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• C++ inheritance and member function pointers

  - by smh

  In C++, can member function pointers be used to point to derived (or even base) class members? EDIT: Perhaps an example will help. Suppose we have a hierarchy of three classes X, Y, Z in order of inheritance. Y therefore has a base class X and a derived class Z. Now we can define a member function pointer p for class Y. This is written as: void (Y::*p)(); (For simplicity, I'll assume we're only interested in functions with the signature void f() ) This pointer p can now be used to point to member functions of class Y. This question (two questions, really) is then: Can p be used to point to a function in the derived class Z? Can p be used to point to a function in the base class X?

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• Custom UI design in Sencha and othere touch framworks

  - by vWebby

  Can someone please guide me regarding which touch framework (javascript) I should use to make a tablet app? I am new to this area and I am looking for something which allows me to play with my own UI design comfortably. I went through sencha as I heard its apt for a tablet app environment but I am (sorry, it might sound odd) not able to make out whether I can use my own UI design to make app in sencha. Or any other framework (stable) allows to use custom UI design?? Any help regarding this is appreciated .. thanks in advance

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• JTable Design Guide in Swing Application

  - by zwang

  I have a really hard design problem in my swing application. Generally Speaking, I have a JTable and a JLabel to display. The label is right below the JTable. When the height of these two components doesn't exceed a threshold, then the jtable and label displays as normal. Then height of these two components will increase as the number of records filled in the table increases. When the height of these two components exceeds a threshold, I want there is a scrollbar in the JTable and the height of these two components will be the threshold. Is this design Possible? I have draft to illustate my UI design requirement. But I don't know how to post it in this forum. And any reply are appreciate. Best Regards, Zheng.

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• Is this the correct why of speaking to a "Content Manager" Class?

  - by DeanMc

  I am creating a silverlight site. I am currently breaking out my ideas into pieces of functionality. One of the idea's I have is the concept of a content manager. This is essentially a UI control with 4 regions. Top, Bottom, Right & Left. I also have a collection of objects that are considered "Menu Items". These are controls that function as a way to navigate around, similar to links. The idea I have is to implement an IMenuItem interface. Among the standard pieces of information (Text, PageReference, etc) I was also going to hold a reference to the content manager. My idea behind this thinking is that I can pass the PageReference to a property on the ContentManager and then call a method which knows how to update the content manager accordingly. Is this the best way of implementing this or is their some sort of pattern for it?

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• Designing operation (a,b) -> (c,d)

  - by golergka

  I have an operation that I need to design. That operation takes two objects of a certain class X, and returns two new objects of the same class (I may need the originals later). The logic that dictates the selection of this object is contained in class Y. On one hand, I don't want class Y to know details about class X implementation; on the other, I don't want class X to know details about selecting the different objects to perform this operation on. If that was all the problem, I'd just create a static method on class A. However, the methods in language I'm working on return only one object. Also, the operation needs to be robust, and calling operation two times to get C and D respectively isn't possible, as both C & D both rely on a single random number. How should I design such operation? Update: I'm using Obejctive C.

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• Designing an email system to guarantee delivery

  - by GlenH7

  We are looking to expand our use of email for notification purposes. We understand it will generate more inbox volume, but we are being selective about which events we fire notification on in order to keep the signal-to-noise ratio high. The big question we are struggling with is designing a system that guarantees that the email was delivered. If an email isn't delivered, we will consider that an exception event that needs to be investigated. In reality, I say almost guarantees because there aren't any true guarantees with email. We're just looking for a practical solution to making sure the email got there and experiences others have had with the various approaches to guaranteeing delivery. For the TL;DR crowd - how do we go about designing a system to guarantee delivery of emails? What techniques should we consider so we know the emails were delivered? Our biggest area of concern is what techniques to use so that we know when a message is sent out that it either lands in an inbox or it failed and we need to do something else. Additional requirements: We're not at the stage of including an escalation response, but we'll want that in the future or so we think. Most notifications will be internal to our enterprise, but we will have some notifications being sent to external clients. Some of our application is in a hosted environment. We haven't determined if those servers can access our corporate email servers for relaying or if they'll be acting as their own mail servers. Base design / modules (at the moment): A module to assign tracking identification A module to send out emails A module to receive delivery notification (perhaps this is the same as the email module) A module that checks sent messages against delivery notification and alerts on undelivered email. Some references: Atwood: Send some email Email Tracking Some approaches: Request a response (aka read-receipt or Message Disposition Notification). Seems prone to failure since we have cross-compatibility issues due to differing mail servers and software. Return receipt (aka Delivery Status Notification). Not sure if all mail servers honor this request or not Require an action and therefore prove reply. Seems burdensome to force the recipients to perform an additional task not related to resolving the issue. And no, we haven't come up with a way of linking getting the issue fixed to whether or not the email was received. Force a click-through / Other site sign-in. Similar to requiring some sort of action, this seems like an additional burden and will annoy the users. On the other hand, it seems the most likely to guarantee someone received the notification. Hidden image tracking. Not all email providers automatically load the image, and how would we associate the image(s) with the email tracking ID? Outsource delivery. This gets us out of the email business, but goes back to how to guarantee the out-sourcer's receipt and subsequent delivery to the end recipient. As a related concern, there will be an n:n relationship between issue notification and recipients. The 1 issue : n recipients subset isn't as much of a concern although if we had a delivery failure we would want to investigate and fix the core issue. Of bigger concern is n issues : 1 recipient, and we're specifically concerned in making sure that all n issues were received by the recipient. How does forum software or issue tracking software handle this requirement? If a tracking identifier is used, Where is it placed in the email? In the Subject, or the Body?

