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  • Compiler construction and DirectX

    - by otkins
    Hi! I am a beginner in the process of designing and coding a project, I already have all the ideas on my head, but I have a problem impeding me of continuing this project. I feel the code is ugly and unreadable and I cannot continue it this way. The project is a programming language I have on my mind, and it has small graphics capabilities. Even being beginner, I want to code it using DirectX because everybody wants it. And I want to code it entirely, not depend on any wrapper libraries like SDL. I did a refactoring of the DirectX module and it exposed all the weaks. There is Direct3D code everywhere, but the code itself does very little! I would start building a project like this using DirectX or I should use just GDI and the Multimedia API of Windows? This is a good progress for a beginner?

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  • C++ compiler error on template specialization

    - by user231536
    I would like to specialize a template method for a class C that is itself templated by an int parameter. How do I do this? template <int D=1> class C { static std::string foo () { stringstream ss; ss << D << endl; return ss.str();} }; template <class X> void test() { cout << "This is a test" << endl;} template <> template <int D> void test<C<D> > () {cout << C<D>::foo() << endl;} The specialization for test() fails with "Too many template parameter lists in declaration of void test()".

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  • Strange compiler complaint when using similar code

    - by Jason
    For a project, I have to ask the user for a file name, and I'm reading it in character by character using getchar. From the main, I call the function char *coursename= introPrint(); //start off to print the usage directions and get the first bit of input. That function is defined as char *introPrint(){ int size= 20; int c; int length=0; char buffer[size]; //instructions printout, cut for brevity //get coursename from user and return it while ( (c=getchar()) != EOF && (c != '\n') ){ buffer[length++]= c; if (length==size-1) break; } buffer[length]=0; return buffer; } This is basically identical code I wrote to ask the user for input, replace the character echo with asterisks, then print out the results. Here, though, I'm getting a function returns address of local variable warning for the return statement. So why am I getting no warnings from the other program, but trigger one for this code?

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  • arrays declaration and addressing

    - by avinash
    I have a few straightforward questions:- Is the following correct according to a normal c++ compiler? int arr[3][4]; void func(int *a, int m, int n) { int i,j; cin>>i>>j; cout<< a[i*n + j]; //is this way of addressing correct provided 0<=i<m and 0<=j<n } int main() { func((int*)arr, 3,4); } If the bounds of an array strictly has to be a constant expression, why doesn't the following generate compiler errors? int func(int m, int n) { int arr[m][n]; //m and n are not known until run time }

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  • Sometimes Java web app hang

    - by zhongshu
    The web app occasionally get hang for about 30 seconds when user request a web page, the server's CPU and memory usage are ok, and the jstack shows: "http-9999-3" daemon prio=6 tid=0x552f3400 nid=0xf40 runnable [0x578fc000] java.lang.Thread.State: RUNNABLE at org.eclipse.jdt.internal.compiler.parser.Parser.getTypeReference(Parser.java:8354) at org.eclipse.jdt.internal.compiler.parser.Parser.consumeClassHeaderExtends(Parser.java:2125) at org.eclipse.jdt.internal.compiler.parser.Parser.consumeRule(Parser.java:5107) at org.eclipse.jdt.internal.compiler.parser.Parser.parse(Parser.java:9020) at org.eclipse.jdt.internal.compiler.parser.Parser.parse(Parser.java:9251) at org.eclipse.jdt.internal.compiler.parser.Parser.parse(Parser.java:9208) at org.eclipse.jdt.internal.compiler.parser.Parser.dietParse(Parser.java:7864) at org.eclipse.jdt.internal.compiler.Compiler.internalBeginToCompile(Compiler.java:587) at org.eclipse.jdt.internal.compiler.Compiler.beginToCompile(Compiler.java:357) at org.eclipse.jdt.internal.compiler.Compiler.compile(Compiler.java:371) at org.apache.jasper.compiler.JDTCompiler.generateClass(JDTCompiler.java:413) at org.apache.jasper.compiler.Compiler.compile(Compiler.java:317) at org.apache.jasper.compiler.Compiler.compile(Compiler.java:295) at org.apache.jasper.compiler.Compiler.compile(Compiler.java:282) at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:586) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:317) - locked <0x10a75fc0> (a org.apache.jasper.servlet.JspServletWrapper) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:630) at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:535) at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:472) ...... seems it's related with some jsp files, how to find the root cause? thanks.

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  • Whats the thing the report bugs in php?

    - by Max Hazard
    Currently I am learning php. Php is understood by browser itself right from php sdk right? SDK include libraries right? So browser is like an interpreter of php codes. I want to know that whenever I type a wrong php syntax what is the thing report me the error? Obviously the browser is reporting the error. But what part of it? I mean I don't get it. Like writing a compiler we do lexical analysis and make the compiler which report any bug in source code. I assume here browser is analogous to compiler. I don't know exactly but compiler contains bug report functions or methods which is debugger. Debugger is part of compiler which report bugs. Does the browser contains such debuggers? Can there be any browser which doesn't understand php?

