Search Results

Search found 2666 results on 107 pages for 'boost lambda'.

Page 82/107 | < Previous Page | 78 79 80 81 82 83 84 85 86 87 88 89  | Next Page >

• Memory leak using shared_ptr

  - by nabulke

  Both code examples compile and run without problems. Using the second variant results in a memory leak. Any ideas why? Thanks in advance for any help. Variant 1: typedef boost::shared_ptr<ParameterTabelle> SpParameterTabelle; struct ParTabSpalteData { ParTabSpalteData(const SpParameterTabelle& tabelle, const string& id) :Tabelle(tabelle), Id(id) { } const SpParameterTabelle& Tabelle; string Id; }; Variant 2: struct ParTabSpalteData { ParTabSpalteData(const SpParameterTabelle& tabelle, const string& id) :Id(id) { // causes memory leak Tabelle2 = tabelle; } SpParameterTabelle Tabelle2; string Id; };

  Read the article

• QPluginLoader with PyQt modules as plugins: possible?

  - by Thorfin

  Hi! I have a C++ application that loads externals plugins thanks to QPluginloader. QPluginLoader provides access to a Qt plugin. A Qt plugin is stored in a shared library (a DLL). The plugins have to inherit from a pure virtual class ( and Q_DECLARE_INTERFACE ) and QObject. I would like to create plugins by using python and PyQt. Is this possible without too much work? For instance if I have to convert the modules to C++ with boost::python, this could be nonsense, as PyQt is already a conversion from C++ to Python... Thanks!

  Read the article

• Laws of Computer Science and Programming

  - by Jonas

  We have Amdahl's law that basically states that if your program is 10% sequential you can get a maximum 10x performance boost by parallelizing your application. Another one is Wadler's law which states that In any language design, the total time spent discussing a feature in this list is proportional to two raised to the power of its position. 0. Semantics 1. Syntax 2. Lexical syntax 3. Lexical syntax of comments My question is this: What are the most important (or at least significant / funny but true / sad but true) laws of Computer Science and programming? I want named laws, and not random theorems, So an answer should look something like Surname's (law|theorem|conjecture|corollary...) Please state the law in your answer, and not only a link. Edit: The name of the law does not need to contain it's inventors surname. But I do want to know who stated (and perhaps proved) the law

  Read the article

• Is this a good code (came across while reading code of a colleague)

  - by eriks

  // file a.hpp class a; typedef boost::shared_ptr<a> aPtr class a{ public: static aPtr CreateImp(); virtual void Foo() = 0 ; .... }; //file aImp.hpp class aImp : public a{ virtual void Foo(); }; //file aImp.cpp aPtr a::CreateImp() { return aPtr(new aImp()); } void aImp::Foo(){} The client must use CreateImp to get ptr to 'a', and can't use 'a' other ways. What do you think about this implementation? what do you think about this king of implementation?

  Read the article

• Virtual Earth Shape Rendering Performance

  - by Mike

  I am overlaying a transparent image on my VEMap control by rendering it as a single VEShape. The shape changes sizes dynamically depeding on the zoom level of my map and can be as large as 4000*4000px. In older browsers such as IE6 and early versions of Firefox 2.x, map control performance degrades rapidly when my shape gets larger than 1500*1500px. The mouse pointer moves slowly and the map responds very slowly to events. I don't see this issue at all in newer browsers (IE7+). Are there any workarounds to boost performance of rendering a large shape for IE6 users?

  Read the article

• LINQ Searching Only Allowing Equivalency

  - by Mad Halfling

  Hi folks, I'm trying to filter a set of records based on a sub-object's criteria. This compiles ok recordList = recordList.Where(r => r.Areas.Where(a => a.Area == "Z").Count() > 0); but this doesn't recordList = recordList.Where(r => r.Areas.Where(a => a.Area <= "Z").Count() > 0); giving these errors Cannot convert lambda expression to type 'string' because it is not a delegate type Delegate 'System.Func' does not take '1' arguments Operator '<=' cannot be applied to operands of type 'string' and 'string' != works ok, by any sort of less than or greater than operation fails.

  Read the article

• Equivalents of Java and .NET technologies/frameworks

  - by Paul Sasik

  I work in a shop that is a mix of mostly Java and .NET technologists. When discussing new solutions and architectures we often encounter impedance in trying to compare the various technologies, frameworks, APIs etc. in use between the two camps. It seems that each camp knows little about the other and we end up comparing apples to oranges and forgetting about the bushels. While researching the topic I found this: Java -- .Net rough equivalents It's a nice list but it's not quite exhaustive and is missing the key .NET 3.0 technologies and a few other tidbits. To complete that list: what are the near/rough equivalents (or a combination of technologies) in Java to the following in .NET? WCF WPF Silverlight WF Generics Lambda expressions Linq (not Linq-to-SQL) TPL F# IronPython IronRuby ...have i missed anything else? Note that I omitted technologies that are already covered in the linked article. I would also like to hear feedback on whether the linked article is accurate. Thanks.

