Search Results

Search found 4613 results on 185 pages for 'circular references'.

Page 39/185 | < Previous Page | 35 36 37 38 39 40 41 42 43 44 45 46  | Next Page >

  • Garbage Collection Java

    - by simion
    On the slides i am revising from it says the following; Live objects can be identified either by maintaining a count of the number of references to each object, or by tracing chains of references from the roots. Reference counting is expensive – it needs action every time a reference changes and it doesn’t spot cyclical structures, but it can reclaim space incrementally. Tracing involves identifying live objects only when you need to reclaim space – moving the cost from general access to the time at which the GC runs, typically only when you are out of memory. I understand the principles of why reference counting is expensive but do not understand what "doesn’t spot cyclical structures, but it can reclaim space incrementally." means. Could anyone help me out a little bit please? Thanks

    Read the article

  • Problem with assembly loading in .NET

    - by Jamie
    Hi guys, I have got two projects in my solution: Silverlight and standard one. The standard one references System.Xml assembly (version 4.0.0.0), however the Silverlight one references System.Xml assembly (v. 2.0.5.0). I want to make an instance of XmlWriter in my Silverlight project. Here comes the problem - the exception is thrown (file not found for System.Xml assembly). I believe it is a matter of different assembly versions. Do you have any idea how to resolve this issue? Ive read something about the binding redirection - is it the key to the solution? If so, how to do this? Thank you in advance for the reply! Cheers.

    Read the article

  • Specializating a template function that takes a universal reference parameter

    - by David Stone
    How do I specialize a template function that takes a universal reference parameter? foo.hpp: template<typename T> void foo(T && t) // universal reference parameter foo.cpp template<> void foo<Class>(Class && class) { // do something complicated } Here, Class is no longer a deduced type and thus is Class exactly; it cannot possibly be Class &, so reference collapsing rules will not help me here. I could perhaps create another specialization that takes a Class & parameter (I'm not sure), but that implies duplicating all of the code contained within foo for every possible combination of rvalue / lvalue references for all parameters, which is what universal references are supposed to avoid. Is there some way to accomplish this? To be more specific about my problem in case there is a better way to solve it: I have a program that can connect to multiple game servers, and each server, for the most part, calls everything by the same name. However, they have slightly different versions for a few things. There are a few different categories that these things can be: a move, an item, etc. I have written a generic sort of "move string to move enum" set of functions for internal code to call, and my server interface code has similar functions. However, some servers have their own internal ID that they communicate with, some use strings, and some use both in different situations. Now what I want to do is make this a little more generic. I want to be able to call something like ServerNamespace::server_cast<Destination>(source). This would allow me to cast from a Move to a std::string or ServerMoveID. Internally, I may need to make a copy (or move from) because some servers require that I keep a history of messages sent. Universal references seem to be the obvious solution to this problem. The header file I'm thinking of right now would expose simply this: namespace ServerNamespace { template<typename Destination, typename Source> Destination server_cast(Source && source); } And the implementation file would define all legal conversions as template specializations.

    Read the article

  • MySQL Removing Some Foreign keys

    - by Drew
    I have a table whose primary key is used in several other tables and has several foreign keys to other tables. CREATE TABLE location ( locationID INT NOT NULL AUTO_INCREMENT PRIMARY KEY ... ) ENGINE = InnoDB; CREATE TABLE assignment ( assignmentID INT NOT NULL AUTO_INCREMENT PRIMARY KEY, locationID INT NOT NULL, FOREIGN KEY locationIDX (locationID) REFERENCES location (locationID) ... ) ENGINE = InnoDB; CREATE TABLE assignmentStuff ( ... assignmentID INT NOT NULL, FOREIGN KEY assignmentIDX (assignmentID) REFERENCES assignment (assignmentID) ) ENGINE = InnoDB; The problem is that when I'm trying to drop one of the foreign key columns (ie locationIDX) it gives me an "ERROR 1025 (HY000): Error on rename" error. How can I drop the column in the assignment table above without getting this error?

