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• Why is Lua considered a game language?

  - by Hoffmann

  I have been learning about Lua in the past month and I'm absolutely in love with the language, but all I see around that is built with lua are games. I mean, the syntax is very simple, there is no fuss, no special meaning characters that makes code look like regex, has all the good things about a script language and integrates so painlessly with other languages like C, Java, etc. The only down-side I saw so far is the prototype based object orientation that some people do not like (or lack of OO built-in). I do not see how ruby or python are better, surely not in performance ( http://shootout.alioth.debian.org/gp4/benchmark.php?test=all&lang=lua&lang2=python ). I was planning on writting a web app using lua with the Kepler framework and Javascript, but the lack of other projects that use lua as a web language makes me feel a bit uneasy since this is my first try with web development. Lua is considered a kids language, most of you on stackoverflow probably only know the language because of the WoW addons. I can't really see why that is... http://lua-users.org/wiki/LuaVersusPython this link provides some insights on Lua against Python, but this is clearly biased.

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• Embedding Lua functions as member variables in Java

  - by Zarion

  Although the program I'm working on is in Java, answering this from a C perspective is also fine, considering that most of this is either language-agnostic, or happens on the Lua side of things. In the outline I have for the architecture of a game I'm programming, individual types of game objects within a particular class (eg: creatures, items, spells, etc.) are loaded from a data file. Most of their properties are simple data types, but I'd like a few of these members to actually contain simple scripts that define, for example, what an item does when it's used. The scripts will be extremely simple, since all fundamental game actions will be exposed through an API from Java. The Lua is simply responsible for stringing a couple of these basic functions together, and setting arguments. The question is largely about the best way to store a reference to a specific Lua function as a member of a Java class. I understand that if I store the Lua code as a string and call lua_dostring, Lua will compile the code fresh every time it's called. So the function needs to be defined somehow, and a reference to this specific function wrapped in a Java function object. One possibility that I've considered is, during the data loading process, when the loader encounters a script definition in a data file, it extracts this string, decorates the function name using the associated object's unique ID, calls lua_dostring on the string containing a full function definition, and then wraps the generated function name in a Java function object. A function declared in script run with lua_dostring should still be added to the global function table, correct? I'm just wondering if there's a better way of going about this. I admit that my knowledge of Lua at this point is rather superficial and theoretical, so it's possible that I'm overlooking something obvious.

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• C# style Action<T>, Func<T,T>, etc in C++0x

  - by Austin Hyde

  C# has generic function types such as Action<T> or Func<T,U,V,...> With the advent of C++0x and the ability to have template typedef's and variadic template parameters, it seems this should be possible. The obvious solution to me would be this: template <typename T> using Action<T> = void (*)(T); however, this does not accommodate for functors or C++0x lambdas, and beyond that, does not compile with the error "expected unqualified-id before 'using'" My next attempt was to perhaps use boost::function: template <typename T> using Action<T> = boost::function<void (T)>; This doesn't compile either, for the same reason. My only other idea would be STL style template arguments: template <typename T, typename Action> void foo(T value, Action f) { f(value); } But this doesn't provide a strongly typed solution, and is only relevant inside the templated function. Now, I will be the first to admit that I am not the C++ wiz I prefer to think I am, so it's very possible there is an obvious solution I'm not seeing. Is it possible to have C# style generic function types in C++?

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• A map and set which uses contiguous memory and has a reserve function

  - by edA-qa mort-ora-y

  I use several maps and sets. The lack of contiguous memory, and high number of (de)allocations, is a performance bottleneck. I need a mainly STL-compatbile map and set class which can use a contiguous block of memory for internal objects (or multiple blocks). It also needs to have a reserve function so that I can preallocate for expected sizes. Before I write my own I'd like to check what is available first. Is there something in Boost which does this? Does somebody know of an available implementation elsewhere? Intrusive collection types are not usable here as the same objects need to exist in several collections. As far as I know STL memory pools are per-type, not per instance. These global pools are not efficient with respect to memory locality in mutli-cpu/core processing. Object pools don't work as the types will be shared between instance but their pool should not. In many cases a hash map may be an option in some cases.