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• Footer not stretching 100% when horizontally scrolled

  - by Dan

  I have a footer which is set to 100% width, but if i size the window smaller so a horizontal scrollbar appears, using the scrollbar shows whitespace to the right of the footer ... its not spanned 100% of the page, just the viewport. <!doctype html> <html lang="en" class="no-js"> <head> <title>test</title> <meta charset="utf-8"> </head> <body> <div id="container" style="width:100%"> <div id="body" style="width:1200px;"> <!-- Body start --> <h1>Main content area</h1> <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh.</p> <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh.</p> <p>Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh.</p> <!-- Body end --> </div> <div id="footer" style="width:100%; background-color:green;"> <!-- Footer start --> <p><b>FOOTER.</b> Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh. Lorem ipsum dolor sit amet, consectetuer adipiscing elit, sed diam nonummy nibh.</p> <!-- Footer end --> </div> </div> </body> </html> Size the browser so horizontal scrollbar appears, and then scroll and you will see the footer background just stops. Any ideas? Or is this site the wrong place for web site design/development .. I did have to read the site description but it still wasnt clear, nor was the meta-discussion? Apologies if its in the wrong place.

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• The Oracle Retail Week Awards - most exciting awards yet?

  - by sarah.taylor(at)oracle.com

  Last night's annual Oracle Retail Week Awards saw the UK's top retailers come together to celebrate the very best of our industry over the last year.  The Grosvenor House Hotel on Park Lane in London was the setting for an exciting ceremony which this year marked several significant milestones in British - and global - retail.  Check out our videos about the event at our Oracle Retail YouTube channel, and see if you were snapped by our photographer on our Oracle Retail Facebook page. There were some extremely hot contests for many of this year's awards - and all very deserving winners.  The entries have demonstrated beyond doubt that retailers have striven to push their standards up yet again in all areas over the past year.  The judging panel includes some of the most prestigious names in the retail industry - to impress the panel enough to win an award is a substantial achievement.  This year the panel included the likes of Andy Clarke - Chief Executive of ASDA Group; Mark Newton Jones - CEO of Shop Direct Group; Richard Pennycook - the finance director at Morrisons; Rob Templeman - Chief Executive of Debenhams; and Stephen Sunnucks - the president of Gap Europe.  These are retail veterans  who have each helped to shape the British High Street over the last decade.  It was great to chat with many of them in the Oracle VIP area last night.  For me, last night's highlight was honouring both Sir Stuart Rose and Sir Terry Leahy for their contributions to the retail industry.  Both have set the standards in retailing over the last twenty years and taken their respective businesses from strength to strength, demonstrating that there is always a need for innovation even in larger businesses, and that a business has to adapt quickly to new technology in order to stay competitive.  Sir Terry Leahy's retirement this year marks the end of an era of global expansion for the Tesco group and a milestone in the progression of British retail.  Sir Terry has helped steer Tesco through nearly 20 years of change, with 14 years as Chief Executive.  During this time he led the drive for international expansion and an aggressive campaign to increase market share.  He has led the way for High Street retailers in adapting to the rise of internet retailing and nurtured a very successful home delivery service.  More recently he has pioneered the notion of cross-channel retailing with the introduction of Tesco apps for the iPhone and Android mobile phones allowing customers to scan barcodes of items to add to a shopping list which they can then either refer to in store or order for delivery.  John Lewis Partnership was a very deserving winner of The Oracle Retailer of the Year award for their overall dedication to excellent retailing practices.  The business was also named the American Express Marketing/Advertising Campaign of the Year award for their memorable 'Never Knowingly Undersold' advert series, which included a very successful viral video and radio campaign with Fyfe Dangerfield's cover of Billy Joel's 'She's Always a Woman' used for the adverts.  Store Design of the Year was another exciting category with Topshop taking the accolade for its flagship Oxford Street store in London, which combines boutique concession-style stalls with high fashion displays and exclusive collections from leading designers.  The store even has its own hairdressers and food hall, making it a truly all-inclusive fashion retail experience and a global landmark for any self-respecting international fashion shopper. Over the next few weeks we'll be exploring some of the winning entries in more detail here on the blog, so keep an eye out for some unique insights into how the winning retailers have made such remarkable achievements. 

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• ResourceSerializable: an alternate to ORM and ActiveRecord

  - by Levi Morrison

  A few opinionated reasons I don't like the traditional ORM and ActiveRecord patterns: They work only with a database. Sometimes I'm dealing with objects from an API and other objects from a database. All the implementations I have seen don't allow for that. Feel free to clue me in if I'm wrong on this. They are brittle. Changes in the database will likely break your implemenation. Some implementations can help reduce this, but a few of the ones I've seen don't. Their very design is influenced by the database. If I want to switch to using an API, I'll have to redesign the object to get it to work (likely). It seems to violate the single-responsibility pattern. They know what they are and how they act, but they also know how they are created, destroyed and saved? Seems a bit much. What about an approach that is somewhat more familiar in PHP: implementing an interface? In php 5.4, we'll have the JsonSerializable interface that defines the data to be json_encoded, so users will become accustomed to this type of thing. What if there was a ResourceSerializable interface? This is still an ORM by name, but certainly not by tradition. interface ResourceSerializable { /** * Returns the id that identifies the resource. */ function resourceId(); /** * Returns the 'type' of the resource. */ function resourceType(); /** * Returns the data to be serialized. */ function resourceSerialize(); } Things might be poorly named, I'll take suggestions. Notes: ResourceId will work for API's and databases. As long as your primary key in the database is the same as the resource ID in the API, there is no conflict. All of the API's I've worked with have a unique ID for the resource, so I don't see any issues there. ResourceType is the group or type associated with the resource. You can use this to map the resource to an API call or a database table. If the ResourceType was person, it could map to /api/1/person/{resourceId} and the table persons (or people, if it's smart enough). resourceSerialize() returns the data to be stored. Keys would identify API parameters and database table columns. This also seems easier to test than ActiveRecord / Orm implemenations. I haven't done much automated testing on traditional ActiveRecord/ORM implemenations, so this is merely a guess. But it seems that I being able to create objects independently of the library helps me. I don't have to use load() to get an existing resource, I can simply create one and set all the right properties. This is not so easy in the ActiveRecord / Orm implemenations I've dealt with. Downsides: You need another object to serialize it. This also means you have more code in general as you have to use more objects. You have to map resource types to API calls and database tables. This is even more work, but some ORMs and ActiveRecord implementations require you to map objects to table names anyway. Are there other downsides that you see? Does this seem feasible to you? How would you improve it? Note: I almost asked this on StackOverflow because it might be too vague for their standards, but I'm still not really familiar with programmers.stackexchange.com, so please help me improve my question if it doesn't shape up to standards here.