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  • GuestPost: Unit Testing Entity Framework (v1) Dependent Code using TypeMock Isolator

    - by Eric Nelson
    Time for another guest post (check out others in the series), this time bringing together the world of mocking with the world of Entity Framework. A big thanks to Moses for agreeing to do this. Unit Testing Entity Framework Dependent Code using TypeMock Isolator by Muhammad Mosa Introduction Unit testing data access code in my opinion is a challenging thing. Let us consider unit tests and integration tests. In integration tests you are allowed to have environmental dependencies such as a physical database connection to insert, update, delete or retrieve your data. However when performing unit tests it is often much more efficient and productive to remove environmental dependencies. Instead you will need to fake these dependencies. Faking a database (also known as mocking) can be relatively straight forward but the version of Entity Framework released with .Net 3.5 SP1 has a number of implementation specifics which actually makes faking the existence of a database quite difficult. Faking Entity Framework As mentioned earlier, to effectively unit test you will need to fake/simulate Entity Framework calls to the database. There are many free open source mocking frameworks that can help you achieve this but it will require additional effort to overcome & workaround a number of limitations in those frameworks. Examples of these limitations include: Not able to fake calls to non virtual methods Not able to fake sealed classes Not able to fake LINQ to Entities queries (replace database calls with in-memory collection calls) There is a mocking framework which is flexible enough to handle limitations such as those above. The commercially available TypeMock Isolator can do the job for you with less code and ultimately more readable unit tests. I’m going to demonstrate tackling one of those limitations using MoQ as my mocking framework. Then I will tackle the same issue using TypeMock Isolator. Mocking Entity Framework with MoQ One basic need when faking Entity Framework is to fake the ObjectContext. This cannot be done by passing any connection string. You have to pass a correct Entity Framework connection string that specifies CSDL, SSDL and MSL locations along with a provider connection string. Assuming we are going to do that, we’ll explore another limitation. The limitation we are going to face now is related to not being able to fake calls to non-virtual/overridable members with MoQ. I have the following repository method that adds an EntityObject (instance of a Blog entity) to Blogs entity set in an ObjectContext. public override void Add(Blog blog) { if(BlogContext.Blogs.Any(b=>b.Name == blog.Name)) { throw new InvalidOperationException("Blog with same name already exists!"); } BlogContext.AddToBlogs(blog); } The method does a very simple check that the name of the new Blog entity instance doesn’t exist. This is done through the simple LINQ query above. If the blog doesn’t already exist it simply adds it to the current context to be saved when SaveChanges of the ObjectContext instance (e.g. BlogContext) is called. However, if a blog with the same name exits, and exception (InvalideOperationException) will be thrown. Let us now create a unit test for the Add method using MoQ. [TestMethod] [ExpectedException(typeof(InvalidOperationException))] public void Add_Should_Throw_InvalidOperationException_When_Blog_With_Same_Name_Already_Exits() { //(1) We shouldn't depend on configuration when doing unit tests! But, //its a workaround to fake the ObjectContext string connectionString = ConfigurationManager .ConnectionStrings["MyBlogConnString"] .ConnectionString; //(2) Arrange: Fake ObjectContext var fakeContext = new Mock<MyBlogContext>(connectionString); //(3) Next Line will pass, as ObjectContext now can be faked with proper connection string var repo = new BlogRepository(fakeContext.Object); //(4) Create fake ObjectQuery<Blog>. Will be used to substitute MyBlogContext.Blogs property var fakeObjectQuery = new Mock<ObjectQuery<Blog>>("[Blogs]", fakeContext.Object); //(5) Arrange: Set Expectations //Next line will throw an exception by MoQ: //System.ArgumentException: Invalid setup on a non-overridable member fakeContext.SetupGet(c=>c.Blogs).Returns(fakeObjectQuery.Object); fakeObjectQuery.Setup(q => q.Any(b => b.Name == "NewBlog")).Returns(true); //Act repo.Add(new Blog { Name = "NewBlog" }); } This test method is checking to see if the correct exception ([ExpectedException(typeof(InvalidOperationException))]) is thrown when a developer attempts to Add a blog with a name that’s already exists. On (1) a connection string is initialized from configuration file. To retrieve the full connection string. On (2) a fake ObjectContext is being created. The ObjectContext here is MyBlogContext and its being created using this var fakeContext = new Mock<MyBlogContext>(connectionString); This way a fake context is being created using MoQ. On (3) a BlogRepository instance is created. BlogRepository has dependency on generate Entity Framework ObjectContext, MyObjectContext. And so the fake context is passed to the constructor. var repo = new BlogRepository(fakeContext.Object); On (4) a fake instance of ObjectQuery<Blog> is being created to use as a substitute to MyObjectContext.Blogs property as we will see in (5). On (5) setup an expectation for calling Blogs property of MyBlogContext and substitute the return result with the fake ObjectQuery<Blog> instance created on (4). When you run this test it will fail with MoQ throwing an exception because of this line: fakeContext.SetupGet(c=>c.Blogs).Returns(fakeObjectQuery.Object); This happens because the generate property MyBlogContext.Blogs is not virtual/overridable. And assuming it is virtual or you managed to make it virtual it will fail at the following line throwing the same exception: fakeObjectQuery.Setup(q => q.Any(b => b.Name == "NewBlog")).Returns(true); This time the test will fail because the Any extension method is not virtual/overridable. You won’t be able to replace ObjectQuery<Blog> with fake in memory collection to test your LINQ to Entities queries. Now lets see how replacing MoQ with TypeMock Isolator can help. Mocking Entity Framework with TypeMock Isolator The following is the same test method we had above for MoQ but this time implemented using TypeMock Isolator: [TestMethod] [ExpectedException(typeof(InvalidOperationException))] public void Add_New_Blog_That_Already_Exists_Should_Throw_InvalidOperationException() { //(1) Create fake in memory collection of blogs var fakeInMemoryBlogs = new List<Blog> {new Blog {Name = "FakeBlog"}}; //(2) create fake context var fakeContext = Isolate.Fake.Instance<MyBlogContext>(); //(3) Setup expected call to MyBlogContext.Blogs property through the fake context Isolate.WhenCalled(() => fakeContext.Blogs) .WillReturnCollectionValuesOf(fakeInMemoryBlogs.AsQueryable()); //(4) Create new blog with a name that already exits in the fake in memory collection in (1) var blog = new Blog {Name = "FakeBlog"}; //(5) Instantiate instance of BlogRepository (Class under test) var repo = new BlogRepository(fakeContext); //(6) Acting by adding the newly created blog () repo.Add(blog); } When running the above test method it will pass as the Add method of BlogRepository is going to throw an InvalidOperationException which is the expected behaviour. Nothing prevents us from faking out the database interaction! Even faking ObjectContext  at (2) didn’t require a connection string. On (3) Isolator sets up a faking result for MyBlogContext.Blogs when its being called through the fake instance fakeContext created on (2). The faking result is just an in-memory collection declared an initialized on (1). Finally at (6) action we call the Add method of BlogRepository passing a new Blog instance that has a name that’s already exists in the fake in-memory collection which we set up at (1). As expected the test will pass because it will throw the expected exception defined on top of the test method - InvalidOperationException. TypeMock Isolator succeeded in faking Entity Framework with ease. Conclusion We explored how to write a simple unit test using TypeMock Isolator for code which is using Entity Framework. We also explored a few of the limitations of other mocking frameworks which TypeMock is successfully able to handle. There are workarounds that you can use to overcome limitations when using MoQ or Rhino Mock, however the workarounds will require you to write more code and your tests will likely be more complex. For a comparison between different mocking frameworks take a look at this document produced by TypeMock. You might also want to check out this open source project to compare mocking frameworks. I hope you enjoyed this post Muhammad Mosa http://mosesofegypt.net/ http://twitter.com/mosessaur Screencast of unit testing Entity Framework Related Links GuestPost: Introduction to Mocking GuesPost: Typemock Isolator – Much more than an Isolation framework

