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  • Need help with many-to-many relationships....

    - by yuudachi
    I have a student and faculty table. The primary key for student is studendID (SID) and faculty's primary key is facultyID, naturally. Student has an advisor column and a requested advisor column, which are foreign key to faculty. That's simple enough, right? However, now I have to throw in dates. I want to be able to view who their advisor was for a certain quarter (such as 2009 Winter) and who they had requested. The result will be a table like this: Year | Term | SID | Current | Requested ------------------------------------------------ 2009 | Winter | 860123456 | 1 | NULL 2009 | Winter | 860445566 | 3 | NULL 2009 | Winter | 860369147 | 5 | 1 And then if I feel like it, I could also go ahead and view a different year and a different term. I am not sure how these new table(s) will look like. Will there be a year table with three columns that are Fall, Spring and Winter? And what will the Fall, Spring, Winter table have? I am new to the art of tables, so this is baffling me... Also, I feel I should clarify how the site works so far now. Admin can approve student requests, and what happens is that the student's current advisor gets overwritten with their request. However, I think I should not do that anymore, right?

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  • Circular dependency and object creation when attempting DDD

    - by Matthew
    I have a domain where an Organization has People. Organization Entity public class Organization { private readonly List<Person> _people = new List<Person>(); public Person CreatePerson(string name) { var person = new Person(organization, name); _people.Add(person); return person; } public IEnumerable<Person> People { get { return _people; } } } Person Entity public class Person { public Person(Organization organization, string name) { if (organization == null) { throw new ArgumentNullException("organization"); } Organization = organization; Name = name; } public Organization { get; private set; } public Name { get; private set; } } The rule for this relationship is that a Person must belong to exactly one Organization. The invariants I want to guarantee are: A person must have an organization this is enforced via the Person's constuctor An organization must know of its people this is why the Organization has a CreatePerson method A person must belong to only one organization this is why the organization's people list is not publicly mutable (ignoring the casting to List, maybe ToEnumerable can enforce that, not too concerned about it though) What I want out of this is that if a person is created, that the organization knows about its creation. However, the problem with the model currently is that you are able to create a person without ever adding it to the organizations collection. Here's a failing unit-test to describe my problem [Test] public void AnOrganizationMustKnowOfItsPeople() { var organization = new Organization(); var person = new Person(organization, "Steve McQueen"); CollectionAssert.Contains(organization.People, person); } What is the most idiomatic way to enforce the invariants and the circular relationship?

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  • How to improve relationships between consultants and staff programmers

    - by Catchops
    I have been a consultant for a small software consulting firm for quite some time now. Our normal business model is not staff augmentation, but such that we find clients who need assistance in building a solution of some kind and then send in a team who can build that solution, work with the existing IT staff, train all involved on supportting that solution, then move on to the next job. We, of course, are still around for any needed ongoing support. We have a great reputation in our area and have been very successful in implementing the solutions that we provide. However, I have noticed a common theme for most of our projects. When we get on-site, there is generally a "stressed" relationship between our team and many of the IT staff currently at the client. I understand completely that there may be some anxiety about our arrival and that defenses can come up when we are around. Many of the folks are understanding and easy to work with, but there are usually some who will not work well with us at all, and who can quickly become a project risk in many ways. We try to go in with open minds and good attitudes, and try NOT to be arrogent or condecending. We generally get deployed when there is a mess to clean up - but we understand that there were reasons decisions were made that got them in the bind they are...so we just try to determine the next step forward and move on. My question is this - I'd like to hear from the IT staff and programmers out there who have had consultants in - what are the things that consultants do that fire up negative feelings and attitudes? What can we do better to make the relationship better, not only in the beginning, but as the project moves forward?

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  • detecting circular imports

    - by wallacoloo
    I'm working with a project that contains about 30 unique modules. It wasn't designed too well, so it's common that I create circular imports when adding some new functionality to the project. Of course, when I add the circular import, I'm unaware of it. Sometimes it's pretty obvious I've made a circular import when I get an error like AttributeError: 'module' object has no attribute 'attribute' where I clearly defined 'attribute'. But other times, the code doesn't throw exceptions because of the way it's used. So, to my question: Is it possible to programmatically detect when and where a circular import is occuring?

