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• Is there an ORM that supports composition w/o Joins

  - by Ken Downs

  EDIT: Changed title from "inheritance" to "composition". Left body of question unchanged. I'm curious if there is an ORM tool that supports inheritance w/o creating separate tables that have to be joined. Simple example. Assume a table of customers, with a Bill-to address, and a table of vendors, with a remit-to address. Keep it simple and assume one address each, not a child table of addresses for each. These addresses will have a handful of values in common: address 1, address 2, city, state/province, postal code. So let's say I'd have a class "addressBlock" and I want the customers and vendors to inherit from this class, and possibly from other classes. But I do not want separate tables that have to be joined, I want the columns in the customer and vendor tables respectively. Is there an ORM that supports this? The closest question I have found on StackOverflow that might be the same question is linked below, but I can't quite figure if the OP is asking what I am asking. He seems to be asking about foregoing inheritance precisely because there will be multiple tables. I'm looking for the case where you can use inheritance w/o generating the multiple tables. Model inheritance approach with Django's ORM

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• Exporting WPF DataGrid to a text file in a nice looking format. Text file must be easy to read.

  - by Andrew

  Hi, Is there a simple way to export a WPF DataGrid to a text file and a .csv file? I've done some searching and can't see that there is a simple DataGrid method to do so. I have got something working (barely) by making use of the ItemsSource of the DataGrid. In my case, this is an array of structs. I do something with StreamWriters and StringBuilders (details available) and basically have: StringBuilder destination = new StringBuilder(); destination.Append(row.CreationDate); destination.Append(seperator); // seperator is '\t' or ',' for csv file destination.Append(row.ProcId); destination.Append(seperator); destination.Append(row.PartNumber); destination.Append(seperator); I do this for each struct in the array (in a loop). This works fine. The problem is that it's not easy to read the text file. The data can be of different lengths within the same column. I'd like to see something like: 2007-03-03 234238423823 823829923 2007-03-03 66 99 And of course, I get something like: 2007-03-03 234238423823 823829923 2007-03-03 66 99 It's not surprising giving that I'm using Tab delimiters, but I hope to do better. It certainly is easy to read in the DataGrid! I could of course have some logic to pad short values with spaces, but that seems quite messy. I thought there might be a better way. I also have a feeling that this is a common problem and one that has probably been solved before (hopefully within the .NET classes themselves). Thanks.

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• Web Shop Schema - Document Db

  - by Maxem

  I'd like to evaluate a document db, probably mongo db in an ASP.Net MVC web shop. A little reasoning at the beginning: There are about 2 million products. The product model would be pretty bad for rdbms as there'd be many different kinds of products with unique attributes. For example, there'd be books which have isbn, authors, title, pages etc as well as dvds with play time, directors, artists etc and quite a few more types. In the end, I'd have about 9 different products with a combined column count (counting common columns like title only once) of about 70 to 100 whereas each individual product has 15 columns at most. The three commonly used ways in RDBMS would be: EAV model which would have pretty bad performance characteristics and would make it either impractical or perform even worse if I'd like to display the author of a book in a list of different products (think start page, recommended products etc.). Ignore the column count and put it all in the product table: Although I deal with somewhat bigger databases (row wise), I don't have any experience with tables with more than 20 columns as far as performance is concered but I guess 100 columns would have some implications. Create a table for each product type: I personally don't like this approach as it complicates everything else. C# Driver / Classes: I'd like to use the NoRM driver and so far I think i'll try to create a product dto that contains all properties (grouped within detail classes like book details, except for those properties that should be displayed on list views etc.). In the app I'll use BookBehavior / DvdBehaviour which are wrappers around a product dto but only expose the revelent Properties. My questions now: Are my performance concerns with the many columns approach valid? Did I overlook something and there is a much better way to do it in an RDBMS? Is MongoDb on Windows stable enough? Does my approach with different behaviour wrappers make sense?

