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  • Foreign keys in django admin list display

    - by Olivier
    If a django model contains a foreign key field, and if that field is shown in list mode, then it shows up as text, instead of displaying a link to the foreign object. Is it possible to automatically display all foreign keys as links instead of flat text? (of course it is possible to do that on a field by field basis, but is there a general method?) Example: class Author(models.Model): ... class Post(models.Model): author = models.ForeignKey(Author) Now I choose a ModelAdmin such that the author shows up in list mode: class PostAdmin(admin.ModelAdmin): list_display = [..., 'author',...] Now in list mode, the author field will just use the __unicode__ method of the Author class to display the author. On the top of that I would like a link pointing to the url of the corresponding author in the admin site. Is that possible? Manual method: For the sake of completeness, I add the manual method. It would be to add a method author_link in the PostAdmin class: def author_link(self, item): return '<a href="../some/path/%d">%s</a>' % (item.id, unicode(item)) author_link.allow_tags = True That will work for that particular field but that is not what I want. I want a general method to achieve the same effect. (One of the problems is how to figure out automatically the path to an object in the django admin site.)

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  • Is there a perfect algorithm for chess?

    - by Overflown
    Dear Stack Overflow community, I was recently in a discussion with a non-coder person on the possibilities of chess computers. I'm not well versed in theory, but think I know enough. I argued that there could not exist a deterministic Turing machine that always won or stalemated at chess. I think that, even if you search the entire space of all combinations of player1/2 moves, the single move that the computer decides upon at each step is based on a heuristic. Being based on a heuristic, it does not necessarily beat ALL of the moves that the opponent could do. My friend thought, to the contrary, that a computer would always win or tie if it never made a "mistake" move (however do you define that?). However, being a programmer who has taken CS, I know that even your good choices - given a wise opponent - can force you to make "mistake" moves in the end. Even if you know everything, your next move is greedy in matching a heuristic. Most chess computers try to match a possible end game to the game in progress, which is essentially a dynamic programming traceback. Again, the endgame in question is avoidable though. -- thanks, Allan Edit: Hmm... looks like I ruffled some feathers here. That's good. Thinking about it again, it seems like there is no theoretical problem with solving a finite game like chess. I would argue that chess is a bit more complicated than checkers in that a win is not necessarily by numerical exhaustion of pieces, but by a mate. My original assertion is probably wrong, but then again I think I've pointed out something that is not yet satisfactorily proven (formally). I guess my thought experiment was that whenever a branch in the tree is taken, then the algorithm (or memorized paths) must find a path to a mate (without getting mated) for any possible branch on the opponent moves. After the discussion, I will buy that given more memory than we can possibly dream of, all these paths could be found.

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  • Why are floating point values so prolific?

    - by Kibbee
    So, title says it all. Why are floating point values so prolific in computer programming. Due to problems like rounding errors, and not being able to even accurately represent numbers such as 0.1, I really can't see how they got as far as they did. I understand that the computation is faster with floating point numbers, however, I can think of only a few cases that they actually the right data type would be using. If you sat back and think about every time you used a floating point value, how many times did you say, well, some error would be ok, as long as the result was a few microseconds faster. It really makes me think because Jeff was talking about NP completeness, and how heuristics give an answer that is kind of right. And well, computers shouldn't do that. They should give you the answer that is correct. Yet we see floating point values used in many applications where they are completely not valid. What really bugs me, isn't that floating point exists, but that in many languages, there isn't even a viable alternative, non-floating point, decimal value. A lot of programmers when doing financial applications have to fall back to storing the number of cents in an integer field. Which brings with it all kinds of other problems. Why do floats continue to be so prolific, even though they can't represent the real answer, and we expect computers to be accurate? [EDIT] Just to clarify, I was talking about Base 2 floating points, and not base 10 floating points. .Net offers the Decimal data type, which is a base 10 floating point value which offers a much better representation of the numbers we deal with on a daily basis in most computer programs. I find it hard to believe that even modern languages like Java don't support base 10 floating point values, unless you want to move into the realm of things like BigDecimal, which isn't really the right answer either in a lot of situations.

