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• null coalescing operator for javascript?

  - by Daniel Schaffer

  I assumed this question has already been asked here, but I couldn't find any, so here it goes: Is there a null coalescing operator in Javascript? For example, in C#, I can do this: String someString = null; var whatIWant = someString ?? "Cookies!"; The best approximation I can figure out for Javascript is using the conditional operator: var someString = null; var whatIWant = someString ? someString : 'Cookies!'; Which is sorta icky IMHO. Can I do better?

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• Examples of interesting implementations of character stats?

  - by Tchalvak

  I've got this BBG going ( http://ninjawars.net ), and the character stats currently are simplistic. I'm looking to add a few stats to the current 1/2 (strength and maximum hitpoints, essentially). I've come up with: (strength (unchanged), speed, stamina, and some others that are somewhat interesting wildcard stats). However, I'm not satisfied with how boring the effects of some of these stats are, because they're very linear. Better stat, better effects of the stat, but the stats don't interact with each-other, there's no Rock-Paper-Scissors interaction, having more is always better all the time. So what I'd really like is to see examples of interesting character stats or effects of stats? Examples that I can think of off hand: Call of Cthulu's Insanity stat (things get really weird/chaotic if you start losing sanity) White Wolf stats, to a certain extent (the stats themselves have some basic effects, and all skills effectiveness base themselves off of stats as well) What are some other ways people have used stats to check out?

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• HTML character reference display problems.

  - by Bren

  Hey folks, I'm currently developing a site in Joomla, and one of the components I'm using makes use of a PHP file to administer the language. (english.php, spanish.php) The problem I'm having is that if I use the plain text version of eg. "á", it will show up in the browser tab title ok, but as a ? in the body of the page. But if I use a character reference (&#225;), the reverse happens! Any ideas? Thanks bren

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• wcf web service in post method, object properties are null, although the object is not null

  - by Abdalhadi Kolayb

  i have this problem in post method when i send object parameter to the method, then the object is not null, but all its properties have the default values. here is data module: [DataContract] public class Products { [DataMember(Order = 1)] public int ProdID { get; set; } [DataMember(Order = 2)] public string ProdName { get; set; } [DataMember(Order = 3)] public float PrpdPrice { get; set; } } and here is the interface: [OperationContract] [WebInvoke( Method = "POST", UriTemplate = "AddProduct", ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.WrappedRequest, RequestFormat = WebMessageFormat.Json)] string AddProduct([MessageParameter(Name = "prod")]Products prod); public string AddProduct(Products prod) { ProductsList.Add(prod); return "return string"; } here is the json request: Content-type:application/json {"prod":[{"ProdID": 111,"ProdName": "P111","PrpdPrice": 111}]} but in the server the object received: {"prod":[{"ProdID": 0,"ProdName": NULL,"PrpdPrice": 0}]}

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• Oral Tradition Check: Two Hundred Meanings for "NULL" in SQL

  - by Thomas L Holaday

  Two decades ago, the topic of "NULL" came up in conversation with a scholarly colleague. As I remember it, he said that C.J.Date, in an essay critical of commercial implementations of SQL, had listed over two hundred meanings for NULL. To my regret, I did not persist the details; but finding that list has since been on my Bucket List. Has anyone else heard this legend? Was it perhaps not Date, but another critic of commercial implementations of SQL?

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• Need to make animation whereby the character shatters into a bunch of pieces

  - by theprojectabot

  I would like to take a 3d character model, cut out a bunch of shapes (or a bunch of triangles in the shape of the pieces I want) and then have the pieces separate from each other at the beginning of the animation and fall apart with gravity so it looks like the model is falling apart in shattered pieces. Is there a way to run a script on a mesh, cut out these pieces, instantiate all of them as separate models and then run gravity on them during the simulation?

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• Character coding / programming

  - by Jery

  Lately I tryed a few times to create characters for some games, but at some certain point (especially when collision detection came in) everything became messy and the interaction between chars, the world and certain items had a lot of bugs. So here is my question, how do you ussualy keep track of actions that your character is allowed to do, or more in general do you have some links / advices how to set up a char efficiantly? I´m working on a char right now, who should at least be able to run, jump, pick items up and use different fighting animations. Most ideas I came up with until now use some kind of action.priority / action.duration system to determain whats possible and what not, or a "action-manager" which defines for every action what is possible from that action on but it all doesnt work that well together.

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• Determining distribution of NULL values

  - by AaronBertrand

  Today on the twitter hash tag #sqlhelp, @leenux_tux asked: How can I figure out the percentage of fields that don't have data ? After further clarification, it turns out he is after what proportion of columns are NULL. Some folks suggested using a data profiling task in SSIS . There may be some validity to that, but I'm still a fan of sticking to T-SQL when I can, so here is how I would approach it: Create a #temp table or @table variable to store the results. Create a cursor that loops through all...(read more)

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• Much ado about NULL: Exploiting a kernel NULL dereference

  <b>Ksplice:</b> "We think that it&#8217;s important for developers and system administrators to be more knowledgeable about the attacks that black hats regularly use to take control of systems, and so, today, we&#8217;re going to start from where we left off and go all the way to a working exploit for a NULL pointer dereference in a toy kernel module."

