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  • Rails database relationships

    - by Danny McClelland
    Hi Everyone, I have three models that I want to interact with each other. Kase, Person and and Company. I have (I think) setup the relationships correctly: class Kase < ActiveRecord::Base #HAS ONE COMPANY has_one :company #HAS MANY PERSONS has_many :persons class Person < ActiveRecord::Base belongs_to :company class Company < ActiveRecord::Base has_many :persons def to_s; companyname; end I have put the select field on the create new Kase view, and the create new Person view as follows: <li>Company<span><%= f.select :company_id, Company.all %> </span></li> All of the above successfully shows a drop down menu dynamically populated with the company names within Companies. What I am trying to do is display the contact of the Company record within the kase and person show.html.erb. For example, If I have a company called "Acme, Inc." and create a new Kase called "Random Case" and choose within the create new case page "Acme, Inc." from the companies drop down menu. I would then want to display "Acme, Inc" along with "Acme, Inc. Mobile" etc. on the "Random Case" show.html.erb. I hope this makes sense to somebody! Thanks, Danny

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  • NHibernate / Fluent - Mapping multiple objects to single lookup table

    - by Al
    Hi all I am struggling a little in getting my mapping right. What I have is a single self joined table of look up values of certain types. Each lookup can have a parent, which can be of a different type. For simplicities sake lets take the Country and State example. So the lookup table would look like this: Lookups Id Key Value LookupType ParentId - self joining to Id base class public class Lookup : BaseEntity { public Lookup() {} public Lookup(string key, string value) { Key = key; Value = value; } public virtual Lookup Parent { get; set; } [DomainSignature] [NotNullNotEmpty] public virtual LookupType LookupType { get; set; } [NotNullNotEmpty] public virtual string Key { get; set; } [NotNullNotEmpty] public virtual string Value { get; set; } } The lookup map public class LookupMap : IAutoMappingOverride<DBLookup> { public void Override(AutoMapping<Lookup> map) { map.Table("Lookups"); map.References(x => x.Parent, "ParentId").ForeignKey("Id"); map.DiscriminateSubClassesOnColumn<string>("LookupType").CustomType(typeof(LookupType)); } } BASE SubClass map for subclasses public class BaseLookupMap : SubclassMap where T : DBLookup { protected BaseLookupMap() { } protected BaseLookupMap(LookupType lookupType) { DiscriminatorValue(lookupType); Table("Lookups"); } } Example subclass map public class StateMap : BaseLookupMap<State> { protected StateMap() : base(LookupType.State) { } } Now I've almost got my mappings set, however the mapping is still expecting a table-per-class setup, so is expecting a 'State' table to exist with a reference to the states Id in the Lookup table. I hope this makes sense. This doesn't seem like an uncommon approach when wanting to keep lookup-type values configurable. Thanks in advance. Al

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  • CONSOLE appender was turned off. But JBoss still writes some traces to STDOUT