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• What is the best practice, point of view of well experienced developers

  - by Damien MIRAS

  My manager pushes me to use his self defined best practices. All of these practices are based on is own assumptions. I disagree with them and I would like to have some feedback of well experienced people about these practices. I would prefer answers from people involved in the maintenance of huge products and people whom have maintained the product for years. Developers with 15+ years of experience are preferred because my manager has that much experience himself. I have 7 years of experience. Here are the practices he wants me to use: never extends classes, use composition and interface instead because extending classes are unmaintainable and difficult to debug. What I think about that Extend when needed, respect "Liskov's Substitution Principle" and you'll never be stuck with a problem, but prefer composition and decoration. I don't know any serious project which has banned inheriting, sometimes it's impossible to not use that, i.e. in a UI framework. Design patterns are just unusable. In PHP, for simple use cases (for example a user needs a web interface to view a database table), his "best practice" is: copy some random php code wich we own, paste and modify it, put html and php code in same file, never use classes in PHP, it doesn't work well for small jobs, and in fact it doesn't work well at all, there is no good tool to work with. Copy & paste PHP code is good practice for maintenance because scripts are independent, if you have a bug somewhere you can fix it without side effects. What I think about that: NEVER EVER COPY code or do it because you have five minutes to deliver something, you will do some refactoring after that. Copy & paste code is a beginners error, if you have errors you'll have the error everywhere any time you have pasted it's a nightmare to maintain. If you repsect the "Open Close Principle" you'll rarely get edge effects, use unit test if you are afraid of that. For small jobs in PHP use at least something you get or write the HTML separately from the PHP code and reuse it any time you need it. Classes in PHP are mature, not as mature as other languages like python or java, but they are usable. There is tools to work with classes in PHP like Zend Studio that work very well. The use of classes or not depends not on the language you use but the programming paradigm you have choosen. I'm a OOP developer, I use PHP5, why do I have to shoot myself in the foot? When you find a simple bug in the code, and you can fix it simply, if you are not working on the code where you have found it, never fix it, even if it takes 5 seconds. He says to me his "best practices" are driven by the fact that he has a lot of experience in maintaining software in production (14 years) and he now knows what works and what doesn't work, what the community says is a fad, and the people advocating such principles as never copy & paste code, are not evolved in maintaining applications. What I think about that: If you find a bug fix it if you can do it quickly inform the people who've touched that code before, check if you have not introduced a new bug, ideally add a unit test for it. I currently work on a web commerce project, which serves 15k unique users per day. The code base has to be maintained and has been maintained this way since 2005. Ideally you include a short description of your position and experience in terms of years effectively maintaining an application which has been in production for real.

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• Designing An ACL Based Permission System

  - by ryanzec

  I am trying to create a permissions system where everything is going to be stored in MySQL (or some database) and pulled using PHP for a project management system I am building.  I am right now trying to do it is an ACL kind of way.  There are a number key features I want to be able to support: 1.  Being able to assign permissions without being tied to a specific object. The reason for this is that I want to be able to selectively show/hide elements of the UI based on permissions at a point where I am not directly looking at a domain object instance.  For instance, a button to create a new project should only should only be shown to users that have the pm.project.create permission but obviously you can assign a create permission to an domain object instance (as it is already created). 2.  Not have to assign permissions for every single object. Obviously creating permissions entries for every single object (projects, tickets, comments, etc…) would become a nightmare to maintain so I want to have some level of permission inheritance. *3.  Be able to filter queries based on permissions. This would be a really nice to have but I am not sure if it is possible.  What I mean by this is say I have a page that list all projects.  I want the query that pulls all projects to incorporate the ACL so that it would not show projects that the current user does not have pm.project.read access to.  This would have to be incorporated into the main query as if it is a process that is done after that main query (which I know I could do) certain features like pagination become much more difficult. Right now this is my basic design for the tables: AclEntities id - the primary key key - the unique identifier for the domain object (usually the primary key of that object) parentId - the parent of the domain object (like the project object if this was a ticket object) aclDomainObjectId - metadata about the domain object AclDomainObjects id - primary key title - simple string to unique identify the domain object(ie. project, ticket, comment, etc…) fullyQualifiedClassName - the fully qualified class name for use in code (I am using namespaces) There would also be tables mapping AclEntities to Users and UserGroups. I also have this interface that all acl entity based object have to implement: IAclEntity getAclKey() - to the the unique key for this specific instance of the acl domain object (generally return the primary key or a concatenated string of a composite primary key) getAclTitle() - to get the unique title for the domain object (generally just returning a static string) getAclDisplayString() - get the string that represents this entity (generally one or more field on the object) getAclParentEntity() - get the parent acl entity object (or null if no parent) getAclEntity() - get the acl enitty object for this instance of the domain object (or null if one has not been created yet) hasPermission($permissionString, $user = null) - whether or not the user has the permission for this instance of the domain object static getFromAclEntityId($aclEntityId) - get a specific instance of the domain object from an acl entity id. Do any of these features I am looking for seems hard to support or are just way off base? Am I missing or not taking in account anything in my implementation? Is performance something I should keep in mind?