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• What is the difference between NULL in C++ and null in Java?

  - by Stephano

  I've been trying to figure out why C++ is making me crazy typing NULL. Suddenly it hits me the other day; I've been typing null (lower case) in Java for years. Now suddenly I'm programming in C++ and that little chunk of muscle memory is making me crazy. Wikiperipatetic defines C++ NULL as part of the stddef: A macro that expands to a null pointer constant. It may be defined as ((void*)0), 0 or 0L depending on the compiler and the language. Sun's docs tells me this about Java's "null literal": The null type has one value, the null reference, represented by the literal null, which is formed from ASCII characters. A null literal is always of the null type. So this is all very nice. I know what a null pointer reference is, and thank you for the compiler notes. Now I'm a little fuzzy on the idea of a literal in Java so I read on... A literal is the source code representation of a fixed value; literals are represented directly in your code without requiring computation. There's also a special null literal that can be used as a value for any reference type. null may be assigned to any variable, except variables of primitive types. There's little you can do with a null value beyond testing for its presence. Therefore, null is often used in programs as a marker to indicate that some object is unavailable. Ok, so I think I get it now. In C++ NULL is a macro that, when compiled, defines the null pointer constant. In Java, null is a fixed value that any non-primitive can be assigned too; great for testing in a handy if statement. Java does not have pointers, so I can see why they kept null a simple value rather than anything fancy. But why did java decide to change the all caps NULL to null? Furthermore, am I missing anything here?

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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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• null values vs "empty" singleton for optional fields

  - by Uko

  First of all I'm developing a parser for an XML-based format for 3D graphics called XGL. But this question can be applied to any situation when you have fields in your class that are optional i.e. the value of this field can be missing. As I was taking a Scala course on coursera there was an interesting pattern when you create an abstract class with all the methods you need and then create a normal fully functional subclass and an "empty" singleton subclass that always returns false for isEmpty method and throws exceptions for the other ones. So my question is: is it better to just assign null if the optional field's value is missing or make a hierarchy described above and assign it an empty singleton implementation?

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• Avoiding null in a controller

  - by Kevin Burke

  I'm trying to work through how to write this code. def get(params): """ Fetch a user's details, or 404 """ user = User.fetch_by_id(params['id']) if not user: abort(404) # Render some template for the user... What's the best way to handle the case where the lookup fails? One principle says you should avoid returning null values from functions. These lead to mistakes and AttributeErrors etc. later on in the file. Another idea is to have fetch_by_id raise a ValueError or similar if no user exists with that id. However there's a general principle that you shouldn't use exceptions for control flow, either, which doesn't help much. What could be done better in this case?

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• Character jump animation is not working when i hit the space bar

