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  • a design to avoid circular reference in this scenario

    - by BDotA
    Here is our dependency tree: BigApp - Child Apps - Libraries ALL of our components are HEAVILY using one of the Libraries as above ( LibA). But it has a ‘few’ public methods that require classes from ‘higher-level’ assemblies and we want to avoid CIRCULAR references. What do you propose as a good design for this?

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  • Core Data - Entity Relationships Not Working as expected

    - by slimms
    I have set up my data model in xcode like so EntityA AttA1 AttA2 EntityB AttB1 AttB2 AttB3 I then set up the relationships EntityA Name: rlpToEntityB Destination: EntityB Inverse: rlpToEntityA To Many: Checked EntityB Name: rlpToEntityA Destination: EntityA Inverse: rlpToEntityB To Many: UnChecked i.e. relationship between the two where Each one of EntityA can have many EntityB's It is my understanding that if i fetch a subset of EntityB's I can then retrieve the values for the related EntityA's. I have this working so that i can retrieve the EntityB values using NSManagedObject *objMO = [fetchedResultsController objectAtIndexPath:indexPath]; strValueFromEntityB = [objMO valueForKey:@"AttB1"]; However, if I try to retrieve a related value from EntityA by doing the following strValueFromEntityA = [objMO valueForKey:@"AttA1"]; I get the error "The entity EntityB is not Key value coding-compliant for the key Atta1" Not surprisingly i suppose if i switch things around to fetch from EntityA i cannot access attributes of EntityB So it appears the defined relationshipare being ignored. Can anyone spot what i am doing wrong? I confess im very new to iPhone programming and especially to Core Data so please go easy on me and provide verbose explanations or point me in the direction a specific resource. I have downloaded the apple sample apps (Core Data Books, Top Songs and recipes) but I still can't work this out. Thanks in advance, Nev.

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  • Rails database relationships

    - by Danny McClelland
    Hi Everyone, I have three models that I want to interact with each other. Kase, Person and and Company. I have (I think) setup the relationships correctly: class Kase < ActiveRecord::Base #HAS ONE COMPANY has_one :company #HAS MANY PERSONS has_many :persons class Person < ActiveRecord::Base belongs_to :company class Company < ActiveRecord::Base has_many :persons def to_s; companyname; end I have put the select field on the create new Kase view, and the create new Person view as follows: <li>Company<span><%= f.select :company_id, Company.all %> </span></li> All of the above successfully shows a drop down menu dynamically populated with the company names within Companies. What I am trying to do is display the contact of the Company record within the kase and person show.html.erb. For example, If I have a company called "Acme, Inc." and create a new Kase called "Random Case" and choose within the create new case page "Acme, Inc." from the companies drop down menu. I would then want to display "Acme, Inc" along with "Acme, Inc. Mobile" etc. on the "Random Case" show.html.erb. I hope this makes sense to somebody! Thanks, Danny

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  • C++: Dependency injection, circular dependency and callbacks

    - by Jonathan
    Consider the (highly simplified) following case: class Dispatcher { public: receive() {/*implementation*/}; // callback } class CommInterface { public: send() = 0; // call } class CommA : public CommInterface { public: send() {/*implementation*/}; } Various classes in the system send messages via the dispatcher. The dispatcher uses a comm to send. Once an answer is returned, the comm relays it back to the dispatcher which dispatches it back to the appropriate original sender. Comm is polymorphic and which implementation to choose can be read from a settings file. Dispatcher has a dependency on the comm in order to send. Comm has a dependency on dispatcher in order to callback. Therefor there's a circular dependency here and I can't seem to implement the dependency injection principle (even after encountering this nice blog post).

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  • Database design: circular references

    - by SlappyTheFish
    I have three database tables: users emails invitations Emails are linked to users by a user_id field. Invitations are also linked to users by a user_id field Emails can be created without an invitation, but every invitation must have an email. I would like to link the emails and invitations tables so it is possible to find the email for a particular invitation. However this creates a circular reference, both an invitation and an email record hold the id for the same user. Is this bad design and if so, how could I improve it? My feeling is that with use of foreign keys and good business logic, it is fine.

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  • Circular Dependency Solution

    - by gfoley
    Our current project has ran into a circular dependency issue. Our business logic assembly is using classes and static methods from our SharedLibrary assembly. The SharedLibrary contains a whole bunch of helper functions, such as a SQL Reader class, Enumerators, Global Variables, Error Handling, Logging and Validation. The SharedLibrary needs access to the Business objects, but the Business objects need access to SharedLibrary. The old developers solved this obvious code smell by replicating the functionality of the business objects in the shared library (very anti-DRY). I've spent a day now trying to read about my options to solve this but i'm hitting a dead end. I'm open to the idea of architecture redesign, but only as a last resort. So how can i have a Shared Helper Library which can access the business objects, with the business objects still accessing the Shared Helper Library?

