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  • dhcpd: varying vendor-class-identifier

    - by jessicah
    I'm having trouble selectively sending parameters in response to a DHCP Inform packet using groups (or even without, just using host declarations) for bootp stuff. My configuration file right now looks like: subnet 130.123.131.128 netmask 255.255.255.128 { allow unknown-clients; } host dev-mac-09 { option vendor-class-identifier "example-identifier"; hardware ethernet 10:9a:dd:51:ff:83; } If I put vendor-class-identifier in the global scope, using tcpdump I can see that the client receives the vendor class option successfully. If I take it out, and just keep it in the host scope (or group scope), the client never receives the option. Specifying option dhcp-parameter-request list 60 doesn't help either. I did try using a class definition inside a group, but then it applied even if the host wasn't a part of the group. As an aside, how do I get detailed logging? At least something to indicate what groups and things got used to generate the response to the client.

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  • How to set the VirtualDocumentRoot based on the files within

    - by Chuck Vose
    I'm trying to set up Apache to use the VirtualDocumentRoot directive but my sites aren't all exactly the same. Most of the sites have a drupal folder which should be the root but there are a few really old drupal sites, a few rails sites, some django sites, etc. that want the Document root to be / or some other folder. Is there a way to set up VirtualDocumentRoot based on a conditional or is there a way to use RewriteRule/Cond to detect that / is the incorrect folder if there is a drupal folder or a public folder? Here's what I have so far: <VirtualHost *:80> # Wildcard ServerAlias, this is the default vhost if no specific vhost matches first. ServerAlias *.unicorn.devserver.com # Automatic ServerName, based on the HTTP_HOST header. UseCanonicalName Off # Automatic DocumentRoot. This uses the 4th level domain name as the document root, # for example http://bar.foo.baz.com/ would respond with /Users/vosechu/Sites/bar/drupal. VirtualDocumentRoot /Users/vosechu/Sites/%-4/drupal </VirtualHost> Thanks in advance! -Chuck

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  • rJava - how to call an abstract class method?

    - by Sarah
    I am trying to create an R function that taps into my JAVA code. I have an abstract class, let's say StudentGroup, that has abstract methods, and one method "getAppropriateStudentGroup" which returns (based on config) a class which extends StudentGroup. This allows calling classes to behave the same regardless of which StudentGroups is actually appropriate. 1) How can I use rJava to call getAppropriateStudentGroup? and 2) How can I call the methods on the returned class? Thank you!

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  • Seeking web-based FTP client for very large file upload

    - by Paul M. Nguyen
    I have looked around for these for some time... the limits imposed by the web server and/or the dynamic programming environment (e.g. PHP) are far too restrictive for the application I'm working on. We need to be able to move large graphics and video files to and from clients (ranging from tens of MB to a few GB in a single file). Plain FTP with a proper desktop client will do the trick, and we're hosting this in Amazon EC2 with EBS. User management will be done from the office via webmin. Users are chroot-jailed into their home dir by proftpd. net2ftp will work for many clients, but we often need to move single files that approach 1GB or exceed 2-3GB which is way out of the range of any http-based uploader. So we turn to Java or Flash - can they do it? From within the web browser establish an FTP connection and grab a huge file? There are licensed applets and such out there, but none seem convincing. Again, I'm looking for some code that can speak FTP and read (& write?) the local disk, that is delivered in a web browser, and can move single files of 2GB+. The reason for having a web-based interface to FTP is to skip the software installation step for our clients. I will consider proper desktop client software as long as it's "portable" and at least Win+Mac and can be easily configured by lay-man users in a hurry.

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  • Virtualbox - differencing disk based on different differencing disk

    - by Klinki
    I'm trying to create differencing image based on differencing image in VirtualBox 4.2.18. Official documentation says it should be possible: http://www.virtualbox.org/manual/ch05.html#diffimages Basically I want to achieve this drive hierarchy: + immutable image with Debian and all software installed +---- differencing image with specific configuration, autoreset=off, readonly +-------- differencing image with autoreset=on +---- another differencing image for different virtual machine +-------- differencing image with autoreset=on I successfully created differencing image based on differencing image, but I'm not able to connect it to virtual machine :( It always shows error: Failed to open the hard disk .... cannot register hard disk ... because hard disk with UUID ... already exists Here is screenshot of Virtual Media Manager and error dialog Virtual Media Manager Window screenshot Very strange is that the new differencing image (tempdrive.vdi) doesn't have Actual Size 0. I wasn't able to connect it, but still, it has 36KB of data on it... This is very similar to this older question: How to create a chained differencing disk of another differencing disk in Virtual Box? but suggested solution is not working anymore in VirtualBox 4.2.18, so I posted it as a new question. (Limit for posting links and screenshots is quite annoying..)