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• Would this be a good web application architecture?

  - by Gustav Bertram

  My problem Our MVC based framework does not allow us to cache only part of our output. Ideally we want to cahce static and semi-static bits, and run dynamic bits. In addition, we need to consider data caching that reacts to database changes. My idea The concept I came up with was to represent a page as a tree of XML fragment objects. (I say XML, but I mean XHTML). Some of the fragments are dynamic, and can pull their data directly from models or other sources, but most of the fragments are static scaffolding. If a subtree of fragments is completely static, then I imagine that they could unfold into pure XML that would then be cached as the text representation of their parent element. This process would ideally continue until we are left with a root element that contains all of the static XML, and has a couple of dynamic XML fragments that are resolved and attached to the relevant nodes of the XML tree just before the page is displayed. In addition to separating content into dynamic and static fragments, some fragments could be dynamic and cached. A simple expiry time which propagates up through the XML fragment tree would indicate that a specific fragment should periodically be refreshed. A newspaper section or front page does not need to be updated each second. Minutes or sometimes even longer is sufficient. Other fragments would be dynamic and uncached. Typically too many articles are viewed for them to be cached - the cache would overflow. Some individual articles may be cached if they are extremely popular. Functional notes The folding mechanism could be to be smart enough to judge when it would be more profitable to fold a dynamic cached fragment and propagate the expiry date to the parent fragment, or to keep it separate and simple attach to the XML tree when resolving the page. If some dynamic cached fragments are associated to database objects through mechanisms like a globally unique content id, then changes to the database could trigger changes to the output cache. If fragments store the identifiers of parent fragments, then they could trigger a refolding process that would then include the updated data. A set of pure XML with an ordered array of fragment objects (that each store the identifying information of the node to which they should be attached), can be resolved in a fairly simple way by walking the XML tree, and merging the data from the fragments. Because it is not necessary to parse and construct the entire tree in memory before attaching nodes, processing should be fairly fast. The identifiers of each fragment would be a combination of relevant identity data and the type of fragment object. Cached parent fragments would contain references to these identifiers, in order to then either pull them from the fragment cache, or to run their code. The controller's responsibility is reduced to making changes to the database, and telling the root XML fragment object to render itself. The Question My question has two parts: Is this a good design? Are there any obvious flaws I'm missing? Has somebody else thought of this before? References? Is there an existing alternative that I should consider? A cool templating engine maybe?

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• Should accessible members of an internal class be internal too?

  - by Jeff Mercado

  I'm designing a set of APIs for some applications I'm working on. I want to keep the code style consistent in all the classes I write but I've found that there are a few inconsistencies that I'm introducing and I don't know what the best way to resolve them is. My example here is specific to C# but this would apply to any language with similar mechanisms. There are a few classes that I need for implementation purposes that I don't necessarily want to expose in the API so I make them internal whereever needed. Generally what I would do is design the class as I normally would (e.g., make members public/protected/private where necessary) and change the visibility level of the class itself to internal. So I might have a few classes that look like this: internal interface IMyItem { ItemSet AddTo(ItemSet set); } internal class _SmallItem : IMyItem { private readonly /* parameters */; public _SmallItem(/* small item parameters */) { /* ... */ } public ItemSet AddTo(ItemSet set) { /* ... */ } } internal abstract class _CompositeItem: IMyItem { private readonly /* parameters */; public _CompositeItem(/* composite item parameters */) { /* ... */ } public abstract object UsefulInformation { get; } protected void HelperMethod(/* parameters */) { /* ... */ } } internal class _BigItem : _CompositeItem { private readonly /* parameters */; public _BigItem(/* big item parameters */) { /* ... */ } public override object UsefulInformation { get { /* ... */ } } public ItemSet AddTo(ItemSet set) { /* ... */ } } In another generated class (part of a parser/scanner), there is a structure that contains fields for all possible values it can represent. The class generated is internal too but I have control over the visibility of the members and decided to make them internal as well. internal partial struct ValueType { internal string String; internal ItemSet ItemSet; internal IMyItem MyItem; } internal class TokenValue { internal static int EQ(ItemSetScanner scanner) { /* ... */ } internal static int NAME(ItemSetScanner scanner, string value) { /* ... */ } internal static int VALUE(ItemSetScanner scanner, string value) { /* ... */ } //... } To me, this feels odd because the first set of classes, I didn't necessarily have to make some members public, they very well could have been made internal. internal members of an internal type can only be accessed internally anyway so why make them public? I just don't like the idea that the way I write my classes has to change drastically (i.e., change all uses of public to internal) just because the class is internal. Any thoughts on what I should do here? It makes sense to me that I might want to make some members of a class declared public, internal. But it's less clear to me when the class is declared internal.

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• Use a custom value object or a Guid as an entity identifier in a distributed system?

