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  • SWIG: Throwing exceptions from Python to C++

    - by wheaties
    We've got an interface we've defined in C++ (abstract class, all functions pure virtual) which will be extended in Python. To overcome the cross-language polymorphism issues we're planning on using SWIG directors. I've read how to catch exceptions thrown from C++ code in our Python code here, here, here, and even on SO. It's fairly straight forward and I'm not expecting issues with handling our library's own exceptions. What I'd like to know and can't seem to find in the documentation is how to have our Python implementation of the extended C++ interface throw those C++ exceptions in a way that makes them visible to the C++ code. We could make small functions within the *.i files such that each function throws our exceptions: void throw_myException(){ throw MyException; } but I'm wondering how it will interact with the Python code. Anyone have any experience with throwing C++ exceptions from Python code?

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  • Data binding in gridview column using eval

    - by ROBIN
    I hava grid containing a column for displaying countrynames. I need to display value in that column as contrycode-first 10 letters of country name (in-India) .I tried it using Eval functions with in the item template: <asp:TemplateField> <ItemTemplate> <asp:Label ID="CountryNameLabe" runat="server" Text='<%# Eval("CorporateAddressCountry").SubString(0,6) %>' ></asp:Label> </ItemTemplate> </asp:TemplateField> But it shows error. Can i use custom functions in eval? please help

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  • Data Annotations validation Built into model

    - by Josh
    I want to build an object model that automatically wires in validation when I attempt to save an object. I am using DataAnnotations for my validation, and it all works well, but I think my inheritance is whacked. I am looking here for some guidance on a better way to wire in my validation. So, to build in validation I have this interface public interface IValidatable { bool IsValid { get; } ValidationResponse ValidationResults { get; } void Validate(); } Then, I have a base class that all my objects inherit from. I did a class because I wanted to wire in the validation calls automatically. The issue is that the validation has to know the type of the class is it validating. So I use Generics like so. public class CoreObjectBase<T> : IValidatable where T : CoreObjectBase<T> { #region IValidatable Members public virtual bool IsValid { get { // First, check rules that always apply to this type var result = new Validator<T>().Validate((T)this); // return false if any violations occurred return !result.HasViolations; } } public virtual ValidationResponse ValidationResults { get { var result = new Validator<T>().Validate((T)this); return result; } } public virtual void Validate() { // First, check rules that always apply to this type var result = new Validator<T>().Validate((T)this); // throw error if any violations were detected if (result.HasViolations) throw new RulesException(result.Errors); } #endregion } So, I have this circular inheritance statement. My classes look like this then: public class MyClass : CoreObjectBase<MyClass> { } But the problem occurs when I have a more complicated model. Because I can only inherit from one class, when I have a situation where inheritance makes sense I believe the child classes won't have validation on their properties. public class Parent : CoreObjectBase<Parent> { //properties validated } public class Child : Parent { //properties not validated? } I haven't really tested the validation in these cases yet, but I am pretty sure that anything in child with a data annotation on it will not be automatically validated when I call Child.Validate(); due to the way the inheritance is configured. Is there a better way to do this?

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  • C++ wrapper for C library

    - by Maximilien
    Hi, Recently I found a C library that I want to use in my C++ project. This code is configured with global variables and writes it's output to memory pointed by static pointers. When I execute my project I would like 2 instances of the C program to run: one with configuration A and one with configuration B. I can't afford to run my program twice, so I think there are 2 options: Make a C++ wrapper: The problem here is that the wrapper-class should contain all global/static variables the C library has. Since the functions in the C library use those variables I will have to create very big argument-lists for those functions. Copy-paste the C library: Here I'll have to adapt the name of every function and every variable inside the C library. Which one is the fastest solution? Are there other possibilities to run 2 instances of the same C source? Thanks, Max

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  • boost scoped_lock mutex crashes

    - by JahSumbar
    hello, I have protected a std::queue's access functions, push, pop, size, with boost::mutexes and boost::mutex::scoped_lock in these functions from time to time it crashes in a scoped lock the call stack is this: 0 0x0040f005 boost::detail::win32::interlocked_bit_test_and_set include/boost/thread/win32/thread_primitives.hpp 361 1 0x0040e879 boost::detail::basic_timed_mutex::timed_lock include/boost/thread/win32/basic_timed_mutex.hpp 68 2 0x0040e9d3 boost::detail::basic_timed_mutex::lock include/boost/thread/win32/basic_timed_mutex.hpp 64 3 0x0040b96b boost::unique_lock<boost::mutex>::lock include/boost/thread/locks.hpp 349 4 0x0040b998 unique_lock include/boost/thread/locks.hpp 227 5 0x00403837 MyClass::inboxSize - this is my inboxSize function that uses this code: MyClass::inboxSize () { boost::mutex::scoped_lock scoped_lock(m_inboxMutex); return m_inbox.size(); } and the mutex is declared like this: boost::mutex m_inboxMutex; it crashes at the last pasted line in this function: inline bool interlocked_bit_test_and_set(long* x,long bit) { long const value=1<<bit; long old=*x; and x has this value: 0xababac17 Thanks for the help

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  • Entity framework 4 many-to-many insertion?