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• Problems with reading into buffer using boost::asio::async_read

  - by Max

  Good day. I have a Types.hpp file in my project. And within it i have: .... namespace RC { ..... ..... struct ViewSettings { .... }; ..... } In the Server.cpp file I'm including this Types.hpp file, and i have there: class Session { ..... RC::ViewSettings tmp; boost::asio::async_read(socket_, boost::asio::buffer(&tmp, sizeof(RC::ViewSettings)), boost::bind(&Session::Finish_Reading_Data, shared_from_this(), boost::asio::placeholders::error)); ..... } And during the compilation i have an errors: error C2825: 'F': must be a class or namespace when followed by '::' : see reference to class template instantiation 'boost::_bi::result_traits<R,F>' being compiled with [ R=boost::_bi::unspecified, F=void (__thiscall Session::* )(void) ] : see reference to class template instantiation 'boost::_bi::bind_t<R,F,L>' being compiled with [ R=boost::_bi::unspecified, F=void (__thiscall Session::* )(void), L=boost::_bi::list2<boost::_bi::value<boost::shared_ptr<Session>>,boost::arg<1>> ] error C2039: 'result_type' : is not a member of '`global namespace'' And the code like this works in proper way: int w; boost::asio::async_read(socket_, boost::asio::buffer(&w, sizeof(int)), boost::bind(&Session::Handle_Read_Width, shared_from_this(), boost::asio::placeholders::error)); Please, help. What's the problem here? Thanks in advance.

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• How to determine which source files are required for an Eclipse run configuration

  - by isme

  When writing code in an Eclipse project, I'm usually quite messy and undisciplined in how I create and organize my classes, at least in the early hacky and experimental stages. In particular, I create more than one class with a main method for testing different ideas that share most of the same classes. If I come up with something like a useful app, I can export it to a runnable jar so I can share it with friends. But this simply packs up the whole project, which can become several megabytes big if I'm relying on large library such as httpclient. Also, if I decide to refactor my lump of code into several projects once I work out what works, and I can't remember which source files are used in a particular run configuration, all I can do it copy the main class to a new project and then keep copying missing types till the new project compiles. Is there a way in Eclipse to determine which classes are actually used in a particular run configuration? EDIT: Here's an example. Say I'm experimenting with web scraping, and so far I've tried to scrape the search-result pages of both youtube.com and wrzuta.pl. I have a bunch of classes that implement scraping in general, a few that are specific to each of youtube and wrzuta. On top of this I have a basic gui common to both scrapers, but a few wrzuta- and youtube-specific buttons and options. The WrzutaGuiMain and YoutubeGuiMain classes each contain a main method to configure and show the gui for each respective website. Can Eclipse look at each of these to determine which types are referenced?

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• Multiple Table Inheritance vs. Single Table Inheritance in Ruby on Rails

  - by Tony

  I have been struggling for the past few hours thinking about which route I should go. I have a Notification model. Up until now I have used a notification_type column to manage the types but I think it will be better to create separate classes for the types of notifications as they behave differently. Right now, there are 3 ways notifications can get sent out: SMS, Twitter, Email Each notification would have: id subject message valediction sent_people_count deliver_by geotarget event_id list_id processed_at deleted_at created_at updated_at Seems like STI is a good candidate right? Of course Twitter/SMS won't have a subject and Twitter won't have a sent_people_count, valediction. I would say in this case they share most of their fields. However what if I add a "reply_to" field for twitter and a boolean for DM? My point here is that right now STI makes sense but is this a case where I may be kicking myself in the future for not just starting with MTI? To further complicate things, I want a Newsletter model which is sort of a notification but the difference is that it won't use event_id or deliver_by. I could see all subclasses of notification using about 2/3 of the notification base class fields. Is STI a no-brainer, or should I use MTI? Thanks!

