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  • this pointer to base class constructor?

    - by Rolle
    I want to implement a derived class that should also implement an interface, that have a function that the base class can call. The following gives a warning as it is not safe to pass a this pointer to the base class constructor: struct IInterface { void FuncToCall() = 0; }; struct Base { Base(IInterface* inter) { m_inter = inter; } void SomeFunc() { inter->FuncToCall(); } IInterface* m_inter; }; struct Derived : Base, IInterface { Derived() : Base(this) {} FuncToCall() {} }; What is the best way around this? I need to supply the interface as an argument to the base constructor, as it is not always the dervied class that is the interface; sometimes it may be a totally different class. I could add a function to the base class, SetInterface(IInterface* inter), but I would like to avoid that.

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  • Are there actually lag times to remove an email address from "the system"? [closed]

    - by Alex Gosselin
    For example, you send an unsubscribe message to a legitimate company or a spam, they reply that they will remove you and it may take up to 72 hours to take effect. I find it hard to believe anything that simple could take more than 3/4 of a second to take effect system wide. Another example would be when you call the visa activation line, there is a "delay" of several minutes while they try to sell you some kind of insurance. Usually just as you get the point across that you don't want it they will tell you your card has been activated and let you go. Are these delays real?

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  • Struct like objects in Java

    - by cdv
    Is it completely against the Java way to create struct like objects? class SomeData1 { public int x; public int y; } I can see a class with accessors and mutators being more Java like. class SomeData2 { int getX(); void setX(int x); int getY(); void setY(int y); private int x; private int y; } The class from the first example is notationally convenient. // a function in a class public int f(SomeData1 d) { return (3 * d.x) / d.y; } This is not as convenient. // a function in a class public int f(SomeData2 d) { return (3 * d.getX()) / d.getY(); }

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  • Having access to a private variable from other classes in Java

    - by Crystal
    If I want to create a form that adds people to a List, how do I have access to that List from another class? Where would I define that List so other classes can access the members, the size, etc? For example, if I have Class Foo that has the GUI for my form, along with buttons to add and remove people to the List, it would make sense to me to declare the List as a private instance variable of Class Foo. But then if I have another class, Class Bar, how does it get the values that are currently in that List to update some other graphical components? Or is that the wrong place to declare the List in general? Thanks.

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  • Business object and linq2SQL

    - by Overdose
    What is the optimal way to write the code which interacts with DB using linq2SQL? I need to add some business logic to the entities. So I guess there are two ways: Write some wrapper class. The main minus is that many fields are the same, so i don't feel it as DRY style. Add business logic methods to linq2sql entities(these classes are partial) directly ???

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  • Are free and open source templates, themes, self content management systems replacing the need of we

    - by metal-gear-solid
    Are free and open source templates, themes, self content management systems replacing the need of web designers? You can find templates online for pretty much anything these days. There are html and css templates, templates for Wordpress, all sorts of different cms templates, e-ecommerce templates, etc. Many of these are pretty cheap and some are even free, so where do web designers fit into this picture? I’ve had many clients and potential customers ask why they should use my services instead of just buying a cheap template. Are web designers being replaced?

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  • how to guarantee atomicity across two databases (the filesystem and your RDBMS)?

    - by Lock up
    i am working on a online file management project.In which we are storing references on the database(sql server) and files data on the on file system;.In which we are facing a problem of coordination between file system and database while we are uploading a file and also in case of deleting a file that first we create a reference in the data base or store files on file system;;the problem is that if create a reference in the database first and then storing a file on file system.bur while storing files on the file system any type of error occur.then reference for that file is created in the database but no file data on the file system;; please give me some solution how to deal with such situation;;i am badly in need of it;; and reason for that?

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  • Why there are no semicolons and {} blocks in some languages

    - by Incognito
    I know the question has no practical value, but it is interesting why in some languages semicolons and {} blocks are removed although their predecessor have them. Actually it makes me nervous to write a code in Python as there are no ";" and {}. Also in new language Google-GO semicolons are also missing although it says that lexer uses a rule to insert semicolons automatically as it scans. So is there any secret :) reason for this.

