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  • HMVC or PAC - how to handle shared abstractions/models?

    - by fig-gnuton
    In HMVC/PAC, what's the recommended way to code if two or more triads/agents share a common model/abstraction? Do you instantiate a new instance of that model wherever needed, and propogate a change in one to all the other instances via the controllers? Or do instantiate one model at some common upper level, and inject that instance wherever needed? (Or neither if I'm missing something fundamental about these patterns?)

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  • When using a HiLo ID generation strategy, what types should be used to hold Ids?

    - by UpTheCreek
    I'm asking this from a c#/NHibnernate perspective, but it's generally applicable. The concern is that the HiLo strategy goes though id's pretty quickly, and for example a low record-count table (Such as Users) is sharing from the same set of id's as a high record-count table (Such as comments). So you can potentially get to high numbers quicker that with other strategies. So what do people recommend? Code side: int/uint/long/ulong? DBSide: int/bigint? My feeling is to go with longs and bigingts, but would like a sanity check :)

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  • Managing inverse relationships without CoreData

    - by Nathaniel Martin
    This is a question for Objective-J/Cappuccino, but I added the cocoa tag since the frameworks are so similar. One of the downsides of Cappuccino is that CoreData hasn't been ported over yet, so you have to make all your model objects manually. In CoreData, your inverse relationships get managed automatically for you... if you add an object to a to-many relationship in another object, you can traverse the graph in both directions. Without CoreData, is there any clean way to setup those inverse relationships automatically? For a more concrete example, let's take the typical Department and Employees example. To use rails terminology, a Department object has-many Employees, and an Employee belongs-to a Department. So our Department model has an NSMutableSet (or CPMutableSet ) "employees" that contains a set of Employees, and our Employee model has a variable "department" that points back to the Department model that owns it. Is there an easy way to make it so that, when I add a new Employee model into the set, the inverse relationship (employee.department) automatically gets set? Or the reverse: If I set the department model of an employee, then it automatically gets added to that department's employee set? Right know I'm making an object, "ValidatedModel" that all my models subclass, which adds a few methods that setup the inverse relationships, using KVO. But I'm afraid that I'm doing a lot of pointless work, and that there's already an easier way to do this. Can someone put my concerns to rest?

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  • Visitor Pattern can be replaced with Callback functions?

    - by getit
    Is there any significant benefit to using either technique? In case there are variations, the Visitor Pattern I mean is this: http://en.wikipedia.org/wiki/Visitor_pattern And below is an example of using a delegate to achieve the same effect (at least I think it is the same) Say there is a collection of nested elements: Schools contain Departments which contain Students Instead of using the Visitor pattern to perform something on each collection item, why not use a simple callback (Action delegate in C#) Say something like this class Department { List Students; } class School { List Departments; VisitStudents(Action<Student> actionDelegate) { foreach(var dep in this.Departments) { foreach(var stu in dep.Students) { actionDelegate(stu); } } } } School A = new School(); ...//populate collections A.Visit((student)=> { ...Do Something with student... }); *EDIT Example with delegate accepting multiple params Say I wanted to pass both the student and department, I could modify the Action definition like so: Action class School { List Departments; VisitStudents(Action<Student, Department> actionDelegate, Action<Department> d2) { foreach(var dep in this.Departments) { d2(dep); //This performs a different process. //Using Visitor pattern would avoid having to keep adding new delegates. //This looks like the main benefit so far foreach(var stu in dep.Students) { actionDelegate(stu, dep); } } } }

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  • How do you create your own drag-n-drop GUI designer ?

    - by panzerschreck
    Hello I was looking at creating a UI for developing web forms, similar to the Netbeans Visual JSF form designer.It will be targeted to use GWT/GXT components.I am looking at a look very similar to VS/Netbeans. Any thoughts on where/how to start ? Initially, I would prefer to have it as a standalone application, later develop it as eclipse plugin. I have already evaluated the extjs designer and the eclipse plugin from instantiations, but i would prefer to have it developed on my own, as it looks challenging, Also, I have few custom components that have been developed. Thanks

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  • How does one implement storage/retrieval of smart-search/mailbox features?

    - by humble_coder
    Hi All, I have a question regarding implementation of smart-search features. For example, consider something like "smart mailboxes" in various email applications. Let's assume you have your data (emails) stored in a database and, depending on the field for which the query will be created, you present different options to the end user. At the moment let's assume the Subject, Verb, Object approach… For instance, say you have the following: SUBJECTs: message, to_address, from_address, subject, date_received VERBs: contains, does_not_contain, is_equal_to, greater_than, less_than OBJECTs: ??????? Now, in case it isn't clear, I want a table structure (although I'm not opposed to an external XMLesque file of some sort) to store (and later retrieve/present) my criteria for smart searches/mailboxes for later use. As an example, using SVO I could easily store then reconstruct a query for "date between two dates" -- simply use "date greater than" AND "date less than". However, what if, in the same smart search, I wanted a "between" OR'ed with another criterion? You can see that it might get out of hand -- not necessarily in the query creation (as that is rather simplistic), but in the option presentation and storage mechanism. Perhaps I need to think more on a more granular level. Perhaps I need to simply allow the user to select AND or OR for each entry independently instead of making it an ALL OR NOTHING type smart search (i.e. instead of MATCH ALL or MATCH ANY, I need to simply allow them to select -- I just don't want it to turn into a Hydra). Any input would be most appreciated. My apologies if the question is a bit incoherent. It is late, and I my brain is toast. Best.

