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• python iterators and thread-safety

  - by Igor

  I have a class which is being operated on by two functions. One function creates a list of widgets and writes it into the class: def updateWidgets(self): widgets = self.generateWidgetList() self.widgets = widgets the other function deals with the widgets in some way: def workOnWidgets(self): for widget in self.widgets: self.workOnWidget(widget) each of these functions runs in it's own thread. the question is, what happens if the updateWidgets() thread executes while the workOnWidgets() thread is running? I am assuming that the iterator created as part of the for...in loop will keep some kind of reference to the old self.widgets object? So I will finish iterating over the old list... but I'd love to know for sure.

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• C++ Class Inheritance architecture - preventing casting

  - by Some One

  I have a structure of base class and a couple of inherited classed. Base class should be pure virtual class, it should prevent instantiation. Inherited classes can be instantiated. Code example below: class BaseClass { public: BaseClass(void); virtual ~BaseClass(void) = 0; }; class InheritedClass : public BaseClass { public: InheritedClass1(void); ~InheritedClass1(void); }; class DifferentInheritedClass : public BaseClass { public: DifferentInheritedClass(void); ~DifferentInheritedClass(void); }; I want to prevent the following operations to happen: InheritedClass *inherited1 = new InheritedClass(); DifferentInheritedClass *inherited2 = new DifferentInheritedClass (); BaseClass *base_1 = inherited1; BaseClass *base_2 = inherited2; *base_1 = *base_2;

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• C++: warning: '...' declared with greater visibility than the type of its field '...::<anonymous>'

  - by Albert

  I'm getting these two warnings (with GCC 4.2 on MacOSX): /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154:0 /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154: warning: 'startMainLockDetector()::MainLockDetector' declared with greater visibility than the type of its field 'startMainLockDetector()::MainLockDetector::<anonymous' /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154:0 /Users/az/Programmierung/openlierox/build/Xcode/../../src/main.cpp:154: warning: 'startMainLockDetector()::MainLockDetector' declared with greater visibility than its base 'Action' In this code: struct Action { virtual ~Action() {} virtual int handle() = 0; }; static void startMainLockDetector() { /* ... */ struct MainLockDetector : Action { bool wait(Uint32 time) { /* ... */ } int handle() { /* ... */ } }; /* ... */ } I'm not exactly sure what these warnings mean (what visibility?) and how to fix them. (I really want the class MainLockDetector to be local for that function only.) I have already compiled the same code with a lot of other compilers (clang, GCC 3.*, GCC 4.0, GCC 4.4, etc) and never got any warning for this code.

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• Outputting variable values in x86?

  - by Airjoe

  Hello All- I'm working on a homework assignment in x86 and it isn't working as I expect (surprise surprise!). I'd like to be able to output values of variables in x86 functions to ensure that the values are what I expect them to be. Is there a simple way to do this, or is it very complex? For what it's worth, the x86 functions are being used by a C file and compiled with gcc, so if that makes it simpler that is how I'm going about it. Thanks for the help.

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• Need help with homework(very short code)

  - by b3y4z1d

  I have a code, and I need to have it done until friday or so.I'd say 95% of it is finished,but the functions and the function-calling could use some grooming. It is really simple for anyone who knows C++ pretty well, but I'm a newbie and I just can't seem to get through this with the functions so if anyone could take a look and correct the few mistakes or add a line or two if needed I'd be very grateful. Here is the link to the full code, you'll understand the purpose of the code once you see it. I use Borland C++ by the way if it helps. Thanks in advance!

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• Returning a C++ reference in a const member functionasses

  - by Chris Kaminski

  A have a class hierarchy that looks somethign like this: class AbstractDataType { public: virtual int getInfo() = 0; }; class DataType: public AbstractDataType { public: virtual int getInfo() { }; } class Accessor { DataType data; public: const AbstractDataType& getData() const { return(data); } } Well, GCC 4.4 reports: In member function ‘const AbstractDataType& Accessor::getData() const’: error: invalid initialization of reference of type ‘const AbstractDataType&’ from expression of type ‘const DataType’ Where am I going wrong - is this a case where I MUST use a pointer?