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  • Download Irony .NET Compiler Construction Kit

    - by Editor
    Irony is a new-generation .NET compiler construction kit. It utilizes the full potential of c# 2.0 and .NET Framework to implement a completely new and streamlined technology of compiler construction. Unlike most existing yacc/lex-style solutions Irony does not employ any scanner or parser code generation from grammar specifications written in a specialized [...]

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  • writing programs without compiler?

    - by Matt
    I am not sure if this is even possible but I have watched a few videos with programming examples where it seems like the program is being written in some kind of command prompt rather than a nice graphical compiler. Im just curious as to what might be going on in these videos. Is it possible to write a program without a compiler? heres two examples: http://www.youtube.com/watch?v=hFSY9cWjO8o( @ 6 min) http://www.youtube.com/watch?v=tKTZoB2Vjuk (@ 5 min) Could anyone explain how this is done?

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  • Error when trying to compile abgx360: C++ compiler cannot create executables

    - by era878
    I am trying to compile the abgx360 GUI. First I run home/eric/Desktop/abgx360-1.0.5/configure but I recieve this error: checking for C++ compiler default output file name... configure: error: C++ compiler cannot create executables See `config.log' for more details. Then i run make but I recieve this error: make: * No rule to make target `/home/eric/Desktop/abgx360-1.0.5/Makefile.am', needed by `/home/eric/Desktop/abgx360-1.0.5/Makefile.in'. Stop. Here is my 'config.log': This file contains any messages produced by compilers while running configure, to aid debugging if configure makes a mistake. It was created by abgx360gui configure 1.0.2, which was generated by GNU Autoconf 2.61. Invocation command line was $ /home/eric/Desktop/abgx360gui-1.0.2/configure ## --------- ## ## Platform. ## ## --------- ## hostname = Eric-Desktop uname -m = x86_64 uname -r = 2.6.35-27-generic uname -s = Linux uname -v = #48-Ubuntu SMP Tue Feb 22 20:25:46 UTC 2011 /usr/bin/uname -p = unknown /bin/uname -X = unknown /bin/arch = unknown /usr/bin/arch -k = unknown /usr/convex/getsysinfo = unknown /usr/bin/hostinfo = unknown /bin/machine = unknown /usr/bin/oslevel = unknown /bin/universe = unknown PATH: /usr/local/sbin PATH: /usr/local/bin PATH: /usr/sbin PATH: /usr/bin PATH: /sbin PATH: /bin PATH: /usr/games ## ----------- ## ## Core tests. ## ## ----------- ## configure:1800: checking for a BSD-compatible install configure:1856: result: /usr/bin/install -c configure:1867: checking whether build environment is sane configure:1910: result: yes configure:1938: checking for a thread-safe mkdir -p configure:1977: result: /bin/mkdir -p configure:1990: checking for gawk configure:2020: result: no configure:1990: checking for mawk configure:2006: found /usr/bin/mawk configure:2017: result: mawk configure:2028: checking whether make sets $(MAKE) configure:2049: result: yes configure:2302: checking for g++ configure:2332: result: no configure:2302: checking for c++ configure:2332: result: no configure:2302: checking for gpp configure:2332: result: no configure:2302: checking for aCC configure:2332: result: no configure:2302: checking for CC configure:2332: result: no configure:2302: checking for cxx configure:2332: result: no configure:2302: checking for cc++ configure:2332: result: no configure:2302: checking for cl.exe configure:2332: result: no configure:2302: checking for FCC configure:2332: result: no configure:2302: checking for KCC configure:2332: result: no configure:2302: checking for RCC configure:2332: result: no configure:2302: checking for xlC_r configure:2332: result: no configure:2302: checking for xlC configure:2332: result: no configure:2360: checking for C++ compiler version configure:2367: g++ --version >&5 /home/eric/Desktop/abgx360gui-1.0.2/configure: line 2368: g++: command not found configure:2370: $? = 127 configure:2377: g++ -v >&5 /home/eric/Desktop/abgx360gui-1.0.2/configure: line 2378: g++: command not found configure:2380: $? = 