  Read the article

• Using local classes with STL algorithms

  - by David Rodríguez - dribeas

  I have always wondered why you cannot use locally defined classes as predicates to STL algorithms. In the question: Approaching STL algorithms, lambda, local classes and other approaches, BubbaT mentions says that 'Since the C++ standard forbids local types to be used as arguments' Example code: int main() { int array[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 }; std::vector<int> v( array, array+10 ); struct pair : public std::unary_function<int,bool> { bool operator()( int x ) { return !( x % 2 ); } }; std::remove_if( v.begin(), v.end(), pair() ); // error } Does anyone know where in the standard is the restriction? What is the rationale for disallowing local types?

  Read the article

• Need to debug LINQ simple queries in Visual Studio 2010

  - by maxima120

  I often get in a position when I need to know why my LINQ doesnt work as intended... I use object collections and extensions. I dont want spend more than couple of minutes on it. LINQ supposed to make developer's life easier not harder. I hoped VS 2010 will have it fixed but I now use RC and it still doesnt let me type LINQ and check what is going on... Says as before "Expression cannot contain lambda expressions"... Is there some add-on for Visual Studio so I can quickly and effectively run ad-hoc queries and find out what is going on and where I am wrong?

  Read the article

• Using numpy.apply

  - by andylei

  What's wrong with this snippet of code? import numpy as np from scipy import stats d = np.arange(10.0) cutoffs = [stats.scoreatpercentile(d, pct) for pct in range(0, 100, 20)] f = lambda x: np.sum(x > cutoffs) fv = np.vectorize(f) # why don't these two lines output the same values? [f(x) for x in d] # => [0, 1, 2, 2, 3, 3, 4, 4, 5, 5] fv(d) # => array([0, 0, 0, 0, 0, 0, 0, 0, 0, 0]) Any ideas?

  Read the article

• What are the pro and cons of statically linking a library?

  - by Mathieu Pagé

  Hi, I want to release an application I developed as a hobby both for Linux and Windows. This application depends on boost (and possibly other libraries). The norm for this kind of application (a chess engine) is to provide only an executable file and possibly some helper files. I tough it would be a good idea to statically link the libraries so the executable would not have any dependencies. So the end user can just put the executable in a directory and start using it. However, while doing some research online I found some negative comments about statically linking libraries, some even arguing that an application with statically linked libraries would be hardly portable, meaning that it would only run on my system of highly similar systems. So what are the pros and cons of statically linking library? I already know that the executable will be bigger. But I can't see why it would make my application less portable.

  Read the article

• Rough/near equivalents of Java and .NET technologies/frameworks

  - by Paul Sasik

  I work in a shop that is a mix of mostly Java and .NET technologists. When discussing new solutions and architectures we often encounter impedance in trying to compare the various technologies, frameworks, APIs etc. in use between the two camps. It seems that each camp knows little about the other and we end up comparing apples to oranges and forgetting about the bushels. While researching the topic I found this: Java -- .Net rough equivalents It's a nice list but it's not quite exhaustive and is missing the key .NET 3.0 technologies and a few other tidbits. To complete that list: what are the near/rough equivalents (or a combination of technologies) in Java to the following in .NET? WCF WPF Silverlight WF Generics Lambda expressions Linq (not Linq-to-SQL) ...have i missed anything else? Note that I omitted technologies that are already covered in the linked article. I would also like to hear feedback on whether the linked article is accurate. Thanks. (Will CW if requested.)

  Read the article

• 'Generic' ViewModel

  - by Ian MacPherson

  Using EF 4, I have several subtypes of a 'Business' entity (customers, suppliers, haulage companies etc). They DO need to be subtypes. I am building a general viewmodel which calls into a service from which a generic repository is accessed. As I have 4 subtypes, it would be good to have a 'generic' viewmodel used for all of these. Problem is of course is that I have to call a specific type into my generic repository, for example: BusinessToRetrieve = _repository .LoadEntity<Customer>(o => o.CustomerID == customerID); It would be good to be able to call <SomethingElse>, somethingElse being one or other of the subtypes), otherwise I shall have to create 4 near identical viemodels, which seems a waste of course! The subtype entity name is available to the viewmodel but I've been unable to figure out how to make the above call convert this into a type. An issue with achieving what I want is that presumably the lambda expression being passed in wouldn't be able to resolve on a 'generic' call ?