  - by muzzy

  i am having an issue with my game in XNA. My jump sprite sheet for my character does not trigger when i hit the space bar. I cant seem to find the problem. Please help me. I am also put the code below to make things easier. namespace WindowsGame4 { public class Game1 : Microsoft.Xna.Framework.Game { GraphicsDeviceManager graphics; SpriteBatch spriteBatch; // start of new code Texture2D playerWalk; // sprite sheet of walk cycle (14 frames) Texture2D idle; // idle animation Texture2D jump; // jump animation Vector2 playerPos; // to hold x and y position info for the player Point frameDimensions; // to hold width and height values for the frames int presentFrame; // to record which frame we are on at any given time int noOfFrames; // to hold the total number of frames in the spritesheet int elapsedTime; // to know how long each frame has been shown int frameDuration; // to hold info about how long each frame should be shown SpriteEffects flipDirection; // SpriteEffects object int speed; //rate of movement int upMovement; int downMovement; int rightMovement; int leftMovement; int jumpApex; string state; //this is going to be "idle","walking" or "jumping". KeyboardState previousKeyboardState; Vector2 originalPlayerPos; Vector2 movementDirection; Vector2 movementSpeed; public Game1() { graphics = new GraphicsDeviceManager(this); Content.RootDirectory = "Content"; } protected override void Initialize() { // textures will be defined in the LoadContent() method playerPos = new Vector2(0, 200); // starting position for the player is at the left of the screen, and a Y position of 200 frameDimensions = new Point(55, 65); // each frame in the idle sprite sheet is 55 wide by 65 high presentFrame = 0; // start at frame 0 noOfFrames = 5; // there are 5 frames in the idle cycle elapsedTime = 0; // set elapsed time to start at 0 frameDuration = 80; // 80 milliseconds is how long each frame will show for (the higher the number, the slower the animation) flipDirection = SpriteEffects.None; // set the value of flipDirection to none speed = 200; upMovement = -2; downMovement = 2; rightMovement = 1; leftMovement = -1; jumpApex = 100; state = "idle"; previousKeyboardState = Keyboard.GetState(); originalPlayerPos = Vector2.Zero; movementDirection = Vector2.Zero; movementSpeed = Vector2.Zero; base.Initialize(); } protected override void LoadContent() { spriteBatch = new SpriteBatch(GraphicsDevice); playerWalk = Content.Load<Texture2D>("sprites/walkSmall"); // load the walk cycle spritesheet idle = Content.Load<Texture2D>("sprites/idleCycle"); // load the idle cycle sprite sheet jump = Content.Load<Texture2D>("sprites/jump"); // load the jump cycle sprite sheet } protected override void UnloadContent() // we're not using this method at the moment { } protected override void Update(GameTime gameTime) // Update method - used it to call a number of other methods { if (Keyboard.GetState().IsKeyDown(Keys.Escape)) { this.Exit(); // Exit the game if the Escape key is pressed } KeyboardState presentKeyboardState = Keyboard.GetState(); UpdateMovement(presentKeyboardState, gameTime); UpdateIdle(presentKeyboardState, gameTime); UpdateJump(presentKeyboardState); UpdateAnimation(gameTime); playerPos += movementDirection * movementSpeed * (float)gameTime.ElapsedGameTime.TotalSeconds; previousKeyboardState = presentKeyboardState; base.Update(gameTime); } private void UpdateAnimation(GameTime gameTime) { elapsedTime += gameTime.ElapsedGameTime.Milliseconds; if (elapsedTime > frameDuration) { elapsedTime -= frameDuration; elapsedTime = elapsedTime - frameDuration; presentFrame++; if (presentFrame > noOfFrames) if (state != "jumping") { presentFrame = 0; } else { presentFrame = 8; } } } protected void UpdateMovement(KeyboardState presentKeyboardState, GameTime gameTime) { if (state == "idle") { movementSpeed = Vector2.Zero; movementDirection = Vector2.Zero; if (presentKeyboardState.IsKeyDown(Keys.Left)) { state = "walking"; movementSpeed.X = speed; movementDirection.X = leftMovement; flipDirection = SpriteEffects.FlipHorizontally; } if (presentKeyboardState.IsKeyDown(Keys.Right)) { state = "walking"; movementSpeed.X = speed; movementDirection.X = rightMovement; flipDirection = SpriteEffects.None; } } } private void UpdateIdle(KeyboardState presentKeyboardState, GameTime gameTime) { if ((presentKeyboardState.IsKeyUp(Keys.Left) && previousKeyboardState.IsKeyDown(Keys.Left) || presentKeyboardState.IsKeyUp(Keys.Right) && previousKeyboardState.IsKeyDown(Keys.Right) && state != "jumping")) { state = "idle"; } } private void UpdateJump(KeyboardState presentKeyboardState) { if (state == "walking" || state == "idle") { if (presentKeyboardState.IsKeyDown(Keys.Space) && !presentKeyboardState.IsKeyDown(Keys.Space)) { presentFrame = 1; DoJump(); } } if (state == "jumping") { if (originalPlayerPos.Y - playerPos.Y > jumpApex) { movementDirection.Y = downMovement; } if (playerPos.Y > originalPlayerPos.Y) { playerPos.Y = originalPlayerPos.Y; state = "idle"; movementDirection = Vector2.Zero; } } } private void DoJump() { if (state != "jumping") { state = "jumping"; originalPlayerPos = playerPos; movementDirection.Y = upMovement; movementSpeed = new Vector2(speed, speed); } } protected override void Draw(GameTime gameTime) // Draw method { GraphicsDevice.Clear(Color.CornflowerBlue); spriteBatch.Begin(); // begin the spritebatch if (state == "walking") { noOfFrames = 14; frameDimensions = new Point(55, 65); Vector2 playerWalkPos = new Vector2(playerPos.X, playerPos.Y - 28); spriteBatch.Draw(playerWalk, playerWalkPos, new Rectangle((presentFrame * frameDimensions.X), 0, frameDimensions.X, frameDimensions.Y), Color.White, 0, Vector2.Zero, 1, flipDirection, 0); } if (state == "idle") { noOfFrames = 5; frameDimensions = new Point(55, 65); Vector2 idlePos = new Vector2(playerPos.X, playerPos.Y - 28); spriteBatch.Draw(idle, idlePos, new Rectangle((presentFrame * frameDimensions.X), 0, frameDimensions.X, frameDimensions.Y), Color.White, 0, Vector2.Zero, 1, flipDirection, 0); } if (state == "jumping") { noOfFrames = 9; frameDimensions = new Point(55, 92); Vector2 jumpPos = new Vector2(playerPos.X, playerPos.Y - 28); spriteBatch.Draw(jump, jumpPos, new Rectangle((presentFrame * frameDimensions.X), 0, frameDimensions.X, frameDimensions.Y), Color.White, 0, Vector2.Zero, 1, flipDirection, 0); } spriteBatch.End(); // end the spritebatch commands base.Draw(gameTime); } } }

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• How to apply effects that occur (or change) over time to characters in a game?