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  • FancyURLOpener failing since moving to python 3.1.2

    - by Andrew Shepherd
    I had an application that was downloading a .CSV file from a password-protected website then processing it futher. I was using FancyURLOpener, and simply hardcoding the username and password. (Obviously, security is not a high priority in this particular instance). Since downloading Python 3.1.2, this code has stopped working. Does anyone know of the changes that have happened to the implementation? Here is a cut down version of the code: import urllib.request; class TracOpener (urllib.request.FancyURLopener) : def prompt_user_passwd(self, host, realm) : return ('andrew_ee', '_my_unenctryped_password') csvUrl='http://mysite/report/19?format=csv@USER=fred_nukre' opener = TracOpener(); f = opener.open(csvUrl); s = f.read(); f.close(); s; For the sake of completeness, here's the entire call stack: Traceback (most recent call last): File "C:\reporting\download_csv_file.py", line 12, in <module> f = opener.open(csvUrl); File "C:\Program Files\Python31\lib\urllib\request.py", line 1454, in open return getattr(self, name)(url) File "C:\Program Files\Python31\lib\urllib\request.py", line 1628, in open_http return self._open_generic_http(http.client.HTTPConnection, url, data) File "C:\Program Files\Python31\lib\urllib\request.py", line 1624, in _open_generic_http response.status, response.reason, response.msg, data) File "C:\Program Files\Python31\lib\urllib\request.py", line 1640, in http_error result = method(url, fp, errcode, errmsg, headers) File "C:\Program Files\Python31\lib\urllib\request.py", line 1878, in http_error_401 return getattr(self,name)(url, realm) File "C:\Program Files\Python31\lib\urllib\request.py", line 1950, in retry_http_basic_auth return self.open(newurl) File "C:\Program Files\Python31\lib\urllib\request.py", line 1454, in open return getattr(self, name)(url) File "C:\Program Files\Python31\lib\urllib\request.py", line 1628, in open_http return self._open_generic_http(http.client.HTTPConnection, url, data) File "C:\Program Files\Python31\lib\urllib\request.py", line 1590, in _open_generic_http auth = base64.b64encode(user_passwd).strip() File "C:\Program Files\Python31\lib\base64.py", line 56, in b64encode raise TypeError("expected bytes, not %s" % s.__class__.__name__) TypeError: expected bytes, not str

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  • Implementing arrays using a stack

    - by Zack
    My programming language has no arrays, no lists, no pointers, no eval and no variable variables. All it has: Ordinary variables like you know them from most programming languages: They all have an exact name and a value. One stack. Functions provided are: push (add element to top), pop (remove element from top, get value) and empty (check if stack is empty) My language is turing-complete. (Basic arithmetics, conditional jumps, etc implemented) That means, it must be possible to implement some sort of list or array, right? But I have no idea how... What I want to achieve: Create a function which can retrieve and/or change an element x of the stack. I could easily add this function in the implementation of my language, in the interpreter, but I want to do it in my programming language. "Solution" one (Accessing an element x, counting from the stack top) Create a loop. Pop off the element from the stack top x times. The last element popped of is element number x. I end up with a destroyed stack. Solution two: Do the same as above, but store all popped off values in a second stack. Then you could move all elements back after you are done. But you know what? I don't have a second stack!

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  • What are the primitive Forth operators?

    - by Barry Brown
    I'm interested in implementing a Forth system, just so I can get some experience building a simple VM and runtime. When starting in Forth, one typically learns about the stack and its operators (DROP, DUP, SWAP, etc.) first, so it's natural to think of these as being among the primitive operators. But they're not. Each of them can be broken down into operators that directly manipulate memory and the stack pointers. Later one learns about store (!) and fetch (@) which can be used to implement DUP, SWAP, and so forth (ha!). So what are the primitive operators? Which ones must be implemented directly in the runtime environment from which all others can be built? I'm not interested in high-performance; I want something that I (and others) can learn from. Operator optimization can come later. (Yes, I'm aware that I can start with a Turing machine and go from there. That's a bit extreme.) Edit: What I'm aiming for is akin to bootstrapping an operating system or a new compiler. What do I need do implement, at minimum, so that I can construct the rest of the system out of those primitive building blocks? I won't implement this on bare hardware; as an educational exercise, I'd write my own minimal VM.

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  • How do people know so much about programming?