  Read the article

• Multiple range product in Python

  - by Tyr

  Is there a better way to do this: perms = product(range(1,7),range(1,7),range(1,7)) so that I can choose how many ranges I use? I want it to be equivalent to this, but scalable. def dice(num) if num == 1: perms = ((i,) for i in range(1,7)) elif num == 2: perms = product(range(1,7),range(1,7)) elif num == 3: perms = product(range(1,7),range(1,7),range(1,7)) #... and so on but I know there has to be a better way. I'm using it for counting dice outcomes. The actual code def dice(selection= lambda d: d[2]): perms = itertools.product(range(1,7),range(1,7),range(1,7)) return collections.Counter(((selection(sorted(i)) for i in perms))) where I can call it with a variety of selectors, like sum(d[0:2]) for the sum of the lowest 2 dice or d[1] to get the middle dice.

  Read the article

• EF Code First - Include(x => x.Properties.Entity) a 1 : Many association

  - by VulgarBinary

  Given a EF-Code First CTP5 entity layout like: public class Person { ... } which has a collection of: public class Address { ... } which has a single association of: public class Mailbox { ... } I want to do: PersonQuery.Include(x => x.Addresses).Include("Addresses.Mailbox") WITHOUT using a magic string. I want to do it using a lambda expression. I am aware what I typed above will compile and will bring back all Persons matching the search criteria with their addresses and each addresses' mailbox eager loaded, but it's in a string which irritates me. How do I do it without a string? Thanks Stack!

  Read the article

• Whats the significance of named scope in rails?

  - by piemesons

  Before going for details. Question 1:-- Whats the meaning of scope here (ie named scope)? whats the benefits of using named scope? Now:- from agile development with rails book:-- class Order < ActiveRecord::Base named_scope :last_n_days, lambda { |days| {:conditions => ['updated < ?' , days] } } named_scope :checks, :conditions => {:pay_type => :check} end Such a named scope would make finding the last weeks worth of orders a snap. orders = Orders.last_n_days(7) Scopes can also be combined orders = Orders.checks.last_n_days(7) why we are using named_scope here. We can do the same using methods. Whats special thing we got using named_scope.

  Read the article

• How can I make named_scope in Rails return one value instead of an array?

  - by sameera207

  I want to write a [named scope] to get a record from its id. For example, I have a model called Event, and I want to simulate Event.find(id) with use of named_scope for future flexibility. I used this code in my model: named_scope :from_id, lambda { |id| {:conditions => ['id= ?', id] } } and I call it from my controller like Event.from_id(id). But my problem is that it returns an array of Event objects instead of just one object. Thus if I want to get event name, I have to write event = Event.from_id(id) event[0].name while what I want is event = Event.from_id(id) event.name Am I doing something wrong here?

  Read the article

• OpenCV, Python (ctypes), and OS X 10.5: dylib errors/confusion

  - by Jeff

  I have tried two brands of ctypes (ctypes-opencv and another) wrappers for OpenCV (2.0 from svn head), can use Python and OpenCV in the Python console, but whenever I try to import the packages (from ctypes_opencv import *) from another Python file, I get the following error message: OSError: dlopen(/usr/local/lib/libcv.dylib, 6): Symbol not found: __ZN2cv10fastMallocEm Referenced from: /usr/local/lib/libcv.dylib Expected in: flat namespace And some more Python errors: module body in __init__.py at line 18 from ctypes_opencv.cxcore import * module body in cxcore.py at line 80 _cxDLL, _cvDLL, _hgDLL = detect_opencv() function detect_opencv in cxcore.py at line 59 cvDLL = cdll.LoadLibrary(find_lib('cv')) function LoadLibrary in __init__.py at line 431 return self._dlltype(name) function __init__ in __init__.py at line 353 self._handle = _dlopen(self._name, mode) I most recently built OpenCV using flags the ctypes_opencv wiki recommended: ENABLE_SSE(2) OFF and BUILD_NEW_PYTHON_SUPPORT OFF. I've tried a number of flag combinations though. I also tried using the MacPorts install of OpenCV, got the same messages, uninstalled it, and now it errors out as well. :P And if that wasn't enough, I tried using the latest ctypes wrapper, but get boost-jam errors. Any help would be very much appreciated.

  Read the article

• Custom iterator for a class based on two sets

  - by Dan Hook

  I have a class that contains two sets. They both contain the same key type but have different compare operations. I would like to provide an iterator for the class that iterates through the elements of both sets. I want to start with one set, then when I increment an iterator pointing to the last element of the first set, I want to go to the first element of the second set. How do I do this? I would like to preserve the bidirectional iterator semantics of std::set, but if it turns out that implementing a forward iterator is much easier, so be it. I'm willing to use the Boost Iterator library if that would help.