    Read the article

  • Calling member method on unmanaged C++ pointer from C# (I think)

    - by Jacob G
    I apologize in advance if this is a trivial question... I'm pretty C++ / unmanaged dumb. Here's a simplified analog to my setup: --In myUnmanagedObject.h in DLL: class myUnmanagedObject { public: virtual void myMethod(){} } --In MyControl.h in Assembly #1: #pragma make_public(myUnmanagedObject) [event_source(managed)] public ref class MyControl : public System::Windows::Forms::UserControl { public: myUnmanagedObject* GetMyUnmanagedObject(); } --in C# in Assembly #2: unsafe { MyControl temp = new MyControl(); myUnmanagedObject* obj = temp.GetMyUnmanagedObject(); obj-myMethod(); } I get a compile error saying that myUnmanagedObject does not contain a definition for myMethod. Assembly #2 references Assembly #1. Assembly #1 references DLL. If I compile the DLL with /clr and reference it directly from Assembly #2, it makes no difference. How, from C#, do I execute myMethod ?

    Read the article

  • T-SQL Unique constraint locked the SQL server

    - by PaN1C_Showt1Me
    HI ! This is my table: CREATE TABLE [ORG].[MyTable]( .. [my_column2] UNIQUEIDENTIFIER NOT NULL CONSTRAINT FK_C1 REFERENCES ORG.MyTable2 (my_column2), [my_column3] INT NOT NULL CONSTRAINT FK_C2 REFERENCES ORG.MyTable3 (my_column3) .. ) I've written this constraint to assure that combination my_column2 and my_column3 is always unique. ALTER TABLE [ORG].[MyTable] ADD CONSTRAINT UQ_MyConstraint UNIQUE NONCLUSTERED ( my_column2, my_column3 ) But then suddenly.. The DB stopped responding.. there is a lock or something.. Do you have any idea why? What is bad with the constraint?

    Read the article

  • Garbage Collection in Java

    - by simion
    On the slides I am revising from it says the following: Live objects can be identified either by maintaining a count of the number of references to each object, or by tracing chains of references from the roots. Reference counting is expensive – it needs action every time a reference changes and it doesn’t spot cyclical structures, but it can reclaim space incrementally. Tracing involves identifying live objects only when you need to reclaim space – moving the cost from general access to the time at which the GC runs, typically only when you are out of memory. I understand the principles of why reference counting is expensive but do not understand what "doesn’t spot cyclical structures, but it can reclaim space incrementally." means. Could anyone help me out a little bit please? Thanks

    Read the article

  • How to run SpecFlow tests in Visual Studio 2010?

    - by testerboy
    Trying to get SpecFlow running with a fresh VS2010 Professional install. Created a new console application and added references to NUnit and SpecFlow. Created a SpecFlow feature. The .feature with the default template code is created. Now I try to run this test, but I don't understand how. When I right-click the project (at the top-level), there is no "Run test(s)" option in the mouse drop down menu. Didn't the SpecFlow install correctly, am I missing some references or some other tool I need to install?

    Read the article

  • C++: Cannot convert from foo& to foo*

    - by Rosarch
    I have a method: odp(foo& bar); I'm trying to call it: foo baz; odp(&baz); I get a compiler error: error C2664: "odp" cannot convert parameter 1 from 'foo *' to 'foo &' What am I doing wrong? Aren't I passing in a reference to baz? UPDATE: Perhaps I have a misconception about the relationship between pointers and references. I thought that they were the same, except references couldn't be null. Is that incorrect?

    Read the article

  • Does lookaround affect which languages can be matched by regular expressions?