    - by Vladimir Bezugliy
    CONSOLE appender was turned off. But JBoss still writes some traces to STDOUT during startup. Why? C:\as\jboss-5.1.0.GA\bin>start.cmd Calling C:\as\jboss-5.1.0.GA\bin\run.conf.bat =============================================================================== JBoss Bootstrap Environment JBOSS_HOME: C:\as\jboss-5.1.0.GA JAVA: C:\as\jdk1.6.0_07\bin\java JAVA_OPTS: -Dprogram.name=run.bat -Xms512M -Xmx758M -XX:MaxPermSize=256M -server CLASSPATH: C:\as\jboss-5.1.0.GA\bin\run.jar =============================================================================== 13:11:25,080 INFO [ServerImpl] Starting JBoss (Microcontainer)... 13:11:25,080 INFO [ServerImpl] Release ID: JBoss [The Oracle] 5.1.0.GA (build: SVNTag=JBoss_5_1_0_GA date=200905221053) 13:11:25,080 INFO [ServerImpl] Bootstrap URL: null 13:11:25,080 INFO [ServerImpl] Home Dir: C:\as\jboss-5.1.0.GA 13:11:25,080 INFO [ServerImpl] Home URL: file:/C:/as/jboss-5.1.0.GA/ 13:11:25,080 INFO [ServerImpl] Library URL: file:/C:/as/jboss-5.1.0.GA/lib/ 13:11:25,080 INFO [ServerImpl] Patch URL: null 13:11:25,080 INFO [ServerImpl] Common Base URL: file:/C:/as/jboss-5.1.0.GA/common/ 13:11:25,080 INFO [ServerImpl] Common Library URL: file:/C:/as/jboss-5.1.0.GA/common/lib/ 13:11:25,080 INFO [ServerImpl] Server Name: web 13:11:25,080 INFO [ServerImpl] Server Base Dir: C:\as\jboss-5.1.0.GA\server 13:11:25,080 INFO [ServerImpl] Server Base URL: file:/C:/as/jboss-5.1.0.GA/server/ 13:11:25,080 INFO [ServerImpl] Server Config URL: file:/C:/as/jboss-5.1.0.GA/server/web/conf/ 13:11:25,080 INFO [ServerImpl] Server Home Dir: C:\as\jboss-5.1.0.GA\server\web 13:11:25,080 INFO [ServerImpl] Server Home URL: file:/C:/as/jboss-5.1.0.GA/server/web/ 13:11:25,080 INFO [ServerImpl] Server Data Dir: C:\as\jboss-5.1.0.GA\server\web\data ...

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  • Yii CGridView and dropdown filter

    - by Dmitriy Gunchenko
    I created dropdown filter, it's display, but don't worked right. As I anderstand trouble in search() method view: $this->widget('zii.widgets.grid.CGridView', array( 'dataProvider'=>$model->search(), 'filter' => $model, 'columns'=>array( array( 'name' => 'client_id', 'filter' => CHtml::listData(Client::model()->findAll(), 'client_id', 'name'), 'value'=>'$data->client->name' ), 'task' ) )); I have to tables, and they relations are shown down model: public function relations() { // NOTE: you may need to adjust the relation name and the related // class name for the relations automatically generated below. return array( 'client' => array(self::BELONGS_TO, 'Client', 'client_id'), ); } public function search() { // Warning: Please modify the following code to remove attributes that // should not be searched. $criteria=new CDbCriteria; $criteria->with = array('client'); $criteria->compare('task_id',$this->task_id); $criteria->compare('client_id',$this->client_id); $criteria->compare('name',$this->client->name); $criteria->compare('task',$this->task,true); $criteria->compare('start_date',$this->start_date,true); $criteria->compare('end_date',$this->end_date,true); $criteria->compare('complete',$this->complete); return new CActiveDataProvider($this, array( 'criteria'=>$criteria, )); }

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  • Keeping updated with the latest technologies.

    - by Prashanth
    I am a software developer and I have been programming since the past six years. I simply love the mental challenge involved in trying to come up with solutions to hard problems, reading up programming literature, blogs by prominent developers and so on. I work on Microsoft platform and I have trouble keeping up with the pace at which various frameworks are rolled out. Remoting,WCF,ASP.NET,ASP.NET MVC, LINQ, WPF, WWF, OSLO, ADO.NET data services, DSL tools etc etc. Even understanding all these frameworks at an abstract level and see how they are all tied up with MS vision itself is a major hurdle. Now when you add other non microsoft technologies, programming languages etc to the equation, I wonder how do people manage? Given that there are only 24 hours in a day, how does one keep himself updated about so many technology changes that happen everyday? My question is , is it even worth doing that? The thing is, I am also interested in other fields such as literature, science. I try my best to at least gain a superficial understanding of what is happening in other fields of my interest and don't want to give up on that :)

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  • Is C++ (one of) the best language to learn at first