    - by Luciano
    I see people in this forums with a lot of points, so I assume they know about a lot of different programming stuff. When I was young I knew about basic (commodore) and the turbo pascal (pc). Then in college I learnt about C, memory management, x86 set, loop invariants, graphs, db query optimization, oop, functional, lambda calculus, prolog, concurrency, polymorphism, newton method, simplex, backtracking, dynamic programming, heuristics, np completeness, LR, LALR, neural networks, static & dynamic typing, turing, godel, and more in between. Then in industry I started with Java several years ago and learnt about it, and its variety of frameworks, and also design patterns, architecture patterns, web development, server development, mobile development, tdd, bdd, uml, use cases, bug trackers, process management, people management if you are a tech lead, profiling, security concerns, etc. I started to forget what I learnt in college... And then there is the stuff I don't know yet, like python, .net, perl, JVM stuff like groovy or scala.. Of course Google is a must for rapid documentation access to know if a problem has been solved already and how, and to keep informed about new stuff by blogs and places like this one. It's just too much or I just have a bad memory.. how do you guys manage it?

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  • What type of webapp is the sweet spot for Scala's Lift framework?

    - by ajay
    What kind of applications are the sweet spot for Scala's lift web framework. My requirements: Ease of development and maintainability Ready for production purposes. i.e. good active online community, regular patches and updates for security and performance fixes etc. Framework should survive a few years. I don't want to write a app in a framework for which no updates/patches are available after 1 year. Has good UI templating engines Interoperation with Java (Scala satisfies this arleady. Just mentioning here for completeness sake) Good component oriented development. Time required to develop should be proportion to the complexity of web application. Should not be totally configuration based. I hate it when code gets automatically generated for me and does all sorts of magic under the hood. That is a debugging nightmare. Amount of Lift knowledge required to develop a webapp should be proportional to the complexity of the web application. i.e I should't have to spend 10+ hours learning Lift just to develop a simple TODO application. (I have knowledge of Databases, Scala) Does Lift satisfy these requirements?

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  • Render action return View(); form problem

    - by Roger Rogers
    I'm new to MVC, so please bear with me. :-) I've got a strongly typed "Story" View. This View (story) can have Comments. I've created two Views (not partials) for my Comments controller "ListStoryComments" and "CreateStoryComment", which do what their names imply. These Views are included in the Story View using RenderAction, e.g.: <!-- List comments --> <h2>All Comments</h2> <% Html.RenderAction("ListStoryComments", "Comments", new { id = Model.Story.Id }); %> <!-- Create new comment --> <% Html.RenderAction("CreateStoryComment", "Comments", new { id = Model.Story.Id }); %> (I pass in the Story id in order to list related comments). All works as I hoped, except, when I post a new comment using the form, it returns the current (parent) View, but the Comments form field is still showing the last content I typed in and the ListStoryComments View isn’t updated to show the new story. Basically, the page is being loaded from cache, as if I had pressed the browser’s back button. If I press f5 it will try to repost the form. If I reload the page manually (reenter the URL in the browser's address bar), and then press f5, I will see my new content and the empty form field, which is my desired result. For completeness, my CreateStoryComment action looks like this: [HttpPost] public ActionResult CreateStoryComment([Bind(Exclude = "Id, Timestamp, ByUserId, ForUserId")]Comment commentToCreate) { try { commentToCreate.ByUserId = userGuid; commentToCreate.ForUserId = userGuid; commentToCreate.StoryId = 2; // hard-coded for testing _repository.CreateComment(commentToCreate); return View(); } catch { return View(); } }

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  • Theory of formal languages - Automaton

    - by dader51
    Hi everybody ! I'm wondering about formal languages. I have a kind of parser : It reads à xml-like serialized tree structure and turn it into a multidimmensionnal array. I figured out that i need at least three variables to achieve the job : $tree = array(); // a new array $pTree = array(&$tree); // a new array which the first element points to $tree; $deep = 0; plus the one containing the sentence splitted into words. My point is on the similarities between the algorithm deing used and the differents kinds of automatons ( state machines turing machines stack ... ). The $words variable is the "tape" of the automaton, the test/conditions of the algorithm are transitions, $deep is the state and $tree is the output. I cannont figure what is $pTree. So the question is : which is the automaton I implictly use here, and to which formal languages family does it fit ? And what's about recursion ?

