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  • Improve a regex statement in order to be as efficient as it can be

    - by user551625
    I have a PHP program that, at some point, needs to analyze a big amount of HTML+javascript text to parse info. All I want to parse needs to be in two parts. Seperate all "HTML goups" to parse Parse each HTML group to get the needed information. In the 1st parse it needs to find: <div id="myHome" And start capturing after that tag. Then stop capturing before <span id="nReaders" And capture the number that comes after this tag and stop. In the 2nd parse use the capture nº 1 (0 has the whole thing and 2 has the number) from the parse made before and then find . I already have code to do that and it works. Is there a way to improve this, make it easier for the machine to parse? preg_match_all('%<div id="myHome"[^>]>(.*?)<span id="nReaders[^>]>([0-9]+)<"%msi', $data, $results, PREG_SET_ORDER); foreach($results AS $result){ preg_match_all('%<div class="myplacement".*?[.]php[?]((?:next|before))=([0-9]+).*?<tbody.*?<td[^>]>.*?[0-9]+"%msi', $result[1], $mydata, PREG_SET_ORDER); //takes care of the data and finish the program Note: I need this for a freeware program so it must be as general as possible and, if possible, not use php extensions ADD: I ommitted some parts here because I didn't expect for answers like those. There is also a need to parse text inside one of the tags that is in the document. It may be the 6th 7th or 8th tag but I know it is after a certain tag. The parser I've checked (thx profitphp) does work to find the script tag. What now? There are more than 1 tag with the same class. I want them all. But I want only with also one of a list of classes..... Where can I find instructions and demos and limitations of DOM parsers (like the one in http://simplehtmldom.sourceforge.net/)? I need something that will work on, at least, a big amount of free servers.

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  • Cast base class object to derived class

    - by Popgalop
    Lets say I have two classes, animal and dog like this. class Animal { }; class Dog : public Animal { }; And I have an animal object named animal, that is actually an instance of dog, how would I cast it back to dog? This may seem like an odd question, but I need it because I am writing a programming language interpreter, and on the stack everything is stored as a BaseObject, and all the other datatypes extend BaseObject. How would I cast the base object from the stack, to a specific data type? I have tried something like this Dog dog = static_cast<Dog>(animal); But it gives me an error 1>------ Build started: Project: StackTests, Configuration: Debug Win32 ------ 1> StackTests.cpp 1>c:\users\owner\documents\visual studio 2012\projects\stacktests\stacktests\stacktests.cpp(173): error C2440: 'static_cast' : cannot convert from 'Animal' to 'Dog' 1> No constructor could take the source type, or constructor overload resolution was ambiguous 1>c:\users\owner\documents\visual studio 2012\projects\stacktests\stacktests\stacktests.cpp(173): error C2512: 'Dog' : no appropriate default constructor available ========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

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  • A public struct inside a class

    - by Koning Baard
    I am new to C++, and let's say I have two classes: Creature and Human: /* creature.h */ class Creature { private: public: struct emotion { /* All emotions are percentages */ char joy; char trust; char fear; char surprise; char sadness; char disgust; char anger; char anticipation; char love; }; }; /* human.h */ class Human : Creature { }; And I have this in my main function in main.cpp: Human foo; My question is: how can I set foo's emotions? I tried this: foo->emotion.fear = 5; But GCC gives me this compile error: error: base operand of '-' has non-pointer type 'Human' This: foo.emotion.fear = 5; Gives: error: 'struct Creature::emotion' is inaccessible error: within this context error: invalid use of 'struct Creature::emotion' Can anyone help me? Thanks P.S. No I did not forget the #includes

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  • C++ variable to const expression

    - by user1344784
    template <typename Real> class A{ }; template <typename Real> class B{ }; //... a few dozen more similar template classes class Computer{ public slots: void setFrom(int from){ from_ = from; } void setTo(int to){ to_ = to; } private: template <int F, int T> void compute(){ using boost::fusion::vector; using boost::fusion::at_c; vector<A<float>, B<float>, ...> v; at_c<from_>(v).operator()(at_c<to_>(v)); //error; needs to be const-expression. }; This question isn't about Qt, but there is a line of Qt code in my example. The setFrom() and setTo() are functions that are called based on user selection via the GUI widget. The root of my problem is that 'from' and 'to' are variables. In my compute member function I need to pick a type (A, B, etc.) based on the values of 'from' and 'to'. The only way I know how to do what I need to do is to use switch statements, but that's extremely tedious in my case and I would like to avoid. Is there anyway to convert the error line to a constant-expression?

