Search Results

Search found 5377 results on 216 pages for 'explicit cast operator'.

Page 151/216 | < Previous Page | 147 148 149 150 151 152 153 154 155 156 157 158  | Next Page >

  • Filter objects within two seconds of one another using SQLAlchemy

    - by Arrieta
    Hello: I have two tables with a column 'date'. One holds (name, date) and the other holds (date, p1, p2). Given a name, I want to use the date in table 1 to query p1 and p2 from table two; the match should happen if date in table one is within two seconds of date in table two. How can you accomplish this using SQLAlchemy? I've tried (unsuccessfully) to use the between operator and with a clause like: td = datetime.timedelta(seconds=2) q = session.query(table1, table2).filter(table1.name=='my_name').\ filter(between(table1.date, table2.date - td, table2.date + td)) Any thoughts?

    Read the article

  • Accessing subclass members from a superclass pointer C++

    - by Dr. Monkey
    I have an array of custom class Student objects. CourseStudent and ResearchStudent both inherit from Student, and all the instances of Student are one or the other of these. I have a function to go through the array, determine the subtype of each Student, then call subtype-specific member functions on them. The problem is, because these functions are not overloaded, they are not found in Student, so the compiler kicks up a fuss. If I have a pointer to Student, is there a way to get a pointer to the subtype of that Student? Would I need to make some sort of fake cast here to get around the compile-time error?

    Read the article

  • How do I dynamically define an instance variable?

    - by Moses
    Hi everyone, I have two classes (class1 and class2) that just store data, no methods. I have a third class that has an instance variable that, depending on some user input, will be set to one of the two classes. So, in the third class I declare the variable generically as NSObject *aClass; and during runtime set it to whatever it should be. aClass = [[Class1 alloc] init]; // or aClass = [[Class2 alloc] init]; However, when I try to access fields from aClass NSString *str = aClass.field1; It gives me the error: request for member 'field1' in something not a structure or a union. Field1 is declared in both class1 and class2. When I try to cast aClass aClass = (Class1 *) aClass; it gives the same error. What am I doing wrong, is there a better way to do this?

    Read the article

  • Purpose of IF, ELSE, FOR macros ?

    - by psihodelia
    I have a source code of a library which has a lot of strange IF, ELSE, FOR, etc. macros for all common C-keywords instead of using just usual if,else,for,while keywords. These macros are defined like this: #define IF( a) if( increment_if(), a) where increment_if() function is defined so: static __inline void increment_if( void) { // If the "IF" operator comes just after an "ELSE", its counter // must not be incremented. ... //implementation } I don't really understand, what is the purpose of such macros? This library is for a real-time application and I suppose that using such macros must slow-down an application.

    Read the article

  • Boost::asio bug in MSVC10 - Failing BOOST_WORKAROUND in ~buffer_debug_check() in buffer.hpp

    - by shaz
    A straight compilation of example http://www.boost.org/doc/libs/1_43_0/doc/html/boost_asio/tutorial/tutdaytime3/src.html results in a runtime null pointer exception. Stack trace points to the buffer_debug_check destructor which contains this comment: // MSVC's string iterator checking may crash in a std::string::iterator // object's destructor when the iterator points to an already-destroyed // std::string object, unless the iterator is cleared first. The test #if BOOST_WORKAROUND(BOOST_MSVC, = 1400) succeeds in MSVC10 and (but) results in a null pointer exception in c:\Program Files (x86)\Microsoft Visual Studio 10.0\VC\include\xutility line 123 _Iterator_base12& operator=(const _Iterator_base12& _Right) { // assign an iterator if (_Myproxy != _Right._Myproxy) _Adopt(_Right._Myproxy->_Mycont); return (*this); } _Right._Myproxy is NULL

    Read the article

  • On Memory Allocation and C++

    - by Arpan
    And I quote from MSDN http://msdn.microsoft.com/en-us/library/aa366533(VS.85).aspx: The malloc function has the disadvantage of being run-time dependent. The new operator has the disadvantage of being compiler dependent and language dependent. Now the questions folks: a) What do we mean that malloc is run-time dependent? What kind of dynamic memory allocation functions can be independent of run-time? This statement sounds real strange. b) new is language dependent? Of course it should be right? Are HeapAlloc, LocalAlloc etc language independent? c) From a pure performance perspective are the MSVC provided routines preferable? Arpan