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• C++0x rvalue references and temporaries

  - by Doug

  (I asked a variation of this question on comp.std.c++ but didn't get an answer.) Why does the call to f(arg) in this code call the const ref overload of f? void f(const std::string &); //less efficient void f(std::string &&); //more efficient void g(const char * arg) { f(arg); } My intuition says that the f(string &&) overload should be chosen, because arg needs to be converted to a temporary no matter what, and the temporary matches the rvalue reference better than the lvalue reference. This is not what happens in GCC and MSVC. In at least G++ and MSVC, any lvalue does not bind to an rvalue reference argument, even if there is an intermediate temporary created. Indeed, if the const ref overload isn't present, the compilers diagnose an error. However, writing f(arg + 0) or f(std::string(arg)) does choose the rvalue reference overload as you would expect. From my reading of the C++0x standard, it seems like the implicit conversion of a const char * to a string should be considered when considering if f(string &&) is viable, just as when passing a const lvalue ref arguments. Section 13.3 (overload resolution) doesn't differentiate between rvalue refs and const references in too many places. Also, it seems that the rule that prevents lvalues from binding to rvalue references (13.3.3.1.4/3) shouldn't apply if there's an intermediate temporary - after all, it's perfectly safe to move from the temporary. Is this: Me misreading/misunderstand the standard, where the implemented behavior is the intended behavior, and there's some good reason why my example should behave the way it does? A mistake that the compiler vendors have somehow all made? Or a mistake based on common implementation strategies? Or a mistake in e.g. GCC (where this lvalue/rvalue reference binding rule was first implemented), that was copied by other vendors? A defect in the standard, or an unintended consequence, or something that should be clarified?

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• How to write custom (odd) authentication plugins for Wordpress, Joomla and MediaWiki?

  - by Bart van Heukelom

  On our network (a group of related websites - not a LAN) we have a common authentication system which works like this: On a network site ("consumer") the user clicks on a login link This redirects the user to a login page on our auth system ("RAS"). Upon successful login the user is directed back to the consumer site. Extra data is passed in the query string. This extra data does not include any information about the user yet. The consumer site's backend contacts RAS, with this extra data, to get the information about the logged in user (id, name, email, preferences, etc.). So as you can see, the consumer site knows nothing about the authentication method. It doesn't know if it's by username/password, fingerprint, smartcard, or winning a game of poker. This is the main problem I'm encountering when trying to find out how I could write custom authentication plugins for these packages, acting as consumer sites: Wordpress Joomla MediaWiki For example Joomla offers a pretty simple auth plugin system, but it depends on a username/password entered on the Joomla site. Any hints on where to start?

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• Django: How to dynamically add tag field to third party apps without touching app's source code

  - by Chris Lawlor

  Scenario: large project with many third party apps. Want to add tagging to those apps without having to modify the apps' source. My first thought was to first specify a list of models in settings.py (like ['appname.modelname',], and call django-tagging's register function on each of them. The register function adds a TagField and a custom manager to the specified model. The problem with that approach is that the function needs to run BEFORE the DB schema is generated. I tried running the register function directly in settings.py, but I need django.db.models.get_model to get the actual model reference from only a string, and I can't seem to import that from settings.py - no matter what I try I get an ImportError. The tagging.register function imports OK however. So I changed tactics and wrote a custom management command in an otherwise empty app. The problem there is that the only signal which hooks into syncdb is post_syncdb which is useless to me since it fires after the DB schema has been generated. The only other approach I can think of at the moment is to generate and run a 'south' like database schema migration. This seems more like a hack than a solution. This seems like it should be a pretty common need, but I haven't been able to find a clean solution. So my question is: Is it possible to dynamically add fields to a model BEFORE the schema is generated, but more specifically, is it possible to add tagging to a third party model without editing it's source. To clarify, I know it is possible to create and store Tags without having a TagField on the model, but there is a major flaw in that approach in that it is difficult to simultaneously create and tag a new model.