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  • DNS-Based Environment Determination

    - by zvolkov
    Found the following here. The questions is: where can I find more details on how exactly implement this on Windows? Any guide or how-to anybody? Or maybe you can provide your invaluable suggestions? Specifically, how do I make so that "all QA servers would first resolve entries in qa.example.com first and then if that lookup failed they would try example.com" (I'm a dev, not a DNS specialist, but our IT Support has refused to help on this:() Use DNS Based Environment Determination for your servers. Do this by initially splitting your top level domain into a number of sub domains depending on their function, and then creating DNS Service Names in each of the sub domains pointing to the relevant server for that service. Based on the list above we would then have: * clientdb.prod.example.com for Production * clientdb.perf.example.com for Performance Testing * clientdb.qa.example.com for QA * clientdb.dev.example.com for Development Servers then resolve entries in their relevant sub domain by function. That is, all QA servers would first resolve entries in qa.example.com first and then if that lookup failed they would try example.com. This allows you to have a single configuration entry for your client database hostname (clientdb) that would resolve correctly in all environments. This technique has the added advantage of still having global services defined in a common top level domain. This seems to be related to Providing "split horizon" DNS service. Reading that, I see that I will probably need separate DNS Server for each environment. Is this true or does Windows support some form of "tagging" the records to be visible depending on the requestor's IP?

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  • Cisco ASA 5510 Time of Day Based Policing

    - by minamhere
    I have a Cisco ASA 5510 setup at a boarding school. I determined that many (most?) of the students were downloading files, watching movies, etc, during the day and this was causing the academic side of our network to suffer. The students should not even be in their rooms during the day, so I configured the ASA to police their network segment and limit their outbound bandwidth. This resolved all of our academic issues, and everyone was happy. Except the resident students. I have been asked to change/remove the policing policy at the end of the day, to allow the residents access to the unused bandwidth at night. There's no reason to let bandwidth sit unused at night just because it would be abused during the day. Is there a way to setup Time of Day based Policies on the ASA? Ideally I'd like to be able to open up the network at night and all day during weekends. If I can't set Time based policies, is is possible to schedule the ASA to load a set of commands at a specific time? I suppose I could just setup a scheduled task on one of our servers to log in and make the changes with a simple script, but this seems like a hack, and I'm hoping there is a better or more standard way to accomplish this. Thanks. Edit: If there is a totally different solution that would accomplish a similar goal, I'd be interested in that as well. Free/Cheap would be ideal, but if a separate internet connection is my only other option, it might be worth fighting for money for hardware or software to do this better or more efficiently.

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  • Require a very simple bash-based webserver for logging XML POST [on hold]

    - by Syffys
    As in title, it's for testing purpose and I need it to be extremely light (1 line to 1 single light file). Here is a XML query sample: XML_QUERY=$(cat <<EOF <?xml version='1.0' encoding='UTF-8'?> <Test></Test> EOF ) curl -H "Content-type: text/xml; charset=utf-8" -H "Soapaction: \"\"" -k -d "${XML_QUERY}" http://localhost:8088 Here are some of the tracks I have found so far even if I wasnt able to adapt them to work as I expect: Netcat minimal webserver: Problem is that my nc does not have the -q option, so the connection is closing before delivering the XML content Netcat Only webserver: Same as above Thanks in advance! EDIT: As it's been asked, I'm running Linux Redhat, even if the distro does not really matter and the OS implied since I'm asking a bash-based solution... Also about my topic being on hold: "Instead, describe your situation and the specific problem you're trying to solve" = I though this was exactly what I was doing, but ok I'll reword: My situation: bash environment (which can also include some standard linux tool: netcat, python or whatever) My specific problem: please see title: Require a very simple bash-based webserver for logging XML in HTTP POST for testing purpose

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  • a brand new FS based on a database without using fuse

    - by Devrim
    hi all, To serve millions of files out of a single directory, being able to connect to a drive from hundreds of endpoints, and for some other reasons (to avoid gluster/nfs/all fs based networking solutions), I want to evaluate the possibility of making a filesystem that's based on a mongodb (or any other). Basically, it works like fusefs, every single file is kept in mongo gridfs. In theory, I do, mount mongodbfs /mountPoint mongodb://localhost then when i say touch /mountPoint/test.txt this file is inserted into mongodb. This FS will also store uid/gid and perms with the file, we can throw hundreds of servers to it, and no useradd will be necessary. I'm not thinking to include all the features of FS, just the ones we need. My question is, how do I start my quest in finding resources, books, links, people, developers who'd help me implement this? at least a proof of concept. Is it feasible? What should I expect as a timeline for such undertaking? Please only think about gazillion small files and folders.