    - by sepp2k
    There are some features in modern regex engines which allow you to match languages that couldn't be matched without that feature. For example the following regex using back references matches the language of all strings that consist of a word that repeats itself: (.+)\1. This language is not regular and can't be matched by a regex, which does not use back references. My question: Does lookaround also affect which languages can be matched by a regular expression? I.e. are there any languages that can be matched using lookaround, which couldn't be matched otherwise? If so, is this true for all flavors of lookaround (negative or positive lookahead or lookbehind) or just for some of them?

    Read the article

  • Rails 3 Join Question for Votes Table

    - by Dex
    I have a table posts and a polymorphic table votes. The votes table looks like this: create_table :votes do |t| t.references :user # user_id t.vote # the vote value t.references :votable # votable_type and votable_id end I want to list all posts that the user has not yet voted on. Right now I'm basically taking all the posts they've already voted on and subtracting that from the entire set of posts. It works but it's not very convenient as I currently have it. def self.where_not_voted_on_by(user) sql = "SELECT P.* FROM posts P LEFT OUTER JOIN (" sql << where_voted_on_by(user).to_sql sql << ") ALREADY_VOTED_FOR ON P.id = ALREADY_VOTED_FOR.id WHERE (user_id is null)" puts sql resultset = connection.select_all(sql) results = [] resultset.each do |r| results << Post.new(r) end results end def self.where_voted_on_by(user) joins(:votes.outer).where("user_id = #{user.id}").select("posts.*, votes.user_id") end

    Read the article

  • C++ IDE for Linux with smart reference searching

    - by Dmitry Yudakov
    Is there an IDE supporting C++ with REALLY smart searching of references? By 'reference' I mean usage of a class (or its member), variable, function in the whole Project or Workspace. There's lots of IDE providing it. Some of them seem just to search for the text with same name giving lots of stuff, others are smarter and check the context (like class boundaries, namespace) but aren't accurate enough. The best I've tried so far was Visual SlickEdit, but still there's more to wish. class C1 { int foo; }; class C2 { int foo; }; For example in this situation when searching for C1::foo references I don't want C2::foo to be shown too. So, is there an IDE that would be so smart?

    Read the article

  • Using the same modules in multiple projects

    - by Andreas Vinther
    I'm using Visual Studio 2010 and coding in VB.NET. My problem is that I've collected all the modules I've written and intend to reuse and placed them in a separate folder. When I want to add a module from the above folder to any given project, it takes a copy of the module and places in the project's source code folder, instead of referencing the module in the folder containing all the other modules. Is it possible to include a module in my project and leave it in the folder with all the other modules, so that when I improve upon a module, it'll affect all the projects that uses/references that module. Instead of me having to manually copy the new module to all the projects that uses/references the module. Right now I have multiple instances of the exact same module that i need to update manually when I improve code or add functionality?

    Read the article

  • SQL HAVING COUNT and JOIN

    - by user1833274
    I have tried to this query: What are the doctors that work on less than 2 Hospitals. I have these tables: CREATE TABLE Hospital ( hid INT PRIMARY KEY, name VARCHAR(127) UNIQUE, country VARCHAR(127), area INT ); CREATE TABLE Doctor ( ic INT PRIMARY KEY, name VARCHAR(127), date_of_birth INT, ); CREATE TABLE Work ( hid INT, ic INT, since INT, FOREIGN KEY (hid) REFERENCES Hospital (hid), FOREIGN KEY (ic) REFERENCES Doctor (ic), PRIMARY KEY (hid,ic) ); I tried with this: SELECT DISTINCT D.ic FROM Doctor D, Work W JOIN Hospital H ON (H.hid = W.hid) WHERE D.bi = W.bi GROUP BY (D.ic) HAVING COUNT(H.hid) < 2 ;

    Read the article

  • Stop invalid data in a attribute with foreign key constraint using triggers?