    Read the article

  • casting between sibling classes, AS3

    - by felix-gasca
    I have two classes, derivedClassA and derivedClassB which both extend parentClass I'm declaring var o:parentClass and then, depending on what's going on, I want to cast o as either being of type derivedClassA or derivedClassB. Essentially, this: var o:parentClass ... if(shouldUseA) o = new derivedClassA(); else o = new derivedClassB(); o.doSomething(); But it's not working, I'm getting all sorts of errors. Isn't this how class inheritance works? I feel like I'm missing something really fundamental, but I can't figure out what. Am I supposed to be using interfaces instead? Is there another way of doing what I want?

    Read the article

  • Force an object to be allocated on the heap

    - by Warren Seine
    A C++ class I'm writing uses shared_from_this() to return a valid boost::shared_ptr<>. Besides, I don't want to manage memory for this kind of object. At the moment, I'm not restricting the way the user allocates the object, which causes an error if shared_from_this() is called on a stack-allocated object. I'd like to force the object to be allocated with new and managed by a smart pointer, no matter how the user declares it. I thought it could be done through a proxy or an overloaded new operator, but I can't find a proper way of doing that. Is there a common design pattern for such usage? If it's not possible, how can I test it at compile time?

    Read the article

  • DependencyProperty Orientation problem

    - by byte
    I am learning WPF and am trying to create my first UserControl. My UserControl consists of StackPanel StackPanel contains a Label and TextBox I am trying to create two Dependency Properties Text for the Label Orientation for the StackPanel - The orientation will affect the position of the Label and TextBox effectively I have successfully created a Text dependency property and bind it to my UserControls . But when I created the Orientation property, I seem to get following error in get property The as operator must be used with a reference type or nullable type ('System.Windows.Controls.Orientation' is a non-nullable value type) public static DependencyProperty OrientationProperty = DependencyProperty.Register("Orientation", typeof(System.Windows.Controls.Orientation), typeof(MyControl), new PropertyMetadata((System.Windows.Controls.Orientation)(Orientation.Horizontal))); public Orientation Orientation { get { return GetValue(OrientationProperty) as System.Windows.Controls.Orientation; } set { SetValue(OrientationProperty, value); } } Appreciate your help.

    Read the article

  • How to force a deep copy when copying structs with arrays?

    - by Danvil
    If have a struct A { public double[] Data; public int X; } How can I force a deep copy when using operator= or adding instances of A to a container? The problem is for example: A a = new A(); var list = new List<A>(); list.Add(a); // does not make a deep copy of Data A b = a; // does not make a deep copy of Data Do I really have to implement my own DeepClone method and call it every time? This would be extremly error-prone ...

    Read the article

  • Why isn't Perl's File::GlobMapper exporting globmap?

    - by justintime
    The following is pretty well copied from the documentation. use File::GlobMapper qw( globmap ); for my $pair (globmap '<*.tar.gz>' => '<#1.tgz>' ) { } And it gives String found where operator expected at globmapper_test1.pl line 4, near "globmap '<*.tar.gz>'" (Do you need to predeclare globmap?) (Using ActivePerl 5.10.0 on Windows) Side questions - if GlobMapper only exports one function, why is it set so you have to export it explicitly?

    Read the article

  • C# Why does calling an interface member from a class generate an error?