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  • Why should I use a puppet parameterized class?

    - by robbyt
    Generally when working with complex puppet modules, I will set variables at the node level or inside a class. e.g., node 'foo.com' { $file_owner = "larry" include bar } class bar { $file_name = "larry.txt" include do_stuff } class do_stuff { file { $file_name: ensure => file, owner => $file_owner, } } How/when/why does parametrized classes help when this situation? How are you using parametrized classes to structure your puppet modules?

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  • Web based KVM management for Ubuntu

    - by Tim
    We've got a single Ubuntu 9.10 root server on which we want to run multiple KVM virtual machines. To administer these virtual machines I'd like a web based KVM management tool, but I don't know which one to choose from the list of tools mentioned on linux-kvm.org. I've used virsh & virt-manager on my desktop, but would like a web interface for the server. I tested ConVirt on my desktop, but it failed to pickup KVM machines from virsh / virt-manager, and I could not get KVM virtual machine import to work (only Xen). oVirt looks good, but I can't find out if and how I can install it on Ubuntu 9.10.. (And I'd really rather not waste another few days on testing stuff that might not work in the end.) Can anyone recommend any good web based KVM management tools that are easy to install on Ubuntu 9.10? I'm looking for something that will also allow me to run other services like apache and postgresql besides hosting virtual machines, so preferably fairly lightweight & no dedicated OS installs. We don't need any professional clustering / migration or anything, just something that will let us create, start, inspect, administer & stop virtual machines from a web page. Best regards, Tim Update: Anyone have any suggestions? It's awfully quiet here..

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  • Ways to parse NCSA combined based log files

    - by Kyle
    I've done a bit of site: searching with Google on Server Fault, Super User and Stack Overflow. I also checked non site specific results and and didn't really see a question like this, so here goes... I did spot this question, related to grep and awk which has some great knowledge but I don't feel the text qualification challenge was addressed. This question also broadens the scope to any platform and any program. I've got squid or apache logs based on the NCSA combined format. When I say based, meaning the first n col's in the file are per NCSA combined standards, there might be more col's with custom stuff. Here is an example line from a squid combined log: 1.1.1.1 - - [11/Dec/2010:03:41:46 -0500] "GET http://yourdomain.com:8080/en/some-page.html HTTP/1.1" 200 2142 "-" "Mozilla/5.0 (Windows; U; Windows NT 6.1; C) AppleWebKit/532.4 (KHTML, like Gecko)" TCP_MEM_HIT:NONE I'd like to be able to parse n logs and output specific columns, for sorting, counting, finding unique values etc The main challenge and what makes it a little tricky and also why I feel this question hasn't yet been asked or answered, is the text qualification conundrum. When I spotted asql from the grep/awk question, I was very excited but then realised that it didn't support combined out of the box, something I'll look at extending I guess. Looking forward to answers, and learning new stuff! Answers doesn't have to be limited to platform or program/language. For the context of this question, the platforms I use the most are Linux or OSX. Cheers

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  • Recommend a UK based VPS host equivalent to Dreamhost [closed]

    - by Pez Cuckow
    I appreciate this question could be considered subjective and argumentative so can people make recommendations rather than arguing about the best. I believe the "correct" answer is the one closest to what I am looking for. Basically I live in the UK but have been using the US based Dreamhost for about 6 years now, and my web projects are getting to the scale where the websites need to the UK based to cope with the demand and load. I originally had shared hosting with Dreamhost but upgraded to a VPS a while ago, getting 512mb of RAM, unlimited disk space, bandwidth and domains for $30. Their control panel is a custom easy to use build that they have created in house and offers features very similar to other web panels (as far as I am aware). So basically my question boils down to, is there anywhere that offers an equivalent package? In all honesty as long as I have over 50gb HDD space and unlimited domains it doesn't really matter? Are there any VPS providers you would recommend as reliable? I promise to check every link posted, many thanks for your time!

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  • Why should I use a puppet parametrized class?

