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  • Way to check for foreign key references before deleting in MySQL?

    - by Chad Johnson
    I'm working with a content management system, and users are prompted with a confirmation screen before deleting records. Some records are foreign key referenced in other tables, and therefore they cannot be deleted. I would like to display a message beside a given record if it has foreign key references. To know whether I should display the message for a record, I could just query the referencing table and see if there are references. But the problem is, there are about a dozen tables with records potentially referencing this record, and a lookup could take a "long" time. Is there an easy way to tell whether the record is delete-ready (ie. has no foreign key references)?

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  • Anyone knows good references for Machine Learning Algorithms and Image Recognition?

    - by RaymondBelonia
    I need it for my thesis and for some reason I am having a hard time finding decent books or websites for it. My thesis topic is "Classification of Modern Art Paintings using Machine Learning Approach". My goal is to classify examples of modern art paintings to its respective modern art movement(expressionism, realism,etc..) using machine learning approach. Also, suggestions and comments about my thesis are greatly appreciated.

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  • I want to build a Virtual Machine, are there any good references?

    - by Michael Stum
    I'm looking to build a Virtual Machine as a platform independent way to run some game code (essentially scripting). The Virtual Machines that I'm aware of in games are rather old: Infocom's Z-Machine, LucasArts' SCUMM, id Software's Quake 3. As a .net Developer, I'm familiar with the CLR and looked into the CIL Instructions to get an overview of what you actually implement on a VM Level (vs. the language level). I've also dabbled a bit in 6502 Assembler during the last year. The thing is, now that I want¹ to implement one, I need to dig a bit deeper. I know that there are stack based and register based VMs, but I don't really know which one is better at what and if there are more or hybrid approaches. I need to deal with memory management, decide which low level types are part of the VM and need to understand why stuff like ldstr works the way it does. My only reference book (apart from the Z-Machine stuff) is the CLI Annotated Standard, but I wonder if there is a better, more general/fundamental lecture for VMs? Basically something like the Dragon Book, but for VMs? I'm aware of Donald Knuth's Art of Computer Programming which uses a register-based VM, but I'm not sure how applicable that series still is, especially since it's still unfinished? Clarification: The goal is to build a specialized VM. For example, Infocom's Z-Machine contains OpCodes for setting the Background Color or playing a sound. So I need to figure out how much goes into the VM as OpCodes vs. the compiler that takes a script (language TBD) and generates the bytecode from it, but for that I need to understand what I'm really doing. ¹ I know, modern technology would allow me to just interpret a high level scripting language on the fly. But where is the fun in that? :) It's also a bit hard to google because Virtual Machines is nowadays often associated with VMWare-type OS Virtualization...

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  • Is there a Design Pattern for preventing dangling references?

    - by iFreilicht
    I was thinking about a design for custom handles. The thought is to prevent clients from copying around large objects. Now a regular handle class would probably suffice for that, but it doesn't solve the "dangling reference problem"; If a client has multiple handles of the same object and deletes the object via one of them, all the others would be invalid, but not know it, so the client could write or read parts of the memory he shouldn't have access to. Is there a design pattern to prevent this from happening? Two ideas: An observer-like pattern where the destructor of an object would notify all handles. "Handle handles" (does such a thing even exist?). All the handles don't really point to the object, but to another handle. When the object gets destroyed, this "master-handle" invalidates itself and therefore all that point to it.

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  • Any technical references for game-oriented icons and symbols?

    - by willc2
    To make localizing easier, I'm using icons to show in-game information like achievements and bonuses. Coming up with good designs isn't easy, especially when it has to be integrated into the rest of the game's art style. Can I do better than looking at some random selection of existing games? Are there any reference books or sites that cover game graphics specifically? I'm looking for more theory and best-practices rather than pre-made graphics.

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  • What happens if we serialize and deserialize two objects which references to each other?

    - by Seregwethrin
    To make it more clear, this is a quick example: class A implements Serializable { public B b; } class B implements Serializable { public A a; } A a = new A(); B b = new B(); a.b = b; b.a = a; So what happens if we serialize a and b objects into a file and deserialize from that file? I thought we get 4 objects, 2 of each. Identical objects but different instances. But I'm not sure if there's anything else or is it right or wrong. If any technology needed to answer, please think based on Java. Thank you.