  - by Joshua Harris

  So assume that I have a system that applies Effects to Characters like so: public class Character { private Collection<Effect> _effects; public void AddEffect (Effect e) { e.ApplyTo(this); _effects.Add(e); } public void RemoveEffect (Effect e) { e.RemoveFrom(this); _effects.Remove(e); } } public interface Effect { public void ApplyTo (Character character); public void RemoveFrom (Character character); } Example Effect: Armor Buff for 5 seconds. void someFunction() { // Do Stuff ... Timer armorTimer = new Timer(5 seconds); ArmorBuff armorbuff = new ArmorBuff(); character.AddEffect(armorBuff); armorTimer.Start(); // Do more stuff ... } // Some where else in code public void ArmorTimer_Complete() { character.RemoveEffect(armorBuff); } public class ArmorBuff implements Effect { public void applyTo(Character character) { character.changeArmor(20); } public void removeFrom(Character character) { character.changeArmor(-20); } } Ok, so this example would buff the Characters armor for 5 seconds. Easy to get working. But what about effects that change over the duration of the effect being applied. Two examples come to mind: Damage Over Time: 200 damage every second for 3 seconds. I could mimic this by applying an Effect that lasts for 1 second and has a counter set to 3, then when it is removed it could deal 200 damage, clone itself, decrement the counter of the clone, and apply the clone to the character. If it repeats this until the counter is 0, then you got a damage over time ability. I'm not a huge fan of this approach, but it does describe the behavior exactly. Degenerating Speed Boost: Gain a speed boost that degrades over 3 seconds until you return to your normal speed. This is a bit harder. I can basically do the same thing as above except having timers set to some portion of a second, such that they occur fast enough to give the appearance of degenerating smoothly over time (even though they are really just stepping down incrementally). I feel like you could get away with only 12 steps over a second (maybe less, I would have to test it and see), but this doesn't seem very elegant to me. The only other way to implement this effect would be to change the system so that the Character checks the _effects collection for effects that alter any of the properties any time that they are being used. I could handle this in functions like getCurrentSpeed() and getCurrentArmor(), but you can imagine how much of a hassle it would be to have that kind of overhead every time you want to do a calculation with movement speed (which would be every time you move your character). Is there a better way to deal with these kinds of effects or events?

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• Comparable and Comparator contract with regards to null

  - by polygenelubricants

  Comparable contract specifies that e.compareTo(null) must throw NullPointerException. From the API: Note that null is not an instance of any class, and e.compareTo(null) should throw a NullPointerException even though e.equals(null) returns false. On the other hand, Comparator API mentions nothing about what needs to happen when comparing null. Consider the following attempt of a generic method that takes a Comparable, and return a Comparator for it that puts null as the minimum element. static <T extends Comparable<? super T>> Comparator<T> nullComparableComparator() { return new Comparator<T>() { @Override public int compare(T el1, T el2) { return el1 == null ? -1 : el2 == null ? +1 : el1.compareTo(el2); } }; } This allows us to do the following: List<Integer> numbers = new ArrayList<Integer>( Arrays.asList(3, 2, 1, null, null, 0) ); Comparator<Integer> numbersComp = nullComparableComparator(); Collections.sort(numbers, numbersComp); System.out.println(numbers); // "[null, null, 0, 1, 2, 3]" List<String> names = new ArrayList<String>( Arrays.asList("Bob", null, "Alice", "Carol") ); Comparator<String> namesComp = nullComparableComparator(); Collections.sort(names, namesComp); System.out.println(names); // "[null, Alice, Bob, Carol]" So the questions are: Is this an acceptable use of a Comparator, or is it violating an unwritten rule regarding comparing null and throwing NullPointerException? Is it ever a good idea to even have to sort a List containing null elements, or is that a sure sign of a design error?

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• NHibernate IUserType convert nullable DateTime to DB not-null value