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  • std::locale breakage on MacOS 10.6 with LANG=en_US.UTF-8

    - by fixermark
    I have a C++ application that I am porting to MacOSX (specifically, 10.6). The app makes heavy use of the C++ standard library and boost. I recently observed some breakage in the app that I'm having difficulty understanding. Basically, the boost filesystem library throws a runtime exception when the program runs. With a bit of debugging and googling, I've reduced the offending call to the following minimal program: #include <locale> int main ( int argc, char *argv [] ) { std::locale::global(std::locale("")); return 0; } This program fails when I run this through g++ and execute the resulting program in an environment where LANG=en_US.UTF-8 is set (which on my computer is part of the default bash session when I create a new console window). Clearing the environment variable (setenv LANG=) allows the program to run without issues. But I'm surprised I'm seeing this breakage in the default configuration. My questions are: Is this expected behavior for this code on MacOS 10.6? What would a proper workaround be? I can't really re-write the function because the version of the boost libraries we are using executes this statement internally as part of the filesystem library. For completeness, I should point out that the program from which this code was synthesized crashes when launched via the 'open' command (or from the Finder) but not when Xcode runs the program in Debug mode. edit The error given by the above code on 10.6.1 is: $ ./locale terminate called after throwing an instance of 'std::runtime_error' what(): locale::facet::_S_create_c_locale name not valid Abort trap

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  • I need to implement C# deep copy constructors with inheritance. What patterns are there to choose fr

    - by Tony Lambert
    I wish to implement a deepcopy of my classes hierarchy in C# public Class ParentObj : ICloneable { protected int myA; public virtual Object Clone () { ParentObj newObj = new ParentObj(); newObj.myA = theObj.MyA; return newObj; } } public Class ChildObj : ParentObj { protected int myB; public override Object Clone ( ) { Parent newObj = this.base.Clone(); newObj.myB = theObj.MyB; return newObj; } } This will not work as when Cloning the Child only a parent is new-ed. In my code some classes have large hierarchies. What is the recommended way of doing this? Cloning everything at each level without calling the base class seems wrong? There must be some neat solutions to this problem, what are they? Can I thank everyone for their answers. It was really interesting to see some of the approaches. I think it would be good if someone gave an example of a reflection answer for completeness. +1 awaiting!

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  • C#: How to run NUnit from my code

    - by Flavio
    Hello, I'd like to use NUnit to run unit tests in my plug-in, but it needs to be run in the context of my application. To solve this, I was trying to develop a plug-in that runs NUnit, which in turn will execute my tests in the application's context. I didn't find a specific documentation on this subject so I dug a piece of information here and there and I came out with the following piece of code (which is similar to one I found here in StackOverflow): SimpleTestRunner runner = new SimpleTestRunner(); TestPackage package = new TestPackage( "Test" ); string loc = Assembly.GetExecutingAssembly().Location package.Assemblies.Add( loc ); if( runner.Load(package) ) { TestResult result = runner.Run( new NullListener() ); } The result variable says "has no TestFixture" although I know for sure it is there. In fact my test file contains two test. Using another approach I found, which is summarized by the following code: TestSuiteBuilder builder = new TestSuiteBuilder(); TestSuite testSuite = builder.Build( package ); // Run tests TestResult result = testSuite.Run( new NullListener(), NUnit.Core.TestFilter.Empty ); I saw nunit data structures with only 1 test and I had the same error. For sake of completeness, I am using the latest version of nunit, which is 2.5.5.10112. Does anyone know what I'm missing? A sample code would be appreciated. thanks

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  • Where can I find a list of all possible messages that an XmlException can contain?

    - by Rahul
    I'm writing an XML code editor and I want to display syntax errors in the user interface. Because my code editor is strongly constrained to a particular problem domain and audience, I want to rewrite certain XMLException messages to be more meaningful for users. For instance, an exception message like this: '"' is an unexpected token. The expected token is '='. Line 30, position 35 .. is very technical and not very informative to my audience. Instead, I'd like to rewrite it and other messages to something else. For completeness' sake that means I need to build up a dictionary of existing messages mapped to the new message I would like to display instead. To accomplish that I'm going to need a list of all possible messages XMLException can contain. Is there such a list somewhere? Or can I find out the possible messages through inspection of objects in C#? Edit: specifically, I am using XmlDocument.LoadXml to parse a string into an XmlDocument, and that method throws an XmlException when there are syntax errors. So specifically, my question is where I can find a list of messages applied to XmlException by XmlDocument.LoadXml. The discussion about there potentially being a limitless variation of actual strings in the Message property of XmlException is moot.