    - by Saxman
    Hi all, I'm not very familiar with the many-to-many insertion process using Entity Framework 4, POCO. I have a blog with 3 tables: Post, Comment, and Tag. A Post can have many Tags and a Tag can be in many Posts. Here are the Post and Tag models: public class Tag { public int Id { get; set; } [Required] [StringLength(25, ErrorMessage = "Tag name can't exceed 25 characters.")] public string Name { get; set; } public virtual ICollection<Post> Posts { get; set; } } public class Post { public int Id { get; set; } [Required] [StringLength(512, ErrorMessage = "Title can't exceed 512 characters")] public string Title { get; set; } [Required] [AllowHtml] public string Content { get; set; } public string FriendlyUrl { get; set; } public DateTime PostedDate { get; set; } public bool IsActive { get; set; } public virtual ICollection<Comment> Comments { get; set; } public virtual ICollection<Tag> Tags { get; set; } } Now when I'm adding a new post, I'm not sure what would be the right way to do. I'm thinking that I'll have a textbox where I can select multiple tags for that post (this part is already done), in my controller, I will check to see if the tag is already exists or not, if not, then I will insert the new tag. But I'm not even sure based on the models that I've created for EF, will they create a PostsTags table, or they are creating just a Tags and a Posts table and links between the two? How would I insert the new Post and set the tags to that post? Is it just newPost.Tags = Tags (where Tags are the one that got selected, do I even need to check to see if they already exists?), and then something like _post.Add(newPost);? Thanks.

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  • How can I write faster JavaScript?

    - by a paid nerd
    I'm writing an HTML5 canvas visualization. According to the Chrome Developer Tools profiler, 90% of the work is being done in (program), which I assume is the V8 interpreter at work calling functions and switching contexts and whatnot. Other than logic optimizations (e.g., only redrawing parts of the visualization that have changed), what can I do to optimize the CPU usage of my JavaScript? I'm willing to sacrifice some amount of readability and extensibility for performance. Is there a big list I'm missing because my Google skills suck? I have some ideas but I'm not sure if they're worth it: Limit function calls When possible, use arrays instead of objects and properties Use variables for math operation results as much as possible Cache common math operations such as Math.PI / 180 Use sin and cos approximation functions instead of Math.sin() and Math.cos() Reuse objects when passing around data instead of creating new ones Replace Math.abs() with ~~ Study jsperf.com until my eyes bleed Use a preprocessor on my JavaScript to do some of the above operations

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  • Getting set accessor for property in abstract class, not possible?

    - by Lars Udengaard
    Given the class': public abstract class AbstractEntity { public virtual Guid Id { get; private set; } } public class Entity { public virtual Guid Id { get; private set; } } And a PropertyInfo for the property 'Id'. When calling the method: PropertyInfo.GetAccessors() It returns both the get-method and the set-method when the class is not abstract (Entity), but only the get-method when the class is abstract (AbstractEntity). Why is this? And is there another way to get the set-method from a property with a private set?

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  • Why doesn't functools.partial return a real function (and how to create one that does)?

    - by epsilon
    So I was playing around with currying functions in Python and one of the things that I noticed was that functools.partial returns a partial object rather than an actual function. One of the things that annoyed me about this was that if I did something along the lines of: five = partial(len, 'hello') five('something') then we get TypeError: len() takes exactly 1 argument (2 given) but what I want to happen is TypeError: five() takes no arguments (1 given) Is there a clean way to make it work like this? I wrote a workaround, but it's too hacky for my taste (doesn't work yet for functions with varargs): def mypartial(f, *args): argcount = f.func_code.co_argcount - len(args) params = ''.join('a' + str(i) + ',' for i in xrange(argcount)) code = ''' def func(f, args): def %s(%s): return f(*(args+(%s))) return %s ''' % (f.func_name, params, params, f.func_name) exec code in locals() return func(f, args)

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  • Why does my CLR function keep disappearing

    - by user208080
    Hi there. I am a rookie to SQL and here is my questions. I have some CLR sql functions and procedures. When I deploy the 1st one, everything is fine. But after the 2nd one deployed, the first one will disappear. Anyone can help me out? Thanks a lot Actually, I simply create a new SQL project in VS, adding a new function or stored procedure, click deploy, and I can see the new function in my SQL instance. Then I close that project and open a new one, repeat the above steps, OK, the 2nd function is there i my instance but the 1st one disappeared or be replaced and no longer queryable for use. Thank you for your reply. All these clr functions and procedures are in the same instance of the database.