    - by Jack
    So I have an interface: interface IFoo { int Bar(); int this[int i] {get; set;} } And a class that derives from it class Foo : IFoo { public int IFoo.Bar() { //Implementation { public int IFoo.this[int i] { //Implementation } } Now, I try to do this: var fooey = new Foo(); int i = Fooey.Bar(); or this: int i = Fooey[4]; I would expect these to work properly. However, the compiler generates an error as if such members don't exist. Why is that? I am aware I can cast Foo as IFoo, but I am also aware that casting is costly to performance, which is often the reason to use interfaces in the first place. EDIT 1: These are the errors generated 'Foo' does not contain a definition for 'Bar' and no extension method 'Bar' accepting a first argument of type 'Foo' could be found (are you missing a using directive or an assembly reference?) "Cannot apply indexing to an expression of type 'Foo'"

    Read the article

  • new with exception with Microsoft

    - by wsd
    As I'm coding for both Windows and Linux, I have a whole host of problems. Microsoft Visual C++ has no stdint header, but for that I wrote my own. Now I found out that MS C++'s new operator does not throw an exception, so I want to fix this a quickly as possible. I know I can define a Macro with Parameters in Parenthesis, can I define a macro that replaces MyClass x = new MyClass(); with #ifdef MSC_VER if(!(MyClass x = new MyClass()) { throw new std::bad_alloc(); } #else MyClass x = new MyClass(); #endif (or something equivalent), AND works in BOTH MS C++ and G++ ? Or alternatively if that is not possible, a batch file to run over the Code to do this? I have become rather dependent on this exception being thrown.

    Read the article

  • How often do you implement the big three?

    - by Neil Butterworth
    I was just musing about the number of questions here that either are about the "big three" (copy constructor, assignment operator and destructor) or about problems caused by them not being implemented correctly, when it occurred to me that I could not remember the last time I had implemented them myself. A swift grep on my two most active projects indicate that I implement all three in only one class out of about 150. That's not to say I don't implement/declare one or more of them - obviously base classes need a virtual destructor, and a large number of my classes forbid copying using the private copy ctor & assignment op idiom. But fully implemented, there is this single lonely class, which does some reference counting. So I was wondering am I unusual in this? How often do you implement all three of these functions? Is there any pattern to the classes where you do implement them?

    Read the article

  • Handling null values with PowerShell dates

    - by Tim Ferrill
    I'm working on a module to pull data from Oracle into a PowerShell data table, so I can automate some analysis and perform various actions based on the results. Everything seems to be working, and I'm casting columns into specific types based on the column type in Oracle. The problem I'm having has to do with null dates. I can't seem to find a good way to capture that a date column in Oracle has a null value. Is there any way to cast a [datetime] as null or empty?

    Read the article

  • Screen orientation change forces data re-entry

    - by Timbermar
    I'm developing a simple app, only a handful of activities and nothing to complicated. The issue I'm having is that in a few of my activities I have EditText widgets, and when the screen is rotated, these widgets loose their values. They still visually, that is, on the handset screen, report their values from before the rotation, but to the code report their default values. An example, I have an activity with an EditText, I enter a number, 15, the calculator starts calculating, displays a result. If at this point I rotate to a different orientation, as expected the activity dies, reloads, shows the new orientation, my value of 15 is still in the EditText, however the calculator (the code) calculates as if it was 0, which is the initial value. I have not tried changing the initial value to see if it is really pulling from the default value, or just setting itself to 0 when I cast it as an int. If I didn't explain this well enough, let me know, I can add source code if I need to. Thanks.

    Read the article

  • PHP code in drupal pages treating > as ?>

    - by AmaDaden
    While working on an existing Drupal site I've noticed a strange glitch that causes any PHP operator with in it to act like a ? tag. This is happening in in Drupal pages that I create that have a 'Input Format' of 'PHP code'. For example this line of code foreach($array as $key = $value){ results in a very broken page that prints out $value){ Does any one know what could be causing this? My Dev environment is XAMPP. Drupal version is 6.15. PHP version is 5.2.9.

    Read the article

  • floats in NSArray

    - by JordanC
    I have an NSArray of floats which I did by encapsulating the floats using [NSNumber numberWithFloat:myFloat] ; Then I passed that array somewhere else and I need to pull those floats out of the array and perform basic arithmatic. When I try [myArray objectAtIndex:i] ; The compiler complains that I'm trying to perform arithmatic on a type id. It also won't let me cast to float or double. Any ideas? This seems like it should be an easy problem. Maybe it will come to me after another cup of coffee, but some help would be appreciated. Thanks.