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  • internal implementation of database Queries

    - by harigm
    In my experience I have used many queries like select, order by, where clause etc.. in mysql, sql-server, oracle etc For a moment i have thought, 1)how is this internally written to implement the above queries 2) which language do they use? 3) is that programming language? if yes which language? 4)what kind of environment required to implement this kind of complex database

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  • help Implementing Object Oriented ansi-C approach??

    - by No Money
    Hey there, I am an Intermediate programmer in Java and know some of the basics in C++. I recently started to scam over "C language" [please note that i emphasized on C language and want to stick with C as i found it to be a perfect tool, so no need for suggestions focusing on why should i move back to C++ or Java]. Moving on, I code an Object Oriented approach in C but kindda scramble with the pointers part. Please understand that I am just a noob trying to extend my knowledge beyond what i learned in High School. Here is my code..... #include <stdio.h> typedef struct per{ int privateint; char *privateString; struct per (*New) (); void (*deleteperOBJ) (struct t_person *); void (*setperNumber) ((struct*) t_person,int); void (*setperString) ((struct*) t_person,char *); void (*dumpperState) ((struct*) t_person); }t_person; void setperNumber(t_person *const per,int num){ if(per==NULL) return; per->privateint=num; } void setperString(t_person *const per,char *string){ if(per==NULL) return; per->privateString=string; } void dumpperState(t_person *const per){ if(per==NULL) return; printf("value of private int==%d\n", per->privateint); printf("value of private string==%s\n", per->privateString); } void deleteperOBJ(struct t_person *const per){ free((void*)t_person->per); t_person ->per = NULL; } main(){ t_person *const per = (struct*) malloc(sizeof(t_person)); per = t_person -> struct per -> New(); per -> setperNumber (t_person *per, 123); per -> setperString(t_person *per, "No money"); dumpperState(t_person *per); deleteperOBJ(t_person *per); } Just to warn you, this program has several errors and since I am a beginner I couldn't help except to post this thread as a question. I am looking forward for assistance. Thanks in advance.

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  • Data Access Layer in ASP.Net: Where do I create the Connection?

    - by atticae
    If I want to create a 3-Layer ASP.Net application (Presentation Layer, Business Layer, Data Access Layer), where is the best place to create the Connection objects? So far I used a helper class in my Presentation Layer to create an IDbCommand from the ConnectionString in the web.config on each page and passed it on to the DAL classes/methods. Now I am not so sure, if this part shouldn't also be included in the DAL somehow, because it obviously is part of the Data Access. The DAL is in a separately compilated project, so I dont have access to the web.config and cannot access the connection string (right?). What is the best practice here?

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  • Data scheme question

    - by Matt
    I am designing a data model for a local city page, more like requirements for it. So 4 tables: Country, State, City, neighbourhood. Real life relationships is: Country owns multiple State which owns multiple cities which ows multiple neighbourhoods. In the data model: Do we link these with FK the same way or link each with each? Like in each table there will even be a Country ID, State ID, CityID and NeighbourhoodID so each connected with each? Other wise to reach neighbourhood from country we need to join 2 other tables in between? There are more tables I need to maintain for IP addess of cities, latitude/longitude, etc.

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  • What are the lengths/limits C preprocessor as a language creation tool? Where can I learn more about

    - by Weston C
    In his FAQ @ http://www2.research.att.com/~bs/bs_faq.html#bootstrapping, Bjarne Stroustrup says: To build [Cfront, the first C++ compiler], I first used C to write a "C with Classes"-to-C preprocessor. "C with Classes" was a C dialect that became the immediate ancestor to C++... I then wrote the first version of Cfront in "C with Classes". When I read this, it piqued my interest in the C preprocessor. I'd seen its macro capabilities as suitable for simplifying common expressions but hadn't thought about its ability to significantly add to syntax and semantics on the level that I imagine bringing classes to C took. So now I have a couple of questions on my mind: 1) Are there other examples of this approach to bootstrapping a language off of C? 2) Is the source to Stroustrup's original work available anywhere? 3) Where could I learn more about the specifics of utilizing this technique? 4) What are the lengths/limits of that approach? Could one, say, create a set of preprocessor macros that let someone write in something significantly Lisp/Scheme like?

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  • How do I call functions of an object inside the same object?