    - by AlexV
    C++ is one of the most used programming language in the world since like 25+ years. My first job as programmer was in C++ and I coded in C++ everyday for nearly 4 years. Now I do mostly PHP, but I will forever cherish this C++ background. C++ has helped me understand many "under the hood" features/behaviors/restrictions of many other (and different) programming languages like PHP and Delphi. I'm a full time programmer for 6+ years now and since I have a quite varied programming background I often get questions by "newbies" as where to start to become a "good" programmer. I think C++ is one of the best language to start with because it gives you a real usefull experience that will last and will teach you how things work under the hood. It's not the easier one to learn for a newbie, but in my opinion it's one that will reward in the long term. I would like to know your opinion on this matter to add to my arguments when I guide "newbies". After this introduction, here's my question : Is C++ (one of) the best language to learn at first for you. Since it's subjective, I've marked this question as community wiki. EDIT: This question is not about why Java (or C# or any other language) is better than C++ to start with, it's about what's make C++ a good choice or not a good choice to learn as one of your firsts languages. For example, for me C++ made me understand how the memory works. Now today in many languages everything is managed by the garbadge collector and some people don't even know that. I'm glad I know how it works underneath and I think it can help you to write better code.

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  • Applying the Decorator Pattern to Forms

    - by devoured elysium
    I am trying to apply the Decorator Design Pattern to the following situation: I have 3 different kind of forms: Green, Yellow, Red. Now, each of those forms can have different set of attributes. They can have a minimize box disabled, a maximized box disabled and they can be always on top. I tried to model this the following way: Form <---------------------------------------FormDecorator /\ /\ |---------|-----------| |----------------------|-----------------| GreenForm YellowForm RedForm MinimizeButtonDisabled MaximizedButtonDisabled AlwaysOnTop Here is my GreenForm code: public class GreenForm : Form { public GreenForm() { this.BackColor = Color.GreenYellow; } public override sealed Color BackColor { get { return base.BackColor; } set { base.BackColor = value; } } } FormDecorator: public abstract class FormDecorator : Form { private Form _decoratorForm; protected FormDecorator(Form decoratorForm) { this._decoratorForm = decoratorForm; } } and finally NoMaximizeDecorator: public class NoMaximizeDecorator : FormDecorator { public NoMaximizeDecorator(Form decoratorForm) : base(decoratorForm) { this.MaximizeBox = false; } } So here is the running code: static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(CreateForm()); } static Form CreateForm() { Form form = new GreenForm(); form = new NoMaximizeDecorator(form); form = new NoMinimizeDecorator(form); return form; } The problem is that I get a form that isn't green and that still allows me to maximize it. It is only taking in consideration the NoMinimizeDecorator form. I do comprehend why this happens but I'm having trouble understanding how to make this work with this Pattern. I know probably there are better ways of achieving what I want. I made this example as an attempt to apply the Decorator Pattern to something. Maybe this wasn't the best pattern I could have used(if one, at all) to this kind of scenario. Is there any other pattern more suitable than the Decorator to accomplish this? Am I doing something wrong when trying to implement the Decorator Pattern? Thanks

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  • Saving an active record, in what order are the associated objects saved?

    - by Bryan
    In rails, when saving an active_record object, its associated objects will be saved as well. But has_one and has_many association have different order in saving objects. I have three simplified models: class Team < ActiveRecord::Base has_many :players has_one :coach end class Player < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end class Coach < ActiveRecord::Base belongs_to :team validates_presence_of :team_id end I expected that when team.save is called, team should be saved before its associated coach and players. I use the following code to test these models: t = Team.new team.coach = Coach.new team.save! team.save! returns true. But in another test: t = Team.new team.players << Player.new team.save! team.save! gives the following error: > ActiveRecord::RecordInvalid: > Validation failed: Players is invalid I figured out that team.save! saves objects in the following order: 1) players, 2) team, and 3) coach. This is why I got the error: When a player is saved, team doesn't yet have a id, so validates_presence_of :team_id fails in player. Can someone explain to me why objects are saved in this order? This seems not logical to me.

