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• How to nest an Enum inside the value of an Enum

  - by Mathieu

  I'd like to know if it is possible in Java to nest Enums. Here what i'd like to be able to do : Have an enum Species made of CAT and DOG wich would grant me access to sub enums of the available CAT and DOG breeds. For example, i'd like to be able to test if wether a CAT or a DOG and if an animal is a PERSAN CAT or a PITBULL DOG. CAT and DOG breeds must be distinct enums ,i.e a CatBreeds enum and a DogBreeds enum. Here is an example of access pattern i'd like to use : Species : Species.CAT Species.DOG Breeds : Species.CAT.breeds.PERSAN Species.DOG.breeds.PITBULL

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• Object as an array

  - by owca

  I need to create class Dog and PurebredDog extending Dog. Problem is that Dog can be at once single object and array of objects (Dogs and PurebreedDogs : Dog pack[]={new Dog(76589,"As","black",18, "Ann","Kowalsky"), new PurebreedDog(45321,"Labrador","Elf","black",25, "Angus","Mati","Barbara","Smith"), new Dog(102467,"Gamma","brown",89, "Josh","Coke"), new PurebreedDog(9678,"York","Theta","brown",8, "Emka","Figaro","Alice","Cat")}; for(int i=0; i < pack.length; i++) System.out.println(pack[i]+"\n\n"); How to write proper constructor for Dog ?

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• Beginner to RUBY - Array Question

  - by WANNABE

  a = [ 1, 3, 5, 7, 9 ] ? [1, 3, 5, 7, 9] a[2, 2] = ’cat’ ? [1, 3, "cat", 9] a[2, 0] = ’dog’ ? [1, 3, "dog", "cat", 9] a[1, 1] = [ 9, 8, 7 ] ? [1, 9, 8, 7, "dog", "cat", 9] a[0..3] = [] ? ["dog", "cat", 9] a[5..6] = 99, 98 ? ["dog", "cat", 9, nil, nil, 99, 98] I can understand how the last four amendments to this array work, but why do they use a[2, 2] = 'cat' and a[2,0] = 'dog' ??? What do the two numbers represent? Couldnt they just use a[2] = 'dog'?

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• Per Pixel Collision Detection

  - by CJ Cohorst

  Just a quick question, I have this collision detection code: public bool PerPixelCollision(Player player, Game1 dog) { Matrix atob = player.Transform * Matrix.Invert(dog.Transform); Vector2 stepX = Vector2.TransformNormal(Vector2.UnitX, atob); Vector2 stepY = Vector2.TransformNormal(Vector2.UnitY, atob); Vector2 iBPos = Vector2.Transform(Vector2.Zero, atob); for(int deltax = 0; deltax < player.playerTexture.Width; deltax++) { Vector2 bpos = iBPos; for (int deltay = 0; deltay < player.playerTexture.Height; deltay++) { int bx = (int)bpos.X; int by = (int)bpos.Y; if (bx >= 0 && bx < dog.dogTexture.Width && by >= 0 && by < dog.dogTexture.Height) { if (player.TextureData[deltax + deltay * player.playerTexture.Width].A > 150 && dog.TextureData[bx + by * dog.Texture.Width].A > 150) { return true; } } bpos += stepY; } iBPos += stepX; } return false; } What I want to know is where to put in the code where something happens. For example, I want to put in player.playerPosition.X -= 200 just as a test, but I don't know where to put it. I tried putting it under the return true and above it, but under it, it said unreachable code, and above it nothing happened. I also tried putting it by bpos += stepY; but that didn't work either. Where do I put the code? Any help is appreciated. Thanks in advance!

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• Where should I place my reaction code in Per-Pixel Collision Detection?