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  • Test if single linked list is circular by traversing it only once

    - by user1589754
    I am a fresher and I was asked this question in a recent interview I gave. The question was --- By traversing each element of linked list just once find if the single linked list is circular at any point. To this I answered that we will store reference of each node while traversing the list in another linked list and for every node in the list being tested we will find if the reference exists in the list I am storing the references. The interviewer said that he needs a more optimized way to solve this problem. Can anyone please tell me what would be a more optimized method to solve this problem.

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  • Circular reference problem Singleton

    - by Ismail
    I'm trying to creating a Singleton class like below where MyRepository lies in separate DAL project. It's causing me a circular reference problem because GetMySingleTon() method returns MySingleTon class and needs its access. Same way I need MyRepository access in constructor of MySingleTon class. public class MySingleTon { static MySingleTon() { if (Instance == null) { MyRepository rep = new MyRepository(); Instance = rep.GetMySingleTon(); } } public static MySingleTon Instance { get; private set; } public string prop1 { get; set; } public string prop2 { get; set; } }

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  • DB Design - Linking to a parent without circular reference issues

    - by zSysop
    Hi all, I'm having trouble coming up with a solution for the following issue. Lets say i have a db that looks something like the following: Issue Table Id | Details | CreateDate | ClosedDate Issue Notes Table Id | ObjectId | Notes | NoteDate Issue Assignment Table Id | ObjectId | AssignedToId| AssignedDate I'd like allow the linking of an issue to another issue. I thought about adding a column to the Issue table called ParentIssueId and that would allow me the ability to link issues, but i foresee circular references occurring within the issue table if i go through with this implementation. Is there a better way to go about doing this, and if so, how? Thanks

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  • FRIEND_TEST in Google Test - possible circular dependency?

    - by Mihaela
    I am trying to figure out how FRIEND_TEST works in Google Tests. http://code.google.com/p/googletest/wiki/AdvancedGuide#Private_Class_Members I am looking at the following item, trying to implement it in my code: // foo.h #include "gtest/gtest_prod.h" // Defines FRIEND_TEST. class Foo { ... private: FRIEND_TEST(FooTest, BarReturnsZeroOnNull); int Bar(void* x); }; // foo_test.cc ... TEST(FooTest, BarReturnsZeroOnNull) { Foo foo; EXPECT_EQ(0, foo.Bar(NULL)); // Uses Foo's private member Bar(). } In the code above, the piece that I can't see, is that foo_test.cc must include foo.h, in order to have access to Foo and Bar(). [Perhaps it works differently for Google ? in my code, I must include it] That will result in circular dependency... Am I missing something ?

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  • How to hash and check for equality of objects with circular references

    - by mfya
    I have a cyclic graph-like structure that is represented by Node objects. A Node is either a scalar value (leaf) or a list of n=1 Nodes (inner node). Because of the possible circular references, I cannot simply use a recursive HashCode() function, that combines the HashCode() of all child nodes: It would end up in an infinite recursion. While the HashCode() part seems at least to be doable by flagging and ignoring already visited nodes, I'm having some troubles to think of a working and efficient algorithm for Equals(). To my surprise I did not find any useful information about this, but I'm sure many smart people have thought about good ways to solve these problems...right? Example (python): A = [ 1, 2, None ]; A[2] = A B = [ 1, 2, None ]; B[2] = B A is equal to B, because it represents exactly the same graph. BTW. This question is not targeted to any specific language, but implementing hashCode() and equals() for the described Node object in Java would be a good practical example.

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  • Circular reference while setting up bidirectional communication line between two remote objects

    - by mphair
    I'm using .Net remoting to set up a bidirectional communication line between two objects. The basic structure is as follows: Instances of RemoteObjectA call methods on StaticObjectA. Instances of RemoteObjectB call methods on StaticObjectB. StaticObjectA needs to be able to call methods provided by RemoteObjectB. StaticObjectB needs to be able to call methods provided by RemoteObjectA. The problem with this setup is the circular reference in RemoteObjectA gets StaticObjectA gets RemoteObjectB gets StaticObjectB gets RemoteObjectA... I implemented an interface IRemoteObjectA and IRemoteObjectB and had the remote objects inheret from their respective interfaces, but then setting up the remoting fails. If the solution to this problem is: "don't use remoting", I can deal with that. Just wanted to make sure I wasn't missing a simple solution.

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  • Resolve circular typedef dependency?