  - by Kazark

  tl;dr I've been told that in domain-driven design, an identifier for an entity could be a custom value object, i.e. something other than Guid, string, int, etc. Can this really be advisable in a distributed system? Long version I will invent an situation analogous to the one I am currently facing. Say I have a distributed system in which a central concept is an egg. The system allows you to order eggs and see spending reports and inventory-centric data such as quantity on hand, usage, valuation and what have you. There area variety of services backing these behaviors. And say there is also another app which allows you to compose recipes that link to a particular egg type. Now egg type is broken down by the species—ostrich, goose, duck, chicken, quail. This is fine and dandy because it means that users don't end up with ostrich eggs when they wanted quail eggs and whatnot. However, we've been getting complaints because jumbo chicken eggs are not even close to equivalent to small ones. The price is different, and they really aren't substitutable in recipes. And here we thought we were doing users a favor by not overwhelming them with too many options. Currently each of the services (say, OrderSubmitter, EggTypeDefiner, SpendingReportsGenerator, InventoryTracker, RecipeCreator, RecipeTracker, or whatever) are identifying egg types with an industry-standard integer representation the species (let's call it speciesCode). We realize we've goofed up because this change could effect every service. There are two basic proposed solutions: Use a predefined identifier type like Guid as the eggTypeID throughout all the services, but make EggTypeDefiner the only service that knows that this maps to a speciesCode and eggSizeCode (and potentially to an isOrganic flag in the future, or whatever). Use an EggTypeID value object which is a combination of speciesCode and eggSizeCode in every service. I've proposed the first solution because I'm hoping it better encapsulates the definition of what an egg type is in the EggTypeDefiner and will be more resilient to changes, say if some people now want to differentiate eggs by whether or not they are "organic". The second solution is being suggested by some people who understand DDD better than I do in the hopes that less enrichment and lookup will be necessary that way, with the justification that in DDD using a value object as an ID is fine. Also, they are saying that EggTypeDefiner is not a domain and EggType is not an entity and as such should not have a Guid for an ID. However, I'm not sure the second solution is viable. This "value object" is going to have to be serialized into JSON and URLs for GET requests and used with a variety of technologies (C#, JavaScript...) which breaks encapsulation and thus removes any behavior of the identifier value object (is either of the fields optional? etc.) Is this a case where we want to avoid something that would normally be fine in DDD because we are trying to do DDD in a distributed fashion? Summary Can it be a good idea to use a custom value object as an identifier in a distributed system (solution #2)?

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• Why is 0 false?

  - by Morwenn

  This question may sound dumb, but why does 0 evaluates to false and any other [integer] value to true is most of programming languages? String comparison Since the question seems a little bit too simple, I will explain myself a little bit more: first of all, it may seem evident to any programmer, but why wouldn't there be a programming language - there may actually be, but not any I used - where 0 evaluates to true and all the other [integer] values to false? That one remark may seem random, but I have a few examples where it may have been a good idea. First of all, let's take the example of strings three-way comparison, I will take C's strcmp as example: any programmer trying C as his first language may be tempted to write the following code: if (strcmp(str1, str2)) { // Do something... } Since strcmp returns 0 which evaluates to false when the strings are equal, what the beginning programmer tried to do fails miserably and he generally does not understand why at first. Had 0 evaluated to true instead, this function could have been used in its most simple expression - the one above - when comparing for equality, and the proper checks for -1 and 1 would have been done only when needed. We would have considered the return type as bool (in our minds I mean) most of the time. Moreover, let's introduce a new type, sign, that just takes values -1, 0 and 1. That can be pretty handy. Imagine there is a spaceship operator in C++ and we want it for std::string (well, there already is the compare function, but spaceship operator is more fun). The declaration would currently be the following one: sign operator<=>(const std::string& lhs, const std::string& rhs); Had 0 been evaluated to true, the spaceship operator wouldn't even exist, and we could have declared operator== that way: sign operator==(const std::string& lhs, const std::string& rhs); This operator== would have handled three-way comparison at once, and could still be used to perform the following check while still being able to check which string is lexicographically superior to the other when needed: if (str1 == str2) { // Do something... } Old errors handling We now have exceptions, so this part only applies to the old languages where no such thing exist (C for example). If we look at C's standard library (and POSIX one too), we can see for sure that maaaaany functions return 0 when successful and any integer otherwise. I have sadly seen some people do this kind of things: #define TRUE 0 // ... if (some_function() == TRUE) { // Here, TRUE would mean success... // Do something } If we think about how we think in programming, we often have the following reasoning pattern: Do something Did it work? Yes -> That's ok, one case to handle No -> Why? Many cases to handle If we think about it again, it would have made sense to put the only neutral value, 0, to yes (and that's how C's functions work), while all the other values can be there to solve the many cases of the no. However, in all the programming languages I know (except maybe some experimental esotheric languages), that yes evaluates to false in an if condition, while all the no cases evaluate to true. There are many situations when "it works" represents one case while "it does not work" represents many probable causes. If we think about it that way, having 0 evaluate to true and the rest to false would have made much more sense. Conclusion My conclusion is essentially my original question: why did we design languages where 0 is false and the other values are true, taking in account my few examples above and maybe some more I did not think of? Follow-up: It's nice to see there are many answers with many ideas and as many possible reasons for it to be like that. I love how passionate you seem to be about it. I originaly asked this question out of boredom, but since you seem so passionate, I decided to go a little further and ask about the rationale behind the Boolean choice for 0 and 1 on Math.SE :)

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• Nullpointerexcption & abrupt IOStream closure with inheritence and subclasses