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  • A generic C++ library that provides QtConcurrent functionality?

    - by Lucas
    QtConcurrent is awesome. I'll let the Qt docs speak for themselves: QtConcurrent includes functional programming style APIs for parallel list processing, including a MapReduce and FilterReduce implementation for shared-memory (non-distributed) systems, and classes for managing asynchronous computations in GUI applications. For instance, you give QtConcurrent::map() an iterable sequence and a function that accepts items of the type stored in the sequence, and that function is applied to all the items in the collection. This is done in a multi-threaded manner, with a thread pool equal to the number of logical CPU's on the system. There are plenty of other function in QtConcurrent, like filter(), filteredReduced() etc. The standard CompSci map/reduce functions and the like. I'm totally in love with this, but I'm starting work on an OSS project that will not be using the Qt framework. It's a library, and I don't want to force others to depend on such a large framework like Qt. I'm trying to keep external dependencies to a minimum (it's the decent thing to do). I'm looking for a generic C++ framework that provides me with the same/similar high-level primitives that QtConcurrent does. AFAIK boost has nothing like this (I may be wrong though). boost::thread is very low-level compared to what I'm looking for. I know C# has something very similar with their Parallel Extensions so I know this isn't a Qt-only idea. What do you suggest I use?

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  • Doxygen including methods twice doc files

    - by Maarek
    I'm having this issue where doxygen is adding the method twice in the documentation file. Is there a setting that stops auto-generation of documentation for methods within the .m file. For example in the documentation I'll see something like whats below where the first definition of + (Status *)registerUser is from the header XXXXXX.h file where the second is from XXXXXX.m. Header documentation : /** @brief Test Yada Yada @return <#(description)#> */ + (Status *)registerUser; Output: + (Status *) registerUser Test Yada Yada. Returns: <#(description)#> + (Status *) registerUser <#(brief description)#> <#(comprehensive description)#> registerUser Returns: <#(description)#> Definition at line 24 of file XXXXXX.m. Here are the build related configuration options. I've tried playing with them. EXTRACT_ALL with YES and NO... Hiding uncodumented Members and Classes. #--------------------------------------------------------------------------- # Build related configuration options #--------------------------------------------------------------------------- EXTRACT_ALL = NO EXTRACT_PRIVATE = NO EXTRACT_STATIC = NO EXTRACT_LOCAL_CLASSES = YES EXTRACT_LOCAL_METHODS = NO EXTRACT_ANON_NSPACES = NO HIDE_UNDOC_MEMBERS = YES HIDE_UNDOC_CLASSES = YES HIDE_FRIEND_COMPOUNDS = NO HIDE_IN_BODY_DOCS = NO INTERNAL_DOCS = NO CASE_SENSE_NAMES = NO HIDE_SCOPE_NAMES = NO SHOW_INCLUDE_FILES = YES FORCE_LOCAL_INCLUDES = NO INLINE_INFO = YES SORT_MEMBER_DOCS = YES SORT_BRIEF_DOCS = NO SORT_MEMBERS_CTORS_1ST = NO SORT_GROUP_NAMES = NO SORT_BY_SCOPE_NAME = NO

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  • How should I handle header files in a bundle?

    - by ldiqual
    I want to develop a program that relies on plugins (here: loadable bundles) to work. Multiple plugins are asked to use the same AFNetworking ressource to make network requests. However, I don't know where to put AFNetworking and CustomPluginProtocol headers. Here is how my program structure looks like for now: MyApp.xcodeproj - AFNetworking - Header.h - Plugins - Plugin1.xcodeproj - PrincipalClass.m - Plugin2.xcodeproj - PrincipalClass.m - Classes - CustomPluginProtocol.h - MainClass.m Of course, every principalClass from PluginN complies to the CustomPluginProtocol. Do the headers have to be copied in each bundle ? Can I just include the main program AFNetworking headers from my plugins ? If so (and that's what I do for now), I don't have any completion. How can I get it ? Edit Ok, so maybe I wasn't clear in my question. I want my plugins to use sources from the main application, let's say CommonClass.m and CommonClass.h. Do the plugins need CommonClass.h in their bundle, and if not, how do I enable completion when I'm in the plugin scope ?