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  • Performance impact of not implementing relationships at the database level?

    - by JVerstry
    Let's imagine a data model with customers and invoices. There is a 1 to n relationship between a customer and its invoices. We uses an ORM (like Hibernate). One can explicitely implement the 1-n relationship (using JPA for example) or not. If not, then one must do a bit more work to fetch invoices. However, it is much easier to maintain, improve and develop the data model of applications where relationships between objects are not explicitely implemented in the database. My question is, has anyone noticed a significant performance impact when not implementing the relationships in the database?

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  • Importing/Exporting Relationships in MS Access

    - by lamcro
    I have a couple of mdb files with the exact table structure. I have to change the primary key of the main table from autonumber to number in all of them, which means I have to: Drop the all the relationships the main table has Change the main table Create the relationships again,... for all the tables. Is there any way to export the relationships from one file and importing them to all the rest? I am sure this can be done with some macro/vb code. Does anyone has an example I could use? Thanks.

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  • Seaching for an element in a circular sorted array

    - by guirgis
    I wanted to share this with you, i had this problem in a google interview. we want to search for a given element in a circular sorted array in complexity not greater than O(Log n). ex: search for 13 in {5,9,13,1,3}. My idea was to convert the circular array into a regular sorted array then do a binary search on the resulting array, but my problem was the algorithm i came up was stupid that it takes O(n) in the worst case: for(i = 1; i < a.length; i++){ if (a[i] < a[i-1]){ minIndex = i; break; } } then the corresponding index of ith element will be determined from the following relation: (i + minInex - 1) % a.length it is clear that my conversion (from circular to regular) algorithm may take O(n), so we need a better one, any suggestions?

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  • Animated Circular bar on hover

    - by Anthony
    I'm building a portfolio website and want to implement a skill set page which feature an animated circular bar which represent each of my skills. There will be 6 buttons around the circle which when the user hovers over, and when one is hovered I want a circular bar to animate anti-clockwise. I've made a quick .gif in photoshop to demonstrate But I can't find any tutorial to help. I found this website which features a similar concept on the left hand side at the top, an animated pie chart - Website Example And this is a quick .gif Mockup I did in photoshop of what I am trying to achieve - Animated Circular Bar Animation

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  • how to fix facebook Circular Redirect?

    - by user1057679
    I have a page that redirects to other page I try to test my url on: https://developers.facebook.com/tools/debug i get this error: Errors That Must Be Fixed: Circular Redirect:? Circular redirect path detected (see Redirect Path section for details). Warnings That Should Be Fixed: ?The og:url property should be explicitly provided, even if a value can be inferred from other tags.? how can i fix this problem? how to detect facebook and if it is facebook dont redirect?

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  • What sort of Circular Dependencies does Oracle allow?

    - by Neil
    Hi all, I am creating test cases and I need to cover circular dependencies. So far I have been able to create two tables such that Table A has a FK to B and B has a FK to A. What other circular dependencies exist / are allowed between objects? I tried to create cycles between Views but Oracle successfully rejected that.

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  • Creating circular generic references

    - by M. Jessup
    I am writing an application to do some distributed calculations in a peer to peer network. In defining the network I have two class the P2PNetwork and P2PClient. I want these to be generic and so have the definitions of: P2PNetwork<T extends P2PClient<? extends P2PNetwork<T>>> P2PClient<T extends P2PNetwork<? extends T>> with P2PClient defining a method of setNetwork(T network). What I am hoping to describe with this code is: A P2PNetwork is constituted of clients of a certain type A P2PClient may only belong to a network whose clients consist of the same type as this client (the circular-reference) This seems correct to me but if I try to create a non-generic version such as MyP2PClient<MyP2PNetwork<? extends MyP2PClient>> myClient; and other variants I receive numerous errors from the compiler. So my questions are as follows: Is a generic circular reference even possible (I have never seen anything explicitly forbidding it)? Is the above generic definition a correct definition of such a circular relationship? If it is valid, is it the "correct" way to describe such a relationship (i.e. is there another valid definition, which is stylistically preferred)? How would I properly define a non-generic instance of a Client and Server given the proper generic definition?