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• Need feedback on two member functions of a Table class in C++

  - by George

  int Table::addPlayer(Player player, int position) { deque<Player>::iterator it = playerList.begin()+position; deque<Player>::iterator itStart = playerList.begin()+postion; while(*it != "(empty seat)") { it++; if (it == playerList.end()) { it = playerList.begin(); } if (it == itStart) { cout << "Table full" << endl; return -1; } } //TODO overload Player assignment, << operator *it = player; cout << "Player " << player << " sits at position " << it - playerList.begin() << endl; return it - playerList.begin(); } } int Table::removePlayer(Player player) { deque<Player>::iterator it = playerList.begin(); //TODO Do I need to overload != in Player? while(*it != player) { it++; if (it == playerList.end()) { cout << "Player " << player << " not found" << endl; return -1; } } *it = "(empty seat)"; cout << "Player " << player << " stands up from position " << it - playerList.begin() << endl; return it - playerList.begin(); } Would like some feedback on these two member functions of a Table class for Texas Hold Em Poker simulation. Any information syntax, efficiency or even common practices would be much appreciated.

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• how can a Win32 App plugin load its DLL in its own directory

  - by Jean-Denis Muys

  My code is a plugin for a specific Application, written in C++ using Visual Studio 8. It uses two DLL from an external provider. Unfortunately, my plugin fails to start because the DLLs are not found (I put them in the same directory as the plugin itself). When I manually move or copy the DLLs to the host application directory, then the plugin loads fine. This moving was deemed unacceptably cumbersome for the end user, and I am looking for a way for my plugin to load its DLLs transparently. What can I do? Relevant details: the host Application plugins are located in a directory mandated by the host application. That directory is not in the DLL search path and I don't control it. The plugin is itself packaged as a subdirectory of the plugin directory, holding the plugin code itself, but also any resource associated with the plugin (eg images, configuration files…). I control what's inside that subdirectory, called a "bundle", but not where it's located. the common plugin installation idiom for that App is for the end user to copy the plugin bundle to the plugin directory. This plugin is a port from the Macintosh version of the plugin. On the Mac there is no issue because each binary contains its own dynamic library search path, which I set as I needed to for my plugin binary. To set that on the Mac simply involves a project setting in the Xcode IDE. This is why I would hope for something similar in Visual Studio, but I could not find anything relevant. Moreover, Visual Studio's help was anything but, and neither was Google. A possible workaround would be for my code to explicitly tell Windows where to find the DLL, but I don't know how, and in any case, since my code is not even started, it hasn't got the opportunity to do so. As a Mac developer, I realize that I may be asking for something very elementary. If such is the case, I apologize, but I have run out of hair to pull out.

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• git: correct way to merge/rebase with respect to svn dcommit

  - by Albert

  I have the following situation (mostly because I didn't really thought it through in the beginning -- or more exactly, I thought it shouldn't be a problem the way I did this but now I am stumbled): ... --- A --- B1 --- ... --- Bn ... --- git-svn Whereby A and git-svn are at the same state (exactly the same files and file content) but they don't have any common point in history. And I want: ... --- git-svn --- B1 --- ... --- Bn Or at least, when I do the svn dcommit, I want exactly to get the commits B1 to Bn and nothing else. I am not exactly sure how dcommit works. So if I would get something like this: ... ------------ A --- B1 --- ... --- Bn \ \ ... --- git-svn -- A' ----------------- B' would the dcommit behave in the way I want? Because if so, that would be easy to get (merging A into git-svn does work just fine because they are content-wise the same). Or should I do some sort of rebase? But I don't want to rebase A on git-svn, just B1 to Bn.

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• Does a CS PhD Help for Software Engineering Career?

  - by SiLent SoNG

  I would like to seek advice on whether or not to take a PhD offer from a good university. My only concern is the PhD will take at least 4 year's commitment. During the period I won't have good monetary income. I am also concerned whether the PhD will help my future career development. My career goal is software engineering only. Some of the PhD info: The PhD is CS related. The research area is Information Retrieval, Machine Learning, and Nature Language Processing. More specifically, the research topic is Deep Web search. Some of backgrounds: I worked in Oracle for 3 years in database development after obtained a CS degree from some good university. In last year I received an email telling an interesting project from a professor and thereafter I was lured into his research team. The team consists of 4 PhD students; those students have little or no industry experiences and their coding skills are really really bad. By saying bad I mean they do not know some common patterns and they do not know pitfalls of the programming languages as well as idioms for doing things right. I guess a at least 4 year commitment is worth of serious consideration. I am 27 at this moment. If I take the offer, that implies I will be 31+ upon graduation. Wah... becoming.. what to say, no longer young. Hence, here I am seeking advice on whether it is good or not to take the PhD offer, and whether a CS PhD is good for my future career growth as a software engineer? I do not intent to go for academia.