  - by barakbbn

  I have legacy DB that store dates that means no-date as 9999-21-31, The column Till_Date is of type DateTime not-null="true". in the application i want to build persisted class that represent no-date as null, So i used nullable DateTime in C# //public DateTime? TillDate {get; set; } I created IUserType that knows to convert the entity null value to DB 9999-12-31 but it seems that NHibernate doesn't call SafeNullGet, SafeNullSet on my IUserType when the entity value is null, and report a null is used for not-null column. I tried to by-pass it by mapping the column as not-null="false" (changed only the mapping file, not the DB) but it still didn't help, only now it tries to insert the null value to the DB and get ADOException. Any knowledge if NHibernate doesn't support IUseType that convert null to not-null values? Thanks //Implementation public class NullableDateTimeToNotNullUserType : IUserType { private static readonly DateTime MaxDate = new DateTime(9999, 12, 31); public new bool Equals(object x, object y) { //This didn't work as well if (ReferenceEquals(x, y)) return true; //if(x == null && y == null) return false; if (x == null || y == null) return false; return x.Equals(y); } public int GetHashCode(object x) { return x == null ? 0 : x.GetHashCode(); } public object NullSafeGet(IDataReader rs, string[] names, object owner) { var value = rs.GetDateTime(rs.GetOrdinal(names[0])); return (value == MaxDate)? null : value; } public void NullSafeSet(IDbCommand cmd, object value, int index) { var dateValue = (DateTime?)value; var dbValue = (dateValue.HasValue) ? dateValue.Value : MaxDate; ((IDataParameter)cmd.Parameters[index]).Value = dbValue; } public object DeepCopy(object value) { return value; } public object Replace(object original, object target, object owner) { return original; } public object Assemble(object cached, object owner) { return cached; } public object Disassemble(object value) { return value; } public SqlType[] SqlTypes { get { return new[] { NHibernateUtil.DateTime.SqlType }; } } public Type ReturnedType { get { return typeof(DateTime?); } } public bool IsMutable { get { return false; } } } } //Final Implementation with fixes. make the column mapping in hbm.xml not-null="false" public class NullableDateTimeToNotNullUserType : IUserType { private static readonly DateTime MaxDate = new DateTime(9999, 12, 31); public new bool Equals(object x, object y) { //This didn't work as well if (ReferenceEquals(x, y)) return true; //if(x == null && y == null) return false; if (x == null || y == null) return false; return x.Equals(y); } public int GetHashCode(object x) { return x == null ? 0 : x.GetHashCode(); } public object NullSafeGet(IDataReader rs, string[] names, object owner) { var value = NHibernateUtil.Date.NullSafeGet(rs, names[0]); return (value == MaxDate)? default(DateTime?) : value; } public void NullSafeSet(IDbCommand cmd, object value, int index) { var dateValue = (DateTime?)value; var dbValue = (dateValue.HasValue) ? dateValue.Value : MaxDate; NHibernateUtil.Date.NullSafeSet(cmd, valueToSet, index); } public object DeepCopy(object value) { return value; } public object Replace(object original, object target, object owner) { return original; } public object Assemble(object cached, object owner) { return cached; } public object Disassemble(object value) { return value; } public SqlType[] SqlTypes { get { return new[] { NHibernateUtil.DateTime.SqlType }; } } public Type ReturnedType { get { return typeof(DateTime?); } } public bool IsMutable { get { return false; } } } }

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• null from C# getting converted into 'NULL' in Sql Server

  - by Anand

  I am trying to insert NULL value in Sql Server if I have null value in corresponding C# String object like below : String Residence = xmlDoc.Descendants("Appointment").Single().Element("StateOfResidence") == null ? null : xmlDoc.Descendants("Appointment").Elements("StateOfResidence").Single().Value; I am using Entity framework for Database access. So if Residence is null, 'NULL' gets inserted into Database instead of NULL. How can insert NULL for null ?

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• MS Access PIVOT with User Defined Field

  - by user2535359

  Any of you good souls please help!! I need to query the source table shown in the below. (NULL are blank fields) UNUM, Ticket, Overflow 1 , 135 , NULL 1 , 136 ,NULL 1, 137, NULL 1, 138, NULL 1, NULL, 2b 2, 135, NULL 2, 136, NULL 2, 137, NULL 3, 135, NULL 3, 136, NULL 3, 137,NULL 3, 138, NULL 3, 139, NULL 3, 140, NULL 3, NULL, 66a 4, NULL, 12a 5, NULL, 14a I need to generate the output as shown below. UserNum, Ticket1, Ticket2, Ticket3, Ticket4, Ticket5, Ticket6, Ticket7, Ticket8, Ticket9, Overflow 1, 135, 136, 137, 138, Null, Null, Null, Null, Null, 2b 2, 135, 136, 137, Null, Null, Null, Null, Null, Null, Null 3, 135, 136, 137, 138, 139, 140, Null, Null, Null, 66a 4, Null, Null, Null, Null, Null, Null, Null, Null, Null, 12a 5, Null, Null, Null, Null, Null, Null, Null, Null, Null, 14a The source table has multiple tickets assigned to user. There are always maximum of 9 tickets. The user either has a ticket or an overflow but here can be only overflow per user. I am having issue pivoting the data in Ticket column to pre-defined field names like Ticket1, Ticket2...

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• Problems Enforcing Referential Integrity on SQL Server Tables