127 configure:2387: g++ -V >&5 /home/eric/Desktop/abgx360gui-1.0.2/configure: line 2388: g++: command not found configure:2390: $? = 127 configure:2413: checking for C++ compiler default output file name configure:2440: g++ conftest.cpp >&5 /home/eric/Desktop/abgx360gui-1.0.2/configure: line 2441: g++: command not found configure:2443: $? = 127 configure:2481: result: configure: failed program was: | /* confdefs.h. */ | #define PACKAGE_NAME "abgx360gui" | #define PACKAGE_TARNAME "abgx360gui" | #define PACKAGE_VERSION "1.0.2" | #define PACKAGE_STRING "abgx360gui 1.0.2" | #define PACKAGE_BUGREPORT "" | #define PACKAGE "abgx360gui" | #define VERSION "1.0.2" | /* end confdefs.h. */ | | int | main () | { | | ; | return 0; | } configure:2488: error: C++ compiler cannot create executables See `config.log' for more details. ## ---------------- ## ## Cache variables. ## ## ---------------- ## ac_cv_env_CCC_set= ac_cv_env_CCC_value= ac_cv_env_CC_set= ac_cv_env_CC_value= ac_cv_env_CFLAGS_set= ac_cv_env_CFLAGS_value= ac_cv_env_CPPFLAGS_set= ac_cv_env_CPPFLAGS_value= ac_cv_env_CPP_set= ac_cv_env_CPP_value= ac_cv_env_CXXFLAGS_set= ac_cv_env_CXXFLAGS_value= ac_cv_env_CXX_set= ac_cv_env_CXX_value= ac_cv_env_LDFLAGS_set= ac_cv_env_LDFLAGS_value= ac_cv_env_LIBS_set= ac_cv_env_LIBS_value= ac_cv_env_build_alias_set= ac_cv_env_build_alias_value= ac_cv_env_host_alias_set= ac_cv_env_host_alias_value= ac_cv_env_target_alias_set= ac_cv_env_target_alias_value= ac_cv_path_install='/usr/bin/install -c' ac_cv_path_mkdir=/bin/mkdir ac_cv_prog_AWK=mawk ac_cv_prog_make_make_set=yes ## ----------------- ## ## Output variables. ## ## ----------------- ## ACLOCAL='${SHELL} /home/eric/Desktop/abgx360gui-1.0.2/missing --run aclocal-1.10' AMDEPBACKSLASH='' AMDEP_FALSE='' AMDEP_TRUE='' AMTAR='${SHELL} /home/eric/Desktop/abgx360gui-1.0.2/missing --run tar' AUTOCONF='${SHELL} /home/eric/Desktop/abgx360gui-1.0.2/missing --run autoconf' AUTOHEADER='${SHELL} /home/eric/Desktop/abgx360gui-1.0.2/missing --run autoheader' AUTOMAKE='${SHELL} /home/eric/Desktop/abgx360gui-1.0.2/missing --run automake-1.10' AWK='mawk' CC='' CCDEPMODE='' CFLAGS='' CPP='' CPPFLAGS='' CXX='g++' CXXDEPMODE='' CXXFLAGS='' CYGPATH_W='echo' DEFS='' DEPDIR='' ECHO_C='' ECHO_N='-n' ECHO_T='' EGREP='' EXEEXT='' GREP='' INSTALL_DATA='${INSTALL} -m 644' INSTALL_PROGRAM='${INSTALL}' INSTALL_SCRIPT='${INSTALL}' INSTALL_STRIP_PROGRAM='$(install_sh) -c -s' LDFLAGS='' LIBOBJS='' LIBS='' LTLIBOBJS='' MAKEINFO='${SHELL} /home/eric/Desktop/abgx360gui-1.0.2/missing --run makeinfo' OBJEXT='' PACKAGE='abgx360gui' PACKAGE_BUGREPORT='' PACKAGE_NAME='abgx360gui' PACKAGE_STRING='abgx360gui 1.0.2' PACKAGE_TARNAME='abgx360gui' PACKAGE_VERSION='1.0.2' PATH_SEPARATOR=':' SET_MAKE='' SHELL='/bin/bash' STRIP='' VERSION='1.0.2' WX_CFLAGS='' WX_CFLAGS_ONLY='' WX_CONFIG_PATH='' WX_CPPFLAGS='' WX_CXXFLAGS='' WX_CXXFLAGS_ONLY='' WX_LIBS='' WX_LIBS_STATIC='' WX_RESCOMP='' WX_VERSION='' ac_ct_CC='' ac_ct_CXX='' am__fastdepCC_FALSE='' am__fastdepCC_TRUE='' am__fastdepCXX_FALSE='' am__fastdepCXX_TRUE='' am__include='' am__isrc=' -I$(srcdir)' am__leading_dot='.' am__quote='' am__tar='${AMTAR} chof - "$$tardir"' am__untar='${AMTAR} xf -' bindir='${exec_prefix}/bin' build_alias='' datadir='${datarootdir}' datarootdir='${prefix}/share' docdir='${datarootdir}/doc/${PACKAGE_TARNAME}' dvidir='${docdir}' exec_prefix='NONE' host_alias='' htmldir='${docdir}' includedir='${prefix}/include' infodir='${datarootdir}/info' install_sh='$(SHELL) /home/eric/Desktop/abgx360gui-1.0.2/install-sh' libdir='${exec_prefix}/lib' libexecdir='${exec_prefix}/libexec' localedir='${datarootdir}/locale' localstatedir='${prefix}/var' mandir='${datarootdir}/man' mkdir_p='/bin/mkdir -p' oldincludedir='/usr/include' pdfdir='${docdir}' prefix='NONE' program_transform_name='s,x,x,' psdir='${docdir}' sbindir='${exec_prefix}/sbin' sharedstatedir='${prefix}/com' sysconfdir='${prefix}/etc' target_alias='' ## ----------- ## ## confdefs.h. ## ## ----------- ## #define PACKAGE_NAME "abgx360gui" #define PACKAGE_TARNAME "abgx360gui" #define PACKAGE_VERSION "1.0.2" #define PACKAGE_STRING "abgx360gui 1.0.2" #define PACKAGE_BUGREPORT "" #define PACKAGE "abgx360gui" #define VERSION "1.0.2" configure: exit 77