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• Django: DatabaseLockError exception with Djapian

  - by jul

  Hi, I've got the exception shown below when executing indexer.update(). I have no idea about what to do: it used to work and now index database seems "locked". Anybody can help? Thanks Environment: Request Method: POST Request URL: http://piem.org:8000/restaurant/add/ Django Version: 1.1.1 Python Version: 2.5.2 Installed Applications: ['django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.comments', 'django.contrib.sites', 'django.contrib.admin', 'registration', 'djapian', 'resto', 'multilingual'] Installed Middleware: ('django.middleware.common.CommonMiddleware', 'django.contrib.sessions.middleware.SessionMiddleware', 'django.contrib.auth.middleware.AuthenticationMiddleware', 'django.middleware.locale.LocaleMiddleware', 'multilingual.middleware.DefaultLanguageMiddleware') Traceback: File "/var/lib/python-support/python2.5/django/core/handlers/base.py" in get_response 92. response = callback(request, *callback_args, **callback_kwargs) File "/home/jul/atable/../atable/resto/views.py" in addRestaurant 639. Restaurant.indexer.update() File "/home/jul/python-modules/Djapian-2.3.1-py2.5.egg/djapian/indexer.py" in update 181. database = self._db.open(write=True) File "/home/jul/python-modules/Djapian-2.3.1-py2.5.egg/djapian/database.py" in open 20. xapian.DB_CREATE_OR_OPEN, File "/usr/lib/python2.5/site-packages/xapian.py" in __init__ 2804. _xapian.WritableDatabase_swiginit(self,_xapian.new_WritableDatabase(*args)) Exception Type: DatabaseLockError at /restaurant/add/ Exception Value: Unable to acquire database write lock on /home/jul/atable /djapian_spaces/resto/restaurant/resto.index.restaurantindexer: already locked

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• How can I make a family of singletons?

  - by Jay

  I want to create a set of classes that share a lot of common behavior. Of course in OOP when you think that you automatically think "abstract class with subclasses". But among the things I want these classes to do is to each have a static list of instances of the class. The list should function as sort of a singleton within the class. I mean each of the sub-classes has a singleton, not that they share one. "Singleton" to that subclass, not a true singleton. But if it's a static, how can I inherit it? Of course code like this won't work: public abstract A { static List<A> myList; public static List getList() { if (myList==null) myList=new ArrayList<A>(10); return myList; } public static A getSomethingFromList() { List listInstance=getList(); ... do stuff with list ... } public int getSomethingFromA() { ... regular code acting against current instance ... } } public class A1 extends A { ... } public class A2 extends A { ... } A1 somethingfromA1List=(A1) A1.getSomethingFromList(); A2 somethingfromA2List=(A2) A2.getSomethingFromList(); The contents of the list for each subclass would be different, but all the code to work on the lists would be the same. The problem with the above code is that I'd only have one list for all the subclasses, and I want one for each. Yes, I could replicate the code to declare the static list in each of the subclasses, but then I'd also have to replicate all the code that adds to the lists and searches the list, etc, which rather defeats the purpose of subclassing. Any ideas on how to do this without replicating code?

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• Making a simple searchable directory of people and their skills in a day - Which technologies?