    - by Roly
    I have the following Javascript code add_num = { f: function(html, num) { alert(this.page); }, page : function() { return parseInt(this.gup('page')); }, gup : function(name) { name = name.replace(/[\[]/,'\\\[').replace(/[\]]/,'\\\]'); var regex = new RegExp('[\\?&]'+name+'=([^&#]*)'); var results = regex.exec(window.location.href); if(results == null) return ''; else return results[1]; } } But when I call add_num.f() what I get from alert() is the actual code of page. That is, it returns function() { return parseInt(this.gup('page')); } I was expecting a numeric value and not any code at all.

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  • Desiging a AJAX website

    - by Narmatha Balasundaram
    What are the things to consider and watch out for when designing a website with AJAX? Must take care of conditions, say timeouts, error handling, for instance? Best practices? What parameters to take care of while designing and coding?

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  • Refactoring tools for namespaces and physical project structure

    - by simendsjo
    When I hack around, some code tend to get much bigger than originally planned. As this happens I usually introduce/collapse/merge namespaces, move files between them, move folders etc etc. Sometimes, if I don't have a clear picture of the end result, this is a real pain and really easy to just "skip". This leads the project deteriorate where classes belong elsewhere, strange namespaces, no folders/wrong folders etc. And then I usually cannot take it anymore and do a larger cleanup - which is usually not difficult, just very tedious and it feels nice to do everything at once, so I do a code freeze while finishing up. So my question is... Are there any tools to help refactoring the namespace/physical aspects of a project?

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  • What does ER_WARN_FIELD_RESOLVED mean?

    - by VolkerK
    When SHOW WARNINGS after a EXPLAIN EXTENDED shows a Note 1276 Field or reference 'test.foo.bar' of SELECT #2 was resolved in SELECT #1 what exactly does that mean and what impact does it have? In my case it prevents mysql from using what seems to be a perfectly good index. But it's not about fixing that specific query (as it is an irrelevant test). I found http://dev.mysql.com/doc/refman/5.0/en/error-messages-server.html butError: 1276 SQLSTATE: HY000 (ER_WARN_FIELD_RESOLVED) Message: Field or reference '%s%s%s%s%s' of SELECT #%d was resolved in SELECT #%d isn't much of an explaination.

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  • what is the easiest way to do this function in c# ?

    - by From.ME.to.YOU
    Hello let say that we have an array [5,5] 01,02,03,04,05 06,07,08,09,10 11,12,13,14,15 16,17,18,19,20 21,22,23,24,25 the user should send 2 values to the function (start,searchFOR) for example (13,25) the function should search for that value in this way 07,08,09 12, ,14 17,18,19 if the value is n't found in this level it will goes a level higher 01,02,03,04,05 06, , , ,10 11, , , ,15 16, , , ,20 21,22,23,24,25 if the array is bigger than this and the value didn't found it will go to a level higher Thanks for your help

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  • some confusions to singleton pattern in PHP

    - by SpawnCxy
    Hi all, In my team I've been told to write resource class like this style: class MemcacheService { private static $instance = null; private function __construct() { } public static function getInstance($fortest = false) { if (self::$instance == null) { self::$instance = new Memcached(); if ($fortest) { self::$instance->addServer(MEMTEST_HOST, MEMTEST_PORT); } else { self::$instance->addServer(MEM_HOST, MEM_PORT); } } return self::$instance; } } But I think in PHP resource handles will be released and initialized again every time after a request over. That means MemcacheService::getInstance() is totally equal new Memcached() which cannot be called singleton pattern at all. Please correct me if I'm wrong. Regards

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  • Why does C++ mandate that complex only be instantiated for float, double, or long double?

    - by templatetypedef
    According to the C++ ISO spec, §26.2/2: The effect of instantiating the template complex for any type other than float, double or long double is unspecified. Why would the standard authors explicitly add this restriction? This makes it unspecified, for example, what happens if you make complex<int> or a complex<MyCustomFixedPointType> and seems like an artificial restriction. Is there a reason for this limitation? Is there a workaround if you want to instantiate complex with your own custom type? I'm primarily asking this question because of this earlier question, in which the OP was confused as to why abs was giving bizarre outputs for complex<int>. That said, this still doesn't quite make sense given that we also might want to make complex numbers out of fixed-points types, higher-precision real numbers, etc. Thanks!

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  • Invoicing vs Quoting or Estimating

    - by FreshCode
    If invoices can be voided, should they be used as quotations? I have an Invoices tables that is created from inventory associated with a Job or Order. I could have a Quotes table as a halfway-house between inventory and invoices, but it feels like I would have duplicate data structures and logic just to handle an "Is this a quote?" bit. From a business perspective, quotes are different from invoices: a quote is sent prior to an undertaking and an invoice is sent once it is complete and payment is due, but how to represent this in my repository and model. What is an elegant way to store and manage quotes & invoices in a database? Edit: indicated Job === Order for this particular instance.

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  • Base class with abstract subclasses in C# ?

    - by Nick Brooks
    public abstract class Request { public class Parameters { //Threre are no members here //But there should be in inherited classes } public Request() { parameters = new Parameters(); } public Parameters parameters; } Two questions: How do I make it so I can add stuff to the constructor but the original constructor will still be executed? How do I make it so the subclasses can add members to the Parameters class?

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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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