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  • Problem in mutiple :dependent=> :destroy when multiple polymorphic is true

    - by piemesons
    I have four models question, answer, comment and vote.Consider it same as stackoverflow. Question has_many comments Answers has_many comments Questions has_many votes answers has_many votes comments has_many votes Here are the models (only relevant things) class Comment < ActiveRecord::Base belongs_to :commentable, :polymorphic => true has_many :votes, :as => :votable, :dependent => :destroy end class Question < ActiveRecord::Base has_many :comments, :as => :commentable, :dependent => :destroy has_many :answers, :dependent => :destroy has_many :votes, :as => :votable, :dependent => :destroy end class Vote < ActiveRecord::Base belongs_to :votable, :polymorphic => true end class Answer < ActiveRecord::Base belongs_to :question, :counter_cache => true has_many :comments, :as => :commentable , :dependent => :destroy end Now the problem is whenever i am trying to delete any question/answer/comment its giving me an error NoMethodError in QuestionsController#destroy undefined method `each' for 0:Fixnum if i remove this line from any of the model (question/answer/comment) has_many :votes, :as => :votable, :dependent => :destroy then it works perfectly. It seems there is a problem while deleting the records active record is not able to find out the proper path because of multiple joins within the tables.

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  • C# Why does calling an interface member from a class generate an error?