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  • problem with live function

    - by Dirty Bird Design
    I had this working to spec, until the specs changed. This function is now brought in via ajax .load. Easy enough to bring it in and I have all my other functions on the page that is brought in working in the parent page except this one: $("#CME").hide(); $(function() { $("#CME1, #CMEQL, #CBT1, #CBTQL, #NYM1, #CMX1").live("change", function(){ var checkBoxes = $("#CME1, #CMEQL, #CBT1, #CBTQL, #NYM1, #CMX1").filter(":not(:checked)"); if(checkBoxes.length == 0){ $("#CME").slideDown("fast"); } else { $("#CME").slideUp("fast"); } }); the div "#CME" is not hidden and the .live('change', function () { isn't working. I have other similar .live functions that are working and structured the same. How do I bind the initial $(function() with .live and why isn't the .hide() working? });//CME

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  • How to pass a function to a function?

    - by ShaChris23
    Suppose I have a class with 2 static functions: class CommandHandler { public: static void command_one(Item); static void command_two(Item); }; I have a problem DRY problem where I have 2 functions that have the exact same code for every single line, except for the function that it calls: void CommandOne_User() { // some code A CommandHandler::command_one(item); // some code B } void CommandTwo_User() { // some code A CommandHandler::command_two(item); // some code B } I would like to remove duplication, and, ideally, do something like this: void CommandOne_User() { Function func = CommandHandler::command_one(); Refactored_CommandUser(func); } void CommandTwo_User() { Function func = CommandHandler::command_one(); Refactored_CommandUser(func); } void Refactored_CommandUser(Function func) { // some code A func(item); } I have access to Qt, but not Boost. Could someone help suggest a way on how I can refactor something like this?

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  • Is this a good approach to execute a list of operations on a data structure in Python?

    - by Sridhar Iyer
    I have a dictionary of data, the key is the file name and the value is another dictionary of its attribute values. Now I'd like to pass this data structure to various functions, each of which runs some test on the attribute and returns True/False. One approach would be to call each function one by one explicitly from the main code. However I can do something like this: #MYmodule.py class Mymodule: def MYfunc1(self): ... def MYfunc2(self): ... #main.py import Mymodule ... #fill the data structure ... #Now call all the functions in Mymodule one by one for funcs in dir(Mymodule): if funcs[:2]=='MY': result=Mymodule.__dict__.get(funcs)(dataStructure) The advantage of this approach is that implementation of main class needn't change when I add more logic/tests to MYmodule. Is this a good way to solve the problem at hand? Are there better alternatives to this solution?

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  • how to access child instances in a vector in c++

    - by tsubasa
    I have a parent class and child class (inherited from parent). In the child class, I have a member function named function_blah(); I used vector<parent*> A to store 5 parent instances, 3 child instances. So the total number of elements in the vector is 8. I can easily access to member functions of element A[0] to A[4], which are parent instances. But whenever I try to have access to member functions of element A[5] to A[7], the compiler complains that class parent has no member named 'function_blah' The way I access to elements is using index. e.x A[i] with i = 0..7. Is it correct? if not, how?

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  • Delphi 2010 - Why can't I declare an abstract method with a generic type parameter?

    - by James
    I am trying to do the following in Delphi 2010: TDataConverter = class abstract public function Convert<T>(const AData: T): string; virtual; abstract; end; However, I keep getting the following compiler error: E2533 Virtual, dynamic and message methods cannot have type parameters I don't quite understand the reason why I can't do this. I can do this in C# e.g. public abstract class DataConverter { public abstract string Convert<T>(T data); } Anyone know the reasoning behind this?

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  • if else-if making code look ugly any cleaner solution?