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  • Grails one-to-many mapping with joinTable

    - by intargc
    I have two domain-classes. One is a "Partner" the other is a "Customer". A customer can be a part of a Partner and a Partner can have 1 or more Customers: class Customer { Integer id String name static hasOne = [partner:Partner] static mapping = { partner joinTable:[name:'PartnerMap',column:'partner_id',key:'customer_id'] } } class Partner { Integer id static hasMany = [customers:Customer] static mapping = { customers joinTable:[name:'PartnerMap',column:'customer_id',key:'partner_id'] } } However, whenever I try to see if a customer is a part of a partner, like this: def customers = Customer.list() customers.each { if (it.partner) { println "Partner!" } } I get the following error: org.springframework.dao.InvalidDataAccessResourceUsageException: could not execute query; SQL [select this_.customer_id as customer1_162_0_, this_.company as company162_0_, this_.display_name as display3_162_0_, this_.parent_customer_id as parent4_162_0_, this_.partner_id as partner5_162_0_, this_.server_id as server6_162_0_, this_.status as status162_0_, this_.vertical_market as vertical8_162_0_ from Customer this_]; nested exception is org.hibernate.exception.SQLGrammarException: could not execute query It looks as if Grails is thinking partner_id is a part of the Customer query, and it's not... It is in the PartnerMap table, which is supposed to find the customer_id, then get the Partner from the corresponding partner_id. Anyone have any clue what I'm doing wrong? Edit: I forgot to mention I'm doing this with legacy database tables. So I have a Partner, Customer and PartnerMap table. PartnerMap has simply a customer_id and partner_id field.

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  • Why strings behave like ValueType

    - by AJP
    I was perplexed after executing this piece of code, where strings seems to behave as if they are value types. I am wondering whether the assignment operator is operating on values like equality operator for strings. Here is the piece of code I did to test this behavior. using System; namespace RefTypeDelimma { class Program { static void Main(string[] args) { string a1, a2; a1 = "ABC"; a2 = a1; //This should assign a1 reference to a2 a2 = "XYZ"; //I expect this should change the a1 value to "XYZ" Console.WriteLine("a1:" + a1 + ", a2:" + a2);//Outputs a1:ABC, a2:XYZ //Expected: a1:XYZ, a2:XYZ (as string being a ref type) Proc(a2); //Altering values of ref types inside a procedure //should reflect in the variable thats being passed into Console.WriteLine("a1: " + a1 + ", a2: " + a2); //Outputs a1:ABC, a2:XYZ //Expected: a1:NEW_VAL, a2:NEW_VAL (as string being a ref type) } static void Proc(string Val) { Val = "NEW_VAL"; } } } In the above code if I use a custom classes instead of strings, I am getting the expected behavior. I doubt is this something to do with the string immutability? welcoming expert views on this.

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  • Is it acceptable to wrap PHP library functions solely to change the names?

    - by Carson Myers
    I'm going to be starting a fairly large PHP application this summer, on which I'll be the sole developer (so I don't have any coding conventions to conform to aside from my own). PHP 5.3 is a decent language IMO, despite the stupid namespace token. But one thing that has always bothered me about it is the standard library and its lack of a naming convention. So I'm curious, would it be seriously bad practice to wrap some of the most common standard library functions in my own functions/classes to make the names a little better? I suppose it could also add or modify some functionality in some cases, although at the moment I don't have any examples (I figure I will find ways to make them OO or make them work a little differently while I am working). If you saw a PHP developer do this, would you think "Man, this is one shoddy developer?" Additionally, I don't know much (or anything) about if/how PHP is optimized, and I know that usually PHP performace doesn't matter. But would doing something like this have a noticeable impact on the performance of my application?

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  • avoiding code duplication in Rails 3 models

    - by Dustin Frazier
    I'm working on a Rails 3.1 application where there are a number of different enum-like models that are stored in the database. There is a lot of identical code in these models, as well as in the associated controllers and views. I've solved the code duplication for the controllers and views via a shared parent controller class and the new view/layout inheritance that's part of Rails 3. Now I'm trying to solve the code duplication in the models, and I'm stuck. An example of one of my enum models is as follows: class Format < ActiveRecord::Base has_and_belongs_to_many :videos attr_accessible :name validates :name, presence: true, length: { maximum: 20 } before_destroy :verify_no_linked_videos def verify_no_linked_videos unless self.videos.empty? self.errors[:base] << "Couldn't delete format with associated videos." raise ActiveRecord::RecordInvalid.new self end end end I have four or five other classes with nearly identical code (the association declaration being the only difference). I've tried creating a module with the shared code that they all include (which seems like the Ruby Way), but much of the duplicate code relies on ActiveRecord, so the methods I'm trying to use in the module (validate, attr_accessible, etc.) aren't available. I know about ActiveModel, but that doesn't get me all the way there. I've also tried creating a common, non-persistent parent class that subclasses ActiveRecord::Base, but all of the code I've seen to accomplish this assumes that you won't have subclasses of your non-persistent class that do persist. Any suggestions for how best to avoid duplicating these identical lines of code across many different enum models?

