Count private fields not exposed to a property private SingleNode firstNode; private SingleNode lastNode; private SingleNode currentNode; Methods public void MoveToFirst() public void MoveToLast() public void Next() public void MoveTo(int index) public void Add(object value) public void InsertAt(int index, object value) public void Remove(object value) public void RemoveAt(int index) Questions I have: What are typical methods you would expect in a linked list? What is typical behaviour when adding new records? For example if I have 4 nodes and I am currently positioned in the second node and perform Add() should it be added after or before the current node? Or should it be added to the end of the list? Some of the designs I have seen explaining things seem to expose outside of the LinkedList class the Node object. In my design you simply add, get, remove values and know nothing about any node object. Should the Head and Tail be placeholder objects that are only used to define the head/tail of the list? I require my Linked List be instantiated with a value which creates the first node of the list which is essentially the head and tail of the list. Would you change that ? What should the rules be when it comes to removing nodes. Should someone be able to remove all nodes? Here is my Double Linked List Constructor public DoubleLinkedList(object value) Properties public bool IsHead public bool IsTail public object Value public int Index public int Count Private fields not exposed via property private DoubleNode currentNode; Methods public void AddFirst(object value) public void AddLast(object value) public void AddBefore(object existingValue, object value) public void AddAfter(object existingValue, object value) public void Add(int index, object value) public void Add(object value) public void Remove(int index) public void Next() public void Previous() public void MoveTo(int index)

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  • Deleting a node in a circular linked list c++?

    - by angad Soni
    I was wondering if anyone could help me understand if this code for deleting a node from a circular linked list would work, or if there is something i'm missing out on. using c++ to code. void circularList::deleteNode(int x) { node *current; node *temp; current = this-start; while(current->next != this->start) { if(current->next->value == x) { temp = current->next; current->next = current->next->next; delete current->next; } } }

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  • Using C++ is a Linked-List implementation without using pointers possible or not?

    - by sonicoder
    My question is very simply, can one using C++, implment a link-list data structure without using pointers (next nodes)? To further qualify my question, I'm mean can one create a Linked-List data structure using only class instantiations. A common node definition might be like so: template<typename T> struct node { T t; node<T>* next; node<T>* prev; }; I'm aware of std::list etc, I'm just curious to know if its possible or not - and if so how? code examples will be greatly appreciated.

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  • Segmentation fault in a function to reverse a singly linked list recursivley.

    - by Amanda
    I am implementing a function to recursively reverse a linked-list, but getting seg-fault. typedef struct _node { int data; struct _node *next; } Node, *NodeP; NodeP recursiveReverseList(NodeP first){ if(first == NULL) return NULL; if(first->next == NULL) return first; NodeP rest = recursiveReverseList(first->next); rest->next = first; first->next = NULL; return first; } Can you please help? P.S. The iterative version is working fine though. Its not homework. Just practicing C. Thank you all :)

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  • Oracle 11gR2 exp does not export some tables

    - by Tilo Prütz
    I have an Oracle 11g (11.2.0.1) Database running on Linux (x64). Within the database I have a schema and 33 tables for it. When I log in via sqlplus I can list all the tables via SELECT OBJECT_NAME FROM USER_OBJECTS WHERE OBJECT_TYPE = 'TABLE'; But when I export the Tablespace using exp ... BUFFER=65536 FULL=N COMPRESS=N CONSISTENT=Y TABLESPACES=... FILE=... Then it only exports 24 of the 33 tables. I have tried to export the missing tables via exp ... TABLES=<missing_table> ... But then I get an error: EXP-00011: NPSMIGRO2_CM.DEFAULT_USR_ATTR_VALUES does not exist How can I find out what's wrong here? How can I export all the tables?

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  • MySQL Privileges required to GRANT EVENT, EXECUTE, LOCK TABLES, and TRIGGER

    - by Brad
    I have an account, user_a, and I would like to grant all available permissions on some_db to user_b. I have tried the following query: GRANT ALTER, ALTER ROUTINE, CREATE, CREATE ROUTINE, CREATE TEMPORARY TABLES, CREATE VIEW, DELETE, DROP, EVENT, EXECUTE, INDEX, INSERT, LOCK TABLES, REFERENCES, SELECT, SHOW VIEW, TRIGGER, UPDATE ON `some_db`.* TO 'user_b'@'%' WITH GRANT OPTION The result: Access denied for user 'user_a'@'%' to database 'some_db' Some experimentation has shown me that the only permissions my account (user_a) is unable to grant are EVENT, EXECUTE, LOCK TABLES, and TRIGGER. What privileges are required for my account to GRANT these privileges to another user? If I run SHOW GRANTS, I get this output: "GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, SHOW DATABASES, SUPER, CREATE TEMPORARY TABLES, REPLICATION SLAVE, REPLICATION CLIENT, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, ALTER ROUTINE, CREATE USER ON *.* TO 'user_a'@'%' IDENTIFIED BY PASSWORD '1234567890abcdef' WITH GRANT OPTION" "GRANT SELECT, INSERT, UPDATE, DELETE, EXECUTE ON `some_other_unrelated_db`.* TO 'user_a'@'%'" "GRANT SELECT, INSERT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE TEMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE ROUTINE, ALTER ROUTINE ON `another_unrelated_db`.* TO 'user_a'@'%' WITH GRANT OPTION"