  - by SidC

  Hello All, I have a SQL Server 2005 database comprised of Customer, Quote, QuoteDetail tables. I want/need to enforce referential integrity such that when an insert is made on quotedetail, the quote and customer tables are also affected. I have tried my best to set up primary/foreign keys on my tables but need some help. Here's the scripts for my tables as they stand now (please don't laugh): Customers: USE [Diel_inventory] GO /****** Object: Table [dbo].[Customers] Script Date: 05/08/2010 03:39:04 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[Customers]( [pkCustID] [int] IDENTITY(1,1) NOT NULL, [CompanyName] [nvarchar](50) NULL, [Address] [nvarchar](50) NULL, [City] [nvarchar](50) NULL, [State] [nvarchar](2) NULL, [ZipCode] [nvarchar](5) NULL, [OfficePhone] [nvarchar](12) NULL, [OfficeFAX] [nvarchar](12) NULL, [Email] [nvarchar](50) NULL, [PrimaryContactName] [nvarchar](50) NULL, CONSTRAINT [PK_Customers] PRIMARY KEY CLUSTERED ([pkCustID] ASC)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] Quotes: USE [Diel_inventory] GO /****** Object: Table [dbo].[Quotes] Script Date: 05/08/2010 03:30:46 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[Quotes]( [pkQuoteID] [int] IDENTITY(1,1) NOT NULL, [fkCustomerID] [int] NOT NULL, [QuoteDate] [timestamp] NOT NULL, [NeedbyDate] [datetime] NULL, [QuoteAmt] [decimal](6, 2) NOT NULL, [QuoteApproved] [bit] NOT NULL, [fkOrderID] [int] NOT NULL, CONSTRAINT [PK_Bids] PRIMARY KEY CLUSTERED ( [pkQuoteID] ASC)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[Quotes] WITH CHECK ADD CONSTRAINT [fkCustomerID] FOREIGN KEY([fkCustomerID]) REFERENCES [dbo].[Customers] ([pkCustID]) GO ALTER TABLE [dbo].[Quotes] CHECK CONSTRAINT [fkCustomerID] QuoteDetail: USE [Diel_inventory] GO /****** Object: Table [dbo].[QuoteDetail] Script Date: 05/08/2010 03:31:58 ******/ SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[QuoteDetail]( [ID] [int] IDENTITY(1,1) NOT NULL, [fkQuoteID] [int] NOT NULL, [fkCustomerID] [int] NOT NULL, [fkPartID] [int] NULL, [PartNumber1] [float] NOT NULL, [Qty1] [int] NOT NULL, [PartNumber2] [float] NULL, [Qty2] [int] NULL, [PartNumber3] [float] NULL, [Qty3] [int] NULL, [PartNumber4] [float] NULL, [Qty4] [int] NULL, [PartNumber5] [float] NULL, [Qty5] [int] NULL, [PartNumber6] [float] NULL, [Qty6] [int] NULL, [PartNumber7] [float] NULL, [Qty7] [int] NULL, [PartNumber8] [float] NULL, [Qty8] [int] NULL, [PartNumber9] [float] NULL, [Qty9] [int] NULL, [PartNumber10] [float] NULL, [Qty10] [int] NULL, [PartNumber11] [float] NULL, [Qty11] [int] NULL, [PartNumber12] [float] NULL, [Qty12] [int] NULL, [PartNumber13] [float] NULL, [Qty13] [int] NULL, [PartNumber14] [float] NULL, [Qty14] [int] NULL, [PartNumber15] [float] NULL, [Qty15] [int] NULL, [PartNumber16] [float] NULL, [Qty16] [int] NULL, [PartNumber17] [float] NULL, [Qty17] [int] NULL, [PartNumber18] [float] NULL, [Qty18] [int] NULL, [PartNumber19] [float] NULL, [Qty19] [int] NULL, [PartNumber20] [float] NULL, [Qty20] [int] NULL, CONSTRAINT [PK_QuoteDetail] PRIMARY KEY CLUSTERED ( [ID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] GO ALTER TABLE [dbo].[QuoteDetail] WITH CHECK ADD CONSTRAINT [FK_QuoteDetail_Customers] FOREIGN KEY ([fkCustomerID]) REFERENCES [dbo].[Customers] ([pkCustID]) GO ALTER TABLE [dbo].[QuoteDetail] CHECK CONSTRAINT [FK_QuoteDetail_Customers] GO ALTER TABLE [dbo].[QuoteDetail] WITH CHECK ADD CONSTRAINT [FK_QuoteDetail_PartList] FOREIGN KEY ([fkPartID]) REFERENCES [dbo].[PartList] ([RecID]) GO ALTER TABLE [dbo].[QuoteDetail] CHECK CONSTRAINT [FK_QuoteDetail_PartList] GO ALTER TABLE [dbo].[QuoteDetail] WITH CHECK ADD CONSTRAINT [FK_QuoteDetail_Quotes] FOREIGN KEY([fkQuoteID]) REFERENCES [dbo].[Quotes] ([pkQuoteID]) GO ALTER TABLE [dbo].[QuoteDetail] CHECK CONSTRAINT [FK_QuoteDetail_Quotes] Your advice/guidance on how to set these up so that customer ID in Customers is the same as in Quotes (referential integrity) and that CustomerID is inserted on Quotes and Customers when an insert is made to QuoteDetial would be much appreciated. Thanks, Sid

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• SQL SERVER – A Puzzle – Fun with NULL – Fix Error 8117