    - by Eternal Learner
    How to specify a trigger which checks if the data inserted into a tables foreign key attribute, actually exists in the references table. If it exist no action should be performed , else the trigger should delete the inserted tuple. Eg: Consider have 2 tables R(A int Primary Key) and S(B int Primary Key , A int Foreign Key References R(A) ) . I have written a trigger like this : Create Trigger DelS BEFORE INSERT ON S FOR EACH ROW BEGIN Delete FROM S where New.A <> ( Select * from R;) ); End; I am sure I am making a mistake while specifying the inner sub query within the Begin and end Blocks of the trigger. My question is how do I make such a trigger ?

    Read the article

  • Visaul Studio 2010, TlbImp generates .net 4.0 interops in 2.0 projects

    - by DJScrib
    In a C# project we add a reference to a COM object via the Add References setup pointing to a COM object which results in the IDE auto-generating the interop assembly. So this is fine and good, but we are building based on .net 3.5 SP1 aka CLR 2.0, and the generated interops are using the 4.0 CLR making them incompatiable. Is there a way to prevent this? I assume the other option is in our build script to try using tlbimp.exe with the /references parameter? to point to mscorlib v2.0? Anyhow, I'm hoping there's a flag somewhere to allow this.

    Read the article

  • Prevent duplicate rows with all non-unique columns (only with MySQL)?

    - by letseatfood
    Ho do I prevent a duplicate row from being created in a table with two columns, neither of which are unique? And can this be done using MySQL only, or does it require checks with my PHP script? Here is the CREATE query for the table in question (two other tables exist, users and roles): CREATE TABLE users_roles ( user_id INT(100) NOT NULL, role_id INT(100) NOT NULL, FOREIGN KEY (user_id) REFERENCES users(user_id), FOREIGN KEY (role_id) REFERENCES roles(role_id) ) ENGINE = INNODB; I would like the following query, if executed more than once, to throw an error: INSERT INTO users_roles (user_id, role_id) VALUES (1, 2); Please do not recommend bitmasks as an answer. Thanks!

    Read the article

  • Visual Studio IDE - how do you quickly find the implementation(s) of an interface's method?

    - by Jess
    Is there a quick way to find all of the implementations of, not references to, an interface's method/property/etc? Here's some sample code: public class SomeClass : IBaseClass { public Int32 GetInt() { return 1; } } public interface IBaseClass { public Int32 GetInt(); } public class SomeOtherClass { ISomeClass _someClass; private TestMethod() { _someClass = new SomeClass(); _someClass.GetInt(); } } I want to quickly get to SomeClass.GetInt() while reviewing SomeOtherClass.TestMethod(). If I right click on _someClass.GetInt() and click 'Go To Definition', it takes me to the interface. If I click 'Find All References', I could potentially see a list of all uses ... not just the classes that implement the GetInt() method. Is there a faster way to find this? Any tips from other developers? We are using D.I. for most of our dependencies, which means that tracing through deeply nested code takes forever.

    Read the article

  • Does JavaScript have an equivalent to Perl's DESTROY method?

    - by Eric Strom
    Is there any method that is called or event that is dispatched right before an Element is cleaned up by the JavaScript garbage collector? In Perl I would write: package MyObj; sub new {bless {}} sub DESTROY {print "cleaning up @_\n"} and then later: { my $obj = MyObj->new; # do something with obj } # scope ends, and assuming there are no external references to $obj, # the DESTROY method will be called before the object's memory is freed My target platform is Firefox (and I have no need to support other browsers), so if there is only a Firefox specific way of doing this, that is fine. And a little background: I am writing the Perl module XUL::Gui which serves as a bridge between Perl and Firefox, and I am currently working on plugging a few memory leaks related to DOM Elements sticking around forever, even after they are gone and no more references remain on the Perl side. So I am looking for ways to either figure out when JavaScript Elements will be destroyed, or a way to force JavaScript to cleanup an object.