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  • What's wrong with circular references?

    - by dash-tom-bang
    I was involved in a programming discussion today where I made some statements that basically assumed axiomatically that circular references (between modules, classes, whatever) are generally bad. Once I got through with my pitch, my coworker asked, "what's wrong with circular references?" I've got strong feelings on this, but it's hard for me to verbalize concisely and concretely. Any explanation that I may come up with tends to rely on other items that I too consider axioms ("can't use in isolation, so can't test", "unknown/undefined behavior as state mutates in the participating objects", etc.), but I'd love to hear a concise reason for why circular references are bad that don't take the kinds of leaps of faith that my own brain does, having spent many hours over the years untangling them to understand, fix, and extend various bits of code. Edit: I am not asking about homogenous circular references, like those in a doubly-linked list or pointer-to-parent. This question is really asking about "larger scope" circular references, like libA calling libB which calls back to libA. Substitute 'module' for 'lib' if you like. Thanks for all of the answers so far!

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  • C - circular character buffer w/ pthreads

    - by Matt
    I have a homework assignment where I have to implement a circular buffer and add and remove chars with separate threads: #include <pthread.h> #include <stdio.h> #define QSIZE 10 pthread_cond_t full,/* count == QSIZE */ empty,/* count == 0 */ ready; pthread_mutex_t m, n; /* implements critical section */ unsigned int iBuf, /* tail of circular queue */ oBuf; /* head of circular queue */ int count; /* count characters */ char buf [QSIZE]; /* the circular queue */ void Put(char s[]) {/* add "ch"; wait if full */ pthread_mutex_lock(&m); int size = sizeof(s)/sizeof(char); printf("size: %d", size); int i; for(i = 0; i < size; i++) { while (count >= QSIZE) pthread_cond_wait(&full, &m);/* is there empty slot? */ buf[iBuf] = s[i]; /* store the character */ iBuf = (iBuf+1) % QSIZE; /* increment mod QSIZE */ count++; if (count == 1) pthread_cond_signal(&empty);/* new character available */ } pthread_mutex_unlock(&m); } char Get() {/* remove "ch" from queue; wait if empty */ char ch; pthread_mutex_lock(&m); while (count <= 0) pthread_cond_wait(&empty, &m);/* is a character present? */ ch = buf[oBuf]; /* retrieve from the head of the queue */ oBuf = (oBuf+1) % QSIZE; count--; if (count == QSIZE-1) pthread_cond_signal(&full);/* signal existence of a slot */ pthread_mutex_unlock(&m); return ch; } void * p1(void *arg) { int i; for (i = 0; i < 5; i++) { Put("hella"); } } void * p2(void *arg) { int i; for (i = 0; i < 5; i++) { Put("goodby"); } } int main() { pthread_t t1, t2; void *r1, *r2; oBuf = 0; iBuf = 0; count=0; /* all slots are empty */ pthread_cond_init(&full, NULL); pthread_cond_init(&empty, NULL); pthread_mutex_init(&m, NULL); pthread_create(&t1, NULL, p1, &r1); pthread_create(&t2, NULL, p2, &r2); printf("Main"); char c; int i = 0; while (i < 55) { c = Get(); printf("%c",c); i++; } pthread_join(t1, &r1); pthread_join(t2, &r2); return 0; } I shouldn't have to change the logic much at all, the requirements are pretty specific. I think my problem lies in the Put() method. I think the first thread is going in and blocking the critical section and causing a deadlock. I was thinking I should make a scheduling attribute? Of course I could be wrong. I am pretty new to pthreads and concurrent programming, so I could really use some help spotting my error.