  - by gav

  Hi All, I am working with a small theatre company. Currently they have a list of people on paper with notes about their skills next to each one. I want to create a database / directory for them so that they can add, delete, update and search for people. It is a very simple and common scenario I know but the issue here is that I only have a day to build a working solution. The search has to be very simple At first I was thinking LAMP but I'd rather not have to create it all from scratch and host it myself. That lead me to Google Spreadsheet as a database, this has the advantage that they already use google docs for everything and if my front end goes tits up they can still get to the data. Presuming none of you can think of some existing software which does exactly what I want the next step is to make a front end for the database. You can create forms for Google Spreadsheets but they only let you add new entries, I can make a Google Gadget but that will only let me implement the search as the Google Visualisation API provides read only access. It's at this point I'm stuck, should I just create a Java Servlet front end for the Google Spreadsheet and use the Java API to add, search and update? I know this is a broad question but I'm just asking 'What would you do?' to implement this system with a day's development time? Gav

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• Google app engine: Poor Performance with JDO + Datastore

  - by Bosh

  I have a simple data model that includes USERS: store basic information (key, name, phone # etc) RELATIONS: describe, e.g. a friendship between two users (supplying a relationship_type + two user keys) I'm getting very poor performance, for instance, if I try to print the first names of all of a user's friends. Say the user has 500 friends: I can fetch the list of friend user_ids very easily in a single query. But then, to pull out first names, I have to do 500 back-and-forth trips to the Datastore, each of which seems to take on the order of 30 ms. If this were SQL, I'd just do a JOIN and get the answer out fast. I understand there are rudimentary facilities for performing joins across un-owned relations in a relaxed implementation of JDO (as described at http://gae-java-persistence.blogspot.com) but they sound experimental and non-standard (e.g. my code won't work in any other JDO implementation). Is this really my best bet? Otherwise, how do people extract satisfactory performance from JDO/Datastore in this kind of (very common) situation? -Bosh

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• How frequently IP packets are fragmented at the source host?

  - by Methos

  I know that if IP payload MTU then routers usually fragment the IP packet. Finally all the fragmented packets are assembled at the destination using the fields IP-ID, IP fragment offsets and fragmentation flags. Max length of IP payload is 64K. Thus its very plausible for L4 to hand over payload which is 64K. If the L2 protocol is Ethernet, which often is the case, then the MTU will be about 1600 bytes. Hence IP packet will be fragmented at the source host itself. However, a quick search about IP implementation in Linux tells me that in recent kernels, L4 protocols are fragment friendly i.e. they try to save the fragmentation work for IP by handing over buffers of size which is close to MTU. Considering these two facts, I am wondering about how frequently does the IP packet gets fragmented at the source host itself. Does it occur sometimes/rarely/never? Does anyone know if there are exceptions to the rule of fragmentation in linux kernel (i.e. are there situations where L4 protocols are not fragment friendly)? How is this handled in other common OSes like windows? In general how frequently IP packets are fragmented?

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• __toString magic and type coercion

  - by TomcatExodus

  I've created a Template class for managing views and their associated data. It implements Iterator and ArrayAccess, and permits "sub-templates" for easy usage like so: <p><?php echo $template['foo']; ?></p> <?php foreach($template->post as $post): ?> <p><?php echo $post['bar']; ?></p> <?php endforeach; ?> Anyways, rather than using inline core functions, such as hash() or date(), I figured it would be useful to create a class called TemplateData, which would act as a wrapper for any data stored in the templates. This way, I can add a list of common methods for formatting, for example: echo $template['foo']->asCase('upper'); echo $template['bar']->asDate('H:i:s'); //etc.. When a value is set via $template['foo'] = 'bar'; in the controllers, the value of 'bar' is stored in it's own TemplateData object. I've used the magic __toString() so when you echo a TemplateData object, it casts to (string) and dumps it's value. However, despite the mantra controllers and views should not modify data, whenever I do something like this: $template['foo'] = 1; echo $template['foo'] + 1; //exception It dies on a Object of class TemplateData could not be converted to int; Unless I recast $template['foo'] to a string: echo ((string) $template['foo']) + 1; //outputs 2 Sort of defeats the purpose having to jump through that hoop. Are there any workarounds for this sort of behavior that exist, or should I just take this as it is, an incidental prevention of data modification in views?

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• Bash script to insert code from one file at a specific location in another file?