  - by user1401652

  A brief background before so we can communicate on the same wave length. I've had about 8-10 university courses on programming from data structure, to one on all languages, to specific ones such as java & c++. I'm a bit rusty because i usually take 2-3 month breaks from coding. This is a personal project that I started thinking of two years back. Okay down to the details, and a specific question, I'm having problems with my mutator functions. It seems to be that I am trying to access a private variable incorrectly. The question is, am I nesting my classes too much and trying to mutate a base class variable the incorrect way. If so point me in the way of the correct literature, or confirm this is my problem so I can restudy this information. Thanks package GroceryReceiptProgram; import java.io.*; import java.util.Vector; public class Date { private int hour, minute, day, month, year; Date() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What's the hour? (Use 1-24 military notation"); hour = Integer.parseInt(keyboard.readLine()); System.out.println("what's the minute? "); minute = Integer.parseInt(keyboard.readLine()); System.out.println("What's the day of the month?"); day = Integer.parseInt(keyboard.readLine()); System.out.println("Which month of the year is it, use an integer"); month = Integer.parseInt(keyboard.readLine()); System.out.println("What year is it?"); year = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (IOException e) { System.out.println("Yo houston we have a problem"); } } public void setHour(int hour) { this.hour = hour; } public void setHour() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What hour, use military notation?"); this.hour = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public int getHour() { return hour; } public void setMinute(int minute) { this.minute = minute; } public void setMinute() { try (BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in))) { System.out.println("What minute?"); this.minute = Integer.parseInt(keyboard.readLine()); } catch (NumberFormatException e) { System.out.println(e.toString() + ": doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString() + ": minute shall not cooperate"); } catch (NullPointerException e) { System.out.println(e.toString() + ": in the setMinute function of the Date class"); } } public int getMinute() { return minute; } public void setDay(int day) { this.day = day; } public void setDay() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What day 0-6?"); this.day = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public int getDay() { return day; } public void setMonth(int month) { this.month = month; } public void setMonth() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What month 0-11?"); this.month = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public int getMonth() { return month; } public void setYear(int year) { this.year = year; } public void setYear() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What year?"); this.year = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public int getYear() { return year; } public void set() { setMinute(); setHour(); setDay(); setMonth(); setYear(); } public Vector<Integer> get() { Vector<Integer> holder = new Vector<Integer>(5); holder.add(hour); holder.add(minute); holder.add(month); holder.add(day); holder.add(year); return holder; } }; That is the Date class obviously, next is the other base class Location. package GroceryReceiptProgram; import java.io.*; import java.util.Vector; public class Location { String streetName, state, city, country; int zipCode, address; Location() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What is the street name"); streetName = keyboard.readLine(); System.out.println("Which state?"); state = keyboard.readLine(); System.out.println("Which city?"); city = keyboard.readLine(); System.out.println("Which country?"); country = keyboard.readLine(); System.out.println("Which zipcode?");//if not u.s. continue around this step zipCode = Integer.parseInt(keyboard.readLine()); System.out.println("What address?"); address = Integer.parseInt(keyboard.readLine()); } catch (IOException e) { System.out.println(e.toString()); } } public void setZipCode(int zipCode) { this.zipCode = zipCode; } public void setZipCode() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What zipCode?"); this.zipCode = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public void set() { setAddress(); setCity(); setCountry(); setState(); setStreetName(); setZipCode(); } public int getZipCode() { return zipCode; } public void setAddress(int address) { this.address = address; } public void setAddress() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.address = Integer.parseInt(keyboard.readLine()); keyboard.close(); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString()); } } public int getAddress() { return address; } public void setStreetName(String streetName) { this.streetName = streetName; } public void setStreetName() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.streetName = keyboard.readLine(); keyboard.close(); } catch (IOException e) { System.out.println(e.toString()); } } public String getStreetName() { return streetName; } public void setState(String state) { this.state = state; } public void setState() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.state = keyboard.readLine(); keyboard.close(); } catch (IOException e) { System.out.println(e.toString()); } } public String getState() { return state; } public void setCity(String city) { this.city = city; } public void setCity() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.city = keyboard.readLine(); keyboard.close(); } catch (IOException e) { System.out.println(e.toString()); } } public String getCity() { return city; } public void setCountry(String country) { this.country = country; } public void setCountry() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.country = keyboard.readLine(); keyboard.close(); } catch (IOException e) { System.out.println(e.toString()); } } public String getCountry() { return country; } }; their parent(What is the proper name?) class package GroceryReceiptProgram; import java.io.*; public class FoodGroup { private int price, count; private Date purchaseDate, expirationDate; private Location location; private String name; public FoodGroup() { try { setPrice(); setCount(); expirationDate.set(); purchaseDate.set(); location.set(); } catch (NullPointerException e) { System.out.println(e.toString() + ": in the constructor of the FoodGroup class"); } } public void setPrice(int price) { this.price = price; } public void setPrice() { try (BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in))) { System.out.println("What Price?"); price = Integer.parseInt(keyboard.readLine()); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString() + ": in the FoodGroup class, setPrice function"); } catch (NullPointerException e) { System.out.println(e.toString() + ": in FoodGroup class. SetPrice()"); } } public int getPrice() { return price; } public void setCount(int count) { this.count = count; } public void setCount() { try (BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in))) { System.out.println("What count?"); count = Integer.parseInt(keyboard.readLine()); } catch (NumberFormatException e) { System.out.println(e.toString() + ":doesnt seem to be a number"); } catch (IOException e) { System.out.println(e.toString() + ": in the FoodGroup class, setCount()"); } catch (NullPointerException e) { System.out.println(e.toString() + ": in FoodGroup class, setCount"); } } public int getCount() { return count; } public void setName(String name) { this.name = name; } public void setName() { try { BufferedReader keyboard = new BufferedReader(new InputStreamReader(System.in)); System.out.println("What minute?"); this.name = keyboard.readLine(); } catch (IOException e) { System.out.println(e.toString()); } } public String getName() { return name; } public void setLocation(Location location) { this.location = location; } public Location getLocation() { return location; } public void setPurchaseDate(Date purchaseDate) { this.purchaseDate = purchaseDate; } public void setPurchaseDate() { this.purchaseDate.set(); } public Date getPurchaseDate() { return purchaseDate; } public void setExpirationDate(Date expirationDate) { this.expirationDate = expirationDate; } public void setExpirationDate() { this.expirationDate.set(); } public Date getExpirationDate() { return expirationDate; } } and finally the main class, so I can get access to all of this work. package GroceryReceiptProgram; public class NewMain { public static void main(String[] args) { FoodGroup test = new FoodGroup(); } } If anyone is further interested, here is a link the UML for this. https://www.dropbox.com/s/1weigjnxih70tbv/GRP.dia