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• Help with MySQL Join Statement

  - by JasonS

  Hi, I just built a website and have realised that I need to have a top 3 highest rated albums.. I haven't built in something that keeps track of the ratings. Ratings are stored separately. Can someone show me how to put these together please. SELECT id, name FROM albums LIMIT 3 SELECT rating FROM ratings WHERE url=CONCAT('albums/show/', album.id) Let me just flesh it out a bit. I need to get back the following: From the albums table. id, name. From the ratings table I need to get back the average rating. ROUND((rating+rating+rating) / total ratings) The ratings. Users can rate everything on my website so I have a generic ratings table. The rating is stored with the url of the page it applies to. Hence, to get album ratings I need to have 'albums/show/{album_id}'. In hind sight I should have had a type and id field but it is a bit late now with a lunch iminient. Any help is much appreciated.

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• question/problem regarding assigning an array of char *

  - by Fantastic Fourier

  Hi I'm working with C and I have a question about assigning pointers. struct foo { int _bar; char * _car[MAXINT]; // this is meant to be an array of char * so that it can hold pointers to names of cars } int foofunc (void * arg) { int bar; char * car[MAXINT]; struct foo thing = (struct foo *) arg; bar = arg->_bar; // this works fine car = arg->_car; // this gives compiler errors of incompatible types in assignment } car and _car have same declaration so why am I getting an error about incompatible types? My guess is that it has something to do with them being pointers (because they are pointers to arrays of char *, right?) but I don't see why that is a problem. when i declared char * car; instead of char * car[MAXINT]; it compiles fine. but I don't see how that would be useful to me later when I need to access certain info using index, it would be very annoying to access that info later. in fact, I'm not even sure if I am going about the right way, maybe there is a better way to store a bunch of strings instead of using array of char *?

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• Error when calling SQL SP via LINQ

  - by PaulC

  Newbie problem: I have a SQL SP with ten parameters (eight input, two output) but when I attempt to call it via LINQ from code I get the following error message: "The best overloaded method match for 'DataClassesDataContext.ST_CR_CREATE_CASE_BASIS(string, string, string, string, System.DateTime?, string, string, string, ref int?, ref int?)' has some invalid arguments". The params with ? appear to be unrecognized, but I'm baffled: the data types match the SQL types, the number of parameters match, the other parmeters don't exhibit the same behaviour. Can anyone tell me what's going on? Thanks in advance. -- SQL SP: create procedure ST_CR_CREATE_CASE_BASIS @p_Pers_No nvarchar (50), @p_Subject nvarchar (255), @p_RQ_XML nvarchar(max), @p_RQ_XSL nvarchar(max), @p_Date_Submit smalldatetime, @p_User_ID_Submit nvarchar (255), @p_RQ_Status nvarchar (50), @p_User_ID_OnBehalf nvarchar (255), @p_Case_Number int output, @p_RQ_ID int output as begin -- ... etc.; the SP works fine when called from SSMS The code-behind proc from the aspx page looks like this: protected void cmdSubmit_Click(object sender, EventArgs e) { using (DataClassesDataContext vDataCont = new DataClassesDataContext()) { Int32 vNewCaseNr; Int32 vNewReqNr; DateTime vNow = System.DateTime.Now; vDataCont.ST_CR_CREATE_CASE_BASIS("101", "Test Subject Late Wed", null, null, vNow , "101", "1", "101", ref vNewCaseNr, vNewReqNr); } }

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• How do I so a select input for a STI column in a Rails model?