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  • MySQL: Complex Join Statement involving two tables and a third correlation table

    - by Stephen
    I have two tables that were built for two disparate systems. I have records in one table (called "leads") that represent customers, and records in another table (called "manager") that are the exact same customers but "manager" uses different fields (For example, "leads" contains an email address, and "manager" contains two fields for two different emails--either of which might be the email from "leads"). So, I've created a correlation table that contains the lead_id and manager_id. currently this correlation table is empty. I'm trying to query the "leads" table to give me records that match either "manager" email field with the single "leads" email field, while at the same time ignoring fields that have already been added to the "correlated" table. (this way I can see how many leads that match have not yet been correlated.) Here's my current, invalid SQL attempt: SELECT leads.id, manager.id FROM leads, manager LEFT OUTER JOIN correlation ON correlation.lead_id = leads.id WHERE correlation.id IS NULL AND leads.project != "someproject" AND (manager.orig_email = leads.email OR manager.dest_email = leads.email) AND leads.created BETWEEN '1999-01-01 00:00:00' AND '2010-05-10 23:59:59' ORDER BY leads.created ASC; I get the error: Unknown column 'leads.id' in 'on clause' Before you wonder: there are records in the "leads" table where leads.project != "someproject" and leads.created falls between those dates. I've included those additional parameters for completeness.

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  • Using Sphinx with a distutils-built C extension

    - by detly
    I have written a Python module including a submodule written in C: the module itself is called foo and the C part is foo._bar. The structure looks like: src/ foo/__init__.py <- contains the public stuff foo/_bar/bar.c <- the C extension doc/ <- Sphinx configuration conf.py ... foo/__init__.py imports _bar to augment it, and the useful stuff is exposed in the foo module. This works fine when it's built, but obviously won't work in uncompiled form, since _bar doesn't exist until it's built. I'd like to use Sphinx to document the project, and use the autodoc extension on the foo module. This means I need to build the project before I can build the documentation. Since I build with distutils, the built module ends up in some variably named dir build/lib.linux-ARCH-PYVERSION — which means I can't just hard-code the directory into a Sphinx' conf.py. So how do I configure my distutils setup.py script to run the Sphinx builder over the built module? For completeness, here's the call to setup (the 'fake' things are custom builders that subclass build and build_ext): setup(cmdclass = { 'fake': fake, 'build_ext_fake' : build_ext_fake }, package_dir = {'': 'src'}, packages = ['foo'], name = 'foo', version = '0.1', description = desc, ext_modules = [module_real])

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  • Lucene Query Syntax

    - by Don
    Hi, I'm trying to use Lucene to query a domain that has the following structure Student 1-------* Attendance *---------1 Course The data in the domain is summarised below Course.name Attendance.mandatory Student.name ------------------------------------------------- cooking N Bob art Y Bob If I execute the query "courseName:cooking AND mandatory:Y" it returns Bob, because Bob is attending the cooking course, and Bob is also attending a mandatory course. However, what I really want to query for is "students attending a mandatory cooking course", which in this case would return nobody. Is it possible to formulate this as a Lucene query? I'm actually using Compass, rather than Lucene directly, so I can use either CompassQueryBuilder or Lucene's query language. For the sake of completeness, the domain classes themselves are shown below. These classes are Grails domain classes, but I'm using the standard Compass annotations and Lucene query syntax. @Searchable class Student { @SearchableProperty(accessor = 'property') String name static hasMany = [attendances: Attendance] @SearchableId(accessor = 'property') Long id @SearchableComponent Set<Attendance> getAttendances() { return attendances } } @Searchable(root = false) class Attendance { static belongsTo = [student: Student, course: Course] @SearchableProperty(accessor = 'property') String mandatory = "Y" @SearchableId(accessor = 'property') Long id @SearchableComponent Course getCourse() { return course } } @Searchable(root = false) class Course { @SearchableProperty(accessor = 'property', name = "courseName") String name @SearchableId(accessor = 'property') Long id }

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  • What is the process involved in viewing a webservice in a browser from within visual studio?