    - by robbyt
    Generally when working with complex puppet modules, I will set variables at the node level or inside a class. e.g., node 'foo.com' { $file_owner = "larry" include bar } class bar { $file_name = "larry.txt" include do_stuff } class do_stuff { file { $file_name: ensure => file, owner => $file_owner, } } How/when/why does parametrized classes help when this situation? How are you using parametrized classes to structure your puppet modules?

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  • VPN: Disable class based route addition for Windows XP/Vista

    - by brgsousa
    Paraphrasing this SuperUser link: When you set up a VPN, the Windows default is to enable "Use default gateway on remote network." A new default route is added to the routing table pointing to the remote network's gateway, and the existing default route has its metric increased to force all Internet traffic to traverse the tunnel and use the remote network's gateway. All traffic uses the VPN, and traffic destined for the outside world is directed to the remote gateway. When the VPN drops, the route to the remote gateway is removed and the original default route is set back to the original metric. Unchecking "use default gateway on remote network" means that new default route isn't added, so Internet traffic goes out the local gateway, but a new classful route is added to the routing table, using the local adapter's IP, pointing down the VPN. Only traffic destined for the classful network of the local adapter goes down the VPN. This may not be what you want. Checking "Disable class based route addition" means that classful route isn't added to your machine when the VPN starts up, and you'll need to add the appropriate routes for networks that should be routed through the tunnel. But, the option "Disable class based route addition" is available ONLY for Windows 7. How can I do something like that for Windows XP or Vista since they don't have that option? I have searched about for that but, no solution yet.

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  • Using Openfire for distributed XMPP-based video-chat

    - by Yitzhak
    I have been tasked with setting up a distributed video-chat system built on XMPP. Currently my setup looks like this: Openfire (XMPP server) + JingleNodes plugin for video chat OpenLDAP (LDAP server) for storing user information and allowing directory queries Kerberos server for authentication and passwords In testing with one set of machines (i.e. only three), everything works as expected: I can log in to Openfire and it looks up the user information in the OpenLDAP database, which in turn authenticates my user with Kerberos. Now, I want to have several clusters, so that there is a cluster on each continent. A typical cluster will probably contain 2-5 servers. Users logging in will be directed to the closest cluster based on geographical location. Something that concerns me particularly is the dynamic maintenance of contact lists. If a user is using a machine in Asia, for example, how would contact lists be updated around the world to reflect the current server he is using? How would that work with LDAP? Specific questions: How do I direct users based on geographical location? What is the best architecture for a cluster? -- would all traffic need to come into a load-balancer on each one, for example? How do I manage the update of contact lists across all these servers? In general, how do I go about setting this up? What are the pitfalls in doing this? I am inexperienced in this area, so any advice and suggestions would be appreciated.

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  • Flash CS3/AS3 - How to Mask Nested MovieClips in External Classes

    - by Max Jackson
    I have a number of external class files that make up (or are trying to build) a portfolio. One of the class files for this project is a Menu.as class I tried extends, but I'm yet to use extends to where it doesn't become a ball of tangled holiday cheer. So my main portfolio class (the one where I'm assembling everything) calls an instance of the Menu class. From the Preloader through the Portfolio class into the Menu class is where I'm passing the content because I want to package things properly. This is Menu content, so naturally I want to position it in a properly names spot. I'm trying to reveal this Menu in a mask and I'm getting the old #1009 error. In a trace, this will work: trace(site_mc.menu_mc.mainMask_mc); // returns [object mainMask_mc_4] However, when I try to truncate the string into a single compact_mc... compactMenu_mc = site_mc.menu_mc.mainMask_mc; trace(compact_mc); // it won't trace (#1009). I said to hell with it, but now I need to have one MovieClip mask another. So I figure I can't go all... parent.parent.parent.clip_mc.mask = parent.parent.parent.masked_mc Probably because of datatyping and whatever else. I hate to be vague, but I'm new and have been working like gangbusters for days to get this portfolio up. Any suggestions or pointers on things my noob brain might've missed are given much thanks. :)

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  • Should I use a collection here?