    Read the article

  • Syntax Highlighting in a ListBox

    - by ph0enix
    Hi all, I've searched the web and I can't seem to find anything that will work for me. I've seen plenty of discussion, and even some fairly extensible open-source tools, for code editors that provide line numbers and syntax highlighting. Here's my dilemma... I'm working on a "digital code review" project in C#.NET that allows users to specify source files, add them to a particular session, and other users can make comments and line references to the files being reviewed. Basic requirements: Must be written in C#.NET I don't need to be able to edit the text in the text box Users need to be able to select a line (or multiple lines), to make line references. It seems to me that I need some fancy implementation of a ListBox control (not a drop-down list) that has some OwnerDraw capabilities to add line numbers and syntax highlighting. Unfortunately, I haven't had any luck putting it together myself, and I can't seem to find a control that's already been written or a reference on how I might be able to accomplish this. Any suggestions??

    Read the article

  • VS 2010 Error “Object reference not set to an instance of an object” when adding Service Reference f

    - by Andy
    I have a VS2010 (RTM) solution which contains: WCF Service project Console WCF client project Class project for DataContracts and members Class project for some simple classes I successfully added a service reference in the console client project and ran the client. I then did a long dev cycle repeatedly modifying the service then updating console service reference. I then changed the namespace and assembly names for the projects as well as the .cs using references and app.config. I of course missed some things as it would not build so I eventually removed the project references and the service reference, cleaned and built successfully. I then attempted to add the service reference again, it discovered it but threw the “Object reference not set to an instance of an object” when OK'ing. Fix in answer below...

    Read the article

  • Visual Studio 2010 Database Project does not understand Schema Names anymore?

    - by Xenan
    I just tried to upgrade a Visual Studio 2008 Database project to VS2010 and actually it is quite a mess. Hundreds of warnings, all unsolved references. It seems to boil down to Visual Studio not to understand Schema Names (aka Ownership) anymore. For example, the standard dbo schema: [$(MyDataBase)].dbo.MyTable is fine but: [$(MyDataBase)].myschema.MyTable gives an unsolved reference. It did work in VS2008. Also the abbreviation for dbo, the double dot: [$(MyDataBase)]..MyTable Doesn't work anymore. In the project property windows I restored the references to the correct servers (which were lost after the conversion) but that didn't help. This seems pretty basic but I don't have a clue how to solve this. Any help is appreciated.

    Read the article

  • Rails has_one vs belongs_to semantics

    - by Anurag
    I have a model representing a Content item that contains some images. The number of images are fixed as these image references are very specific to the content. For example, the Content model refers to the Image model twice (profile image, and background image). I am trying to avoid a generic has_many, and sticking to multiple has_one's. The current database structure looks like: contents - id:integer - integer:profile_image_id - integer:background_image_id images - integer:id - string:filename - integer:content_id I just can't figure out how to setup the associations correctly here. The Content model could contain two belongs_to references to an Image, but that doesn't seem semantically right cause ideally an image belongs to the content, or in other words, the content has two images. This is the best I could think of (by breaking the semantics): class Content belongs_to :profile_image, :class_name => 'Image', :foreign_key => 'profile_image_id' belongs_to :background_image, :class_name => 'Image', :foreign_key => 'background_image_id' end Am I way off, and there a better way to achieve this association?

    Read the article

  • Is it legal for a C++ reference to be NULL?

    - by BCS
    A while back I ran into a bug the looked something like this: void fn(int &i) { printf(&i == NULL ? "NULL\n" : "!NULL\n"); } int main() { int i; int *ip = NULL; fn(i); // prints !NULL fn(*ip); // prints NULL return 0; } More recently, I ran into this comment about C++ references: [References arguments make] it clear, unlike with pointers, that NULL is not a possible value. But, as show above, NULL is a possible value. So where is the error? In the language spec? (Unlikely.) Is the compiler in error for allowing that? Is that coding guide in error (or a little ambiguous)? Or am I just wandering into the minefield known as undefined behavior?

    Read the article

< Previous Page | 35 36 37 38 39 40 41 42 43 44 45 46  | Next Page >