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  • Existing tables with binaries to use filestream

    - by user1098487
    I've got a few tables for which I want to use filestream storage. These tables already contain binary data and have rowguids. However at the time they were were created, the tables were not added to a filestream enabled filegroup. What is the best way to have these tables use filestream at this point? Do I need to drop + recreate the tables and migrate the data? Is there an easier way? The database already has filestream enabled and there are other tables which are using them.

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  • How to find nth element from the end of a singly linked list?

    - by Codenotguru
    The following function is trying to find the nth to last element of a singly linked list. For example: If the elements are 8->10->5->7->2->1->5->4->10->10 then the result is 7th to last node is 7. Can anybody help me on how this code is working or is there a better and simpler approach? LinkedListNode nthToLast(LinkedListNode head, int n) { if (head == null || n < 1) { return null; } LinkedListNode p1 = head; LinkedListNode p2 = head; for (int j = 0; j < n - 1; ++j) { // skip n-1 steps ahead if (p2 == null) { return null; // not found since list size < n } p2 = p2.next; } while (p2.next != null) { p1 = p1.next; p2 = p2.next; } return p1; }

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  • Achieve Named Criteria with multiple tables in EJB Data control

    - by Deepak Siddappa
    In EJB create a named criteria using sparse xml and in named criteria wizard, only attributes related to the that particular entities will be displayed.  So here we can filter results only on particular entity bean. Take a scenario where we need to create Named Criteria based on multiple tables using EJB. In BC4J we can achieve this by creating view object based on multiple tables. So in this article, we will try to achieve named criteria based on multiple tables using EJB.Implementation StepsCreate Java EE Web Application with entity based on Departments and Employees, then create a session bean and data control for the session bean.Create a Java Bean, name as CustomBean and add below code to the file. Here in java bean from both Departments and Employees tables three fields are taken. public class CustomBean { private BigDecimal departmentId; private String departmentName; private BigDecimal locationId; private BigDecimal employeeId; private String firstName; private String lastName; public CustomBean() { super(); } public void setDepartmentId(BigDecimal departmentId) { this.departmentId = departmentId; } public BigDecimal getDepartmentId() { return departmentId; } public void setDepartmentName(String departmentName) { this.departmentName = departmentName; } public String getDepartmentName() { return departmentName; } public void setLocationId(BigDecimal locationId) { this.locationId = locationId; } public BigDecimal getLocationId() { return locationId; } public void setEmployeeId(BigDecimal employeeId) { this.employeeId = employeeId; } public BigDecimal getEmployeeId() { return employeeId; } public void setFirstName(String firstName) { this.firstName = firstName; } public String getFirstName() { return firstName; } public void setLastName(String lastName) { this.lastName = lastName; } public String getLastName() { return lastName; } } Open the sessionEJb file and add the below code to the session bean and expose the method in local/remote interface and generate a data control for that. Note:- Here in the below code "em" is a EntityManager. public List<CustomBean> getCustomBeanFindAll() { String queryString = "select d.department_id, d.department_name, d.location_id, e.employee_id, e.first_name, e.last_name from departments d, employees e\n" + "where e.department_id = d.department_id"; Query genericSearchQuery = em.createNativeQuery(queryString, "CustomQuery"); List resultList = genericSearchQuery.getResultList(); Iterator resultListIterator = resultList.iterator(); List<CustomBean> customList = new ArrayList(); while (resultListIterator.hasNext()) { Object col[] = (Object[])resultListIterator.next(); CustomBean custom = new CustomBean(); custom.setDepartmentId((BigDecimal)col[0]); custom.setDepartmentName((String)col[1]); custom.setLocationId((BigDecimal)col[2]); custom.setEmployeeId((BigDecimal)col[3]); custom.setFirstName((String)col[4]); custom.setLastName((String)col[5]); customList.add(custom); } return customList; } Open the DataControls.dcx file and create sparse xml for customBean. In sparse xml navigate to Named criteria tab -> Bind Variable section, create two binding variables deptId,fName. In sparse xml navigate to Named criteria tab ->Named criteria, create a named criteria and map the query attributes to the bind variables. In the ViewController create a file jspx page, from data control palette drop customBeanFindAll->Named Criteria->CustomBeanCriteria->Query as ADF Query Panel with Table. Run the jspx page and enter values in search form with departmentId as 50 and firstName as "M". Named criteria will filter the query of a data source and display the result like below.

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