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  • Proper structure for dependency injection (using Guice)

    - by David B.
    I would like some suggestions and feedback on the best way to structure dependency injection for a system with the structure described below. I'm using Guice and thus would prefer solutions centered around it's annotation-based declarations, not XML-heavy Spring-style configuration. Consider a set of similar objects, Ball, Box, and Tube, each dependent on a Logger, supplied via the constructor. (This might not be important, but all four classes happen to be singletons --- of the application, not Gang-of-Four, variety.) A ToyChest class is responsible for creating and managing the three shape objects. ToyChest itself is not dependent on Logger, aside from creating the shape objects which are. The ToyChest class is instantiated as an application singleton in a Main class. I'm confused about the best way to construct the shapes in ToyChest. I either (1) need access to a Guice Injector instance already attached to a Module binding Logger to an implementation or (2) need to create a new Injector attached to the right Module. (1) is accomplished by adding an @Inject Injector injectorfield to ToyChest, but this feels weird because ToyChest doesn't actually have any direct dependencies --- only those of the children it instantiates. For (2), I'm not sure how to pass in the appropriate Module. Am I on the right track? Is there a better way to structure this? The answers to this question mention passing in a Provider instead of using the Injector directly, but I'm not sure how that is supposed to work. EDIT: Perhaps a more simple question is: when using Guice, where is the proper place to construct the shapes objects? ToyChest will do some configuration with them, but I suppose they could be constructed elsewhere. ToyChest (as the container managing them), and not Main, just seems to me like the appropriate place to construct them.

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  • Omit Properties from WebControl Serialization

    - by Laramie
    I have to serialize several objects inheriting from WebControl for database storage. These include several unecessary (to me) properties that I would prefer to omit from serialization. For example BackColor, BorderColor, etc. Here is an example of an XML serialization of one of my controls inheriting from WebControl. <Control xsi:type="SerializePanel"> <ID>grCont</ID> <Controls /> <BackColor /> <BorderColor /> <BorderWidth /> <CssClass>grActVid bwText</CssClass> <ForeColor /> <Height /> <Width /> ... </Control> I have been trying to create a common base class for my controls that inherits from WebControl and uses the "xxxSpecified" trick to selectively choose not to serialize certain properties. For example to ignore an empty BorderColor property, I'd expect [XmlIgnore] public bool BorderColorSpecified() { return !base.BorderColor.IsEmpty; } to work, but it's never called during serialization. I've also tried it in the class to be serialized as well as the base class. Since the classes themselves might change, I'd prefer not to have to create a custom serializer. Any ideas?

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  • What is an interface in C (COM) is it the same as a interface in C#

    - by numerical25
    Ok, I know what a interface is, but since I got into C and working with COM objects, it seems an interface in COM is a little different from the interface I know of. So what I am trying to do is bridge the gaps here cause since I been learning C, alot of things have been sounding very familiar to me but are not exactly what they seem. The interface I know of are like contracts. They are objects that have only method declarations, with no body. All classes that implement an interface must include the methods of the interface. The interface I hear about in COM seems to be just pointers. They can not retrieve objects directly but only can retrieve objects through the means of a method. Is this what a COM Interface is ?? If so, then why did they give them the same names if they are completely different. Also I just wanted to add that headers in C++ kind of remind me of the C# Interfaces. Not sure if their are any relations. But anyways, I am just trying to clear that up.

