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  • C# Lambda Problem

    - by Chris Klepeis
    Probably something simple, but as I'm new to lambda expressions, the problem evades me: m => m.contactID == contactID && m.primaryAddress == true && (m.addressTypeID == 2 || m.addressTypeID == 3) I tried to use that lambda expression but I receive an invalid operator. Is there a way to simplify this so that it would work? Edit: The equivolent sql query would be: SELECT * FROM Contact WHERE contactID = 3 AND primaryAddress = 1 AND (addressTypeID = 2 OR addressTypeID = 3) I have a repository function defined like so: public E Single(Expression<Func<E, bool>> where) { return objectSet.Single<E>(where); } I'm passing the lambda expression above into this function. Invalid operator error.

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  • How can I have a serializable struct that wraps it's self as an int32 implicitly? in C#?

    - by firoso
    Long story short, I have a struct (see below) that contains exactly one field: private int value; I've also implemented implicit conversion operators: public static implicit operator int(Outlet val) { return val.value; } public static implicit operator Outlet(int val) { return new Outlet(val); } I've implemented all of the following : IComparable, IComparable<Cart>, IComparable<int>, IConvertible, IEquatable<Cart>, IEquatable<int>, IFormattable I'm at a point where I really have no clue why, but whenever I serialize this object, I get no value. For instance, with XmlSerialization: <Outlet /> Also, I'm not solely concerned about XmlSerialization, I'm concerned about ALL serialization (binary for instance) How can I ensure that this serializes properly? NOTE: I did this because mapping an int,int dictionary seemed rather poorly typed to me when explicit objects with validation behavior were desired.

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  • What are the common programming mistakes in Python?

    - by Paul McGuire
    I was about to tag the recent question in which the OP accidentally shadowed the builtin operator module with his own local operator.py with the "common-mistakes" tag, and I saw that there are a number of interesting questions posted asking for common mistakes to avoid in Java, Ruby, Scala, Clojure, .Net, jQuery, Haskell, SQL, ColdFusion, and so on, but I didn't see any for Python. For the benefit of Python beginners, can we enumerate the common mistakes that we have all committed at one time or another, in the hopes of maybe steering a newbie or two clear of them? (In homage to "The Princess Bride", I call these the Classic Blunders.) If possible, a little supporting explanation on what the problem is, and the generally accepted resolution/workaround, so that the beginning Pythoner doesn't read your answer and say "ok, that's a mistake, how do I fix it?"

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  • Returning references while using shared_ptrs

    - by Goose Bumper
    Suppose I have a rather large class Matrix, and I've overloaded operator== to check for equality like so: bool operator==(Matrix &a, Matrix &b); Of course I'm passing the Matrix objects by reference because they are so large. Now i have a method Matrix::inverse() that returns a new Matrix object. Now I want to use the inverse directly in a comparison, like so: if (a.inverse()==b) { ... }` The problem is, this means the inverse method needs to return a reference to a Matrix object. Two questions: Since I'm just using that reference in this once comparison, is this a memory leak? What happens if the object-to-be-returned in the inverse() method belongs to a boost::shared_ptr? As soon as the method exits, the shared_ptr is destroyed and the object is no longer valid. Is there a way to return a reference to an object that belongs to a shared_ptr?

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  • how to run foreach loop with ternary condition

    - by I Like PHP
    i have two foreach loop to display some data, but i want to use a single foreach on basis of database result. means if there is any row returns from database then forach($first as $fk=>$fv) should execute otherwise foreach($other as $ok) should execute. i m unsing below ternary operator which gives parse error $n=$db->numRows($taskData); // databsse results <?php ($n) ? foreach ($first as $fk=>$fv) : foreach ($other as $ok) { ?> <table><tr><td>......some data...</td></tr></table> <?php } ?> please suggest me how to handle such condition via ternary operator or any other idea. Thanks

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  • Little Employee/Shift timetable HELP!!!