  - by Kurtosis

  I have a fileA with a snippet of code, and I need a script to insert that snippet into fileB on the line after a specific pattern. I'm trying to make the accepted answer in this thread work, but it's not, and is not giving an error so not sure why not: sed -e '/pattern/r text2insert' filewithpattern Any suggestions? pattern (insert snippet on line after): def boot { also tried escaped pattern but no luck: def\ boot\ { def\ boot\ \{ fileA snippet: LiftRules.htmlProperties.default.set((r: Req) => new Html5Properties(r.userAgent)) fileB (Boot.scala): package bootstrap.liftweb import net.liftweb._ import util._ import Helpers._ import common._ import http._ import sitemap._ import Loc._ /** * A class that's instantiated early and run. It allows the application * to modify lift's environment */ class Boot { def boot { // where to search snippet LiftRules.addToPackages("code") // Build SiteMap val entries = List( Menu.i("Home") / "index", // the simple way to declare a menu // more complex because this menu allows anything in the // /static path to be visible Menu(Loc("Static", Link(List("static"), true, "/static/index"), "Static Content"))) // set the sitemap. Note if you don't want access control for // each page, just comment this line out. LiftRules.setSiteMap(SiteMap(entries:_*)) // Use jQuery 1.4 LiftRules.jsArtifacts = net.liftweb.http.js.jquery.JQuery14Artifacts //Show the spinny image when an Ajax call starts LiftRules.ajaxStart = Full(() => LiftRules.jsArtifacts.show("ajax-loader").cmd) // Make the spinny image go away when it ends LiftRules.ajaxEnd = Full(() => LiftRules.jsArtifacts.hide("ajax-loader").cmd) // Force the request to be UTF-8 LiftRules.early.append(_.setCharacterEncoding("UTF-8")) } }

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• java 6 web services share domain specific classes between server and client

  - by user173446

  Hi all, Context: Considering below defined Engine class being parameter of some webservice method. As we have both server and client in java we may have some benefits (???) in sharing Engine class between server and client ( i.e we may put in a common jar file to be added to both client and server classpath ) Some benefits would be : we keep specific operations like 'brushEngine' in same place build is faster as we do not need in our case to generate java code for client classes but to use them from the server build) if we later change server implementation for 'brushEngine' this is reflected automatically in client . Questions: How to share below detailed Engine class using java 6 tools ( i.e wsimport , wsgen etc )? Is there other tools for java that can achieve this sharing ? Is sharing a case that java 6 web services support is missing ? Can this case be reduced to other web service usage patterns? Thanks. Code: public class Engine { private String engineData; public String getData(){ return data; } public setData(String value){ this.data = value; } public void brushEngine(){ engineData = "BrushedEngine"+engineData; } }

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• program won't find math.h anymore

  - by 130490868091234

  After a long time, I downloaded a program I co-developed and tried to recompile it on my Ubuntu Linux 12.04, but it seems it does not find math.h anymore. This may be because something has changed recently in gcc, but I can't figure out if it's something wrong in src/Makefile.am or a missing dependency: Download from http://www.ub.edu/softevol/variscan/: tar xzf variscan-2.0.2.tar.gz cd variscan-2.0.2/ make distclean sh ./autogen.sh make I get: [...] gcc -DNDEBUG -O3 -W -Wall -ansi -pedantic -lm -o variscan variscan.o statistics.o common.o linefile.o memalloc.o dlist.o errabort.o dystring.o intExp.o kxTok.o pop.o window.o free.o output.o readphylip.o readaxt.o readmga.o readmaf.o readhapmap.o readxmfa.o readmav.o ran1.o swcolumn.o swnet.o swpoly.o swref.o statistics.o: In function `calculate_Fu_and_Li_D': statistics.c:(.text+0x497): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_F': statistics.c:(.text+0x569): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_D_star': statistics.c:(.text+0x63b): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_and_Li_F_star': statistics.c:(.text+0x75c): undefined reference to `sqrt' statistics.o: In function `calculate_Tajima_D': statistics.c:(.text+0x85d): undefined reference to `sqrt' statistics.o:statistics.c:(.text+0xcb1): more undefined references to `sqrt' follow statistics.o: In function `calcRunMode21Stats': statistics.c:(.text+0xe02): undefined reference to `log' statistics.o: In function `correctedDivergence': statistics.c:(.text+0xe5a): undefined reference to `log' statistics.o: In function `calcRunMode22Stats': statistics.c:(.text+0x104a): undefined reference to `sqrt' statistics.o: In function `calculate_Fu_fs': statistics.c:(.text+0x11a8): undefined reference to `fabsl' statistics.c:(.text+0x11ca): undefined reference to `powl' statistics.c:(.text+0x11f2): undefined reference to `logl' statistics.o: In function `calculateStatistics': statistics.c:(.text+0x13f2): undefined reference to `log' collect2: ld returned 1 exit status make[1]: *** [variscan] Error 1 make[1]: Leaving directory `/home/avilella/variscan/latest/variscan-2.0.2/src' make: *** [all-recursive] Error 1 The libraries are there because this simple example works perfectly well: $ gcc test.c -o test -lm $ cat test.c #include <stdio.h> #include <math.h> int main(void) { double x = 0.5; double result = sqrt(x); printf("The hyperbolic cosine of %lf is %lf\n", x, result); return 0; } Any ideas?