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  • C++, array declaration, templates, linker error

    - by justik
    There is a linker error in my SW. I am using the following structure based on h, hpp, cpp files. Some classes are templatized, some not, some have function templates. Declaration: test.h #ifndef TEST_H #define TEST_H class Test { public: template <typename T> void foo1(); void foo2 () }; #include "test.hpp" #endif Definition: test.hpp #ifndef TEST_HPP #define TEST_HPP template <typename T> void Test::foo1() {} inline void Test::foo2() {} //or in cpp file #endif CPP file: test.cpp #include "test.h" void Test::foo2() {} //or in hpp file as inline I have the following problem. The variable vars[] is declared in my h file test.h #ifndef TEST_H #define TEST_H char *vars[] = { "first", "second"...}; class Test { public: void foo(); }; #include "test.hpp" #endif and used as a local variable inside foo() method defined in hpp file as inline. test.hpp #ifndef TEST_HPP #define TEST_HPP inline void Test::foo() { char *var = vars[0]; //A Linker Error } #endif However, the following linker error occurs: Error 745 error LNK2005: "char * * vars" (?vars@@3PAPADA) already defined in test2.obj How and where to declare vars[] to avoid linker errors? After including #include "test.hpp" it is late to declare it...

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  • Speed comparison - Template specialization vs. Virtual Function vs. If-Statement

    - by Person
    Just to get it out of the way... Premature optimization is the root of all evil Make use of OOP etc. I understand. Just looking for some advice regarding the speed of certain operations that I can store in my grey matter for future reference. Say you have an Animation class. An animation can be looped (plays over and over) or not looped (plays once), it may have unique frame times or not, etc. Let's say there are 3 of these "either or" attributes. Note that any method of the Animation class will at most check for one of these (i.e. this isn't a case of a giant branch of if-elseif). Here are some options. 1) Give it boolean members for the attributes given above, and use an if statement to check against them when playing the animation to perform the appropriate action. Problem: Conditional checked every single time the animation is played. 2) Make a base animation class, and derive other animations classes such as LoopedAnimation and AnimationUniqueFrames, etc. Problem: Vtable check upon every call to play the animation given that you have something like a vector<Animation>. Also, making a separate class for all of the possible combinations seems code bloaty. 3) Use template specialization, and specialize those functions that depend on those attributes. Like template<bool looped, bool uniqueFrameTimes> class Animation. Problem: The problem with this is that you couldn't just have a vector<Animation> for something's animations. Could also be bloaty. I'm wondering what kind of speed each of these options offer? I'm particularly interested in the 1st and 2nd option because the 3rd doesn't allow one to iterate through a general container of Animations. In short, what is faster - a vtable fetch or a conditional?

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  • JSP displaying source code instead of executing

    - by DJStroky
    I'm new to jsp and have ran into some trouble. Initially, the jsp file and associated java classes were built and tested fine on a test Tomcat server. Now, they've been transitioned to another server of what I believe is the same setup (except it's linux now instead of windows). But when the jsp page is accessed the source code is displayed instead of the jsp actually executing. I've googled for a while but received no success. I had thought that this page might solve the problem since there was no reference to the jsp file I was using or even the following snippets in my web.xml file in the WEB-INF folder: <servlet> <servlet-name>jsp</servlet-name> <servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class> <init-param> <param-name>logVerbosityLevel</param-name> <param-value>WARNING</param-value> </init-param> <load-on-startup>3</load-on-startup> </servlet> <servlet-mapping> <servlet-name>jsp</servlet-name> <url-pattern>*.jsp</url-pattern> </servlet-mapping> I tried inserting these lines and restarting Tomcat, but no success. Any ideas?

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  • JDO architecture: One to many relationship and cascading deleting

    - by user361897
    I’m new to object oriented database designs and I’m trying to understand how I should be structuring my classes in JDO for google app engine, particularly one to many relationships. Let’s say I’m building a structure for a department store where there are many departments, and each department has many products. So I’d want to have a class called Department, with a variable that is a list of a Product class. @PersistenceCapable public class Department { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private String deptID; @Persistent private String departmentName; @Persistent private List<Product>; } @PersistenceCapable public class Product { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) private String productID; @Persistent private String productName; } But one Product can be in more than one Department (like a battery could be in electronics and household supplies). So the next question is, how do I not duplicate data in the OOD world and have only one copy of product data in numerous departments? And the next question is, let’s say I delete out a particular product, how do each of the departments know it was deleted?

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  • CSS - Why is this invisible margin being applied to my <a> tag css-button?