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• An agenda in Korn Shell: New / Edit / Delete / View appointment

  - by Abaco

  As stated in the title, I have to write a simple script which should perform some typical agenda's functions. The script must use crontab. The functions are: Creating a new appointment Edit an existent appointment Delete an appointment List the appointment I really don't have a clue how to do this, can you help me with some hint? Maybe a bit of sweet code? Thank you very much, Abaco EDIT: To be more specific on my question Point 1: how can I edit a crontab thorugh ksh? How can I insert a new line? Can you link me some documentation or a bit of code about this?

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• Jquery Delay Function Calls

  - by fizgig07

  I'm trying to find a way to delay all code that takes place after I make a service call. The reason for this delay is that my service returns code necesarry for the following functions and the result I pass is to these following functions is undefined. I have tried attaching the setTimeout() to the function that is called directly after the service call, but then it just skips the function I set the timeout on and jumps to the next function...My web method that I am calling is not that big and is not doing anything that is too intensive public bool GetSpreadsheetStatusForAdmin(string cacId) { SpreadSheetStatus result = new SpreadSheetStatus(); List<Data.Spreadsheet> spreadsheets = SpreadsheetManager.GetUserSpreadsheets(GetCurrent.Identity); if (spreadsheets.Count != 0) { foreach (Data.Spreadsheet spreadsheet in spreadsheets) { if (spreadsheet.Status == SpreadsheetStatus.Pending) { return true; } } } return false; } I had found the delay() and thought that might work, but I don't have jquery 1.4 and can't use it as of yet. is there anything that can help..?

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• How to Sort Typed List Collection

  - by Muhammad Akhtar

  I have class like public class ProgressBars { public ProgressBars() { } private Int32 _ID; private string _Name; public virtual Int32 ID {get { return _ID; } set { _ID = value; } } public virtual string Name { get { return _Name; } set { _Name = value; }} } here is List collection List<ProgressBars> progress; progress.Sort //I need to get sort here by Name how can I sort this collection by Name? Thanks

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• Python list as *args?

  - by Cap

  I have two Python functions, both of which take variable arguments in their function definitions. To give a simple example: def func1(*args): for arg in args: print arg def func2(*args): return [2 * arg for arg in args] I'd like to compose them -- as in func1(func2(3, 4, 5)) -- but I don't want args in func1 to be ([6, 7, 8],), I want it to be (6, 7, 8), as if it was called as func1(6, 7, 8) rather than func1([6, 7, 8]). Normally, I would just use func1(*func2(3, 4, 5)) or have func1 check to see if args[0] was a list. Unfortunately, I can't use the first solution in this particular instance and to apply the second would require doing such a check in many places (there are a lot of functions in the role of func1). Does anybody have an idea how to do this? I imagine some sort of introspection could be used, but I could be wrong.

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• What causes my borderless C++ app to crash when overriding WndProc?

  - by Ste

  I use a form with border NONE. I need to override WndProc for resize and move form. However, using this code, my app crashes! static const int WM_NCHITTEST = 0x0084; static const int HTCLIENT = 1; static const int HTCAPTION = 2; protected: virtual void Form1::WndProc(System::Windows::Forms::Message %m) override { switch (m.Msg) { case WM_NCHITTEST: if (m.Result == IntPtr(HTCLIENT)) { m.Result = IntPtr(HTCAPTION); } break; } Form1::WndProc(m); } virtual System::Windows::Forms::CreateParams^ get() override { System::Windows::Forms::CreateParams^ cp = __super::CreateParams; cp->Style |= 0x40000; return cp; } How can I fix my code not to crash but still allow my form to be moved and resized?

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• Php wrapper class for XML

  - by gms8994

  I'm working on a new class to wrap XML handling. I want my class to use simplexml if it's installed, and the built in XML functions if it's not. Can anyone give me some suggestions on a skeleton class to do this? It seems "wrong" to litter each method with a bunch of if statements, and that also seems like it would make it nearly impossible to correctly test. Any upfront suggestions would be great! EDIT: I'm talking about these built-in xml functions.