    - by DAVID
    Morning Guys, I have the following tables: operator(ope_id, ope_name) ope_shift(ope_id, shift_id, shift_date) shift(shift_id, shift_start, shift_end) here is a better view of the data http://latinunit.net/emp_shift.txt here is the screenshot of a select statement to the tables http://img256.imageshack.us/img256/4013/opeshift.jpg im using this code SELECT OPE_ID, COUNT(OPE_ID) AS Total_shifts from operator_shift group by ope_id; to view the current total shifts per operator and it works, BUT if there was 500 more rows it would count them all aswell, THE QUESTION is, anyone has a better way of making my database work, or how can i tell the system that those rows are a whole month, i remember i friend said something about count then devide by 30 but im not sure, what if the month isnt finished? and you want to show the emp with highest shifts to date

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  • Android - modes of connectivity, device identification and device inter-communication?

    - by MalcomTucker
    Can someone explain a couple of very simple concepts to me - I'm interested in mobile devices running android and how they are identified over networks. Some scenarios: Device is connected over WiFi - presumably the device has a standard IP address as with any host and can communicate with any other android host over TCP/IP (assuming it knows the participating device's IP? Device is connected over bluetooth - how are devices identified in this case? Device is connected over mobile operator's network - this is the one I'm interested in and confused by - is there anyway for two or more devices to discover each other and communicate via the mobile operator's network? How does a device communicate with a backend server in this scenario? In other words, how do apps and devices communicate when not connected to a WiFi network? Thanks for any advice..

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  • E4X in ActionScript

    - by Brian Genisio
    Hey all, Looking at the E4X implementation in ActionScript, it occurs to me that they had to figure out how to do three things that I am not sure can be done within ActionScript regularly: Properties/Getters prefixed with @: var myAttribute = xmlPerson.@name; Nameless functions for filtering: xmlData.person.(/* predicate */) lambda syntax for predicates: xmlData.person.(@name == "Brian") So here is my question: Are these just one-off capabilities (much like Vector.<>) they put in just for E4X, therefore keeping out of reach for us? Or do we, as ActionScript developers, have access to these features? More specifically, I'd love to get access to the expression tree of that lambda predicate for my own code (not tied to the XML classes in any way). I figured out that this is called the "filter operator"... but I am not sure how to harness it. Not sure I can... since ActionScript does not allow for operator overloading :(

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  • Why doesn't C have rotate left/right operators?

    - by icepack
    A bit of a philosophical question, I suppose. Hope it belongs here. C language has the standard set of bit-wise operations, including OR, AND, XOR, SHIFT LEFT/RIGHT, NOT. Anyone has an idea why rotate left/rotate right isn't included in the language? These operators are of the same complexity as other bit-wise operators and normally require a single assembly instruction, like the others. Besides, I can think of a lot of uses for rotate operator, probably not less than, say, xor operator - so it sounds a bit strange to me that they aren't included in C along with the rest. Edit: Please stop suggesting implementations of rotation operators. I know how to do that and it's not what the question about.

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  • Iterator for second to last element in a list

    - by BSchlinker
    I currently have the following for loop: for(list<string>::iterator jt=it->begin(); jt!=it->end()-1; jt++) I have a list of strings which is in a larger list (list<list<string> >). I want to loop through the contents of the innerlist until I get to the 2nd to last element. This is because I have already processed the contents of the final element, and have no reason to process them again. However, using it->end()-1 is invalid -- I cannot use the - operator here. While I could use the -- operator, this would decrement this final iterator on each cycle. I believe a STL list is a doubly linked list, so from my perspective, it should be possible to do this. Advice? Thanks in advance

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  • R: How can I use apply on rows of a data.frame and get out $column_name?

    - by John
    I'm trying to access $a using the following example: df<-data.frame(a=c("x","x","y","y"),b=c(1,2,3,4)) > df a b 1 x 1 2 x 2 3 y 3 4 y 4 test_fun <- function (data.frame_in) { print (data.frame_in[1]) } I can now access $a if I use an index for the first column: apply(df, 1, test_fun) a "x" a "x" a "y" a "y" [1] "x" "x" "y" "y" But I cannot access column $a with the $ notation: error: "$ operator is invalid for atomic vectors" test_fun_2 <- function (data.frame_in) { print (data.frame_in$a) } >apply(df, 1, test_fun_2) Error in data.frame_in$a : $ operator is invalid for atomic vectors Is this not possible?