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  • Accessing Server-Side Data from Client Script: Using Ajax Web Services, Script References, and ...

    Today's websites commonly exchange information between the browser and the web server using Ajax techniques. In a nutshell, the browser executes JavaScript code typically in response to the page loading or some user action. This JavaScript makes an asynchronous HTTP request to the server. The server processes this request and, perhaps, returns data that the browser can then seamlessly integrate into the web page. Typically, the information exchanged between the browser and server is serialized into JSON, an open, text-based serialization format that is both human-readable and platform independent.Adding such targeted, lightweight Ajax capabilities to your ASP.NET website requires two steps: first, you must create some mechanism on

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  • How can I check for missing references in VB.NET?

    - by Tea With Cookies
    I need to check if all the references in a project exist to avoid possible errors but I can't find anywhere how to do it in VB.NET. I can do it in VBA like this: Dim vbProj As VBProject Dim chkRef As Reference Set vbProj = ThisWorkbook.VBProject For Each chkRef In vbProj.References If chkRef.IsBroken Then Debug.Print chkRef.Name " reference doesn't exist!" End If Next How do I accomplish this in VB.NET?

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  • I am working with Visual Studio 2008. Actually there is References folder missing

    - by Azhar
    I am working with Visual Studio 2008. Actually there is References folder missing in its solution explorer. When I create a New web Application it has References folder but when I add new .aspx file it also adds .aspx.designer.cs file with it and its does not show master page option in add dialogue. but in the old web application it shows the master page option where master page file is already added. whats the difference between these two solutions.

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  • How to pickle and unpickle objects with self-references and from a class with slots?

    - by EOL
    Is it possible to pickle an object from a class with slots, when this object references itself through one of its attributes? Here is a simple example: import weakref import pickle class my_class(object): __slots__ = ('an_int', 'ref_to_self', '__weakref__') def __init__(self): self.an_int = 42 self.ref_to_self = weakref.WeakKeyDictionary({self: 1}) # __getstate__ and __setstate__ not defined: how should this be done? if __name__ == '__main__': obj = my_class() # How to make the following work? obj_pickled = pickle.dumps(obj) obj_unpickled = pickle.loads(obj_pickled) # Self-references should be kept: print "OK?", obj_unpickled == obj_unpickled.ref_to_self.keys()[0]

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  • Do I always need to rebuild the project containing references to sub project's dll, if sub projects

    - by Puneet Dudeja
    I have a solution containing 4 class library projects and one "web site" project. The web site project contains references to the 3 class library projects, whenever I make changes in any of the class library projects, the only option I see is to rebuild the web site which takes a lot of time. Is there any option that I can only update the dll references and the changes are reflected in the web site project ?

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  • Foreign key onto weak entity set in MS SQL Server 2008?

    - by Nic Waller
    I'm using Microsoft SQL Server 2008 Management Studio to create a relational schema by following an Entity-Relationship diagram. (included below; unrelated details removed) Until now, primary and foreign keys have been working as expected. But when I try to create a foreign key from the entity relationship takes onto the weak entity set section, I get an error. Section is identified by a composite primary key in the context of course, which has course_id as a primary key. Therefore, the primary key of section is a 4-way composite key. The entity relationship takes needs to refer to section, so it includes all 4 primary attributes from section in it's own primary key. When trying to establish a foreign key relationship from takes to section, Studio gives the following error: The columns in table 'section' do not match an existing primary key or UNIQUE constraint. Am I doing something wrong, or is this an unsupported configuration? I can provide more details or the SQL schema if necessary.

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  • Why don't I have a "Web Service References" menu item in excel/VBA?

    - by Draemon
    I'm trying to consume a SOAP web service from excel. Now according to This article (and confirmed by other articles and MSDN) if I do the following: Install the web services toolkit (I've installed v2.01) Install SOAP Toolkit 3.0 Add a reference to Microsoft Soap Type Library (I've tried v3.0 and an older one) I should get a "Web Service References" menu item in the Tools menu but I don't. I've also tried adding every reference that seemed to have anything to do with SOAP or XML, but it hasn't helped. Any ideas?