    - by Jack
    So I have an interface: interface IFoo { int Bar(); int this[int i] {get; set;} } And a class that derives from it class Foo : IFoo { public int IFoo.Bar() { //Implementation { public int IFoo.this[int i] { //Implementation } } Now, I try to do this: var fooey = new Foo(); int i = Fooey.Bar(); or this: int i = Fooey[4]; I would expect these to work properly. However, the compiler generates an error as if such members don't exist. Why is that? I am aware I can cast Foo as IFoo, but I am also aware that casting is costly to performance, which is often the reason to use interfaces in the first place. EDIT 1: These are the errors generated 'Foo' does not contain a definition for 'Bar' and no extension method 'Bar' accepting a first argument of type 'Foo' could be found (are you missing a using directive or an assembly reference?) "Cannot apply indexing to an expression of type 'Foo'"

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  • How do I create my own programming language and a compiler for it

    - by Dave
    I am thorough with programming and have come across languages including BASIC, FORTRAN, COBOL, LISP, LOGO, Java, C++, C, MATLAB, Mathematica, Python, Ruby, Perl, JavaScript, Assembly and so on. I can't understand how people create programming languages and devise compilers for it. I also couldn't understand how people create OS like Windows, Mac, UNIX, DOS and so on. The other thing that is mysterious to me is how people create libraries like OpenGL, OpenCL, OpenCV, Cocoa, MFC and so on. The last thing I am unable to figure out is how scientists devise an assembly language and an assembler for a microprocessor. I would really like to learn all of these stuff and I am 15 years old. I always wanted to be a computer scientist someone like Babbage, Turing, Shannon, or Dennis Ritchie. I have already read Aho's Compiler Design and Tanenbaum's OS concepts book and they all only discuss concepts and code in a high level. They don't go into the details and nuances and how to devise a compiler or operating system. I want a concrete understanding so that I can create one myself and not just an understanding of what a thread, semaphore, process, or parsing is. I asked my brother about all this. He is a SB student in EECS at MIT and hasn't got a clue of how to actually create all these stuff in the real world. All he knows is just an understanding of Compiler Design and OS concepts like the ones that you guys have mentioned (i.e. like Thread, Synchronization, Concurrency, memory management, Lexical Analysis, Intermediate code generation and so on)

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  • How do I create my own programming language and a compiler for it

    - by Dave
    I am thorough with programming and have come across languages including BASIC, FORTRAN, COBOL, LISP, LOGO, Java, C++, C, MATLAB, Mathematica, Python, Ruby, Perl, Javascript, Assembly and so on. I can't understand how people create programming languages and devise compilers for it. I also couldn't understand how people create OS like Windows, Mac, UNIX, DOS and so on. The other thing that is mysterious to me is how people create libraries like OpenGL, OpenCL, OpenCV, Cocoa, MFC and so on. The last thing I am unable to figure out is how scientists devise an assembly language and an assembler for a microprocessor. I would really like to learn all of these stuff and I am 15 years old. I always wanted to be a computer scientist some one like Babbage, Turing, Shannon, or Dennis Ritchie. I have already read Aho's Compiler Design and Tanenbaum's OS concepts book and they all only discuss concepts and code in a high level. They don't go into the details and nuances and how to devise a compiler or operating system. I want a concrete understanding so that I can create one myself and not just an understanding of what a thread, semaphore, process, or parsing is. I asked my brother about all this. He is a SB student in EECS at MIT and hasn't got a clue of how to actually create all these stuff in the real world. All he knows is just an understanding of Compiler Design and OS concepts like the ones that you guys have mentioned (ie like Thread, Synchronisation, Concurrency, memory management, Lexical Analysis, Intermediate code generation and so on)

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  • In asp.Net, writing code in the control tag generates compile error

    - by Nour Sabouny
    Hi this is really strange !! But look at the following asp code: <div runat="server" id="MainDiv"> <%foreach (string str in new string[]{"First#", "Second#"}) { %> <div id="<%=str.Replace("#","div") %>"> </div> <%} %> </div> now if you put this code inside any web page (and don't worry about the moral of this code, I made it just to show the idea) you'll get this error : Compiler Error Message: CS1518: Expected class, delegate, enum, interface, or struct Of course the error has nothing to do with the real problem, I searched for the code that was generated by asp.net and figured out the following : private void @__RenderMainDiv(System.Web.UI.HtmlTextWriter @__w, System.Web.UI.Control parameterContainer) { @__w.Write("\r\n "); #line 20 "blabla\blabla\Default.aspx" foreach (string str in new string[] { "First#", "Second#" }) { #line default #line hidden @__w.Write("\r\n <div id=\""); #line 22 "blabla\blabla\Default.aspx" @__w.Write(str.Replace("#", "div")); #line default #line hidden @__w.Write("\">\r\n "); } This is the code that was generated from the asp page and this is the method that is meant to render our div (MainDiv), I found out that there is a missing bracket "}" that closes the method or the (for loop). now the problem has three parts: 1- first you should have a server control (in our situation is the MainDiv) and I'm not sure if it is only the div tag. 2- HTML control inside the server control and a code inside it using the double quotation mark ( for example <div id="<%=str instead of <div id='<%=str. 3-Any keyword which has block brackets e.g.:for{},while{},using{}...etc. now removing any part, will solve the problem !!! how is this happening ?? any ideas ? BTW: please help me to make the question more obvious, because I couldn't find the best words to describe the problem.