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• Mapping interface or abstract class component

  - by Yann Trevin

  Please consider the following simple use case: public class Foo { public virtual int Id { get; protected set; } public virtual IBar Bar { get; set; } } public interface IBar { string Text { get; set; } } public class Bar : IBar { public virtual string Text { get; set; } } And the fluent-nhibernate map class: public class FooMap : ClassMap<Foo> { public FooMap() { Id(x => x.Id); Component(x => x.Bar, m => { m.Map(x => x.Text); }); } } While running any query with configuration, I get the following exception: NHibernate.InstantiationException: "Cannot instantiate abstract class or interface: NHMappingTest.IBar" It seems that NHibernate tries to instantiate an IBar object instead of the Bar concrete class. How to let Fluent-NHibernate know which concrete class to instantiate when the property returns an interface or an abstract base class? EDIT: Explicitly specify the type of component by writing Component<Bar> (as suggested by Sly) has no effect and causes the same exception to occur. EDIT2: Thanks to vedklyv and Paul Batum: such a mapping should be soon is now possible.

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• Validating DataAnnotations with Validator class

  - by Pablote

  I'm trying to validate a class decorated with dataannotation with the Validator class. It works fine when the attributes are applied to the same class. But when I try to use a metadata class it doesn't work. Is there anything I should do with the Validator so it uses the metadata class? Here's some code.. this works: public class Persona { [Required(AllowEmptyStrings = false, ErrorMessage = "El nombre es obligatorio")] public string Nombre { get; set; } [Range(0, int.MaxValue, ErrorMessage="La edad no puede ser negativa")] public int Edad { get; set; } } this doesnt work: [MetadataType(typeof(Persona_Validation))] public class Persona { public string Nombre { get; set; } public int Edad { get; set; } } public class Persona_Validation { [Required(AllowEmptyStrings = false, ErrorMessage = "El nombre es obligatorio")] public string Nombre { get; set; } [Range(0, int.MaxValue, ErrorMessage = "La edad no puede ser negativa")] public int Edad { get; set; } } this is how I validate the instances: ValidationContext context = new ValidationContext(p, null, null); List<ValidationResult> results = new List<ValidationResult>(); bool valid = Validator.TryValidateObject(p, context, results, true); thanks.

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• Java Swingworker: Not as encapsulated class

  - by Thomas Matthews

  I'm having problems passing information, updating progress and indicating "done" with a SwingWorker class that is not an encapsulated class. I have a simple class that processes files and directories on a hard drive. The user clicks on the Start button and that launches an instance of the SwingWorker. I would like to print the names of the files that are processed on the JTextArea in the Event Driven Thread from the SwingWorker as update a progress bar. All the examples on the web are for an nested class, and the nested class accesses variables in the outer class (such as the done method). I would also like to signal the Event Driven Thread that the SwingWorker is finished so the EDT can perform actions such as enabling the Start button (and clearing fields). Here are my questions: 1. How does the SwingWorker class put text into the JTextArea of the Event Driven Thread and update a progress bar? How does the EDT determine when the {external} SwingWorker thread is finished? {I don't want the SwingWorker as a nested class because there is a lot of code (and processing) done.}

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• How to befriend a templated class's constructor?

  - by Kyle

  Why does class A; template<typename T> class B { private: A* a; public: B(); }; class A : public B<int> { private: friend B<int>::B<int>(); int x; }; template<typename T> B<T>::B() { a = new A; a->x = 5; } int main() { return 0; } result in ../src/main.cpp:15: error: invalid use of constructor as a template ../src/main.cpp:15: note: use ‘B::B’ instead of ‘B::class B’ to name the constructor in a qualified name yet changing friend B<int>::B<int>() to friend B<int>::B() results in ../src/main.cpp:15: error: no ‘void B::B()’ member function declared in class ‘B’ while removing the template completely class A; class B { private: A* a; public: B(); }; class A : public B { private: friend B::B(); int x; }; B::B() { a = new A; a->x = 5; } int main() { return 0; } compiles and executes just fine -- despite my IDE saying friend B::B() is invalid syntax?

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• Creating instance of a service-side DataContract class on client-side in WCF

  - by hgulyan

  Hi, I have my custom class Customer with its properties. I added DataContract mark above the class and DataMember to properties and it was working fine, but I'm calling a service class's function, passing customer instance as parameter and some of my properties get 0 values. While debugging I can see my properties values and after it gets to the function, some properties' values are 0. Why it can be so? There's no code between this two actions. DataContract mark workes fine, everything's ok. Any suggestions on this issue? I tried to change ByRef to ByVal, but it doesn't change anything. Why it would pass other values right and some of integer types just 0? Maybe the answer is simple, but I can't figure it out. Thank You. <DataContract()> Public Class Customer Private Type_of_clientField As Integer = -1 <DataMember(Order:=1)> Public Property type_of_client() As Integer Get Return Type_of_clientField End Get Set(ByVal value As Integer) Type_of_clientField = value End Set End Property End Class <ServiceContract(SessionMode:=SessionMode.Allowed)> <DataContractFormat()> Public Interface CustomerService <OperationContract()> Function addCustomer(ByRef customer As Customer) As Long End Interface type_of_client properties value is 6 before I call addCustomer function. After it enters that function the value is 0. UPDATE: The issue is in instance creating. When I create an instance of a class on client side, that is stored on service side, some of my properties pass 0 or nothing, but when I call a function of a service class, that returns a new instance of that class, it works fine. What's is the difference? Could that be serialization issue?