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  • Strategies for dealing with Circular references caused by JPA relationships?

    - by ams
    I am trying to partition my application into modules by features packaged into separate jars such as feature-a.jar, feature-b.jar, ... etc. Individual feature jars such as feature-a.jar should contain all the code for a feature a including jpa entities, business logic, rest apis, unit tests, integration test ... etc. The problem I am running into is that bi-directional relationships between JPA entities cause circular references between the jar files. For example Customer entity should be in customer.jar and the Order should be in order.jar but Customer references order and order references customer making it hard to split them into separate jars / eclipse projects. Options I see for dealing with the circular dependencies in JPA entities: Option 1: Put all the entities into one jar / one project Option 2: Don't map certain bi-directianl relationships to avoid circular dependencies across projects. Questions: What rules / principles have you used to decide when to do bi-directional mapping vs. not? Have you been able to break jpa entities into their own projects / jar by features if so how did you avoid the circular dependencies issues?

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  • ON DELETE RESTRICT Causing Error 150

    - by Levi Hackwith
    CREATE TABLE project ( id INTEGER NOT NULL AUTO_INCREMENT, created_at DATETIME NOT NULL, name VARCHAR(75) NOT NULL, description LONGTEXT NOT NULL, is_active TINYINT NOT NULL DEFAULT '1', PRIMARY KEY (id), INDEX(name, created_at) ) ENGINE = INNODB; CREATE TABLE role ( id INTEGER NOT NULL, name VARCHAR(50) NOT NULL, description LONGTEXT NOT NULL, PRIMARY KEY (id) ) ENGINE = INNODB; CREATE TABLE organization ( id INTEGER NOT NULL AUTO_INCREMENT, created_at DATETIME NOT NULL, name VARCHAR(100) NOT NULL, is_active TINYINT NOT NULL DEFAULT '1', PRIMARY KEY (id) ) ENGINE = INNODB; CREATE TABLE user ( id INTEGER NOT NULL AUTO_INCREMENT, created_at DATETIME NOT NULL, role_id INTEGER NOT NULL, organization_id INTEGER NOT NULL, last_login_at DATETIME NOT NULL, last_ip_address VARCHAR(25) NOT NULL, username VARCHAR(45) NOT NULL, password CHAR(32) NOT NULL, email_address VARCHAR(255) NOT NULL, first_name VARCHAR(45) NOT NULL, last_name VARCHAR(45) NOT NULL, address_1 VARCHAR(100) NOT NULL, address_2 VARCHAR(25) NULL, city VARCHAR(25) NOT NULL, state CHAR(2) NOT NULL, zip_code VARCHAR(10) NOT NULL, primary_phone_number VARCHAR(10) NOT NULL, secondary_phone_number VARCHAR(10) NOT NULL, is_primary_organization_contact TINYINT NOT NULL DEFAULT '0', is_active TINYINT NOT NULL DEFAULT '1', PRIMARY KEY (id), CONSTRAINT fk_user_role_id FOREIGN KEY (role_id) REFERENCES role (id) ON UPDATE RESTRICT ON DELETE RESTRICT, CONSTRAINT fk_user_organization_id FOREIGN KEY (organization_id) REFERENCES organization (id) ON UPDATE RESTRICT ON DELETE RESTRICT ) ENGINE = INNODB; CREATE TABLE project_user ( user_id INTEGER NOT NULL, project_id INTEGER NOT NULL, PRIMARY KEY (user_id, project_id), CONSTRAINT fk_project_user_user_id FOREIGN KEY (user_id) REFERENCES user (id) ON UPDATE RESTRICT ON DELETE CASCADE, CONSTRAINT fk_project_user_project_id FOREIGN KEY (project_id) REFERENCES