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• Efficient Clojure workflow?

  - by Alex B

  I am developing a pet project with Clojure, but wonder if I can speed up my workflow a bit. My current workflow (with Compojure) is: Start Swank with lein swank. Go to Emacs, connect with M-x slime-connect. Load all existing source files one by one. This also starts a Jetty server and an application. Write some code in REPL. When satisfied with experiments, write a full version of a construct I had in mind. Eval (C-c C-c) it. Switch REPL to namespace where this construct resides and test it. Switch to browser and reload browser tab with the affected page. Tweak the code, eval it, check in the browser. Repeat any of the above. There are a number of annoyances with it: I have to switch between Emacs and the browser (or browsers if I am testing things like templating with multiple browsers) all the time. Is there a common idiom to automate this? I used to have a JavaScript bit that reloads the page continuously, but it's of limited utility, obviously, when I have to interact with the page for more than a few seconds. My JVM instance becomes "dirty" when I experiment and write test functions. Basically namespaces become polluted, especially if I'm refactoring and moving the functions between namespaces. This can lead to symbol collisions and I need to restart Swank. Can I undef a symbol? I load all source files one by one (C-c C-k) upon restarting Swank. I suspect I'm doing it all wrong. Switching between the REPL and the file editor can be a bit irritating, especially when I have a lot of Emacs tabs open, alongside the browser(s). I'm looking for ways to improve the above points and the entire workflow in general, so I'd appreciate if you'd share yours. P. S. I have also used Vimclojure before, so Vimclojure-based workflows are welcome too.

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• MVVM Listbox DataTemplate SelectedItem

  - by StinkerPeter

  I am using a ListBox with a DataTemplate as shown below (xaml simplified and variable names changed). <ListBox ItemsSource="{Binding Path=ObservCollectionItems}" SelectedItem="{Binding Path=SelectedItemVar, Mode=TwoWay}"> <ListBox.ItemTemplate> <DataTemplate> <StackPanel> <TextBlock Text="{Binding SomeVar}" /> <Border> <StackPanel> <Button Content="String1" Command="{Binding DataContext.Command1} RelativeSource={RelativeSource FindAncestor, ListBox, 1}}" /> <Button Content="String2" Command="{Binding DataContext.Command2} RelativeSource={RelativeSource FindAncestor, ListBox, 1}}" /> </StackPanel> </Border> </StackPanel> </DataTemplate> <ListBox.ItemTemplate> </ListBox> I need the SelectedItemVar (dependency property) to update when I click on one of the buttons. SelectedItemVar is then used for the respective button's command. SelectedItemVar does update when I click on the TextBlock or the Border, but not when I click either button. I found a non-MVVM solution to this problem here. I do not want to add code in the file-behind to solve this, as they did in the link. Is there a clean solution that can be done in XAML. Beyond the non-MVVM solutions, I have not found anyone with this problem. I would have thought this was fairly common. Finally, I found this Command="{Binding DataContext.CommandName} RelativeSource={RelativeSource FindAncestor, ListBox, 1} for the Command binding. I do not fully understand what it is doing, but I do know that the command wasn't firing when I was binding directly to CommandName.