  - by pinaldave

  During my 8 years of career, I have been involved in many interviews. Quite often, I act as the  interview. If I am the interviewer, I ask many questions – from easy questions to difficult ones. When I am the interviewee, I frequently get an opportunity to ask the interviewer some questions back. Regardless of the my capacity in attending the interview, I always make it a point to ask the interviewer at least one question. What is NULL? It’s always fun to ask this question during interviews, because in every interview, I get a different answer. NULL is often confused with false, absence of value or infinite value. Honestly, NULL is a very interesting subject as it bases its behavior in server settings. There are a few properties of NULL that are universal, but the knowledge about these properties is not known in a universal sense. Let us run this simple puzzle. Run the following T-SQL script: SELECT SUM(data) FROM (SELECT NULL AS data) t It will return the following error: Msg 8117, Level 16, State 1, Line 1 Operand data type NULL is invalid for sum operator. Now the error makes it very clear that NULL is invalid for sum Operator. Frequently enough, I have showed this simple query to many folks whom I came across. I asked them if they could modify the subquery and return the result as NULL. Here is what I expected: Even though this is a very simple looking query, so far I’ve got the correct answer from only 10% of the people to whom I have asked this question. It was common for me to receive this kind of answer – convert the NULL to some data type. However, doing so usually returns the value as 0 or the integer they passed. SELECT SUM(data) FROM (SELECT ISNULL(NULL,0) AS data) t I usually see many people modifying the outer query to get desired NULL result, but that is not allowed in this simple puzzle. This small puzzle made me wonder how many people have a clear understanding about NULL. Well, here is the answer to my simple puzzle. Just CAST NULL AS INT and it will return the final result as NULL: SELECT SUM(data) FROM (SELECT CAST(NULL AS INT) AS data) t Now that you know the answer, don’t you think it was very simple indeed? This blog post is especially dedicated to my friend Madhivanan who has written an excellent blog post about NULL. I am confident that after reading the blog post from Madhivanan, you will have no confusion regarding NULL in the future. Read: NULL, NULL, NULL and nothing but NULL. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Puzzle, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• In retrospect, has it been a good idea to use three-valued logic for SQL NULL comparisons?

  - by Heinzi

  In SQL, NULL means "unknown value". Thus, every comparison with NULL yields NULL (unknown) rather than TRUE or FALSE. From a conceptional point of view, this three-valued logic makes sense. From a practical point of view, every learner of SQL has, one time or another, made the classic WHERE myField = NULL mistake or learned the hard way that NOT IN does not do what one would expect when NULL values are present. It is my impression (please correct me if I am wrong) that the cases where this three-valued logic helps (e.g. WHERE myField IS NOT NULL AND myField <> 2 can be shortened to WHERE myField <> 2) are rare and, in those cases, people tend to use the longer version anyway for clarity, just like you would add a comment when using a clever, non-obvious hack. Is there some obvious advantage that I am missing? Or is there a general consensus among the development community that this has been a mistake?

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• Java Constructor Style (Check parameters aren't null)

  - by Peter

  What are the best practices if you have a class which accepts some parameters but none of them are allowed to be null? The following is obvious but the exception is a little unspecific: public class SomeClass { public SomeClass(Object one, Object two) { if (one == null || two == null) { throw new IllegalArgumentException("Parameters can't be null"); } //... } } Here the exceptions let you know which parameter is null, but the constructor is now pretty ugly: public class SomeClass { public SomeClass(Object one, Object two) { if (one == null) { throw new IllegalArgumentException("one can't be null"); } if (two == null) { throw new IllegalArgumentException("two can't be null"); } //... } Here the constructor is neater, but now the constructor code isn't really in the constructor: public class SomeClass { public SomeClass(Object one, Object two) { setOne(one); setTwo(two); } public void setOne(Object one) { if (one == null) { throw new IllegalArgumentException("one can't be null"); } //... } public void setTwo(Object two) { if (two == null) { throw new IllegalArgumentException("two can't be null"); } //... } } Which of these styles is best? Or is there an alternative which is more widely accepted? Cheers, Pete

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• segfault when cd-ing into certain directories in bash