  - by James A. Rosen

  I have a model with single-table inheritance on the type column: class Pet < ActiveRecord::Base TYPES = [Dog, Cat, Hamster] validates_presence_of :name end I want to offer a <select> dropdown on the new and edit pages: <% form_for @model do |f| %> <%= f.label :name %> <%= f.text_input :name %> <%= f.label :type %> <%= f.select :type, Pet::TYPES.map { |t| [t.human_name, t.to_s] } %> <% end %> That gives me the following error: ActionView::TemplateError (wrong argument type String (expected Module)) I read a suggestion to use an alias for the field #type since Ruby considers that a reserved word that's the same as #class. I tried both class Pet < ActiveRecord::Base ... alias_attribute :klass, :type end and class Pet < ActiveRecord::Base ... def klass self.type end def klass=(k) self.type = k end end Neither worked. Any suggestions? Oddly, it works fine on my machine (MRI 1.8.6 on RVM), but fails on the staging server (MRI 1.8.7 not on RVM).

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• Good mobile oriented GWT widget library alternatives

  - by Michael Donohue

  I've been developing a travel planning site - tripgrep.com - which is built on appengine, GWT and smartgwt, among other technologies. It is still early days, and the site is now working well on my development environment, which is either a windows or mac computer. However, I am frequently talking up the website to my friends when we are at a bar or other venue, so I am standing there while they try to access the site via an iPhone, Android or Blackberry - I've witnessed all three. It has been painfully obvious that the browser based frontend takes a long time to download on a mobile device. I am pretty sure this is because of the javascript download for SmartGWT. So, I would like to look at alternatives to SmartGWT. What I like about SmartGWT is that it has a reasonable look and feel out of the box - I don't need to learn any design or css and it has an office application look. This is considerably better than the GWT built-in widgets, which just get a blue border. The better look-and-feel is why I went with SmartGWT early on. However, the slow load times are killing me on these mobile demos. So now I want a fast loading widget alternative that has good look-and-feel out of the box. The features I care about are: tabs, good form layout, Google maps API integration, grid data viewing. If those are all available in a library that loads quickly on a mobile device, then that's the library I want.

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• WPF - Why doesn't Microsoft supply a decent set of most-used controls ?

  - by IUsedToBeAPygmy

  I've been playing with WPF for some months now, and I quite like it. But one of the things I don't get is why MS doesn't put a little more effort in helping developers by supplying basic controls, and I need to get this off my chest :) For example, I figure most applications somewhere will need to let you edit some properties - for configuration or whatever. What would be the most used types in a proprety-grid editor ? text numbers (byte, float/double, int, etc) colors ....etc. So why isn't there even something as simple as a control to edit numbers ? Like a generic NumericUpDown control that allows you to type in numbers (no text, no pasting invalid input) or spin them up/down according to some given rules (decimal, floating point, min/maxvalue) ? Why isn't there a generic colorpicker, so people get the same user-experience in every application ? Why isn't there a standard implementation of a SearchTextBox, a BreadCrumb-control, or all these other standard control types users have gotten accustomed to the last 10 years ? (..but at least they DID have the time to implement a generic splashscreen - because everyone knows that greatly increases user-productivity....) The well-known ideal is always to give people the same user-experience over different applications. So even if some of those controls would be easy to make - it would be preferred to have one version over different applications. I see people all over the internet trying to do the same stuff over and over again. Okay, so MS started a WPF Toolkit project on Codeplex that tries to implement some controls, but only did so half-heartedly and is completely dead by now (last update of the roadmap dates back to Mar 21 2009). The result of this is that a lot of people starting a WPF-project end up spending a lot of time on trying to figure out how to create some generic controls and get really frustrated. Wasn't the mantra "Developers, developers, developers!" ..? /Rant

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• What header file is where the boost libray define its own primitive data type?