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  • Avoiding circular project/assembly references in Visual Studio with statically typed dependency conf

    - by svnpttrssn
    First, I want to say that I am not interested in debating about any non-helpful "answers" to my question, with suggestions to putting everything in one assembly, i.e. there is no need for anyone to provide webpages such as the page titled with "Separate Assemblies != Loose Coupling". Now, my question is if it somehow (maybe with some Visual Studio configuration to allow for circular project dependencies?) is possible to use one project/assembly (I am here calling it the "ServiceLocator" assembly) for retrieving concrete implementation classes, (e.g. with StructureMap) which can be referred to from other projects, while it of course is also necessary for the the ServiceLocator itself to refer to other projects with the interfaces and the implementations ? Visual Studio project example, illustrating the kind of dependency structure I am talking about: http://img10.imageshack.us/img10/8838/testingdependencyinject.png Please note in the above picture, the problem is how to let the classes in "ApplicationLayerServiceImplementations" retrieve and instantiate classes that implement the interfaces in "DomainLayerServiceInterfaces". The goal is here to not refer directly to the classes in "DomainLayerServiceImplementations", but rather to try using the project "ServiceLocator" to retrieve such classes, but then the circular dependency problem occurrs... For example, a "UserInterfaceLayer" project/assembly might contain this kind of code: ContainerBootstrapper.BootstrapStructureMap(); // located in "ServiceLocator" project/assembly MyDomainLayerInterface myDomainLayerInterface = ObjectFactory.GetInstance<MyDomainLayerInterface>(); // refering to project/assembly "DomainLayerServiceInterfaces" myDomainLayerInterface.MyDomainLayerMethod(); MyApplicationLayerInterface myApplicationLayerInterface = ObjectFactory.GetInstance<MyApplicationLayerInterface>(); // refering to project/assembly "ApplicationLayerServiceInterfaces" myApplicationLayerInterface.MyApplicationLayerMethod(); The above code do not refer to the implementation projects/assemblies ApplicationLayerServiceImplementations and DomainLayerServiceImplementations, which contain this kind of code: public class MyApplicationLayerImplementation : MyApplicationLayerInterface and public class MyDomainLayerImplementation : MyDomainLayerInterface The "ServiceLocator" project/assembly might contain this code: using ApplicationLayerServiceImplementations; using ApplicationLayerServiceInterfaces; using DomainLayerServiceImplementations; using DomainLayerServiceInterfaces; using StructureMap; namespace ServiceLocator { public static class ContainerBootstrapper { public static void BootstrapStructureMap() { ObjectFactory.Initialize(x => { // The two interfaces and the two implementations below are located in four different Visual Studio projects x.ForRequestedType<MyDomainLayerInterface>().TheDefaultIsConcreteType<MyDomainLayerImplementation>(); x.ForRequestedType<MyApplicationLayerInterface>().TheDefaultIsConcreteType<MyApplicationLayerImplementation>(); }); } } } So far, no problem, but the problem occurs when I want to let the class "MyApplicationLayerImplementation" in the project/assembly "ApplicationLayerServiceImplementations" use the "ServiceLocator" project/assembly for retrieving an implementation of "MyDomainLayerInterface". When I try to do that, i.e. add a reference from "MyApplicationLayerImplementation" to "ServiceLocator", then Visual Studio complains about circular dependencies between projects. Is there any nice solution to this problem, which does not imply using refactoring-unfriendly string based xml-configuration which breaks whenever an interface or class or its namespace is renamed ? / Sven

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  • Setting up Eloquent relationships in Laravel for existing InnoDB relationships

    - by adam
    I have an initial migration that sets up two tables (users and projects), with a relationship (innoDB). $table->foreign('user_id')->references('id')->on('users'); I have two Eloquent models set up, blank except for the relationship: return $this->has_many('Project'); Do i definitely need to tell eloquent about the relationship in the models and the database? I'd assumed something as comprehensive as Laravel would infer it from the Schema? Is there something I'm missing?