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  • Copying a Polymorphic object in C++

    - by doron
    I have base-class Base from which is derived Derived1, Derived2 and Derived3. I have constructed an instance for one of the the derived classes which I store as Base* a. I now need to make a deep copy of the object which I will store as Base* b. As far as I know, the normal way of copying a class is to use copy constructors and to overload operator=. However since I don't know whether a is of type Derived1, Derived2 or Derived3, I cannot think of a way of using either the copy constructor or operator=. The only way I can think of to cleanly make this work is to implement something like: class Base { public: virtual Base* Clone() = 0; }; and the implement Clone in in the derived class as in: class Derivedn : public Base { public: Base* Clone() { Derived1* ret = new Derived1; copy all the data members } }; Java tends to use Clone quite a bit is there more of a C++ way of doing this?

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  • Aquamacs and IDLWAVE

    - by nicolavianello
    I've just installed the new Aquamacs 2.0 in my Mac Os X 10.6.3 and I'm an happy user of IDLWAVE on Aquamacs for programming in IDL. Unfortunately I run into a problem which I can't understand. I used in my configuration file to put the following (setq idlwave-surround-by-blank t) for the beautiful space around operator. This used to work till Aquamacs 2.0 preview b3 (third beta release) from that on, it stops to work and every time I type an operator (the same for '=' '<' '' etc) I got the following message Debugger entered--Lisp error: (void-variable idlwave-expand-equal) (lambda nil (interactive) (self-insert-command 1) idlwave-expand- equal -1 -1)() call-interactively((lambda nil (interactive) (self-insert-command 1) idlwave-expand-equal -1 -1) nil nil) Any help is welcommed

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  • converting string to int in C++

    - by xbonez
    I am trying to convert a string I read in from a file to an int value so I can store it in an integer variable. This is what my code looks like: ifstream sin; sin.open("movie_output.txt"); string line; getline(sin,line); myMovie.setYear(atoi(line)); Over here, setYear is a mutator in the Movie class (myMovie is an object of Movie class) that looks like this: void Movie::setYear(unsigned int year) { year_ = year; } When I run the code, I get the following error: error C2664: 'atoi' : cannot convert parameter 1 from 'std::string' to 'const char *' 1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called

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  • Help translating Reflector deconstruction into compilable code

    - by code poet
    So I am Reflector-ing some framework 2.0 code and end up with the following deconstruction fixed (void* voidRef3 = ((void*) &_someMember)) { ... } This won't compile due to 'The right hand side of a fixed statement assignment may not be a cast expression' I understand that Reflector can only approximate and generally I can see a clear path but this is a bit outside my experience. Question: what is Reflector trying to describe to me? Update: Am also seeing the following fixed (IntPtr* ptrRef3 = ((IntPtr*) &this._someMember)) Update: So, as Mitch says, it is not a bitwise operator, but an addressOf operator. Question is now: fixed (IntPtr* ptrRef3 = &_someMember) fails with an 'Cannot implicitly convert type 'xxx*' to 'System.IntPtr*'. An explicit conversion exists (are you missing a cast?)' compilation error. So I seemed to be damned if I do and damned if I dont. Any ideas?

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  • Silencing GCC warnings when using an "Uncopyable" class

    - by Kazade
    I have several classes that I don't want to be copyable, some of these classes have pointer data members. To make these classes uncopyable I privately inherit the following class template: template <class T> class Uncopyable { protected: Uncopyable() {} virtual ~Uncopyable() {} private: Uncopyable(const Uncopyable &); T & operator=(const T&); }; Which I used like so: class Entity : private Uncopyable<Entity> { } This works fine, however when I compile with -Weffc++ I still get the following warning: class Entity has pointer data members but does not override Entity(const Entity&) or operator=(const Entity&) Why is it still giving me this warning?

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  • generate image of basic figures with perl

    - by jonny
    I am using jalava library as a diagram drawing tool. It displays firgures as images in order to maintain compatibility with majority of browsers. When diagram block is being resized a request is being made and new gif image is generated and send to browser. What I need is generating image of basic blocks, like rounded rectangle, circle, diamond with specified parameters (height, width and color). I want to do all server-side; my server part is written on Perl.