project (id) ON UPDATE RESTRICT ON DELETE RESTRICT ) ENGINE = INNODB; CREATE TABLE ticket_category ( id INTEGER NOT NULL AUTO_INCREMENT, name VARCHAR(20) NOT NULL, description LONGTEXT NOT NULL, PRIMARY KEY (id) ) ENGINE = INNODB; CREATE TABLE ticket_type ( id INTEGER NOT NULL AUTO_INCREMENT, name VARCHAR(20) NOT NULL, description LONGTEXT NOT NULL, PRIMARY KEY (id) ) ENGINE = INNODB; CREATE TABLE ticket_status ( id INTEGER NOT NULL AUTO_INCREMENT, name VARCHAR(20) NOT NULL, description LONGTEXT NOT NULL, PRIMARY KEY (id) ) ENGINE = INNODB; CREATE TABLE ticket ( id INTEGER NOT NULL AUTO_INCREMENT, created_at DATETIME NOT NULL, project_id INTEGER NOT NULL, created_by INTEGER NOT NULL, submitted_by INTEGER NOT NULL, assigned_to INTEGER NULL, category_id INTEGER NOT NULL, type_id INTEGER NOT NULL, title VARCHAR(75) NOT NULL, description LONGTEXT NOT NULL, contact_type_id TINYINT NOT NULL, affects_all_clients TINYINT NOT NULL DEFAULT '0', is_billable TINYINT NOT NULL DEFAULT '1', esimated_hours DECIMAL(4, 1) NOT NULL DEFAULT '0', hours_worked DECIMAL (4, 1) NOT NULL DEFAULT '0', status_id TINYINT NOT NULL, PRIMARY KEY (id), CONSTRAINT fk_ticket_project_id FOREIGN KEY (project_id) REFERENCES project (id) ON UPDATE RESTRICT ON DELETE RESTRICT, CONSTRAINT fk_ticket_created_by FOREIGN KEY (created_by) REFERENCES user (id) ON UPDATE RESTRICT ON DELETE RESTRICT, CONSTRAINT fk_ticket_submitted_by FOREIGN KEY (submitted_by) REFERENCES user (id) ON UPDATE RESTRICT ON DELETE RESTRICT, CONSTRAINT fk_ticket_assigned_to FOREIGN KEY (assigned_to) REFERENCES user (id) ON UPDATE RESTRICT ON DELETE RESTRICT, CONSTRAINT fk_ticket_category_id FOREIGN KEY (category_id) REFERENCES ticket_category (id) ON UPDATE RESTRICT ON DELETE RESTRICT, CONSTRAINT fk_ticket_type_id FOREIGN KEY (type_id) REFERENCES ticket_type (id) ON UPDATE RESTRICT ON DELETE RESTRICT, CONSTRAINT fk_ticket_status_id FOREIGN KEY (status_id) REFERENCES ticket_status (id) ON UPDATE RESTRICT ON DELETE RESTRICT ) ENGINE = INNODB; CREATE TABLE ticket_time_entry ( id INTEGER NOT NULL AUTO_INCREMENT, user_id INTEGER NOT NULL, ticket_id INTEGER NOT NULL, started_at DATETIME NOT NULL, ended_at DATETIME NOT NULL, PRIMARY KEY (id), CONSTRAINT fk_ticket_time_entry_user_id FOREIGN KEY (user_id) REFERENCES user (id) ON UPDATE RESTRICT ON DELETE RESTRICT, CONSTRAINT fk_ticket_time_entry_ticket_id FOREIGN KEY (ticket_id) REFERENCES ticket (id) ON UPDATE RESTRICT ON DELETE RESTRICT ) ENGINE = INNODB; The ticket table's create statement causes an error 150. I have no clue why. When I remove the ON DELETE RESTRICT statements from the table declaration, it works. Why is that?

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  • Can computer crashes and reboots mean weak power supply?

    - by TomA
    Recently I replaced the videocard in my PC for a newer, faster one. All games work perfectly but I get random system crashes and reboots. This happens even when the system is almost idle (browsing, playing music). It never happened with the old card. All drivers are up-to-date. Is it possible that the power supply is not powerful enough for the new card?

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  • How to make Exchange 2010 use In-Reply-To and References headers as well as Thread-Index?