  Read the article

• console windows not close after stopping program

  - by robUK

  Hello, Visual Studio 2005 C++ Windows XP Pro I have a sample application that I am testing, that links with boost libraries. However, the program runs ok. However, when I try and stop the program by clicking the 'Stop Debugging' button. The program ends, but the console window remains open. So I have many of them, as during my testing I am starting and stopping the application. Even when I try and close it by clicking the close button it has no affect. And it doesn't seem to appear under task manager when the program ends. The only way I can close them if I reboot windows. I am thinking it might be a thread that has not closed, and maybe that is keeping the console windows open. Many thanks for any advice,

  Read the article

• How to compile scheme into native binary files ?

  - by Joe

  I am very new to scheme. And now I am trying to compile some scheme code into binary file which will be loaded faster into interpreter. (The interpreter is a hybrid interpreter)Some one told me that I can compile the code into native binary file and then load it into interperter. And my question is: 1. What is the native binary file? 2. How can I compile the scheme code into a native binary file? 3. How can I load native bianry file into scheme interpreter? Thanks in advance. Joe Suggested that I want to compile below code into native binary file: (define test (lambda() (display "this is a test")) And then load the bianry file into interpreter and call the function "test".

  Read the article

• Inverted index in a search engine

  - by Ayman

  Hello there, I'm trying to write some code to make a small application for searching text from files. Files should be crawled, and I need to put an inverted index to boost searches. My problem is that I kind of have ideas about how the parser would be, I'm willing to implement the AND, NOT, OR in the query. Whereas, I couldn't figure out how my index should be... I have never created an inverted index so if any body could suggest a feasable way to do it I would be very grateful... I do know in theory how it works but my problem is I absolutely have no idea to make happen in MySql I need to give keywords being indexed a weight too... Thank you so much.

  Read the article

• Expression Tree

  - by nettguy

  My understanding of expression tree is : Expression trees are in-memory representation of expression like arithmetic or boolean expression.The expressions are stored into the parsed tree.so we can easily transalate into any other language. Linq to SQL uses expression tree.Normally in LINQ to SQL query the compiler translates it into parsed expression trees.These are passed to Sql Server as T-SQL Statements.The Sql server executes the T-SQL query and sends down the result back.That is why when you execute LINQ to SQL you gets IQueryable<T> not IEnumetrable<T>.Because IQuerybale contains public IQueryable:IEnumerable { Type Element {get;} Expression Expression {get;} IQueryaleProvider Provider {get;} } Questions : Microsoft uses Expression trees to play with LINQ-to-Sql.What are the different ways can i use expression trees to boost my code. Apart from LINQ to SQL,Linq to amazon ,who used expression trees in their applications? Linq to Object return IEnumerable,Linq to SQL return IQueryable ,What does LINQ to XML return?

  Read the article

• Where and which data to save into session on an ASP.NET MVC 2 application?

  - by Shaharyar

  I am having some trouble saving the state of my current view. Currenly I have several selectlist calling their own Action method on the controller that returns the Index view with the filtered model based on the values of the selectlist. I have also written a little FileResult action that creates a csv file based on the current model. But I am only covering one selectlist right now as I only save the value of selectList1 into the session and access it with Session["SelectListValue1"] What are the best practices in this situation? Should I redo the entire (each action for each SelectList) part? Should I save each SelectLists value into the session and check if it's null? Or should I just save the Lambda Expression into the session and modify it during every call?

  Read the article

• Sorting objects in Python

  - by Curious2learn

  I want to sort objects using by one of their attributes. As of now, I am doing it in the following way USpeople.sort(key=lambda person: person.utility[chosenCar],reverse=True) This works fine, but I have read that using operator.attrgetter() might be a faster way to achieve this sort. First, is this correct? Assuming that it is correct, how do I use operator.attrgetter() to achieve this sort? I tried, keyFunc=operator.attrgetter('utility[chosenCar]') USpeople.sort(key=keyFunc,reverse=True) However, I get an error saying that there is no attribute 'utility[chosenCar]'. The problem is that the attribute by which I want to sort is in a dictionary. For example, the utility attribute is in the following form: utility={chosenCar:25000,anotherCar:24000,yetAnotherCar:24500} I want to sort by the utility of the chosenCar using operator.attrgetter(). How could I do this? Thanks in advance.

  Read the article

< Previous Page | 78 79 80 81 82 83 84 85 86 87 88 89  | Next Page >