    - by Sam Holder
    I have created a new VS2008 ASP.Net Web service project, with the default name WebService1. If I right click on the Service1.asmx file and select 'View in Browser' what are the processes that go on to make this happen? I am asking because I have a situation where when I run this from a visual studio project started in our development shell (which sets up a common build environment) I cannot get the web service to show up in the browser. It starts the asp.net development server and creates a single file: C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\c43ddc22\268ae91b\hash\hash.web but when I start it from a stand alone project i get a whole slew of files in here: C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\edad4eee\d198cf0e\App_Web_defaultwsdlhelpgenerator.aspx.cdcab7d2.vicgkf94.dll C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\root\edad4eee\d198cf0e\service1.asmx.cdcab7d2.compiled etc etc I am trying to debug this but not really getting anywhere. i have inspected the output from VS but the only option I get is for the build output, which is basic and doesn't really contain any information that is useful. I have tried running both versions with DebugView running but no output there either. I would like to know if there are any log files I could look at, or if anyone has any suggestions on how I might be able to debug what is going wrong here? For completeness the output I get when it doesn't work is: Parser Error Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately. Parser Error Message: Could not create type 'WebService1.Service1'. Source Error: Line 1: Source File: /Service1.asmx Line: 1 Version Information: Microsoft .NET Framework Version:2.0.50727.3603; ASP.NET Version:2.0.50727.3082

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  • problems with retrieving data that was saved outside of a grails webflow

    - by callie16
    Hi, this is actually connected to an earlier question of mine here. Anyway, I have 3 domains that look like this: class A { ... static hasMany = [ b : B ] ... } class B { ... static belongsTo = [ a : A ] static hasMany = [ c : C ] ... } class C { ... static belongsTo = [ b : B ] ... } In my GSP page, I call an action in the Controller via a remote function in a javascript block (I'm using Dojo so I'm passing data to be saved this way... it's not a form per se so I use JSON for now to pass the data to the Controller). Let's say, I'm calling something like this: def someAction = { def jsonArr = [parse the JSON here] def tmpA = A.get(params.id) ... def tmpB = new B() b.someParam = jsonArr.someParam ... def tmpC = new C() tmpC.cParam = jsonArr.cParam tmpB.addToC(tmpC) tmpB.save(flush: true) //this may or may not be here but I'm adding it for the sake of completeness tmpA.addToB(tmpB) tmpA.save(flush: true) // NOTE: If I check here via println or whatnot, tmpA has a tmpB which has a tmpC... in other words, the data got saved. It's also in the DB. redirect(action: 'order' ...) } Then comes the fun part. Here's the webflow sample: def orderFlow = { ... someStateIShouldEndUpIn { on("next") { // or on previous... doesn't matter def anId = params.id def currA = A.get(anId) // this does NOT return a null value def testB = currA.b // this DOES return a null value }.to("somePage") ... } ... } Any ideas on why this happens? Moreover, when I dump the data of currA, b=null... instead of b=[] or b=[contents of tmpB]. Any help would be seriously appreciated... been at this for a couple of days now... Thanks!

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  • How do I create an exception-wrapping fubumvc behaviour?

    - by Jon M
    How can I create a fubumvc behaviour that wraps actions with a particular return type, and if an exception occurs while executing the action, then the behaviour logs the exception and populates some fields on the return object? I have tried the following: public class JsonExceptionHandlingBehaviour : IActionBehavior { private static readonly Logger logger = LogManager.GetCurrentClassLogger(); private readonly IActionBehavior _innerBehavior; private readonly IFubuRequest _request; public JsonExceptionHandlingBehaviour(IActionBehavior innerBehavior, IFubuRequest request) { _innerBehavior = innerBehavior; _request = request; } public void Invoke() { try { _innerBehavior.Invoke(); var response = _request.Get<AjaxResponse>(); response.Success = true; } catch(Exception ex) { logger.ErrorException("Error processing JSON request", ex); var response = _request.Get<AjaxResponse>(); response.Success = false; response.Exception = ex.ToString(); } } public void InvokePartial() { _innerBehavior.InvokePartial(); } } But, although I get the AjaxResponse object from the request, any changes I make don't get sent back to the client. Also, any exceptions thrown by the action don't make it as far as this, the request is terminated before execution gets to the catch block. What am I doing wrong? For completeness, the behaviour is wired up with the following in my WebRegistry: Policies .EnrichCallsWith<JsonExceptionHandlingBehaviour>(action => typeof(AjaxResponse).IsAssignableFrom(action.Method.ReturnType)); And AjaxResponse looks like: public class AjaxResponse { public bool Success { get; set; } public object Data { get; set; } public string Exception { get; set; } }