    - by Eva
    So I have code set up like this: public interface IInterface { public void setField(Object field); } public abstract class AbstractClass extends JPanel implements IInterface { private Object field_; public void setField(Object field) { field_ = field; } } public class ClassA extends AbstractClass { public ClassA() { // unique ClassA constructor stuff } public Dimension getPreferredSize() { return new Dimension(1, 1); } } public class ClassB extends AbstractClass { public ClassB() { // unique ClassB constructor stuff } public Dimension getPreferredSize() { return new Dimension(42, 42); } } public class ConsumerA { public ConsumerA(Collection<AbstractClass> collection) { for (AbstractClass abstractClass : collection) { abstractClass.setField(this); abstractClass.repaint(); } } } All hunky-dory so far, until public class ConsumerB { // Option 1 public ConsumerB(ClassA a, ClassB b) { methodThatOnlyTakesA(a); methodThatOnlyTakesB(b); } // Option 2 public ConsumerB(Collection<AbstractClass> collection) { for (IInterface i : collection) { if (i instanceof ClassA) { methodThatOnlyTakesA((ClassA) i); else if (i instanceof ClassB) { methodThatOnlyTakesB((ClassB) i); } } } } public class UsingOption1 { public static void main(String[] args) { ClassA a = new ClassA(); ClassB b = new ClassB(); Collection<AbstractClass> collection = Arrays.asList(a, b); ConsumerA consumerA = new ConsumerA(collection); ConsumerB consumerB = new ConsumerB(a, b); } } public class UsingOption2 { public static void main(String[] args) { Collection<AbstractClass> collection = Arrays.asList(new ClassA(), new ClassB()); ConsumerA = new ConsumerA(collection); ConsumerB = new ConsumerB(collection); } } With a lot more classes extending AbstractClass, both options get unwieldly. Option1 would make the constructor of ConsumerB really long. Also UsingOption1 would get long too. Option2 would have way more if statements than I feel comfortable with. Is there a viable Option3? If it helps, ClassA and ClassB have all the same methods, they're just implemented differently. Thanks for slogging through my code!

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  • How would i go about showing the closest paragraph element to a unique link with jQuery?

    - by Nike
    The title is a bit rusty, sorry about that. Now let me explain what i'm trying to do. I have a few listed items, like this: <li> <a id="toggle" class="0"><h4>ämne<small>2010-04-17 kl 12:54</small></h4></a> <p id="meddel" class="0">text</p> </li> <li class='odd'> <a id="toggle" class="1"><h4>test<small>2010-04-17 kl 15:01</small></h4></a> <p id="meddel" class="1">test meddelande :) [a]http://youtube.com[/a]</p> </li> The function i'm trying to achieve, is that when a user clicks a "toggle" link (the h4 text), i want the paragraph element below it to fade in. I thought of the idea of giving both the toggle link and the paragraph the same class, and then somehow make it get the paragraph with the same class as the toggle link clicked, and show it? But i'm not entirely sure how to do that either, and tbh, it doesn't sound like the greatest idea, but maybe that's the only way? I don't know... Is there some way to just simply get the nearest paragraph (below the link) with the id "meddel" and fade it in? That sounds a bit easier... I hope you can at least give me a few hints. Thanks in advance, -Nike

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  • Disabling checkboxes based on selection of another checkbox in jquery

    - by Prady
    Hi, I want to disable a set of checkbox based on selection of one textbox and enable the disabled ones if the checkbox is unchecked. In the code below. If someone checks the checkbox for project cost under change this parameter then checkbox for project cost under Generate simulated value for this param should be disabled and all the checkboxes under change this parameter should be disabled except for checked one. Similarly this should be done each parameter like Project cost,avg hours,Project completion date, hourly rate etc. One way i could think of was of on the click function disable each checkbox by the id. Is there a better way of doing it? <table> <tr> <td></td> <td></td> <td>Change this parameter</td> <td>Generate simulated value for this param</td> </tr> <tr> <td>Project cost</td> <td><input type ="text" id ="pc"/></td> <td><input class="change" type="checkbox" name="chkBox" id="chkBox"></input></td> <td><input class="sim" type="checkbox" name="chkBox1" id="chkBox1"></input></td> </tr> <tr> <td>Avg hours</td> <td><input type ="text" id ="avghrs"/></td> <td><input class="change" type="checkbox" name="chkBoxa" id="chkBoxa"></input></td> <td><input class="sim" type="checkbox" name="chkBox1a" id="chkBox1a"></input></td> </tr> <tr> <td>Project completion date</td> <td><input type ="text" id ="cd"/></td> <td><input class="change" type="checkbox" name="chkBoxb" id="chkBoxb"></input></td> <td><input class="sim" type="checkbox" name="chkBox1b" id="chkBox1b"></input></td> </tr> <tr> <td>Hourly rate</td> <td><input type ="text" id ="hr"/></td> <td><input class="change" type="checkbox" name="chkBoxc" id="chkBoxc"></input></td> <td><input class="sim" type="checkbox" name="chkBox1c" id="chkBox1c"></input></td> </tr> </table> Thanks Prady

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  • protected abstract override Foo(); &ndash; er... what?