    Read the article

  • Core Data NSFetchedResultsController sorting in certain sequence

    - by Moze
    I'm writing iphone app that has UITableView and uses Core Data. Data in UITableView is shown using NSFetchedResultsController. I use NSPredicate operator "IN" to fetch only needed entries. NSArray *filterArray = [NSArray arrayWithObjects:@"789", @"963", @"445", @"198", nil]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"id IN %@", filterArray]; Now the problem is that I need to show entries in same sequence they are in filterArray. How can I do it? How I can create NSSortDescriptor that would sort all entries in that way? I tried without sort descriptor, but I get error that NSFetchedResultsController needs sortDescriptor to be set.

    Read the article

  • nhibernate3 weaknesses

    - by Adrakadabra
    from the moment we've migrated from hibernate 2 to hibernate3 ,around 30% of queries can not execute anymore,while there were not any problem with the previous version. does anybody have such problems? for example some of errors we see r like these Specified cast is not valid: Repository<CountrySubdivision>.Find(p => p.Parent.Id == parentId); specified method is not supported: public JsonResult AllEducationDegree(string search) { var data = Repository<EducationDegree> .FindBySpecification(new EducationDegreeSpecification().Search(search)) .Take(10) .Select(p => new NameValue(p.Title, (int)p.Id)) .ToList(); // .AsDropdown(" "); return Json(data, JsonRequestBehavior.AllowGet); } public class EducationDegreeSpecification : FluentSpecification<EducationDegree> { public EducationDegreeSpecification Search(string EducationDegreeSearch) { if (!String.IsNullOrEmpty(EducationDegreeSearch)) { string[] searchs = EducationDegreeSearch.Split(' '); foreach (string search in searchs) { if (!String.IsNullOrEmpty(search)) { AddExpression(p => p.Title.Contains(search)); } } } return this; } }

    Read the article

  • C++ Segmentation fault in binary_function

    - by noryb009
    I'm using Visual Studio 2010 Beta 2 (also tried with NetBeans), and I'm having a segmentation fault in the following code: // One of the @link s20_3_3_comparisons comparison functors@endlink. template <class _Tp> struct less : public binary_function<_Tp, _Tp, bool> { bool operator()(const _Tp& __x, const _Tp& __y) const { return __x < __y; } //this is the problem line }; I don't know what in my program calls it, but I am trying to find out. (I think it's a map) Does anyone know what to do, or has encountered this before?

    Read the article

  • Query filter design for string field

    - by Midhat
    A field in my table can have arbitrary strings. On the UI, there is a drop down having options like All, Value1, Value2 And the results were filtered by the selected option value. So far this is easy and adding new filters to the UI is not a problem. Needs no changes in my stored procedure. Now I want to have an "Others" option here as well, which will return rows not having the column value as Value1 or Value2. Apparently this will require a "not in" operator in my query, and will make maintenance difficult, as the list of values is likely to change Any suggestions, design tips?

    Read the article

  • C++ Segementation fault in binary_function

    - by noryb009
    I'm using Visual Studio 2010 Beta 2 (also tried with NetBeans), and I'm having a segmentation fault in the following code: // One of the @link s20_3_3_comparisons comparison functors@endlink. template <class _Tp> struct less : public binary_function<_Tp, _Tp, bool> { bool operator()(const _Tp& __x, const _Tp& __y) const { return __x < __y; } //this is the problem line }; I don't know what in my program calls it, but I am trying to find out. (I think it's a map) Does anyone know what to do, or has encountered this before?

    Read the article

  • Is it possible to reinterpret pointer as dimensioned array reference?

    - by aaa
    hi. Suppose I have some pointer, which I want to reinterpret as static dimension array reference: double *p; double (&r)[4] = ?(p); // some construct? // clarify template< size_t N> void function(double (&a)[N]); ... double *p; function(p); // this will not work. // I would like to cast p as to make it appear as double[N] Is it possible to do so? how do I do it?

    Read the article

< Previous Page | 147 148 149 150 151 152 153 154 155 156 157 158  | Next Page >