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• Why doesn't MySQL support millisecond precision?

  - by Byron Whitlock

  So I just found the most frustrating bug ever in MySQL. Apparently the TIMESTAMP field, and supporting functions do not support any greater precision than seconds!? So I am using PHP and Doctrine, and I really need those microseconds (I am using the actAs: [Timestampable] property). I found a that I can use a BIGINT field to store the values. But will doctrine add the milliseconds? I think it just assigns NOW() to the field. I am also worried the date manipulation functions (in SQL) sprinkled through the code will break. I also saw something about compiling a UDF extension. This is not an acceptable workaround because I or a future maintainer will upgrade and poof, change gone. Has anyone found a suitable workaround?

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• What's the purpose of having a separate "operator new[]" ?

  - by sharptooth

  Looks like operator new and operator new[] have exactly the same signature: void* operator new( size_t size ); void* operator new[]( size_t size ); and do exactly the same: either return a pointer to a big enough block of raw (not initialized in any way) memory or throw an exception. Also operator new is called internally when I create an object with new and operator new[] - when I create an array of objects with new[]. Still the above two special functions are called by C++ internally in exactly the same manner and I don't se how the two calls can have different meanings. What's the purpose of having two different functions with exactly the same signatures and exactly the same behavior?

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• Web App fails when moved to production environment. Which server permissions do I need?

  - by Ashley Ward

  I have developed a small web app. This app allows users to upload images. It also produces text files with the names of those images (the names are stored and retrieved to/from an MySQL Database.) I have developed this app using MAMP. To create the uploaded image files I use the PHP function imagejpeg('my/path/name.jpg') and to delete the files I use the PHP function unlink('folder1/folder2/name.jpg') to write to the text document I am using the function fopen('folder1/folder2/name.txt', 'w') all three of these functions produce errors related to permissions - now the site has been moved to a live hosting environment. Why is this? and what permissions do I need to set the folder's folder1 and folder2 to? I know that permission 777 is generally bad because it opens up your server to the public. However what I have found is that the functions fail to work unless I use 777 on the folders. Can anyone shed any light on my dilemma?

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• XPCOM C++: Does it support RegExps?

  - by hvtuananh

  I'm developing a XPCOM C++ component that have to use some RegExps functions Does XPCOM C++ have build-in support for RegExps?

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• Is there any valid reason radians are used as the inputs to trig function in many modern languages?

  - by johnmortal

  Is there any pressing reason trig functions should use radian inputs in modern programming languages? As far as I know radians are typically ugly to deal with except in three cases: (1) You want to compute an arc length and you know the angle of the arc and (2) You need to do symbolic calculus with trig functions (3) certain infinite series expansion look prettier if the input is in radians. None of these scenarios seem like a worthy justification for every programming language I am familiar with using radian inputs for Sin, Cos, Tangent, etc... The third one sounds good because it might mean one gets faster computations using radians (very slightly faster- the cost of one additional floating point multiplication ) , but I am dubious even of that because most commonly the developer had to take an extra step to put the angle in radians in the first place. The other two are ridiculous justifications for all the added obscurity.

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• Compare values in each column of two Oracle Types

  - by colinjameswebb

  I've been playing around with the pluto-test-framework today, and I'd like to get some existing functions into a test harness with it. I have lots of functions with this type of specification. FUNCTION DO_SOME_STUFF (pOldSchedule IN SCHEDULE_OBJ, pNewSchedule OUT SCHEDULE_OBJ, pLoggerContext IN OUT LOGGER_CONTEXT_OBJ) RETURN NUMBER; It takes pOldSchedule, does some stuff to it, and then returns pNewSchedule. The logger_context just does logging. As part of a test, I'd like to be able to compare the values in each of the columns of the type, without having to write individual IF statements. It'll need to return boolean to signify whether or not pOldSchedule and pNewSchedule match. Any ideas?