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• Wicket: How to implement an IDataProvider/LoadableDetachableModel for indexed lists

  - by cretzel

  What's the best way to implement an IDataProvider and a LoadableDetachable in Wicket for an indexed list? Suppose I have a Customer who has a list of Adresses. class Customer { List adresses; } Now I want to implement a data provider/ldm for the adresses of a customer. I suppose the usual way is an IDataProvider as an inner class which refers to the customer model of the component, like: class AdressDataProvider implements IDataProvider { public Iterator iterator() { Customer c = (Customer)Component.this.getModel(); // somehow get the customer model return c.getAdresses().iterator(); } public IModel model(Object o) { Adress a = (Adress) o; // Return an LDM which loads the adress by id. return new AdressLoadableDetachableModel(a.getId()); } } Question: How would I implement this, when the adress does not have an ID (e.g. it's a Hibernate Embeddable/CollectionOfElements) but can only be identified by its index in the customer.adresses list? How do I keep reference to the owning entity and the index? In fact, I know a solution, but I wonder if there's a common pattern to do this.

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• Comparison operators not supported for type IList when Paging data in Linq to Sql

  - by Dan

  I can understand what the error is saying - it can't compare a list. Not a problem, other than the fact that I don't know how to not have it compare a list when I want to page through a model with a list as a property. My Model: Event : IEvent int Id string Title // Other stuff.. LazyList<EventDate> Dates // The "problem" property Method which pages the data (truncated): public JsonResult JsonEventList(int skip, int take) { var query = _eventService.GetEvents(); // Do some filtering, then page data.. query = query.Skip(skip).Take(take); return Json(query.ToArray()); } As I said, the above is truncated quite a bit, leaving only the main point of the function: filter, page and return JSON'd data. The exception occurs when I enumerate (.ToArray()). The Event object is really only used to list the common objects of all the event types (Meetings, Birthdays, etc - for example). It still implements IEvent like the other types, so I can't just remove the LazyList<EventDate> Dates' property unless I no longer implementIEvent` Anyway, is there a way to avoid this? I don't really want to compare a LazyList when I page, but I do not know how to resolve this issue. Thank you in advance! :)

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• How can I bind a javascript dialog using Knockout?

  - by Brian

  I've got a list of data in an observableArray and I want to show it in a javascript dialog window (I'm using jQuery.blockUI if it matters). Unfortunately the dialog seems to come unbound after the page is loaded. The dialog initializes correctly (the data is displayed), but it isn't updating with changes. There are no Javascript errors and I've moved the binding to after the dialog is generated and added to the document (no effect). I've also tried calling ko.applyBinding on the main div that makes up the dialog but that, for some reason, causes part of the main page to hide (the DOM is there, but they are hidden). EDIT: I've created a project on jsfiddle that reproduces the problem. The main culprit seems to be wrapping the content of the dialog in a div. If I show the content directly it seems to work (of course I can't do that, the wrappers provide a common style for our dialogs). I'm recovering from the flu and could easily be missing something obvious, but I've been trying all day and nothing is coming to me. Any ideas?

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• Controlling shell command line wildcard expansion in C or C++

  - by Adrian McCarthy

  I'm writing a program, foo, in C++. It's typically invoked on the command line like this: foo *.txt My main() receives the arguments in the normal way. On many systems, argv[1] is literally *.txt, and I have to call system routines to do the wildcard expansion. On Unix systems, however, the shell expands the wildcard before invoking my program, and all of the matching filenames will be in argv. Suppose I wanted to add a switch to foo that causes it to recurse into subdirectories. foo -a *.txt would process all text files in the current directory and all of its subdirectories. I don't see how this is done, since, by the time my program gets a chance to see the -a, then shell has already done the expansion and the user's *.txt input is lost. Yet there are common Unix programs that work this way. How do they do it? In Unix land, how can I control the wildcard expansion? (Recursing through subdirectories is just one example. Ideally, I'm trying to understand the general solution to controlling the wildcard expansion.)

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