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  • A quick question on data returned by jquery.ajax() call (EDITED)

    - by recipriversexclusion
    EDIT: The original problem was due a stupid syntax mistake somewhere else, whicj I fixed. I have a new problem though, as described below I have the following jquery.ajax call: $.ajax({ type: 'GET', url: servicesUrl + "/" + ID + "/tasks", dataType: "xml", success : createTaskListTable }); The createTaskListTable function is defined as function createTaskListTable(taskListXml) { $(taskListXml).find("Task").each(function(){ alert("Found task") }); // each task } Problem is: this doesn't work, I get an error saying taskListXml is not defined. JQuery documentation states that the success functions gets passed three arguments, the first of which is the data. How can I pass the data returned by .ajax() to my function with a variable name of my own choosing. My problem now is that I'm getting the XML from a previous ajax call! How is this even possible? That previous function is defined as function convertServiceXmlDataToTable(xml), so they don't use the same variable name. Utterly confused. Is this some caching issue? If so, how can I clear the browser cache to get rid of the earlier XML? Thanks!

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  • How do virtual destructors work?

    - by Prabhu
    Few hours back I was fiddling with a Memory Leak issue and it turned out that I really got some basic stuff about virtual destructors wrong! Let me put explain my class design. class Base { virtual push_elements() {} }; class Derived:public Base { vector<int> x; public: void push_elements(){ for(int i=0;i <5;i++) x.push_back(i); } }; void main() { Base* b = new Derived(); b->push_elements(); delete b; } The bounds checker tool reported a memory leak in the derived class vector. And I figured out that the destructor is not virtual and the derived class destructor is not called. And it surprisingly got fixed when I made the destructor virtual. Isn't the vector deallocated automatically even if the derived class destructor is not called? Is that a quirk in BoundsChecker tool or is my understanding of virtual destructor wrong?

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  • What are some of the core principles needed to master Multi threading using Delphi?

    - by Gary Becks
    I am kind of new to programming in general (about 8 months with on and off in delphi and a little python here and there) and I am in the process of buying some books. I am interested in learning about concurrent programming and building multi threaded apps using Delphi. Whenever I do a search for "multithreading delphi" or "delphi multithreading tutorial" I seem to get conflicting results as some of the stuff is about using certain libraries (omnithread library) and other stuff seems to be more geared towards programmers with more experience. I have studied quite a few books on delphi and for the most part they seem to kind of skim the surface and not really go into depth on the subject. I have a friend who is a programmer (he uses c++) who recommends I learn what is actually going on with the underlying system when using threads as opposed to jumping into how to actually implement them in my programs first. On amazon.com there are quite a few books on concurrent programming but none of them seem to be made with Delphi in mind. Basically I need to know what are the main things I should be focused on learning before jumping into using threads, if I can/should attempt to learn them using books that are not specifically aimed at delphi developers (don't want to confuse myself reading books with a bunch of code examples in other languages right now) and if there are any reliable resources/books on the subject that anyone here could recommend. Thanks in advance.

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  • How do I add code automatically to a derived function in C++

    - by Ian
    I have code that's meant to manage operations on both a networked client and a server, since there is significant overlap between the two. However, there are a few functions here and there that are meant to be exclusively called by the client or server, and accidentally calling a client function on the server (or vice versa) is a significant source of bugs. To reduce these sorts of programming errors, I'm trying to tag functions so that they'll raise a ruckus if they're misused. My current solution is a simple macro at the start of each function that calls an assert if the client or server accesses members they shouldn't. However, this runs into problems when there are multiple derived instances of classes, in that I have to tag the implementation as client or server side in EVERY child class. What I'd like to be able to do is put a tag in the virtual member's signature in the base class, so that I only have to tag it once and not run into errors by forgetting to do it repeatedly. I've considered putting a check in a base class implementation and then referring to it with something like base::functionName, but that runs into the same issue as far as needing to manually add the function call to every implementation. Ideally, I'd be able to have parent versions of the function called automatically like default constructors do. Does anybody know how to achieve something like this in C++? Is there an alternate approach I should be considering? Thanks!

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  • How should I handle multiple links ot the same page with different Query Strings

    - by RandomBen
    In the website I am working on, there is a product page with 8 tabs on it, showing different aspects of the product. There are quick links on other pages within the site that take you to the page and to a specific link specified by a query string. For example the base page would be www.example.com/Product1. And then there are links like this: www.example.com/Product1?tab=CADDrawing www.example.com/Product1?tab=Schematics www.example.com/Product1?tab=Reviews My concern is that Google sees each of these links as a different URL but they aren't and the data on the page is 100% the same. Is there any easy way to make it so Google either knows that www.example.com/Product1 is the base page or doesn't follow the links with Query Strings? I thought about using rel="nofollow" but that seems like it would actually hurt my page ranking. Most of the websites, including Googles on webmaster pages, is unclear. The other option is to add the rel="canonical" to the pages that have a query string but not to the base page. Does that succeed in stopping all of the noisy links?