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• Class template specializations with shared functionality

  - by Thomas

  I'm writing a simple maths library with a template vector type: template<typename T, size_t N> class Vector { public: Vector<T, N> &operator+=(Vector<T, N> const &other); // ... more operators, functions ... }; Now I want some additional functionality specifically for some of these. Let's say I want functions x() and y() on Vector<T, 2> to access particular coordinates. I could create a partial specialization for this: template<typename T> class Vector<T, 3> { public: Vector<T, 3> &operator+=(Vector<T, 3> const &other); // ... and again all the operators and functions ... T x() const; T y() const; }; But now I'm repeating everything that already existed in the generic template. I could also use inheritance. Renaming the generic template to VectorBase, I could do this: template<typename T, size_t N> class Vector : public VectorBase<T, N> { }; template<typename T> class Vector<T, 3> : public VectorBase<T, 3> { public: T x() const; T y() const; }; However, now the problem is that all operators are defined on VectorBase, so they return VectorBase instances. These cannot be assigned to Vector variables: Vector<float, 3> v; Vector<float, 3> w; w = 5 * v; // error: no conversion from VectorBase<float, 3> to Vector<float, 3> I could give Vector an implicit conversion constructor to make this possible: template<typename T, size_t N> class Vector : public VectorBase<T, N> { public: Vector(VectorBase<T, N> const &other); }; However, now I'm converting from Vector to VectorBase and back again. Even though the types are the same in memory, and the compiler might optimize all this away, it feels clunky and I don't really like to have potential run-time overhead for what is essentially a compile-time problem. Is there any other way to solve this?

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• A smoother alternative to jQuery show() and hide()

  - by David B

  I have a page setup with a hidden column using the jQuery show() and hide() functions to slide the column in and out. However it's kind of "clunky" and does not look very smooth when showing/hiding; in contrast I also have a section of the page using jquery UI accordion. When switching between these sections the transition looks very nice and smooth... Is there a better function than show()/hide() which looks as nice as the accordion does? (maybe the "easing" parameter can be used in the show/hide functions, but i'm not sure how to use this properly?)

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• The most elegant way to encapsulate WinAPI callbacks inside a class

  - by FractalizeR

  Hello. I am thinking about elegant way to encapsulate WinAPI callbacks inside a class. Suppose I am making a class handling asynchronous I/O. All Windows callbacks should be stdcall functions, not class methods (I need to pass their addresses to ReadFileEx WinAPI function for example). So, I cannot just pass method addresses as a callback routines to WinAPI functions. What is the most elegant way to encapsulate functionality of this type inside a class so that the class have events OnReadCompleted and OnWriteCompleted (I am using Delphi as a primary language, but I guess the situation must be the same in C++ because class methods are different from simple methods by the fact, that the first hidden parameter of them is this link. Of course this class is not a singleton and there can be many of them created by app at the same time. What do you think would be the good way to implement this?

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• C# - Sending keyboard events to (last) selected window

  - by Mil

  Hi guys, I want to use virtual keyboard assembly found here http://www.codeproject.com/KB/miscctrl/touchscreenkeyboard.aspx like on screen keyboard (OSK.exe) in Windows. Can someone please tell me how can I use it so that it always stays on top and yet for user to be able to select other windows on dekstop for keyboard input, just like "on screen keyboard" in Windows, specifically I don't know how to select last selected window (can't use GetForegroundWindow or GetFocus only, because when user clicks on virtual keyboard it gets focused and I get handle of keyboard window itself)? This is very urgent to me so any advice would be greatly appreciated. Thanks in advance.