    - by Kenny Bones
    I was having trouble with two types of buttons. It was a form button and a css button basically. And I was advised that the css button whould use display:inline-block; This made the whole a href tag actually look like a button. But this invisible margin seems to be screwing up something. I tried separating them into separate css classes, but oddly, applying a real margin to the css button gives an additional margin as well. What's causing this? You can easily see it here (low graphics): www.matkalenderen.no Basically, code looks like this: <input type="submit" value="Logg inn" class="button_blue" alt="ready to login"> <a class="button_css_red" href="access.php">Glemt passord</a> CSS .button_red, .button_blue, .button_css_red, .button_css_blue { background-image:url("../img/sprite_buttons.png"); background-repeat:no-repeat; border: none; color:#FFFFFF; display:inline-block; display:inline-block; font-size:12px; height:27px; width:98px; } .button_css_red, .button_css_blue { margin-top:20px; }

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  • Oddities in Linq-to-SQL generated code related to property change/changing events

    - by Lasse V. Karlsen
    I'm working on creating my own Linq-to-Sql generated classes in order to learn the concepts behind it all. I have some questions, if anyone knows the answer to one or more of these I'd be much obliged. The code below, and thus the questions, are from looking at code generated by creating a .DBML file in the Visual Studio 2010 designer, and inspecting the .Designer.cs file afterwards. 1. Why is INotifyPropertyChanging not passing the property name The event raising method is defined like this: protected virtual void SendPropertyChanging() Why isn't the name of the property that is changing passed to the event here? It is defined to be part of the EventArgs descendant that is passed to the event handler, but the method only passes an empty such value to it. 2. Why are the EntitySet<X> attach/detach methods not raising property changed? For an EntitySet<X> reference, the following two methods are generated: private void attach_EmailAddress1s(EmailAddress1 entity) { this.SendPropertyChanging(); entity.Person1 = this; } private void detach_EmailAddress1s(EmailAddress1 entity) { this.SendPropertyChanging(); entity.Person1 = null; } Why isn't SendPropertyChanged also called here? I'm sure I have more questions later, but for now these will suffice :)

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  • Refer to a Spark view component in code

    - by David
    I'm building a mobile AIR app using Flash Builder 4.5. The initial view in my views package is TestHomeView.mxml. I want to refer to it in one of my .as classes elsewhere in the app, and I'm not sure how to do that. Theoretically I should be able to add an "id" attribute to TestHomeView.mxml, but FB gives me an error: "id is not allowed on the root tag of a component". The root tag is s:view. The reason I need to do this is that within another class I make various calculations and then need to pass an array of values to a component in my view class. So in SomeOtherActionScriptClass.as I first assemble the array, myArray, and then in that class I want to do this: myViewComponent.viewArray = myArray; If I'm going to do that, I also need to import the view class into the .as class, which strikes me as weird. So is there a simple way to do what I want, or do I have to dispatch a custom event which contains the array, and listen for it in the view class? Thanks.

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  • Immutability and shared references - how to reconcile?

    - by davetron5000
    Consider this simplified application domain: Criminal Investigative database Person is anyone involved in an investigation Report is a bit of info that is part of an investigation A Report references a primary Person (the subject of an investigation) A Report has accomplices who are secondarily related (and could certainly be primary in other investigations or reports These classes have ids that are used to store them in a database, since their info can change over time (e.g. we might find new aliases for a person, or add persons of interest to a report) If these are stored in some sort of database and I wish to use immutable objects, there seems to be an issue regarding state and referencing. Supposing that I change some meta-data about a Person. Since my Person objects immutable, I might have some code like: class Person( val id:UUID, val aliases:List[String], val reports:List[Report]) { def addAlias(name:String) = new Person(id,name :: aliases,reports) } So that my Person with a new alias becomes a new object, also immutable. If a Report refers to that person, but the alias was changed elsewhere in the system, my Report now refers to the "old" person, i.e. the person without the new alias. Similarly, I might have: class Report(val id:UUID, val content:String) { /** Adding more info to our report */ def updateContent(newContent:String) = new Report(id,newContent) } Since these objects don't know who refers to them, it's not clear to me how to let all the "referrers" know that there is a new object available representing the most recent state. This could be done by having all objects "refresh" from a central data store and all operations that create new, updated, objects store to the central data store, but this feels like a cheesy reimplementation of the underlying language's referencing. i.e. it would be more clear to just make these "secondary storable objects" mutable. So, if I add an alias to a Person, all referrers see the new value without doing anything. How is this dealt with when we want to avoid mutability, or is this a case where immutability is not helpful?