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  • how to share a variable between two threads

    - by prmatta
    I just inherited some code, two threads within this code need to perform a system task. One thread should do the system task before the other thread. They should not be performing the system task together. The two threads do not have references to each other. Now, I know I can use some sort of a semaphore to achieve this. But my question is what is the right way to get both threads to access this semaphore. I could create a static variable/method a new class : public class SharedSemaphore { private static Semaphore s = new Semaphore (1, true); public static void performSystemTask () { s.acquire(); } public static void donePerformingSystemTask() { s.release(); } } This would work (right?) but this doesn't seem like the right thing to do. Because, the threads now have access to a semaphore, without ever having a reference to it. This sort of thing doesn't seem like a good programming practice. Am I wrong?

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  • gcc -finline-functions behaviour?

    - by user176168
    I'm using gcc with the -finline-functions optimization for release builds. In order to combat code bloat because I work on an embedded system I want to say don't inline particular functions. The obvious way to do this would be through function attributes ie attribute(noinline). The problem is this doesn't seem to work when I switch on the global -finline-functions optimisation which is part of the -O3 switch. It also has something to do with it being templated as a non templated version of the same function doesn't get inlined which is as expected. Has anybody any idea of how to control inlining when this global switch is on? Here's the code: #include <cstdlib> #include <iostream> using namespace std; class Base { public: template<typename _Type_> static _Type_ fooT( _Type_ x, _Type_ y ) __attribute__ (( noinline )); }; template<typename _Type_> _Type_ Base::fooT( _Type_ x, _Type_ y ) { asm(""); return x + y; } int main(int argc, char *argv[]) { int test = Base::fooT( 1, 2 ); printf( "test = %d\n", test ); system("PAUSE"); return EXIT_SUCCESS; }

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  • Rails Association Problem

    - by looloobs
    I am having trouble with this association. I need to get an array of the primaries that belong to the soldiers in a platoon. So once I get all the soldiers in a platoon: @company = Company.find_by_id(1) @platoons = @company.platoons <% @platoons.each do |p| %> <%= p.soldiers.primaries.find(:all,:conditions => ["relationship = ? AND contacted = ?", 'Spouse', 'Yes'])) %> <% end %> * So there is no method for primaries, I assume this is because I am trying to call an association on an array. Soldiers have a platoon_id but primaries do not, they only have the association to soldiers in that platoon. How do I do this? I need it to return an array of Primaries. Thanks in advance! class Soldier < ActiveRecord::Base belongs_to :company belongs_to :platoon has_many :primaries, :dependent => :destroy end class Platoon < ActiveRecord::Base belongs_to :company belongs_to :battalion has_many :soldiers end class Primary < ActiveRecord::Base belongs_to :soldier belongs_to :company end

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  • Error in my web.xml

    - by Mercer
    Why i have an error in my web.xml when i want add servlet..? <servlet> <servlet-name>ClientServlet</servlet-name> <servlet-class>org.task.ClientServlet</servlet-class> <servlet-name>FactoryServlet</servlet-name> <servlet-class>org.task.FactoryServlet</servlet-class> <servlet-name>TraderServlet</servlet-name> <servlet-class>org.task.TraderServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>ClientServlet</servlet-name> <url-pattern>/ClientServlet</url-pattern> <servlet-name>FactoryServlet</servlet-name> <url-pattern>/FactoryServlet</url-pattern> <servlet-name>TraderServlet</servlet-name> <url-pattern>/TraderServlet</url-pattern> </servlet-mapping>

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  • About Interview structure for test automation lab developers