  - by CJ Cohorst

  I have this collision detection code: public bool PerPixelCollision(Player player, Game1 dog) { Matrix atob = player.Transform * Matrix.Invert(dog.Transform); Vector2 stepX = Vector2.TransformNormal(Vector2.UnitX, atob); Vector2 stepY = Vector2.TransformNormal(Vector2.UnitY, atob); Vector2 iBPos = Vector2.Transform(Vector2.Zero, atob); for(int deltax = 0; deltax < player.playerTexture.Width; deltax++) { Vector2 bpos = iBPos; for (int deltay = 0; deltay < player.playerTexture.Height; deltay++) { int bx = (int)bpos.X; int by = (int)bpos.Y; if (bx >= 0 && bx < dog.dogTexture.Width && by >= 0 && by < dog.dogTexture.Height) { if (player.TextureData[deltax + deltay * player.playerTexture.Width].A > 150 && dog.TextureData[bx + by * dog.Texture.Width].A > 150) { return true; } } bpos += stepY; } iBPos += stepX; } return false; } What I want to know is where to put in the code where something happens. For example, I want to put in player.playerPosition.X -= 200 just as a test, but I don't know where to put it. I tried putting it under the return true and above it, but under it, it said unreachable code, and above it nothing happened. I also tried putting it by bpos += stepY; but that didn't work either. Where do I put the code?

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• Unique string values in range

  - by Dean Smith

  I have some spreadsheets where there are large number of cells that have essentially been used for free text. There is a finite set of values for this free text and most, if not all repeat. eg. A B C D 1 Monkey Gorilla Cat Dog 2 Dog Cat Gorilla Gorilla 3 Dog Dog Dog Cat There are probably 50 or so different cell values spread over multiple sheets and hundreds of rows and columns. I need to analyse this data and count occurancies, which is not a problem other than getting a list of unique values to start with and this has been driving me up the wall. What is the best way to produce this list. So from the above we would have Monkey Dog Cat Gorilla In order of preferred solutions, as this will need to be done monthly. Dynamic formula based VB Script Other ( Advanced filtering or other manual steps )

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• php includes that include another php file

  - by Emma

  I'm getting really muddled up now and my brain hurts! :( lol Root: index.php Includes: cat.php dog.php index includes dog: include("includes/dog.php"); dog includes cat: include("cat.php"); When I run index, for cat it says: A link to the server could not be established Access denied for user ... However, if I run dog, I get no problems... I'm guessing its the path, but i've tried ./includes/cat.php to no joy...

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• Please help on multiple match replacement

  - by duenguyen

  I have a perl code: my $s = "The+quick+brown+fox+jumps+over+the+lazy+dog+that+is+my+dog"; what I want is to replace every + with space and dog with cat i have this regular expression $s =~ s/+(.*)dog/ ${1}cat/g; But it only match first occurrence of + and last dog. Please help

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• How do I perform multiple replacements with Perl?

  - by duenguyen

  I have Perl code: my $s = "The+quick+brown+fox+jumps+over+the+lazy+dog+that+is+my+dog"; I want to replace every + with space and dog with cat. I have this regular expression: $s =~ s/\+(.*)dog/ ${1}cat/g; But, it only matches the first occurrence of + and last dog.

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• Splitting list into a list of possible tuples

  - by user1742646

  I need to split a list into a list of all possible tuples, but I'm unsure of how to do so. For example pairs ["cat","dog","mouse"] should result in [("cat","dog"), ("cat","mouse"), ("dog","cat"), ("dog","mouse"), ("mouse","cat"), ("mouse","dog")] I was able to form the first two, but am unsure of how to get the rest. Here's what I have so far: pairs :: [a] -> [(a,a)] pairs (x:xs) = [(m,n) | m <- [x], n <- xs]