    - by Muljadi Budiman
    A couple of weeks back, a co-worker was pondering a situation he was facing.  He was looking at the following class hierarchy: abstract class OriginalBase { protected virtual void Test() { } } abstract class SecondaryBase : OriginalBase { } class FirstConcrete : SecondaryBase { } class SecondConcrete : SecondaryBase { } Basically, the first 2 classes are abstract classes, but the OriginalBase class has Test implemented as a virtual method.  What he needed was to force concrete class implementations to provide a proper body for the Test method, but he can’t do mark the method as abstract since it is already implemented in the OriginalBase class. One way to solve this is to hide the original implementation and then force further derived classes to properly implemented another method that will replace it.  The code will look like the following: abstract class OriginalBase { protected virtual void Test() { } } abstract class SecondaryBase : OriginalBase { protected sealed override void Test() { Test2(); } protected abstract void Test2(); } class FirstConcrete : SecondaryBase { // Have to override Test2 here } class SecondConcrete : SecondaryBase { // Have to override Test2 here } With the above code, SecondaryBase class will seal the Test method so it can no longer be overridden.  Then it also made an abstract method Test2 available, which will force the concrete classes to override and provide the proper implementation.  Calling Test will properly call the proper Test2 implementation in each respective concrete classes. I was wondering if there’s a way to tell the compiler to treat the Test method in SecondaryBase as abstract, and apparently you can, by combining the abstract and override keywords.  The code looks like the following: abstract class OriginalBase { protected virtual void Test() { } } abstract class SecondaryBase : OriginalBase { protected abstract override void Test(); } class FirstConcrete : SecondaryBase { // Have to override Test here } class SecondConcrete : SecondaryBase { // Have to override Test here } The method signature makes it look a bit funky, because most people will treat the override keyword to mean you then need to provide the implementation as well, but the effect is exactly as we desired.  The concepts are still valid: you’re overriding the Test method from its original implementation in the OriginalBase class, but you don’t want to implement it, rather you want to classes that derive from SecondaryBase to provide the proper implementation, so you also make it as an abstract method. I don’t think I’ve ever seen this before in the wild, so it was pretty neat to find that the compiler does support this case.

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  • Is this way of storing typed objects in memory good?

    - by Pindatjuh
    This is an "is this okay, or can it be done better" question. Topic: Storing typed objects in memory. Background information: I'm building a compiler for the x86-32 platform for my language. My goal includes typed objects. Idea: Every primitive is a semi-class (it can be used as if it was a normal class, but it's stored more compact). Every class is represented by primitives and some meta-data (containing class-properties, inheritance stuff, etc.). The meta-data is complex: it doesn't use fields but instead context-switches. For primitives, the meta-data is very small, compared to a "real" class, which is alot bigger. This enables another idea that "primitives are objects", in my language, which I found nessecairy. Example: If I have an array of 32 booleans, then the pure content of this array is exactly 4 byte (32 bits of booleans). The meta-data will contain flags that the type is an array of booleans, which contains 32 entries. The meta-data is very compacted, on bit-level: using a sort of "packing" mechanism, which is read by a FSM at runtime, when doing inspection of the type (like when passing the object to methods for checking, etc.) For instance (read from left to right, top to bottom, remember vertical possition when going to the right, and check nearest column header for meaning of switch): Primitive? Array? Type-Meta 1 Byte? || Size (1 byte) 1 1 [...] 1 [...] done 0 2 Bytes? || Size (2 bytes) 1 [...] done || Size (4 bytes) 0 [...] done Integer? 1 Byte? 2 Bytes? 0 1 0 1 done 1 done 0 done Boolean? Byte? 0 1 0 done 1 done More-Primitives 0 .... Class-Stuff (Huge) 0 ... (After reaching done the data is inserted. || = byte alignement. [...] is variable sized. ... is not described here, for simplicity. And let's call them cost-based-data-structures.) For an array of 32 booleans containing all true values, the memory for this type would be (read top-down): 1 Primitive 1 Array 1 ArrayType: Primitive 0 Not-Array 0 Not-Integer 1 Boolean 0 Not-Byte (thus bit) 1 Integer Size: 1 Byte 00100000 Array size 11111111 11111111 11111111 11111111 Data Thus, 8 bytes represent 32 booleans in an array: 11100101 00100000 11111111 11111111 11111111 11111111 Is this okay, or can it be done better?

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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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  • 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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