  - by ronghai

  Recently, I try to use the boost::spirit::qi binary endian parser to parse some binary data depends on the endianness of the Platform. There is a simple example, like following: Using declarations and variables: using boost::spirit::qi::little_word; using boost::spirit::qi::little_dword; using boost::spirit::qi::little_qword; boost::uint16_t us; boost::uint32_t ui; boost::uint64_t ul; Basic usage of the little endian binary parsers: test_parser_attr("\x01\x02", little_word, us); assert(us == 0x0201); test_parser_attr("\x01\x02\x03\x04", little_dword, ui); assert(ui == 0x04030201); test_parser_attr("\x01\x02\x03\x04\x05\x06\x07\x08", little_qword, ul); assert(ul == 0x0807060504030201LL); test_parser("\x01\x02", little_word(0x0201)); test_parser("\x01\x02\x03\x04", little_dword(0x04030201)); test_parser("\x01\x02\x03\x04\x05\x06\x07\x08", little_qword(0x0807060504030201LL)); It works very well. But my questions come, why do we need use some data types like boost::uint16_t, boost::uint32_t here? Can I use unsigned long or unsigned int here? And if I want to parse double or float data type, what boost data type should I use? And please tell me where is boost define the above these types? Thanks a lot.

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• How to program critical section for reader-writer systems?

  - by Srinivas Nayak

  Hi, Lets say, I have a reader-writer system where reader and writer are concurrently running. 'a' and 'b' are two shared variables, which are related to each other, so modification to them needs to be an atomic operation. A reader-writer system can be of the following types: rr ww r-w r-ww rr-w rr-ww where [ r : single reader rr: multiple reader w : single writer ww: multiple writer ] Now, We can have a read method for a reader and a write method for a writer as follows. I have written them system type wise. rr read_method { read a; read b; } ww write_method { lock(m); write a; write b; unlock(m); } r-w r-ww rr-w rr-ww read_method { lock(m); read a; read b; unlock(m); } write_method { lock(m); write a; write b; unlock(m); } For multiple reader system, shared variable access doesn't need to be atomic. For multiple writer system, shared variable access need to be atomic, so locked with 'm'. But, for system types 3 to 6, is my read_method and write_method correct? How can I improve? Sincerely, Srinivas Nayak

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• Prolog check if

  - by NickLee

  I'm creating a text adventure game on SWI-Prolog and I want to include (some kind of) dialogs. What I have so far is: dialog1(1):- nl,write('blah blah'),nl write('a: this is answer a'),nl, write('b: this is answer b'),nl. a:- write('respond to answer a'),nl. b:- write('respond to answer b'),nl. That's pretty much the first dialog. Now I want to create a second dialog similar to the first one. dialog1(2):- nl,write('blah blah'),nl, write('a: this is answer a'),nl, write('b: this is answer b'),nl. a:- write('respond to answer a'),nl. b:- write('respond to answer b'),nl. How can I check if the dialog is the first or the second one? I want to do that because when the user types a., I need the right answer a to be shown. I thought I could use something like a(1):- write('respond to answer a'),nl. b(1):- write('respond to answer b'),nl. /* and on the second dialog*/ a(2):- write('respond to answer a'),nl. b(2):- write('respond to answer b'),nl. But still, if the user is on dialog 2 and he types a(1),the first answer will appear.

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• Setting Up OpenCV and .lib files

  - by jhaip

  I have been trying to set up OpenCV for the past few days with no results. I am using Windows 7 and VS C++ 2008 express edition. I have downloaded and installed OpenCV 2.1 and some of the examples work. I downloaded CMake and ran it to generate the VS project files and built all of them but there with several errors, and couldn't get any farther than that. When I ran CMake I configured it to use the VS 9 compiler, and then it brought up a list of items in red such as BUILD_EXAMPLES, BUILD_LATEX_DOCS, ect. All of them were unchecked except BUILD_NEW_PYTHON_SUPPORT, BUILD_TESTS, ENABLE_OPENMP, and OPENCV_BUILD_3RDPARTY_LIBS. I configured and generate without changing anything and then it generated the VS files such as ALL_BUILD.vcproj. I built the OpenCV VS solution in debug mode and it had 15 failures (maybe this is part of the problem or is it because I don't have python and stuff like that?) Now there was a lib folder created after building but inside there was just this VC++ Minimum Rebuild Dependency file and Program Debug Database file, both called cvhaartraining. I believe it should have created the .lib files I need instead of this. Also, the bin folder now has a folder called Debug with the same types of files with names like cv200d and cvaux200d. Believe I need those .lib files to move forward. I would also greatly appreciate if someone could direct me to a reliable tutorial to set up VS for OpenCV because I have been reading a lot of tutorials and they all say different things such as some say to configure Window's environment variables and other say files are located in folders such as OpenCV/cv which I don't have. I have gotten past the point of clear headed thinking so if anyone could offer some direction or a simple list of the files I need to link then I would be thankful. Also a side question: why when linking the OpenCV libs do you have to put them in quotes?