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  • Constructor initializer list: code from the C++ Primer, chapter 16

    - by Alexandros Gezerlis
    Toward the end of Chapter 16 of the "C++ Primer" I encountered the following code (I've removed a bunch of lines): class Sales_item { public: // default constructor: unbound handle Sales_item(): h() { } private: Handle<Item_base> h; // use-counted handle }; My problem is with the Sales_item(): h() { } line. For the sake of completeness, let me also quote the parts of the Handle class template that I think are relevant to my question (I think I don't need to show the Item_base class): template <class T> class Handle { public: // unbound handle Handle(T *p = 0): ptr(p), use(new size_t(1)) { } private: T* ptr; // shared object size_t *use; // count of how many Handles point to *ptr }; I would have expected something like either: a) Sales_item(): h(0) { } which is a convention the authors have used repeatedly in earlier chapters, or b) Handle<Item_base>() if the intention was to invoke the default constructor of the Handle class. Instead, what the book has is Sales_item(): h() { }. My gut reaction is that this is a typo, since h() looks suspiciously similar to a function declaration. On the other hand, I just tried compiling under g++ and running the example code that uses this class and it seems to be working correctly. Any thoughts?

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  • Advice: Python Framework Server/Worker Queue management (not Website)

    - by Muppet Geoff
    I am looking for some advice/opinions of which Python Framework to use in an implementation of multiple 'Worker' PCs co-ordinated from a central Queue Manager. For completeness, the 'Worker' PCs will be running Audio Conversion routines (which I do not need advice on, and have standalone code that works). The Audio conversion takes a long time, and I need to co-ordinate an arbitrary number of the 'Workers' from a central location, handing them conversion tasks (such as where to get the source files, or where to ask for the job configuration) with them reporting back some additional info, such as the runtime of the converted audio etc. At present, I have a script that makes a webservice call to get the 'configuration' for a conversion task, based on source files located on the worker already (we manually copy the source files to the worker, and that triggers a conversion routine). I want to change this, so that we can distribute conversion tasks ("Oy you, process this: xxx") based on availability, and in an ideal world, based on pending tasks too. There is a chance that Workers can go offline mid-conversion (but this is not likely). All the workers are Windows based, the co-ordinator can be WIndows or Linux. I have (in my initial searches) come across the following - and I know that some are cross-dependent: Celery (with RabbitMQ) Twisted Django Using a framework, rather than home-brewing, seems to make more sense to me right now. I have a limited timeframe in which to develop this functional extension. An additional consideration would be using a Framework that is compatible with PyQT/PySide so that I can write a simple UI to display Queue status etc. I appreciate that the specifics above are a little vague, and I hope that someone can offer me a pointer or two. Again: I am looking for general advice on which Python framework to investigate further, for developing a Server/Worker 'Queue management' solution, for non-web activities (this is why DJango didn't seem the right fit).

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  • SCons and dependencies for python function generating source

    - by elmo
    I have an input file data, a python function parse and a template. What I am trying to do is use parse function to get dictionary out of data and use that to replace fields in template. Now to make this a bit more generic (I perform the same action in few places) I have defined a custom function to do so. Below is definition of custom builder and values is a dictionary with { 'name': (data_file, parse_function) } (you don't really need to read through this, I simply put it here for completeness). def TOOL_ADD_FILL_TEMPLATE(env): def FillTemplate(env, output, template, values): out = output[0] subs = {} for name, (node, process) in values.iteritems(): def Process(env, target, source): with open( env.GetBuildPath(target[0]), 'w') as out: out.write( process( source[0] ) ) builder = env.Builder( action = Process ) subs[name] = builder( env, env.GetBuildPath(output[0])+'_'+name+'_processed.cpp', node )[0] def Fill(env, target, source): values = dict( (name, n.get_contents()) for name, n in subs.iteritems() ) contents = template[0].get_contents().format( **values ) open( env.GetBuildPath(target[0]), 'w').write( contents ) builder = env.Builder( action = Fill ) builder( env, output[0], template + subs.values() ) return output env.Append(BUILDERS = {'FillTemplate': FillTemplate}) It works fine when it comes to checking if data or template changed. If it did it rebuilds the output. It even works if I edit process function directly. However if my process function looks like this: def process( node ): return subprocess(node) and I edit subprocess the change goes unnoticed. Is there any way to get correct builds without making process functions being always invoked?