    - by Paul Wagland
    The problem that I have is simple. We have recently upgraded from Exchange 2003 to Exchange 2010. Everything went fine, and there are very few complaints. In Exchange 2003, some of our OWA users liked the Threading view, these users love the conversations view, especially with the cross-mailbox threading. The problem is that some of these users are now complaining that old e-mails that they got from systems like bugzilla were migrated across correctly threaded, but the new e-mails are not being correctly threaded. If I look at the mail source using an IMAP client then I can see that all of the mails that are turning up as being threaded have the (Microsoft specific) Thread-Index header, and the mails that are not getting grouped do not have this header. The question is, how can I make the webmail client respect the normal threading? That is, is there a way to Make the OWA client use the standard In-Reply-To and References headers, or Make Exchange generate the Thread-Index headers for Outlook and OWA to use?

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  • Excel cell references not updating when referenced cells are sorted.

    - by Robert Kerr
    There are two tables, each with 75 entries. Each entry in the 2nd table calls an entry in the first table a parent. One of my 2nd table columns contains the "Parent Price", referencing the Price column in the first table, such as "=E50". Table 1 Id Price 1001 79.25 1002 8.99 1003 24.50 Table 2 Id Price Parent Price 2001 50.00 =B2 2002 2.81 =B3 2003 12.00 =B4 The problem is when I sort the first table, none of the second table's "Parent Price" references are updated, and still point to the =E50 cell, which is no longer the correct parent. I don't want to have to name the cells if possible. What style of formula do I enter in the parent price column so that they properly track the cells in the referenced table?

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  • How to debug unreleased COM references from managed code?

    - by Marek
    I have been searching for a tool to debug unreleased COM references, that usually cause e.g. Word/Outlook processes to hang in memory in case the code does not call Marshal.ReleaseCOMObject on all COM instances correctly. (Outlook 2007 partially fixes this for outlook addins, but this is a generic question). Is there a tool that would display at least a list of COM references (by type) held by managed code? Ideally, it would also display memory profiler-style object trees helping to debug where the reference increment occured. Debugging at runtime is not that important as being able to attach to a hung process - because the problem typically occurs when the code is done with the COM interface and someone forgot to release something - the application (e.g. winword) hangs in memory even after the calling managed application quits. If such tool does not exist, what is the (technical?) reason? It would be very useful for debugging a lot of otherwise very hard to find problems when working with COM interop.

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  • C++: Why don't I need to check if references are invalid/null?

    - by jbu
    Hi all, Reading http://www.cprogramming.com/tutorial/references.html, it says: In general, references should always be valid because you must always initialize a reference. This means that barring some bizarre circumstances (see below), you can be certain that using a reference is just like using a plain old non-reference variable. You don't need to check to make sure that a reference isn't pointing to NULL, and you won't get bitten by an uninitialized reference that you forgot to allocate memory for. My question is how do I know that the object's memory hasn't been freed/deleted AFTER you've initialized the reference. What it comes down to is that I can't take this advice on faith and I need a better explanation. Can anyone shed some light? Thanks, jbu

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  • Problem in Saving Multi Level Models in YII