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• BDD / TDD with JSpec - Removing code duplication

  - by Chetan

  How do I refactor to remove the code duplication in this spec: describe 'TestPlugins' describe '.MovieScanner(document)' before_each MoviePage_loggedIn = fixture("movie_logged_in.html") // Get logged-in movie page MoviePage_notloggedIn = fixture("movie_not_logged_in.html") // Get non logged-in movie page scanner = new MovieScanner() // Get movie scanner end it 'should scan logged-in movie page for movie data' doc = MoviePage_loggedIn // Get document to scan // Unit Tests // ------------------------------------------------------------ // Test movie scanner's functions scanner.getMovieTitle(doc).should.eql "The Jacket" scanner.getMovieYear(doc).should.eql "2005" // Test movie scanner's main scan function scannedData = scanner.scan(doc) scannedData.title.should.eql "The Jacket" scannedData.year.should.eql "2005" end it 'should scan non logged-in movie page for movie data' doc = MoviePage_notloggedIn // Get document to scan // Unit Tests // ------------------------------------------------------------ // Test movie scanner's functions scanner.getMovieTitle(doc).should.eql "The Jacket" scanner.getMovieYear(doc).should.eql "2005" // Test movie scanner's main scan function scannedData = scanner.scan(doc) scannedData.title.should.eql "The Jacket" scannedData.year.should.eql "2005" end end end

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• Trying to understand the usage of class_eval

  - by eMxyzptlk

  Hello everyone, I'm using the rails-settings gem, and I'm trying to understand how you add functions to ActiveRecord classes (I'm building my own library for card games), and I noticed that this gem uses one of the Meta-programming techniques to add the function to the ActiveRecord::Base class (I'm far from Meta-programming master in ruby, but I'm trying to learn it) module RailsSettings class Railtie < Rails::Railtie initializer 'rails_settings.initialize', :after => :after_initialize do Railtie.extend_active_record end end class Railtie def self.extend_active_record ActiveRecord::Base.class_eval do def self.has_settings class_eval do def settings RailsSettings::ScopedSettings.for_thing(self) end scope :with_settings, :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :select => "DISTINCT #{self.table_name}.*" scope :with_settings_for, lambda { |var| { :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'" } } scope :without_settings, :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :conditions => 'settings.id IS NULL' scope :without_settings_for, lambda { |var| { :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'", :conditions => 'settings.id IS NULL' } } end end end end end end What I don't understand is why he uses class_eval on ActiveRecord::Base, wasn't it easier if he just open the ActiveRecord::Base class and define the functions? Specially that there's nothing dynamic in the block (What I mean by dynamic is when you do class_eval or instance_eval on a string containing variables) something like this: module ActiveRecord class Base def self.has_settings class_eval do def settings RailsSettings::ScopedSettings.for_thing(self) end scope :with_settings, :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :select => "DISTINCT #{self.table_name}.*" scope :with_settings_for, lambda { |var| { :joins => "JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'" } } scope :without_settings, :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}')", :conditions => 'settings.id IS NULL' scope :without_settings_for, lambda { |var| { :joins => "LEFT JOIN settings ON (settings.thing_id = #{self.table_name}.#{self.primary_key} AND settings.thing_type = '#{self.base_class.name}') AND settings.var = '#{var}'", :conditions => 'settings.id IS NULL' } } end end end end I understand the second class_eval (before the def settings) is to define functions on the fly on every class that 'has_settings' right ? Same question here, I think he could use "def self.settings" instead of "class_eval.... def settings", no ?

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• Comparison between pointer and integer (cocoa)

  - by Cal S

  Hi, I'm just learning cocoa (coming from C#) but I'm getting a strange error for something that seems really simple... (charsSinceLastUpdate=36) #import "CSMainController.h" @implementation CSMainController //global vars int *charsSinceLastUpdate = 0; NSString *myString = @"Hello world"; // - (void)applicationDidFinishLaunching:(NSNotification *)aNotification { ... } //other functions - (void)textDidChange:(NSNotification *)aNotification { NSLog(@"charsSinceLastUpdate=%i",charsSinceLastUpdate); if (charsSinceLastUpdate>=36) { // <- THIS line returns the error: Comparison between pointer and integer charsSinceLastUpdate=0; [statusText setStringValue:@"Will save now!"]; } else { charsSinceLastUpdate++; [statusText setStringValue:@"Not saving"]; } } //my functions - (void)showNetworkErrorAlert:(BOOL)showContinueWithoutSavingOption { ... } // @end Any help would be appreciated, thanks!

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