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• What is the basic pattern for using (N)Hibernate?

  - by Vilx-

  I'm creating a simple Windows Forms application with NHibernate and I'm a bit confused about how I'm supposed to use it. To quote the manual: ISession (NHibernate.ISession) A single-threaded, short-lived object representing a conversation between the application and the persistent store. Wraps an ADO.NET connection. Factory for ITransaction. Holds a mandatory (first-level) cache of persistent objects, used when navigating the object graph or looking up objects by identifier. Now, suppose I have the following scenario: I have a simple classifier which is a MSSQL table with two columns - ID (auto_increment) and Name (nvarchar). To edit this classifier I create a form which contains a single gridview and two buttons - OK and Cancel. The user can nearly directly edit the table in the gridview, and when he hits OK the changes he made are persisted to the DB (or if he hits cancel, nothing happens). Now, I have several questions about how to organize this: What should the lifetime of my ISession be? Should I create a single ISession for my whole application; an ISession for each of my forms (the application is single-threaded MDI); or an ISession for every DB operation/transaction? Does NHibernate offer some kind of built-in dirty tracking or must I do this myself? The manual mentions something like it here and there but does not go into details. How is this done? Is there not a huge overhead? Is it somehow tied with the cache(s) that NHibernate has? What are these caches for? Are they not specific to a single ISession? That is, if I use a seperate ISession for every transaction, won't it break the dirty tracking? How does the built-in dirty tracking detect deleted objects?

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• Using generics in Unity ... InvalidCastException

  - by Sunny D

  Hi, My interface definition is: public interface IInterface where T:UserControl My class definition is: public partial class App1Control : UserControl, IInterface The unity section of my app.config looks as below: <unity> <typeAliases> <typeAlias alias="singleton" type="Microsoft.Practices.Unity.ContainerControlledLifetimeManager, Microsoft.Practices.Unity" /> <typeAlias alias="myInterface" type="MyApplication.IInterface`1, MyApplication" /> <typeAlias alias="App1" type="MyApplication.App1Control, MyApplication" /> </typeAliases> <containers> <container> <types> <type type="myInterface" mapTo="App1" name="Application 1"> <lifetime type="singleton"/> </type> </types> </container> </containers> </unity> The app runs fine but, the following code gives a InvalidCastException container.Resolve<IInterface<UserControl>>("Application 1"); The error message is : Unable to cast object of type 'MyApplication.App1Control' to type 'MyApplication.IInterface`1[System.Windows.Forms.UserControl]' I believe there is a minor mistake in my code ... but am not able to figure out what. Any thoughts?

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• git doesn't show where code was removed.