    - by Vishal
    I have around 20 functions (is_func1, is_fucn2, is_func3...) returning boolean I assume there is only one function which returns true and I want that! I am doing: if is_func1(param1, param2): # I pass 1 to following abc(1) # I pass 1 some_list.append(1) elif is_func2(param1, param2): # I pass 2 to following abc(2) # I pass 1 some_list.append(2) ... . . elif is_func20(param1, param2): ... Please note: param1 and param2 are different for each, abc and some_list take parameters depending on the function. The code looks big and there is repetition in calling abc and some_list, I can pull this login in a function! but is there any other cleaner solution? I can think of putting functions in a data structure and loop to call them.

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  • Efficient retrieval of lists over WebServices

    - by Chris
    I have a WCF WebService that uses LINQ and EF to connect to an SQL database. I have an ASP.NET MVC front end that collects its data from the webservice. It currently has functions such as List<Customer> GetCustomers(); As the number of customers increases massively the amount of data being passed increases also reducing efficiency. What is the best way to "page data" across WebServices etc. My current idea is to implement a crude paging system such as List<Customer> GetCustomers(int start, int length); This, however, means I would have to replicate such code for all functions returning List types. It is unfortunate that I cannot use LINQ as it would be much nicer. Does anyone have any advice or ideas of patterns to implement that would be "as nice as possible" Thanks

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  • Is it OK to put a standard, pure C header #include directive inside a namespace?

    - by mic_e
    I've got a project with a class log in the global namespace (::log). So, naturally, after #include <cmath>, the compiler gives an error message each time I try to instantiate an object of my log class, because <cmath> pollutes the global namespace with lots of three-letter methods, one of them being the logarithm function log(). So there are three possible solutions, each having their unique ugly side-effects. Move the log class to it's own namespace and always access it with it's fully qualified name. I really want to avoid this because the logger should be as convenient as possible to use. Write a mathwrapper.cpp file which is the only file in the project that includes <cmath>, and makes all the required <cmath> functions available through wrappers in a namespace math. I don't want to use this approach because I have to write a wrapper for every single required math function, and it would add additional call penalty (cancelled out partially by the -flto compiler flag) The solution I'm currently considering: Replace #include <cmath> by namespace math { #include "math.h" } and then calculating the logarithm function via math::log(). I have tried it out and it does, indeed, compile, link and run as expected. It does, however, have multiple downsides: It's (obviously) impossible to use <cmath>, because the <cmath> code accesses the functions by their fully qualified names, and it's deprecated to use in C++. I've got a really, really bad feeling about it, like I'm gonna get attacked and eaten alive by raptors. So my question is: Is there any recommendation/convention/etc that forbid putting include directives in namespaces? Could anything go wrong with diferent C standard library implementations (I use glibc), different compilers (I use g++ 4.7, -std=c++11), linking? Have you ever tried doing this? Are there any alternate ways to banish the math functions from the global namespace? I've found several similar questions on stackoverflow, but most were about including other C++ headers, which obviously is a bad idea, and those that weren't made contradictory statements about linking behaviour for C libraries. Also, would it be beneficial to additionally put the #include <math.h> inside extern "C" {}?

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  • C++ enforce conditions on inherited classes

    - by user231536
    I would like to define an abstract base class X and enforce the following: a) every concrete class Y that inherits from X define a constructor Y(int x) b) it should be possible to test whether two Y objects are equal. For a, one not very good solution is to put a pure virtual fromInt method in X which concrete class will have to define. But I cannot enforce construction. For b), I cannot seem to use a pure virtual method in X bool operator == (const X& other) const =0; because in overridden classes this remains undefined. It is not enough to define bool operator == (const Y& other) const { //stuff} because the types don't match. How do I solve these problems?

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  • Angularjs code/naming conventions

    - by Dalorzo
    Does anyone know if exists any official or most accepted reference for Angular naming conventions to use when we build our applications? Angular has a lot of different type of components such as filters, directives, services and so on. Wouldn't you agree that having a reference naming convention when we implement them in our applications will make sense? For example: If we need to create new filters how should we name them like [Something]Filter or filter[Something] or something else? And same applies for Controllers, Services, Directives and so on. Other things I wonder about is if variables/functions that belongs to the scope should have an special prefix or suffix. In some situations it may be useful to have a way to differentiate them from functions and other (none angular code).

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  • maching strings

    - by kiran
    Write two functions, called countSubStringMatch and countSubStringMatchRecursive that take two arguments, a key string and a target string. These functions iteratively and recursively count the number of instances of the key in the target string. You should complete definitions for def countSubStringMatch(target,key): and def countSubStringMatchRecursive (target, key): For the remaining problems, we are going to explore other substring matching ideas. These problems can be solved with either an iterative function or a recursive one. You are welcome to use either approach, though you may find iterative approaches more intuitive in these cases of matching linear structures.

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