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  • Dependent on CVS tagging for automated builds

    - by OMG Ponies
    My current work relies on using tags in CVS for an automated build process (ANT currently) to build for respective environments (development, QA, production). From our research, neither Git or Subversion support tagging in the same manner. If we use Subversion or Git, they don't support tags (in the same manner - please correct me?). So how would ANT or Maven know what to pick up for the respective build? Example: For a webapp, when viewing our repository say for the web.xml file -- the history would look like: web.xml v1 ... web.xml v1.2.3 Tag: Prod web.xml v1.2.4 web.xml v1.2.5 Tag: QA web.xml v1.2.6 web.xml v1.2.7 Head The ANT build scripts are run as CRON jobs, at different times & intervals for different environments. The environment build is based on the repository checkout, based on the tag. Development continues, and eventually the respective tags are moved: web.xml v1 ... web.xml v1.2.3 web.xml v1.2.4 web.xml v1.2.5 web.xml v1.2.6 Tag: Prod web.xml v1.2.7 Tag: QA web.xml v1.2.8 Head

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  • Looking for best practice for version numbering of dependent software components

    - by bit-pirate
    We are trying to decide on a good way to do version numbering for software components, which are depending on each other. Let's be more specific: Software component A is a firmware running on an embedded device and component B is its respective driver for a normal PC (Linux/Windows machine). They are communicating with each other using a custom protocol. Since, our product is also targeted at developers, we will offer stable and unstable (experimental) versions of both components (the firmware is closed-source, while the driver is open-source). Our biggest difficulty is how to handle API changes in the communication protocol. While we were implementing a compatibility check in the driver - it checks if the firmware version is compatible to the driver's version - we started to discuss multiple ways of version numbering. We came up with one solution, but we also felt like reinventing the wheel. That is why I'd like to get some feedback from the programmer/software developer community, since we think this is a common problem. So here is our solution: We plan to follow the widely used major.minor.patch version numbering and to use even/odd minor numbers for the stable/unstable versions. If we introduce changes in the API, we will increase the minor number. This convention will lead to the following example situation: Current stable branch is 1.2.1 and unstable is 1.3.7. Now, a new patch for unstable changes the API, what will cause the new unstable version number to become 1.5.0. Once, the unstable branch is considered stable, let's say in 1.5.3, we will release it as 1.4.0. I would be happy about an answer to any of the related questions below: Can you suggest a best practice for handling the issues described above? Do you think our "custom" convention is good? What changes would you apply to the described convention? Thanks a lot for your feedback! PS: Since I'm new here, I can't create new tags (e.g. best-practice). So, I'm wondering if best-pactice is just misspelled or I don't get its meaning.

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  • Alternate method to dependent, nested if statements to check multiple states

    - by octopusgrabbus
    Is there an easier way to process multiple true/false states than using nested if statements? I think there is, and it would be to create a sequence of states, and then use a function like when to determine if all states were true, and drop out if not. I am asking the question to make sure there is not a preferred Clojure way to do this. Here is the background of my problem: I have an application that depends on quite a few input files. The application depends on .csv data reports; column headers for each report (.csv files also), so each sequence in the sequence of sequences can be zipped together with its columns for the purposes of creating a smaller sequence; and column files for output data. I use the following functions to find out if a file is present: (defn kind [filename] (let [f (File. filename)] (cond (.isFile f) "file" (.isDirectory f) "directory" (.exists f) "other" :else "(cannot be found)" ))) (defn look-for [filename expected-type] (let [find-status (kind-stat filename expected-type)] find-status)) And here are the first few lines of a multiple if which looks ugly and is hard to maintain: (defn extract-re-values "Plain old-fashioned sub-routine to process real-estate values / 3rd Q re bills extract." [opts] (if (= (utl/look-for (:ifm1 opts) "f") 0) ; got re columns? (if (= (utl/look-for (:ifn1 opts) "f") 0) ; got re data? (if (= (utl/look-for (:ifm3 opts) "f") 0) ; got re values output columns? (if (= (utl/look-for (:ifm4 opts) "f") 0) ; got re_mixed_use_ratio columns? (let [re-in-col-nams (first (utl/fetch-csv-data (:ifm1 opts))) re-in-data (utl/fetch-csv-data (:ifn1 opts)) re-val-cols-out (first (utl/fetch-csv-data (:ifm3 opts))) mu-val-cols-out (first (utl/fetch-csv-data (:ifm4 opts))) chk-results (utl/chk-seq-len re-in-col-nams (first re-in-data) re-rec-count)] I am not looking for a discussion of the best way, but what is in Clojure that facilitates solving a problem like this.