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• How to exclude R*.class files from a proguard build

  - by Jeremy Bell

  I am one step away from making the method described here: http://stackoverflow.com/questions/2761443/targeting-android-with-scala-2-8-trunk-builds work with a single project (vs one project for scala and one for android). I've come across a problem. Using this input file (arguments to) proguard: -injars bin;lib/scala-library.jar(!META-INF/MANIFEST.MF,!library.properties) -outjar lib/scandroid.jar -libraryjars lib/android.jar -dontwarn -dontoptimize -dontobfuscate -dontskipnonpubliclibraryclasses -dontskipnonpubliclibraryclassmembers -keepattributes Exceptions,InnerClasses,Signature,Deprecated, SourceFile,LineNumberTable,*Annotation*,EnclosingMethod -keep public class org.scala.jeb.** { public protected *; } -keep public class org.xml.sax.EntityResolver { public protected *; } Proguard successfully builds scandroid.jar, however it appears to have included the generated R classes that the android resource builder generates and compiles. In this case, they are located in bin/org/jeb/R*.class. This is not what I want. The android dalvik converter cannot build because it thinks there is a duplicate of the R class (it's in scandroid and also the R*.class files). How can I modify the above proguard arguments to exclude the R*.class files from the scandroid.jar so the dalvik converter is happy? Edit: I should note that I tried adding ;bin/org/jeb/R.class;etc... to the -libraryjars argument, and that only seemed to cause it to complain about duplicate classes, and in addition proguard decided to exclude my scala class files too.

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• matching an element's class to another element's ID, or *part* of another element's ID

  - by shecky

  hello again Such a simple concept but I'm struggling to express it ... apologies in advance for my verbosity. I have a container div with a class, e.g., ; I want to use that class to do two things: add a class (e.g., 'active') to the nav element whose ID matches the class of div#container (e.g., #nav-primary li# apples) add the same class to another element if part of this element's ID matches the class of #container (e.g., div#secondary-apples) I assume there's an .each() loop to check the primary nav's list items' IDs, and to check the div IDs of the secondary nav ... though the latter needs to have its prefix trimmed ... or should I say more simply if the secondary nav div IDs contain the class of div#container? I've tried a few variations of something like this: <script type="text/javascript"> $(document).ready(function() { $('#nav-primary li').each(function(){ var containerClass = $('#container').attr('class'); var secondaryID = $('#nav-primary li').attr('id'); // something like if ('#nav-primary li id' == (containerClass) { } // or should I first store a variable of the LI's ID and do something like this: if ( secondaryID == containerClass ) { } // and for the trickier part, how do I filter/trim the secondary nav div IDs, something like this: var secondaryNavID = $('#aux-left div[id ... something here to strip the 'secondary-' bit ... ]'); }); // end each }); // end doc.ready.func </script> The markup is, e.g.: ... ... ... ... ... ... ... Many thanks in advance for any suggestions, svs

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• Base class deleted before subclass during python __del__ processing

  - by Oddthinking

  Context I am aware that if I ask a question about Python destructors, the standard argument will be to use contexts instead. Let me start by explaining why I am not doing that. I am writing a subclass to logging.Handler. When an instance is closed, it posts a sentinel value to a Queue.Queue. If it doesn't, a second thread will be left running forever, waiting for Queue.Queue.get() to complete. I am writing this with other developers in mind, so I don't want a failure to call close() on a handler object to cause the program to hang. Therefore, I am adding a check in __del__() to ensure the object was closed properly. I understand circular references may cause it to fail in some circumstances. There's not a lot I can do about that. Problem Here is some simple example code: explicit_delete = True class Base: def __del__(self): print "Base class cleaning up." class Sub(Base): def __del__(self): print "Sub-class cleaning up." Base.__del__(self) x = Sub() if explicit_delete: del x print "End of thread" When I run this I get, as expected: Sub-class cleaning up. Base class cleaning up. End of thread If I set explicit_delete to False in the first line, I get: End of thread Sub-class cleaning up. Exception AttributeError: "'NoneType' object has no attribute '__del__'" in <bound method Sub.__del__ of <__main__.Sub instance at 0x00F0B698>> ignored It seems the definition of Base is removed before the x._del_() is called. The Python Documentation on _del_() warns that the subclass needs to call the base-class to get a clean deletion, but here that appears to be impossible. Can you see where I made a bad step?

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• Editing a .class file directly, playing around with opcodes

  - by echox

  Hi, today I just tried to play a little bit around with the opcodes in compiled java class file. After inserting iinc 1,1 the java virtual machine responds with: Exception in thread "main" java.lang.ClassFormatError: Truncated class file at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632) at java.lang.ClassLoader.defineClass(ClassLoader.java:616) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141) at java.net.URLClassLoader.defineClass(URLClassLoader.java:283) at java.net.URLClassLoader.access$000(URLClassLoader.java:58) at java.net.URLClassLoader$1.run(URLClassLoader.java:197) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:190) at java.lang.ClassLoader.loadClass(ClassLoader.java:307) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301) at java.lang.ClassLoader.loadClass(ClassLoader.java:248) Could not find the main class: Test. Program will exit. This is my example source code: public class Test { public static void main(String[] args) { int i = 5; i++; i++; i++; System.out.println("Number: " + i + "\n"); } } The opcode for an increment is 0x84 + 2 bytes for operands. There's only one section in the resulting class file, which contains 0x84: [..] 8401 0184 0101 8401 01[..] So I would translate this as: iinc 1,1 iinc 1,1 iinc 1,1 corresponding to my i++; i++; i++; I then tried to append just 840101 to increment the variable once more, but that didn't work and resulted in the ClassFormatError. Is there anything like a checksum for the class file? I looked up the format of a classfile in http://java.sun.com/docs/books/jvms/second_edition/html/ClassFile.doc.html but could not find anything which points out to some kind of bytes_of_classfile or something. I also don't understand why the error is "Truncated Class File", because I did append something :-) I know its not a good idea to edit class files directly, but I'm just interested on the VM internals here.

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