    - by Waqar
    My Table structure for user and his adress detail is as follows CREATE TABLE tbl_users ( id bigint(20) unsigned NOT NULL AUTO_INCREMENT, loginname varchar(128) NOT NULL, enabled enum("True","False"), approved enum("True","False"), password varchar(128) NOT NULL, email varchar(128) NOT NULL, role_id int(20) NOT NULL DEFAULT '2', name varchar(70) NOT NULL, co_type enum("S/O","D/O","W/O") DEFAULT "S/O", co_name varchar(70), gender enum("MALE","FEMALE","OTHER") DEFAULT "MALE", dob date DEFAULT NULL, maritalstatus enum("SINGLE","MARRIED","DIVORCED","WIDOWER") DEFAULT "MARRIED", occupation varchar(100) DEFAULT NULL, occupationtype_id int(20) DEFAULT NULL, occupationindustry_id int(20) DEFAULT NULL, contact_id bigint(20) unsigned DEFAULT NULL, signupreason varchar(500), PRIMARY KEY (id), UNIQUE KEY loginname (loginname), UNIQUE KEY email (email), FOREIGN KEY (role_id) REFERENCES tbl_roles (id), FOREIGN KEY (occupationtype_id) REFERENCES tbl_occupationtypes (id), FOREIGN KEY (occupationindustry_id) REFERENCES tbl_occupationindustries (id), FOREIGN KEY (contact_id) REFERENCES tbl_contacts (id) ) ENGINE=InnoDB; CREATE TABLE tbl_contacts ( id bigint(20) unsigned NOT NULL AUTO_INCREMENT, contact_type enum("cres","pres","coff"), address varchar(300) DEFAULT NULL, landmark varchar(100) DEFAULT NULL, district_id int(11) DEFAULT NULL, city_id int(20) DEFAULT NULL, state_id int(20) DEFAULT NULL, pin_id bigint(20) unsigned DEFAULT NULL, area_id bigint(20) unsigned DEFAULT NULL, po_id bigint(20) unsigned DEFAULT NULL, phone1 varchar(20) DEFAULT NULL, phone2 varchar(20) DEFAULT NULL, mobile1 varchar(20) DEFAULT NULL, mobile2 varchar(20) DEFAULT NULL, PRIMARY KEY (id), FOREIGN KEY (district_id) REFERENCES tbl_districts (id), FOREIGN KEY (city_id) REFERENCES tbl_cities (id), FOREIGN KEY (state_id) REFERENCES tbl_states (id) ) ENGINE=InnoDB; CREATE TABLE tbl_states ( id int(20) NOT NULL AUTO_INCREMENT, name varchar(70) DEFAULT NULL, PRIMARY KEY (id) ) ENGINE=InnoDB; CREATE TABLE tbl_districts ( id int(20) NOT NULL AUTO_INCREMENT, name varchar(70) DEFAULT NULL, state_id int(20) DEFAULT NULL, PRIMARY KEY (id), FOREIGN KEY (state_id) REFERENCES tbl_states (id) ) ENGINE=InnoDB; CREATE TABLE tbl_cities ( id int(20) NOT NULL AUTO_INCREMENT, name varchar(70) DEFAULT NULL, district_id int(20) DEFAULT NULL, state_id int(20) DEFAULT NULL, PRIMARY KEY (id), FOREIGN KEY (district_id) REFERENCES tbl_districts (id), FOREIGN KEY (state_id) REFERENCES tbl_states (id) ) ENGINE=InnoDB; The relationship is as follows User has multiple contacts i.e Permanent Address, Current Address, Office Address. Each Contact has state and City. User-Contact-state like this How to save models of this structure in one go. Please provide a reply ASAP

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  • Can I trigger PHP garbage collection to happen automatically if I have circular references?

    - by Beau Simensen
    I seem to recall a way to setup the __destruct for a class in such a way that it would ensure that circular references would be cleaned up as soon as the outside object falls out of scope. However, the simple test I built seems to indicate that this is not behaving as I had expected/hoped. Is there a way to setup my classes in such a way that PHP would clean them up correctly when the outermost object falls out of scope? I am not looking for alternate ways to write this code, I am looking for whether or not this can be done, and if so, how? I generally try to avoid these types of circular references where possible. class Bar { private $foo; public function __construct($foo) { $this->foo = $foo; } public function __destruct() { print "[destroying bar]\n"; unset($this->foo); } } class Foo { private $bar; public function __construct() { $this->bar = new Bar($this); } public function __destruct() { print "[destroying foo]\n"; unset($this->bar); } } function testGarbageCollection() { $foo = new Foo(); } for ( $i = 0; $i < 25; $i++ ) { echo memory_get_usage() . "\n"; testGarbageCollection(); } The output looks like this: 60440 61504 62036 62564 63092 63620 [ destroying foo ] [ destroying bar ] [ destroying foo ] [ destroying bar ] [ destroying foo ] [ destroying bar ] [ destroying foo ] [ destroying bar ] [ destroying foo ] [ destroying bar ] What I had hoped for: 60440 [ destorying foo ] [ destorying bar ] 60440 [ destorying foo ] [ destorying bar ] 60440 [ destorying foo ] [ destorying bar ] 60440 [ destorying foo ] [ destorying bar ] 60440 [ destorying foo ] [ destorying bar ] 60440 [ destorying foo ] [ destorying bar ]

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