  - by Andrew Myers

  So I was tasked at replacing some dummy code that our project requires for historical compatibility reasons but has mysteriously dropped out sometime since the last release. Since disappearing code makes me nervous about what else might have gone missing but un-noticed I've been digging through the logs trying to find in what commit this handful of lines was removed. I've tried a number of things including "git log -S'add-visit-resource-pcf'", git blame, and even git bisect with a script that simply checks for the existence of the line but have been unable to pinpoint exactly where these lines were removed. I find this very perplexing, particularly since the last log entry (obtained by the above command) before my re-introduction of this code was someone else adding the code as well. commit 0b0556fa87ff80d0ffcc2b451cca1581289bbc3c Author: Andrew Date: Thu May 13 10:55:32 2010 -0400 Re-introduced add-visit-resource-pcf, see PR-65034. diff --git a/spike/hst/scheduler/defpackage.lisp b/spike/hst/scheduler/defpackage.lisp index f8e692d..a6f8d38 100644 --- a/spike/hst/scheduler/defpackage.lisp +++ b/spike/hst/scheduler/defpackage.lisp @@ -115,6 +115,7 @@ #:add-to-current-resource-pcf #:add-user-package-nickname #:add-value-criteria + #:add-visit-resource-pcf #:add-window-to-gs-params #:adjust-derived-resources #:adjust-links-candidate-criteria-types commit 9fb10e25572c537076284a248be1fbf757c1a6e1 Author: Bob Date: Sun Jan 17 18:35:16 2010 -0500 update-defpackage for Spike 33.1 Delivery diff --git a/spike/hst/scheduler/defpackage.lisp b/spike/hst/scheduler/defpackage.lisp index 983666d..47f1a9a 100644 --- a/spike/hst/scheduler/defpackage.lisp +++ b/spike/hst/scheduler/defpackage.lisp @@ -118,6 +118,7 @@ #:add-user-package-nickname #:add-value-criteria #:add-vars-from-proposal + #:add-visit-resource-pcf #:add-window-to-gs-params #:adjust-derived-resources #:adjust-links-candidate-criteria-types This is for one of our package definition files, but the relevant source file reflects something similar. Does anyone know what could be going on here and how I could find the information I want? It's not really that important but this kind of things makes me a bit nervous.

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• What's the difference between an option type and a nullable type?

  - by Peter Olson

  In F# mantra there seems to be a visceral avoidance of null, Nullable<T> and its ilk. In exchange, we are supposed to instead use option types. To be honest, I don't really see the difference. My understanding of the F# option type is that it allows you to specify a type which can contain any of its normal values, or None. For example, an Option<int> allows all of the values that an int can have, in addition to None. My understanding of the C# nullable types is that it allows you to specify a type which can contain any of its normal values, or null. For example, a Nullable<int> a.k.a int? allows all of the values that an int can have, in addition to null. What's the difference? Do some vocabulary replacement with Nullable and Option, null and None, and you basically have the same thing. What's all the fuss over null about?

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• KD-Trees and missing values (vector comparison)

  - by labratmatt

  I have a system that stores vectors and allows a user to find the n most similar vectors to the user's query vector. That is, a user submits a vector (I call it a query vector) and my system spits out "here are the n most similar vectors." I generate the similar vectors using a KD-Tree and everything works well, but I want to do more. I want to present a list of the n most similar vectors even if the user doesn't submit a complete vector (a vector with missing values). That is, if a user submits a vector with three dimensions, I still want to find the n nearest vectors (stored vectors are of 11 dimensions) I have stored. I have a couple of obvious solutions, but I'm not sure either one seem very good: Create multiple KD-Trees each built using the most popular subset of dimensions a user will search for. That is, if a user submits a query vector of thee dimensions, x, y, z, I match that query to my already built KD-Tree which only contains vectors of three dimensions, x, y, z. Ignore KD-Trees when a user submits a query vector with missing values and compare the query vector to the vectors (stored in a table in a DB) one by one using something like a dot product. This has to be a common problem, any suggestions? Thanks for the help.

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• Do the new NoPIA and Type Equivalence features in C#/.NET 4.0 mean Microsoft.mshtml.dll is no longer

  - by jpierson

  I'm maintaining a WPF based application which contains a WinForms based WebBrowser control that based on the IE web browser control. When we deploy, we have had to also supply Microsoft.mshtml.dll and do some custom configuration stuff for our ClickOnce publishing process as well in order to get things to work. I'm curious that with the new NoPIA and Type Equivalence features and dynamic type capabilities in C# 4.0 can we expect that if we upgrade that we can remove the dependencies on the Microsoft.mshtml.dll assembly? If so this will not only reduce the size of our deployment quite a bit but will also simplify our publishing process as well. It is my understanding that we should be able embed the types that normally get automatically generated into extra assemblies for COM types such as the MapPoint Control by Visual Studio. I don't know if this also applies to the Microsoft.mshtml.dll or even how it is done even in the most simple of cases. If somebody could provide an explanation about what the practical impact of these new features are on a project that relies on COM interop and especially the Microsoft.mshtml.dll assembly it would be of great help to me.