    - by Nick
    What is the best way to resolve the following circular dependency in typedef-ing these structs? Note the C language tag - I'm looking for a solution in standard gcc C. typedef struct { char* name; int age; int lefthanded; People* friends; } Person; typedef struct { int count; int max; Person* data; } People;

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  • Resolving Circular References for Objects Implementing ISerializable

    - by Chris
    I'm writing my own IFormatter implementation and I cannot think of a way to resolve circular references between two types that both implement ISerializable. Here's the usual pattern: [Serializable] class Foo : ISerializable { private Bar m_bar; public Foo(Bar bar) { m_bar = bar; m_bar.Foo = this; } public Bar Bar { get { return m_bar; } } protected Foo(SerializationInfo info, StreamingContext context) { m_bar = (Bar)info.GetValue("1", typeof(Bar)); } public void GetObjectData(SerializationInfo info, StreamingContext context) { info.AddValue("1", m_bar); } } [Serializable] class Bar : ISerializable { private Foo m_foo; public Foo Foo { get { return m_foo; } set { m_foo = value; } } public Bar() { } protected Bar(SerializationInfo info, StreamingContext context) { m_foo = (Foo)info.GetValue("1", typeof(Foo)); } public void GetObjectData(SerializationInfo info, StreamingContext context) { info.AddValue("1", m_foo); } } I then do this: Bar b = new Bar(); Foo f = new Foo(b); bool equal = ReferenceEquals(b, b.Foo.Bar); // true // Serialise and deserialise b equal = ReferenceEquals(b, b.Foo.Bar); If I use an out-of-the-box BinaryFormatter to serialise and deserialise b, the above test for reference-equality returns true as one would expect. But I cannot conceive of a way to achieve this in my custom IFormatter. In a non-ISerializable situation I can simply revisit "pending" object fields using reflection once the target references have been resolved. But for objects implementing ISerializable it is not possible to inject new data using SerializationInfo. Can anyone point me in the right direction?

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  • Reversing a circular deque without a sentinel

    - by SDLFunTimes
    Hey Stackoverflow I'm working on my homework and I'm trying to reverse a circular-linked deque without a sentinel. Here are my data structures: struct DLink { TYPE value; struct DLink * next; struct DLink * prev; }; struct cirListDeque { int size; struct DLink *back; }; Here's my approach to reversing the deque: void reverseCirListDeque(struct cirListDeque* q) { struct DLink* current; struct DLink* temp; temp = q->back->next; q->back->next = q->back->prev; q->back->prev = temp; current = q->back->next; while(current != q->back->next) { temp = current->next; current->next = current->prev; current->prev = temp; current = current->next; } } However when I run it and put values 1, 2 and 3 on it (TYPE is just a alias for int in this case) and reverse it I get 2, 3, null. Does anyone have any ideas as to what I may be doing wrong? Thanks in advance.

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  • Circular dependency with generics

    - by devoured elysium
    I have defined the following interface: public interface IStateSpace<State, Action> where State : IState where Action : IAction<State, Action> // <-- this is the line that bothers me { void SetValueAt(State state, Action action); Action GetValueAt(State state); } Basically, an IStateSpace interface should be something like a chess board, and in each position of the chess board you have a set of possible movements to do. Those movements here are called IActions. I have defined this interface this way so I can accommodate for different implementations: I can then define concrete classes that implement 2D matrix, 3D matrix, graphs, etc. public interface IAction<State, Action> { IStateSpace<State, Action> StateSpace { get; } } An IAction, would be to move up(this is, if in (2, 2) move to (2, 1)), move down, etc. Now, I'll want that each action has access to a StateSpace so it can do some checking logic. Is this implementation correct? Or is this a bad case of a circular dependence? If yes, how to accomplish "the same" in a different way? Thanks

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  • Refinery CMS (Rails): Creating a plugin or plugins with multiple models and relationships

    - by jklina
    My goal is to create a way for an admin to create two models in the Refinery admin: Campaigns and Videos I would like to have it setup so that a Campaign has many Videos and that each Video belongs to a Campaign. Both Videos and Campaigns will have a title, description, and a preview image. I'm not certain of the best way to go about this. Is it possible to setup two plugins and form a relationship between the two? Or, should I create one plugin with both models. If someone could point me in the right direction or a good example of a solution to a similar problem, I would be grateful. Thank you for looking!

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  • Database relationships using phpmyAdmin (composite keys)

    - by Cool Hand Luke UK
    Hi, I hope this question is not me being dense. I am using phpmyAdmin to create a database. I have the following four tables. Don't worry about that fact place and price are optional they just are. Person (Mandatory) Item (Mandatory) Place (Optional) Price (Optional) Item is the main table. It will always have person linked. * I know you do joins in mysql for the tables. If I want to link the tables together I could use composite keys (using the ids from each table), however is this the most correct way to link the tables? It also means item will have 5 ids including its own. This all cause null values (apparently a big no no, which I can understand) because if place and price are optional and are not used on one entry to the items table I will have a null value there. Please help! Thanks in advance. I hope this makes sense.