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  • Map inheritance from generic class in Linq To SQL

    - by Ksenia Mukhortova
    Hi everyone, I'm trying to map my inheritance hierarchy to DB using Linq to SQL: Inheritance is like this, classes are POCO, without any LINQ to SQL attributes: public interface IStage { ... } public abstract class SimpleStage<T> : IStage where T : Process { ... } public class ConcreteStage : SimpleStage<ConcreteProcess> { ... } Here is the mapping: <Database Name="NNN" xmlns="http://schemas.microsoft.com/linqtosql/mapping/2007"> <Table Name="dbo.Stage" Member="Stage"> <Type Name="BusinessLogic.Domain.IStage"> <Column Name="ID" Member="ID" DbType="Int NOT NULL IDENTITY" IsPrimaryKey="true" IsDbGenerated="true" AutoSync="OnInsert" /> <Column Name="StageType" Member="StageType" IsDiscriminator="true" /> <Type Name="BusinessLogic.Domain.SimpleStage" IsInheritanceDefault="true"> <Type Name="BusinessLogic.Domain.ConcreteStage" IsInheritanceDefault="true" InheritanceCode="1"/> </Type> </Type> </Table> </Database> In the runtime I get error: System.InvalidOperationException was unhandled Message="Mapping Problem: Cannot find runtime type for type mapping 'BusinessLogic.Domain.SimpleStage'." Neither specifying SimpleStage, nor SimpleStage<T> in mapping file helps - runtime keeps producing different types of errors. DC is created like this: StreamReader sr = new StreamReader(@"MappingFile.map"); XmlMappingSource mapping = XmlMappingSource.FromStream(sr.BaseStream); DataContext dc = new DataContext(@"connection string", mapping); If Linq to SQL doesn't support this, could you, please, advise some other ORM, which does. Thanks in advance, Regards! Ksenia

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  • What would be a better implementation of shared variable among subclass

    - by Churk
    So currently I have a spring unit testing application. And it requires me to get a session cookie from a foreign authentication source. Problem what that is, this authentication process is fairly expensive and time consuming, and I am trying to create a structure where I am authenticate once, by any subclass, and any subsequent subclass is created, it will reuse this session cookie without hitting the authentication process again. My problem right now is, the static cookie is null each time another subclass is created. And I been reading that using static as a global variable is a bad idea, but I couldn't think of another way to do this because of Spring framework setting things during run time and how I would set the cookie so that all other classes can use it. Another piece of information. The variable is being use, but is change able during run time. It is not a single user being signed in and used across the board. But more like a Sub1 would call login, and we have a cookie. Then multiple test will be using that login until SubX will come in and say, I am using different credential, so I need to login as something else. And repeats. Here is a outline of my code: public class Parent implements InitializingBean { protected static String BASE_URL; public static Cookie cookie; ... All default InitializingBean methods ... afterPropertiesSet() { cookie = // login process returns a cookie } } public class Sub1 extends Parent { @resource public String baseURL; @PostConstruct public void init() { // set parents with my baseURL; BASE_URL = baseURL; } public void doSomething() { // Do something with cookie, because it should have been set by parent class } } public class Sub2 extends Parent { @resource public String baseURL; @PostConstruct public void init() { // set parents with my baseURL; BASE_URL = baseURL; } public void doSomethingElse() { // Do something with cookie, because it should have been set by parent class } }

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  • Reusable non generic method for generic methods

    - by Jehof
    I have the following base interface public interface IHandler{ void Handle(IMessage message); } and an generic interface inheriting the base interface public interface IHandler<TMessage> : IHandler where TMessage : IMessage{ void Handle(TMessage message); } My classes can implement the interface IHandler<TMessage> mutiple times. IMessage is an base interface for messages and isn´t relevant here. Currently i´m implementing the interfaces as follows. public class ExampleHandler : IHandler<ExampleMessage>, IHandler<OtherExampleMessag>{ void IHandler.Handle(IMessage message){ ExampleMessage example = message as ExampleMessage; if (example != null) { Handle(example); } else { OtherExampleMessage otherExample = message as OtherExampleMessage; if (otherExample != null) { Handle(otherExample); } } public void Handle(ExampleMessage) { //handle message; } public void Handle(OtherExampleMessage) { //handle message; } } What bothers me is the way i have to implement the Handle(IMessage) method, cause in my opinion its many redundant code, and i have to extend the method each time when i implement a new IHandler<TMessage> interface on my class. What i´m looking for is a more generic way to implement the Handle(IMessage) method (maybe in a base class for Handlers), but i´m currently stuck how to do that.

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