  - by user84207

  I have noticed this very strange behavior recently. After cd into certain directories, I get a segfault on the terminal. --- SIGSEGV (Segmentation fault) @ 0 (0) --- --- SIGSEGV (Segmentation fault) @ 0 (0) --- +++ killed by SIGSEGV (core dumped) +++ segmentation fault (core dumped) I proceeded to strace a bash session in which I cd into the target directory, and was able to reproduce the problem. I attached the log to this pastebin: I paste below the few lines from the read of "cd stumpwm", which is the directory in question, until the segfault. I included a few of the repetitions of calls to "rt_sigprocmask" and "brk" to give a glimpse of the pattern, which occurs for most of the strace, read(0, cd stumpwm "c", 1) = 1 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 read(0, "d", 1) = 1 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 read(0, " ", 1) = 1 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 read(0, "s", 1) = 1 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 read(0, "t", 1) = 1 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 read(0, "u", 1) = 1 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 read(0, "m", 1) = 1 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 read(0, "p", 1) = 1 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 read(0, "w", 1) = 1 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 read(0, "m", 1) = 1 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 read(0, "\n", 1) = 1 rt_sigprocmask(SIG_BLOCK, [INT], [], 8) = 0 ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig -icanon -echo ...}) = 0 ioctl(0, SNDCTL_TMR_STOP or TCSETSW, {B38400 opost isig icanon -echo ...}) = 0 ioctl(0, SNDCTL_TMR_TIMEBASE or TCGETS, {B38400 opost isig icanon -echo ...}) = 0 rt_sigprocmask(SIG_SETMASK, [], NULL, 8) = 0 rt_sigaction(SIGINT, {0x457d50, [], SA_RESTORER, 0x7ffff76254a0}, {0x49edc0, [], SA_RESTORER, 0x7ffff76254a0}, 8) = 0 rt_sigaction(SIGTERM, {SIG_IGN, [], SA_RESTORER, 0x7ffff76254a0}, {SIG_IGN, [], SA_RESTORER, 0x7ffff76254a0}, 8) = 0 rt_sigaction(SIGQUIT, {SIG_IGN, [], SA_RESTORER, 0x7ffff76254a0}, {SIG_IGN, [], SA_RESTORER, 0x7ffff76254a0}, 8) = 0 rt_sigaction(SIGALRM, {0x457f50, [HUP INT ILL TRAP ABRT BUS FPE USR1 SEGV USR2 PIPE ALRM TERM XCPU XFSZ VTALRM SYS], SA_RESTORER, 0x7ffff76254a0}, {0x49edc0, [], SA_RESTORER, 0x7ffff76254a0}, 8) = 0 rt_sigaction(SIGTSTP, {SIG_IGN, [], SA_RESTORER, 0x7ffff76254a0}, {SIG_IGN, [], SA_RESTORER, 0x7ffff76254a0}, 8) = 0 rt_sigaction(SIGTTOU, {SIG_IGN, [], SA_RESTORER, 0x7ffff76254a0}, {SIG_IGN, [], SA_RESTORER, 0x7ffff76254a0}, 8) = 0 rt_sigaction(SIGTTIN, {SIG_IGN, [], SA_RESTORER, 0x7ffff76254a0}, {SIG_IGN, [], SA_RESTORER, 0x7ffff76254a0}, 8) = 0 rt_sigaction(SIGWINCH, {0x457920, [], SA_RESTORER, 0x7ffff76254a0}, {0x49e6e0, [], SA_RESTORER|SA_RESTART, 0x7ffff76254a0}, 8) = 0 rt_sigaction(SIGINT, {0x457d50, [], SA_RESTORER, 0x7ffff76254a0}, {0x457d50, [], SA_RESTORER, 0x7ffff76254a0}, 8) = 0 brk(0xa9a000) = 0xa9a000 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 brk(0xa9b000) = 0xa9b000 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 brk(0xa9c000) = 0xa9c000 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 brk(0xa9d000) = 0xa9d000 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 brk(0xa9e000) = 0xa9e000 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 brk(0xa9f000) = 0xa9f000 brk(0xaa0000) = 0xaa0000 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 brk(0xaa1000) = 0xaa1000 brk(0xaa2000) = 0xaa2000 (pattern of rt_sigprocmask, brk continues ...) rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 brk(0x1d5b000) = 0x1d5b000 brk(0x1d5c000) = 0x1d5c000 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 brk(0x1d5d000) = 0x1d5d000 brk(0x1d5e000) = 0x1d5e000 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 rt_sigprocmask(SIG_BLOCK, NULL, [], 8) = 0 --- SIGSEGV (Segmentation fault) @ 0 (0) --- --- SIGSEGV (Segmentation fault) @ 0 (0) --- +++ killed by SIGSEGV (core dumped) +++ segmentation fault (core dumped) How can I debug this? Is this likely to be a bash problem? The error does not occur with another shell, such as eshell. I have also run an fschk, although I haven't been able to see the output because of this bug.

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• Avoiding That Null Reference!

  - by TheJuice

  A coworker had this conversation with another of our developers. Names have been changed to protect the guilty. Clueless: hey! Clueless: I am using the ?? operator for null check below Nice Guy: hey Clueless: FundLoanRequestBoatCollateral boatCollateral = request.BoatCollateral ?? null; Nice Guy: that's not exactly how it works Clueless: I want to achive: FundLoanRequestBoatCollateral boatCollateral = request.BoatCollateral != null ? request.BoatCollateral : null; Clueless: isnt that equal to:  FundLoanRequestBoatCollateral boatCollateral = request.BoatCollateral ?? null; Nice Guy: that is functionally equivalent to FundLoanRequestBoatCollateral boatCollateral = request.BoatCollateral Nice Guy: you're checking if it's null and if so setting it to null Clueless: yeah Clueless: if its null I want to set it to null Nice Guy: if it's null then you're already going to set it to null, no special logic needed Clueless: I wanted to avoid a null reference if BoatCollateral is null   The sad part of all of this is that "Clueless" has been with our company for years and has a Master's in Computer Science.

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