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  • Setting SQL Relationships For LINQ Queries

    - by Soo
    I have two tables that I'm trying to create a relationship between so I can write nice LINQ queries that don't require join. Widgets WidgetId WidgetDescription Orders OrderId WidgetId OrderDate What I want to be able to do is create a LINQ query that does something similar to: var result = from x in db.Widgets Where x.Orders.OrderDate == "5/11/2010" select x; I can't seem to get intellitext to pick up the other database despite creating a relationship in SQL server. Are there any additional steps I need to take to make this work?

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  • Database table relationships: Always also relate to specified value (Linq to SQL in .NET Framework)

    - by sinni800
    I really can not describe my question better in the title. If anyone has suggestions: Please tell! I use the Linq to SQL framework in .NET. I ran into something which could be easily solved if the framework supported this, it would be a lot of extra coding otherwise: I have a n to n relation with a helper table in between. Those tables are: Items, places and the connection table which relates items to places and the other way. One item can be found in many places, so can one place have many items. Now of course there will be many items which will be in ALL places. Now there is a problem: Places can always be added. So I need a place-ID which encompasses ALL places, always. Like maybe a place-id "0". If the helper table has a row with the place-id of zero, this should be visible in all places. In SQL this would be a simple "Where [...] or place-id = 0", but how do I do this in Linq relations? Also, for a little side question: How could I manage "all but this place" kind of exclusions?

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  • Relationships in a Chen ERD

    - by Nibroc A Rehpotsirhc
    I am working on a Chen ERD to model our organizations merchandise. Our central entity is a Style. We have supplemental entities of Color and Season. I am defining our assortment as the relationship between these three entities, and this relationship itself will have attributes and is defined by the three entities which participate in the mandatory relationship. The rules are; Many Styles can be offered in a Season, and a Style can be offered in many Seasons. Within a Season, a Style can be offered in Many Colors. I then have 2 other entities, one of which I believe is a weak entity, Climate, and the other may be weak, but I am not sure, this being Transaction Channel. I am thinking of these as relationships off of a relationship? Meaning, for a given Style/Color combination offered in a Season, it can be available through 1 or more Transaction Channels. Additionally, within a season, a given Style/Color combination can be intended for 1 or more Climates. Is it valid to have relationships off of relationships? Or does this requirement dictate that I should think of this Style/Color/Season relationship as an entity itself, and define the relationships to Climate and Transaction Channel off of this entity?

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  • Circular Shifts on Strings in Bash

    - by Kyle Van Koevering
    I have a homework assignment where I need to take input from a file and continuously remove the first word in a line and append it to the end of the line until all combinations have been done. I really don't know where to begin and would be thankful for any sort of direction. The part that has me confused is that this is suppose to be performed without the use of arrays. I'm not just fishing for someone to solve the problem for me, I'm just looking for some direction. Thank you very much for your time and help. SAMPlE INPUT: Pipes and Filters Java Swing Software Requirements Analysis SAMPLE OUTPUT: Analysis Software Requirements Filters Pipes and Java Swing Pipes and Filters Requirements Analysis Software Software Requirements Analysis Swing Java

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  • Building Java projects with circular imports in Eclipse

    - by Buggieboy
    I have a legacy Java (not my native language) app that I'm trying to build in Eclipse Galileo. As it's not my own, I can't speak to the quality of the design, but I am coming across a number of instances where I'll have something like this: In a project called, say, "lib_a", I'll have a file containing this: import com.acme.lib_b.onething; Project "lib_b" on the other hand, will contain: import com.acme.lib_a.anotherthing; Of course, the problem is that one project can't be built because the errors prevent me from creating a .jar file that can be added as an external archive to the other project, and vice versa. It seems to me that this must be a fairly common occurence in building Java applications. Rewriting it from scratch is not an option here, so I'd like to know "what other folks do."

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  • C++ Template Classes Circular Dependency Problem

    - by TomWij
    We have two classes: template<typename T, typename Size, typename Stack, typename Sparse> class Matrix and template<typename T, typename Size> class Iterator Matrix should be able to return begin and end iterators and Iterator will keep a referrence to the Matrix to access the elements via it's interface. We don't want Iterator to depend on the internal storage of the Matrix to prevent coupling. How can we solve this cyclic dependency problem? (The internal Storage class has the same template parameters as the Matrix class and the same access procedures as the Matrix itself)

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  • Making a circular NSSlide look and behave like in GarageBand

    - by Koning Baard
    I am new to drawing with Cocoa, and I am making some software which will have sliders similar to these found in GarageBand: These look beautiful and can be controld by moving the mouse up and down. Can you help me with customizing NSSliders by subclassing them, so I can make them look and behave exactly as in GarageBand? Thanks. I have one image for the knob which should be rotated as they do not need to be in 3D .

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