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  • StructureMap problems with bidirectional/circular dependencies

    - by leozilla
    I am currently integrating StructureMap within our business layer but have problems because of bidirectional dependencies. The layer contains multiple manager where each manager can call methods on each other, there are no restrictions or rules for communication. This also includes possible circular dependencies like in the example below. I know the design itself is questionable but currently we just want StructureMap to work and will focus on further refactoring in the future. Every manager implements the IManager interface internal interface IManager { bool IsStarted { get; } void Start(); void Stop(); } And does also have his own specific interface. internal interface IManagerA : IManager { void ALogic(); } internal interface IManagerB : IManager { void BLogic(); } Here are to dummy manager implementations. internal class ManagerA : IManagerA { public IManagerB ManagerB { get; set; } public void ALogic() { } public bool IsStarted { get; private set; } public void Start() { } public void Stop() { } } internal class ManagerB : IManagerB { public IManagerA ManagerA { get; set; } public void BLogic() { } public bool IsStarted { get; private set; } public void Start() { } public void Stop() { } } Here is the StructureMap configuration i use atm. I am still not sure how i should register the managers so currently i use a manual registration. Maybee someone could help me with this too. For<IManagerA>().Singleton().Use<ManagerA>(); For<IManagerB>().Singleton().Use<ManagerB>(); SetAllProperties(convention => { // configure the property injection for all managers convention.Matching(prop => typeof(IManager).IsAssignableFrom(prop.PropertyType)); }); After all i cannot create IManagerA because StructureMap complians about the circular dependency between ManagerA and ManagerB. Is there an easy and clean solution to solve this problem but keep to current design? br David

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  • typedef struct, circular dependency, forward definitions

    - by BlueChip
    The problem I have is a circular dependency issue in C header files ...Having looked around I suspect the solution will have something to do with Forward Definitions, but although there are many similar problems listed, none seem to offer the information I require to resolve this one... I have the following 5 source files: // fwd1.h #ifndef __FWD1_H #define __FWD1_H #include "fwd2.h" typedef struct Fwd1 { Fwd2 *f; } Fwd1; void fwd1 (Fwd1 *f1, Fwd2 *f2) ; #endif // __FWD1_H . // fwd1.c #include "fwd1.h" #include "fwd2.h" void fwd1 (Fwd1 *f1, Fwd2 *f2) { return; } . // fwd2.h #ifndef __FWD2_H #define __FWD2_H #include "fwd1.h" typedef struct Fwd2 { Fwd1 *f; } Fwd2; void fwd2 (Fwd1 *f1, Fwd2 *f2) ; #endif // __FWD2_H . // fwd2.c #include "fwd1.h" #include "fwd2.h" void fwd2 (Fwd1 *f1, Fwd2 *f2) { return; } . // fwdMain.c #include "fwd1.h" #include "fwd2.h" int main (int argc, char** argv, char** env) { Fwd1 *f1 = (Fwd1*)0; Fwd2 *f2 = (Fwd2*)0; fwd1(f1, f2); fwd2(f1, f2); return 0; } Which I am compiling with the command: gcc fwdMain.c fwd1.c fwd2.c -o fwd -Wall I have tried several ideas to resolve the compile errors, but have only managed to replace the errors with other errors ...How do I resolve the circular dependency issue with the least changes to my code? ...Ideally, as a matter of coding style, I would like to avoid putting the word "struct" all over my code.

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  • Make circular joystick

    - by Jaba
    How do I make a joystick like the one in i dig it, using UIImageView's that the smaller one can be used to move around, I just really would like to know how I would get the smaller UIImageView to stay inside the larger one, I just don't know how I would do this because they are both circular. I have an Image below:

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  • iPhone Circular Progress Indicator

    - by Ward
    I'm trying to create a circular progress indicator like Shazam. It will represent progress during recording. There will be a finite amount of time and I want it to react to the sound level like Shazam's does. Any clues where to begin? Thanks

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