    - by Ikaso
    Hi, I am interviewing new applicants for a team that is doing test automation on our company product(s). The team is composed of junior software developers and a team leader. The product runs on windows and has both managed and unmanaged parts. The test automation is done on both client side (user mode and kernel mode) and server side (IIS, Windows Services, backend). We are doing mainly intergration tests and black box tests. I am trying to figure out how to organize my interview. My overall idea is to ask about a project they have done, then ask some technical questions (multithreading, GC, design patterns) and one programming question. Please note that there is another interview done before me with 2 programming questions. My programming question is rather simple (for example: reversing a singly-linked linked list). My coworkers think that my questions will not find good developers since my questions are rather simple and well known, but so far most of the applicants fail those questions. My questions are: Should I change the structure of my interview for this kind of job? What questions do you ask to figure our if the applicant is test oriented? (Maybe I should provide a buggy implementation of a problem and let them find the bugs and then ask them about what tests they would have done) Regards,

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  • HTML relative links with URL Rewrite

    - by Adam Kiss
    I have quickie: When you code/develop themes, how do you link to various files in your html/css code? Example: We at our firm use mostly <base target="http://whatever"> in our main template and then just <img src="./images/file.png"> in our html, "/category/page" as links and something alike in our css. However, when testing on different machines, we use ip address rather than localhost on main dev station of coder, so all base links don't work (because localhost goes to viewing machine, not coder's, in our network). Same thing happens when updating pages - on dev server, we have to edit base target, so browsing site won't take us to live site - this part is actually rather simple PHP (if ... echo else echo something else), but it still not solve problem of more coding-testing problems. So, my question is, how do YOU solve it? How do you use relative links, which basically don't care for what domain is the page on and don't care for url rewrite? (because ../images/ is different for / and different for /something/somethingElse/page)?

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  • Java Executor: Small tasks or big ones?

    - by Arash Shahkar
    Consider one big task which could be broken into hundreds of small, independently-runnable tasks. To be more specific, each small task is to send a light network request and decide upon the answer received from the server. These small tasks are not expected to take longer than a second, and involve a few servers in total. I have in mind two approaches to implement this using the Executor framework, and I want to know which one's better and why. Create a few, say 5 to 10 tasks each involving doing a bunch of send and receives. Create a single task (Callable or Runnable) for each send & receive and schedule all of them (hundreds) to be run by the executor. I'm sorry if my question shows that I'm lazy to test these and see for myself what's better (at least performance-wise). My question, while looking after an answer to this specific case, has a more general aspect. In situations like these when you want to use an executor to do all the scheduling and other stuff, is it better to create lots of small tasks or to group those into a less number of bigger tasks?

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  • Is there really such a thing as "being good at math"?

    - by thezhaba
    Aside from gifted individuals able to perform complex calculations in their head, I'm wondering if proficiency in mathematics, namely calculus and algebra, has really got to do with one's natural inclination towards sciences, if you can put it that way. A number of students in my calculus course pick up material in seemingly no time whereas I, personally, have to spend time thinking about and understanding most concepts. Even then, if a question that requires a bit more 'imagination' comes up I don't always recognize the concepts behind it, as is the case with calculus proofs, for instance. Nevertheless, I refuse to believe that I'm simply not made for it. I do very well in programming and software engineering courses where a lot of students struggle. At first I could not grasp what they found to be so difficult, but eventually I realized that having previous programming experience is a great asset -- once I've seen and made practical use of the programming concepts learning about them in depth in an academic setting became much easier as I have then already seen their use "in the wild". I suppose I'm hoping that something similar happens with mathematics -- perhaps once the practical idea behind a concept (which authors of textbooks sure do a great job of concealing..) is evident, understanding the seemingly dry and symbolic ideas and proofs would be more obvious? I'm really not sure. All I'm sure of is I'd like to get better at calculus, but I don't yet understand why some of us pick it up easily while others have to spend considerable amounts of time on it and still not have complete understanding if an unusual problem is given.

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  • Is boost shared_ptr <XXX> thread safe?