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  • Powershell: If statements dependent on installed exchange role

    - by marc dekeyser
    Something I need to keep for usage in the future:$hostname=hostnameIf (get-exchangeserver $hostname | where {$_.isClientAccessServer -eq $true})    {    } else {    }    If (get-exchangeserver $hostname | where {$_.isHubTransportServer -eq $true})    {    } else {    }If (get-exchangeserver $hostname | where {$_.isMailboxServer -eq $true})    {    } else {    }If (get-exchangeserver $hostname | where {$_.isUnifiedMessagingServer -eq $true})    {    } else {    }If (get-exchangeserver $hostname | where {$_.isEdgeServer -eq $true})    {    } else {    }

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  • What Pattern will solve this - fetching dependent record from database

    - by tunmise fasipe
    I have these classes class Match { int MatchID, int TeamID, //used to reference Team ... other fields } Note: Match actually have 2 teams which means 2 TeamID class Team { int TeamID, string TeamName } In my view I need to display List<Match> showing the TeamName. So I added another field class Match { int MatchID, int TeamID, //used to reference Team ... other fields string TeamName; } I can now do Match m = getMatch(id); m.TeamName = getTeamName(m.TeamId); //get name from database But for a List<Match>, getTeamName(TeamId) will go to the database to fetch TeamName for each TeamID. For a page of 10 Matches per page, that could be (10x2Teams)=20 trip to database. To avoid this, I had the idea of loading everything once, store it in memory and only lookup the TeamName in memory. This made me have a rethink that what if the records are 5000 or more. What pattern is used to solve this and how?

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  • Adding JavaScript to your code dependent upon conditions

    - by DavidMadden
    You might be in an environment where you code is source controlled and where you might have build options to different environments.  I recently encountered this where the same code, built on different configurations, would have the website at a different URL.  If you are working with ASP.NET as I am you will have to do something a bit crazy but worth while.  If someone has a more efficient solution please share. Here is what I came up with to make sure the client side script was placed into the HEAD element for the Google Analytics script.  GA wants to be the last in the HEAD element so if you are doing others in the Page_Load then you should do theirs last. The settings object below is an instance of a class that holds information I collection.  You could read from different sources depending on where you stored your unique ID for Google Analytics. *** This has been formatted to fit this screen. *** if (!IsPostBack) { if (settings.GoogleAnalyticsID != null || settings.GoogleAnalyticsID != string.Empty) { string str = @"//<!CDATA[ var _gaq = _gaq || []; _gaq.push(['_setAccount', '"  + settings.GoogleAnalyticsID + "']); _gaq.push(['_trackPageview']);  (function () {  var ga = document.createElement('script');  ga.type = 'text/javascript';  ga.async = true;  ga.src = ('https:' == document.location.protocol  ? 'https://ssl' :  'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0];  s.parentNode.insertBefore(ga, s);})();"; System.Web.UI.HtmlControls.HtmlGenericControl si =  new System.Web.UI.HtmlControls.HtmlGenericControl(); si.TagName = "script"; si.Attributes.Add("type", @"text/javascript"); si.InnerHtml = sb.ToString(); this.Page.Header.Controls.Add(si); } } The code above will prevent the code from executing if it is a PostBack and then if the ID was not able to be read or something caused the settings to be lost by accident. If you have larger function to declare, you can use a StringBuilder to separate the lines. This is the most compact I wished to go and manage readability.

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  • Best approach for tracking dependent state

    - by Pace
    Let's pretend I work on a project tracking application. The application is a database backed, server hosted, web application. In this application there are Projects which have many Activities which have many Tasks. A Task has two date fields an originalDueDate and a projectedDueDate. In addition, there are dynamic fields on the Activities and the Projects which indicate whether the Activity or Project is behind schedule based on the projected due dates of the child tasks and various other variables such as remaining buffer time, etc. There are a number of things that can cause the projectedDueDate to change. For example, an employee working on the project may (via a server request) enter in a shipping delay. Alternatively, a site may (via a server request) enter in an unexpected closure. When any of these things occur I need to not only update the projectedDueDate of the Task but also trigger the corresponding Project and Activity to update as well. What is the best way to do this? I've thought of the observer pattern but I don't keep a single copy of all these objects in memory. When a request comes in, I query the Task in from the database, at that point there is no associated Activity in memory that would be a listener. I could remove the ability to query for Tasks and force the application to query first by Project, then by Activity (in context of Project), then by task (in context of Activity) adding the observer relationships at each step but I'm not sure if that is the best way. I could setup a database event listening system so when a Task modified event is dispatched I have a handler which queries for the Activity at that point. I could simply setup a two-way relationship between Task and Activity so that the Task knows about the parent Activity and when the Task updates his state the Task grabs his parent and updates state. Right now I'm stuck considering all the options and am wondering if any single approach (doesn't have to be a listed approach) is jumping out at others as the best approach.

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  • Dependent checkbox, do you think this can be simplified more?

    - by Louie Miranda
    I have the following code which is working, I was wondering if this can simplified more. Demo: http://jsfiddle.net/TnpNV/8/ <form name="cbform"> <input type="checkbox" value="1" name="one" id="one" /> one<br /> <input type="checkbox" value="1" name="two" id="two" /> two </form>? <script> $('#one, #two').click(function(event) { var checked = $(this).is(':checked'); if (checked) { $('#one').attr('checked', true); $('#two').attr('checked', true); } else { $('#one').attr('checked', false); $('#two').attr('checked', false); } }); </script> It's basically a two checkbox that is dependent on each other. Jquery was used to check and uncheck them. Regards

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