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• Inner join and outer join options in Entity Framework 4.0

  - by bigb

  I am using EF 4.0 and I need to implement query with one inner join and with N outer joins I started to implement this using different approaches but get into trouble at some point. Here is two examples how I started of doing this using ObjectQuery<'T' and Linq to Entity 1)Using ObjectQuery<'T' I implement flexible outer join but I don't know how to perform inner join with entity Rules in that case (by default Include("Rules") doing outer join, but i need to inner join by Id). public static IEnumerable<Race> GetRace(List<string> includes, DateTime date) { IRepository repository = new Repository(new BEntities()); ObjectQuery<Race> result = (ObjectQuery<Race>)repository.AsQueryable<Race>(); //perform outer joins with related entities if (includes != null) foreach (string include in includes) result = result.Include(include); //here i need inner join insteard of default outer join result = result.Include("Rules"); return result.ToList(); } 2)Using Linq To Entity I need to have kind of outer join(somethin like in GetRace()) where i may pass a List with entities to include) and also i need to perform correct inner join with entity Rules public static IEnumerable<Race> GetRace2(List<string> includes, DateTime date) { IRepository repository = new Repository(new BEntities()); IEnumerable<Race> result = from o in repository.AsQueryable<Race>() from b in o.RaceBetRules select new { o }); //I need here: // 1. to perform the same way inner joins with related entities like with ObjectQuery above //here i getting List<AnonymousType> which i cant cast to //IEnumerable<Race> when i did try to cast like //(IEnumerable<Race>)result.ToList(); i did get error: //Unable to cast object of type //'System.Collections.Generic.List`1[<>f__AnonymousType0`1[BetsTipster.Entity.Tip.Types.Race]]' //to type //'System.Collections.Generic.IEnumerable`1[BetsTipster.Entity.Tip.Types.Race]'. return result.ToList(); } May be someone have some ideas about that.

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• Excel Automation Addin UDFs not accesible

  - by Eric

  I created the following automation addin: namespace AutomationAddin { [Guid("6652EC43-B48C-428a-A32A-5F2E89B9F305")] [ClassInterface(ClassInterfaceType.AutoDual)] [ComVisible(true)] public class MyFunctions { public MyFunctions() { } #region UDFs public string ToUpperCase(string input) { return input.ToUpper(); } #endregion [ComRegisterFunctionAttribute] public static void RegisterFunction(Type type) { Registry.ClassesRoot.CreateSubKey( GetSubKeyName(type, "Programmable")); RegistryKey key = Registry.ClassesRoot.OpenSubKey( GetSubKeyName(type, "InprocServer32"), true); key.SetValue("", System.Environment.SystemDirectory + @"\mscoree.dll", RegistryValueKind.String); } [ComUnregisterFunctionAttribute] public static void UnregisterFunction(Type type) { Registry.ClassesRoot.DeleteSubKey( GetSubKeyName(type, "Programmable"), false); } private static string GetSubKeyName(Type type, string subKeyName) { System.Text.StringBuilder s = new System.Text.StringBuilder(); s.Append(@"CLSID\{"); s.Append(type.GUID.ToString().ToUpper()); s.Append(@"}\"); s.Append(subKeyName); return s.ToString(); } } } I build it and it registers just fine. I open excel 2003, go to tools-Add-ins, click on the automation button and the addin appears in the list. I add it and it shows up in the addins list. but, the functions themselves don't appear. If I type it in it doesn't work and if I look in the function wizard, my addin doesn't show up as a category and the functions are not in the list. I am using excel 2003 on windows 7 x86. I built the project with visual studio 2010. This addin worked fine on windows xp built with visual studio 2008.

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