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  • How to catch this low level MySQL (?) error in PHP/Magento

    - by andnil
    When I'm executing the following statement in Magento with a really large $sku, the execution terminates without any errors thrown what so ever. There are no errors in either Magento's, Apache's or PHP's error logs. Mage::getModel('catalog/product')-loadByAttribute('sku', $sku); Question: How do I catch the error? I've tried to set custom error handlers, and for testing purposes I've also managed to trigger error situations where each of the error handler functions are invoked. But when running the previously mentioned Magento code with a large $sku, none of the error handling functions are executed. error_reporting( -1 ); set_error_handler( array( 'Error', 'captureNormal' ) ); set_exception_handler( array( 'Error', 'captureException' ) ); register_shutdown_function( array( 'Error', 'captureShutdown' ) ); For completeness, this is the $sku I'm passing to loadByAttribute(). (The sku is invalid, but that is not the issue) 1- 9685 0102046|1- 9685 1212100|1- 9685 1212092|1- 9685 1212096|1- 9685 1102100|1- 9685 1102108|1- 9685 1102112|1- 9685 1102092|1- 9685 0102048|1- 9685 0102054|1- 9685 0102056|1- 9685 0102058|1- 9685 1212104|1- 9685 1212108|1- 9685 0212058|1- 9685 0104050|1- 9685 0212050|1- 9685 0212056|1- 9685 0212044|1- 9685 0212048|1- 9685 0212052|1- 9685 0212054|1- 9685 1102104|1- 9685 1102124 Any insight into this matter is much appreciated! Update: Upon further investigation, this is the exact point in the code where execution terminates. when the foreach is executed I guess Magento goes into MySQL world and starts loading up data from the database. \Mage\Catalog\Model\Abstract.php public function loadByAttribute($attribute, $value, $additionalAttributes = '*') { $collection = $this->getResourceCollection() ->addAttributeToSelect($additionalAttributes) ->addAttributeToFilter($attribute, $value) ->setPage(1,1); foreach ($collection as $object) { // <--------------- HERE return $object; } return false; } Note, I'm ONLY interested in finding out how to properly CATCH these kinds of errors, not "fix" the logic. This is so that I can present a proper error message to the user. The example above with the malformed sku is contrived and I have no desire to make my Magento app work with those erroneous skus.

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  • Validating a phone number in Android PreferenceScreen

    - by djechelon
    I have a PreferenceScreen in which the user is capable, if system can't autodetect it, to enter the device's phone number. I'm still learning this part of Android but I managed to understand a bit of PreferenceScreens by examples provided by Android SDK itself and a few tutorials. What I want is that the user can save the phone number only if null or valid, where by "valid" I mean running a generic validation logic (ie. an anonymous method that returns true or false, that can be reused in any possible situation*) or better, just to simplify things, ^(\+39)?3[0-9]{9}$ For now I have the following XML snip <EditTextPreference android:inputType="phone" android:key="@string/preference_phoneNo" android:selectAllOnFocus="true" android:singleLine="true" android:summary="@string/pref_phoneNumber_description" android:title="@string/pref_phoneNumber" /> and following code by courtesy of Eclipse New Activity wizard: private void setupSimplePreferencesScreen() { if (!isSimplePreferences(this)) { return; } addPreferencesFromResource(R.xml.pref_general); bindPreferenceSummaryToValue(findPreference(getString(R.string.preference_phoneNo))); } addPreferenceFromResource is supposed to load the XML node and add the preference to the screen, while binPreferenceSummaryToValue is supposed to make description text change when preference is updated. Just for sake of completeness for those who don't like code courtesy of the IDE, the second method is provided by Eclipse who also provides a private class in the code file that is /** * A preference value change listener that updates the preference's summary * to reflect its new value. */ In the general case, what should I do to perform validation logic before the preference gets saved when I click OK on the preference editor? Where is the validation logic to be put in a PreferenceScreen? *Aren't we all here to learn?

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