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  • database deign advice wanted: double data entry

    - by john
    hi, I'm designing a database for capturing clinical trial data. The data are entered twice by two persons, independently and the results must be matched. What are the best database tools to use to achieve the best results. Any one has similar experiences? Your helps are highly appreciated. thanks.

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  • Why are interfaces unusable in PHP?

    - by streetparade
    I mean an interface definition without defining the return type makes it unusable? This makes more Clear Interface run { public function getInteger(); } class MyString implements run { public function myNumber() { } public function getInteger() { return "Not a number"; } } In Java every Interface has a return type like Integer,String,Void I know that PHP is unfortunately a loosly typed Language but isnt there a Solution for that Problem? Is it Possible to defining a Interface with a Return type like Integer?

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  • How to get it working in O(n)?

    - by evermean
    I came across an interview task/question that really got me thinking ... so here it goes: You have an array A[N] of N numbers. You have to compose an array Output[N] such that Output[i] will be equal to multiplication of all the elements of A[N] except A[i]. For example Output[0] will be multiplication of A[1] to A[N-1] and Output[1] will be multiplication of A[0] and from A[2] to A[N-1]. Solve it without division operator and in O(n). I really tried to come up with a solution but I always end up with a complexity of O(n^2). Perhaps the is anyone smarter than me who can tell me an algorithm that works in O(n) or at least give me a hint...

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  • OOP beginner: classB extends classA. classA already object. method in classB needed.. etc.

    - by Yvo
    Hey guys, I'm learning myself to go from function based PHP coding to OOP. And this is the situation: ClassA holds many basic tool methods (functions). it's __construct makes a DB connection. ClassB holds specific methods based on a certain activity (extract widgets). ClassB extends ClassA because it uses some of the basic tools in there e.g. a database call. In a php file I create a $a_class = new ClassA object (thus a new DB connection). Now I need a method in ClassB. I do $b_class = new ClassB; and call a method, which uses a method from it's parent:: ClassA. In this example, i'm having ClassA 'used' twice. Onces as object, and onces via a parent:: call, so ClassA creates another DB connection (or not?). So what is the best setup for this basic classes parent, child (extend) situation? I only want to make one connection of course? I don't like to forward the object to ClassB like this $b_class = new ClassB($a_object); or is that the best way? Thanks for thinking with me, and helping :d

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  • When to Use Properties & When to Use Methods?

    - by DaveDev
    Hi Guys I was looking at the following line of code foreach (PropertyInfo prop in t.GetProperties()) and I noticed that tprovides a method to return the type's properties instead of a property like t.Properties This makes me wonder why sometimes people use properties to make a type's data avilable and other times there's a method provided? Is there some logic behind the decision? Thanks Dave

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  • Organize address cache

    - by Orsol
    Hi, I need to organize cache in mySql database for address - coordinates. What is the best practice to store address? Do i need to compress address string or use it as is? edit: Ok, let's I reassert my question. How to store long (up to 512) string in database if I need to search by exactly this string in future.

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  • PHP Booking timeslot

    - by boyee007
    Im developing a php booking system based on timeslot for daily basis. Ive set up 4 database tables! Bookslot (which store all the ids - id_bookslot, id_user, id_timeslot) Timeslot (store all the times on 15 minutes gap ex: 09:00, 09:15, 09:30, etc) Therapist (store all therapist details) User (store all the members detail) ID_BOOKSLOT ID_USER ID_THERAPIST ID_TIMESLOT 1 10 1 1 (09:00) 2 11 2 1 (09:00) 3 12 3 2 (09:15) 4 15 3 1 (09:00) Now, my issue is, it keep showing repeation for timeslot when i want echoing the data for example: thera a thera b thera c ------------------------------------------------- 09:00 BOOKED available available 09:00 available BOOKED available 09:00 available available BOOKED 09:15 available BOOKED available as you can see, 09:00 showing three times, and i want something like below thera a thera b thera c ------------------------------------------------- 09:00 BOOKED BOOKED BOOKED 09:15 available BOOKED available There might be something wrong with joining the table or else. The code to join the table $mysqli->query("SELECT * FROM bookslot RIGHT JOIN timeslot ON bookslot.id_timeslot = timeslot.id_timeslot LEFT JOIN therapist ON bookslot.id_therapist = therapist.id_therapist" if anyone have the solution for this system, please help me out and i appriciate it much!

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