    - by sxingfeng
    I have a question about boost :: shared_ptr. There are lots of thread. class CResource { xxxxxx } class CResourceBase { public: void SetResource(shared_ptr<CResource> res) { m_Res = res; } shared_ptr<CResource> GetResource() { return m_Res; } private: shared_ptr<CResource> m_Res; } CResourceBase base; //---------------------------------------------- Thread A: while (true) { ...... shared_ptr<CResource> nowResource = base.GetResource(); nowResource.doSomeThing(); ... } Thread B: shared_ptr<CResource> nowResource; base.SetResource(nowResource); ... //----------------------------------------------------------- If thread A do not care the nowResource is the newest . Will this part of code have problem? I mean when ThreadB do not SetResource completely, Thread A get a wrong smart point by GetResource? Another question : what does thread-safe mean? If I do not care about whether the resource is newest, will the shared_ptr nowResource crash the program when the nowResource is released or will the problem destroy the shared_point?

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  • HTML relative links on various domains

    - by Adam Kiss
    I have quickie: When you code/develop themes, how do you link to various files in your html/css code? Example: We at our firm use mostly <base target="http://whatever"> in our main template and then just <img src="./images/file.png"> in our html, "/category/page" as links and something alike in our css. However, when testing on different machines, we use ip address rather than localhost on main dev station of coder, so all base links don't work (because localhost goes to viewing machine, not coder's, in our network). Same thing happens when updating pages - on dev server, we have to edit base target, so browsing site won't take us to live site - this part is actually rather simple PHP (if ... echo else echo something else), but it still not solve problem of more coding-testing problems. So, my question is, how do YOU solve it? How do you use relative links, which basically don't care for what domain is the page on and don't care for url rewrite? (because ../images/ is different for / and different for /something/somethingElse/page)?

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  • Is the C++ compiler optimizer allowed to break my destructor ability to be called multiple times?

    - by sharptooth
    We once had an interview with a very experienced C++ developer who couldn't answer the following question: is it necessary to call the base class destructor from the derived class destructor in C++? Obviously the answer is no, C++ will call the base class destructor automagically anyway. But what if we attempt to do the call? As I see it the result will depend on whether the base class destructor can be called twice without invoking erroneous behavior. For example in this case: class BaseSafe { public: ~BaseSafe() { } private: int data; }; class DerivedSafe { public: ~DerivedSafe() { BaseSafe::~BaseSafe(); } }; everything will be fine - the BaseSafe destructor can be called twice safely and the program will run allright. But in this case: class BaseUnsafe { public: BaseUnsafe() { buffer = new char[100]; } ~BaseUnsafe () { delete[] buffer; } private: char* buffer; }; class DerivedUnsafe { public: ~DerivedUnsafe () { BaseUnsafe::~BaseUnsafe(); } }; the explicic call will run fine, but then the implicit (automagic) call to the destructor will trigger double-delete and undefined behavior. Looks like it is easy to avoid the UB in the second case. Just set buffer to null pointer after delete[]. But will this help? I mean the destructor is expected to only be run once on a fully constructed object, so the optimizer could decide that setting buffer to null pointer makes no sense and eliminate that code exposing the program to double-delete. Is the compiler allowed to do that?

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  • How can variadic char template arguments from user defined literals be converted back into numeric types?

    - by Pubby
    This question is being asked because of this one. C++11 allows you to define literals like this for numeric literals: template<char...> OutputType operator "" _suffix(); Which means that 503_suffix would become <'5','0','3'> This is nice, although it isn't very useful in the form it's in. How can I transform this back into a numeric type? This would turn <'5','0','3'> into a constexpr 503. Additionally, it must also work on floating point literals. <'5','.','3> would turn into int 5 or float 5.3 A partial solution was found in the previous question, but it doesn't work on non-integers: template <typename t> constexpr t pow(t base, int exp) { return (exp > 0) ? base * pow(base, exp-1) : 1; }; template <char...> struct literal; template <> struct literal<> { static const unsigned int to_int = 0; }; template <char c, char ...cv> struct literal<c, cv...> { static const unsigned int to_int = (c - '0') * pow(10, sizeof...(cv)) + literal<cv...>::to_int; }; // use: literal<...>::to_int // literal<'1','.','5'>::to_int doesn't work // literal<'1','.','5'>::to_float not implemented

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