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  • Which style is preferable when writing this boolean expression?

    - by Jeppe Stig Nielsen
    I know this question is to some degree a matter of taste. I admit this is not something I don't understand, it's just something I want to hear others' opinion about. I need to write a method that takes two arguments, a boolean and a string. The boolean is in a sense (which will be obvious shortly) redundant, but it is part of a specification that the method must take in both arguments, and must raise an exception with a specific message text if the boolean has the "wrong" value. The bool must be true if and only if the string is not null or empty. So here are some different styles to write (hopefully!) the same thing. Which one do you find is the most readable, and compliant with good coding practice? // option A: Use two if, repeat throw statement and duplication of message string public void SomeMethod(bool useName, string name) { if (useName && string.IsNullOrEmpty(name)) throw new SomeException("..."); if (!useName && !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option B: Long expression but using only && and || public void SomeMethod(bool useName, string name) { if (useName && string.IsNullOrEmpty(name) || !useName && !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option C: With == operator between booleans public void SomeMethod(bool useName, string name) { if (useName == string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option D1: With XOR operator public void SomeMethod(bool useName, string name) { if (!(useName ^ string.IsNullOrEmpty(name))) throw new SomeException("..."); // rest of method } // option D2: With XOR operator public void SomeMethod(bool useName, string name) { if (useName ^ !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } Of course you're welcome to suggest other possibilities too. Message text "..." would be something like "If 'useName' is true a name must be given, and if 'useName' is false no name is allowed".

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  • Checking for uppercase/lowercase/numbers with Jquery

    - by user1725794
    Either I'm being really retarded here or its just the lack of sleep but why doesn't this work? If I use the "or" operator it works for each separate test but as soon as it change it to the "and" operator it stops working. I'm trying to test the password input of a form to see if its contains lowercase, uppercase and at least 1 number of symbol. I'm having a lot of trouble with this so help would be lovely, here is the code I have. var upperCase= new RegExp('[^A-Z]'); var lowerCase= new RegExp('[^a-z]'); var numbers = new RegExp('[^0-9]'); if(!$(this).val().match(upperCase) && !$(this).val().match(lowerCase) && !$(this).val().match(numbers)) { $("#passwordErrorMsg").html("Your password must be between 6 and 20 characters. It must contain a mixture of upper and lower case letters, and at least one number or symbol."); } else { $("#passwordErrorMsg").html("OK") }

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  • NHibernate - define where condition

    - by t.kehl
    Hi. In my application the user can defines search-conditions. He can choose a column, set an operator (equals, like, greater than, less or equal than, etc.) and give in the value. After the user clicks on a button and the application should do a search on the database with the condition. I use NHibernate and ask me now, what is the efficientest way to do this with NHibernate. Should I create a query with it like (Column=Name, Operator=Like, Value=%John%) var a = session.CreateCriteria<Customer>(); a.Add(Restrictions.Like("Name", "%John%")); return a.List<Customer>(); Or should I do this with HQL: var q = session.CreateQuery("from Customer where " + where); return q.List<Customer >(); Or is there a more bether solution? Thanks for your help. Best Regards, Thomas

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  • help in compare validate in c#

    - by scatman
    i have 2 textboxes that i am filling with StartDate, and Endate. i want to use the compareValidator to make sure that the StartDate is less that the EndDate. i used this: <asp:CompareValidator ID="Comp" ControlToValidate="txtStartDate" ControlToCompare="txtEndDate" Operator="LessThan" Type="Date" runat="server" Display="dynamic" Text="Failed!" /> the validator is always giving me Failed no matter what the dates are. if startdateendate or vise versa, Failed appears. i am using (MM/dd/yyyy) format in the textboxes. EDIT: ok i solved the problem. if anyone interested here is the new comparevalidator: <asp:CompareValidator ID="Comp" ControlToValidate="txtEndDate" ControlToCompare="txtStartDate" Operator="GreaterThan" Type="Date" runat="server" Display="dynamic" Text="Failed!" />

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