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• Tykie

  - by Brian

  Here’s the obituary my mother wrote for Tykie, I still miss the little guy quite a bit. Anyone who’s interested in further information on hearing dogs should check out the IHDI website. I cannot begin to express how helpful a hearing dog can be for the hearing impaired. If you feel so inclined, please make a donation. In Memoriam, Tykie 1993-2010 The American Legion Post 401, South Wichita, KS, supported one of its members and commander by sponsoring a service dog for him. Unlike most service dogs this one was for the hearing impaired. Both Ocie and Betty Sims had hearing loss – Ocie more than Betty. The Post and Auxilliary had garage sales, auctions and other fund-raising endeavors to get donations for the dog. Betty made Teddy bears with growlers that were auctioned for donations to bring a hearing dog from International Hearing Dog, Henderson, Colorado. Tykie, a small wiry, salt and pepper terrier, arrived September 1, 1994 to begin his work that included attending Post 401 meetings and celebrations as well as raising more money to be donated to IHD to help others have hearing dogs. Tykie was a young dog less than a year old when he came to Wichita. He was always anxious to please and seldom barked, though he did put out a kind of cry when he was giving his urgent announcement that someone was at the door or the telephone was ringing. He also enjoyed chasing squirrels in the backyard garden that Ocie prized. In 1995, Betty almost died of a lung infection. Tykie was at the hospital with Ocie when he could visit. Several weeks after she was able to come home after a miraculous recovery, Tykie and Ocie went to a car show in downtown Wichita. Ocie’s retina tore loose in the only eye he could see out of and he almost blind was in great pain. How Ocie and Tykie got home is still a mystery, but the family legend goes that Tykie added seeing eye dog to his repertoire and helped drive him home. Health problems continued for Ocie and when he was placed in a nursing home, Tykie was moved to be Betty’s hearing dog. No problem for Tykie, he still saw his friends at the post and continued to help with visitors at the door. The night of May 3, 1999, Betty and Tykie were in the bedroom watching TV when Tykie began hitting her with both front paws as he would if something were urgent. She said later she thought he wanted to go out. As she and the dog walked down the hall towards the back of the house, Tykie hit her again with his front paws with such urgency that she fell into a small coat closet. That small 2-by-2 closet became their refuge as that very second the roof of her house went off as the f4 tornado raced through the city. Betty acquired one small wound on her hand from a piece of flying glass as she pulled Tykie into the closet with her. Tykie was a hero that day and a lot of days after. He kept Betty going as she rebuilt her home and after her husband died April 15, 2000. Tykie had to be cared for so she had to take him outside and bring him inside. He attended weddings of grandchildren and funerals of Post friends. When Betty died February 17, 2002 Tykie’s life changed again. IHD gave approval for his transfer and retirement to Betty and Ocie’s grandson, Brian Laird, who has a similar hearing loss to his grandfather. A few days after the funeral Tykie flew to his new home in Rutherford, NJ where he was able to take long walks for a couple of years before moving back to the Kansas City area. He was still full of adventure. He was written up in a book about service dogs and his story of the tornado and his picture appeared. He spent weekends at Brian’s mother’s farm to get muddy and be afraid of cats and chickens. He also took on an odyssey as he slipped from his fenced yard in Lenexa one day and walked more than seven miles in Overland Park traffic before being found by a good Samaritan who called IHD to find out where he belonged. Tykie was deaf for about the last two years of his long life and became blind as well, but he continued to strive to please. Tykie was 16 years and 4 months when he was cremated. His ashes were scattered on the graves of Betty and Ocie Sims at Greenwood Cemetery west of Wichita on the afternoon of March 21, 2010, with about a dozen family and Post 401 members. It is still the rule. Service dogs are the only dogs allowed inside the Post home. Submitted by Linda Laird, daughter of Betty and Ocie and mother of Brian Laird.

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• Why does Jcreator show iIlegal start of expression?

  - by Inusual Whisper Sinclair

  I am new at programming and currently in our classes we are learning java. I am trying to create a routine in which I need to use String variables only. Below it is the code in which I am working with: public static void main(String[] args) throws java.io.IOException { BufferedReader in = new BufferedReader(new InputStreamReader(System. in )); PrintStream out = System.out; String hair.equals("damagedHair"); cutHair(marvin); cleanHair(michelle); for (int i = 0; i < 2; i++) { static void cutHair(String marvin) { String cabello; marvin.equals(hair); if (marvin.equals("damagedHair")) { cabello.equals("newHaircut"); result(hair); } static void cleanHair(String michelle) { String hair; michelle.equals(hair); if (michelle.equals(newHaircut)) { hair.equals("putShampooAndConditioner"); result(hair); } static void result(String pHair) {; PrintStream out = System.out; out.println("============="); out.println(pHair); out.println("============="); } } Jcreator is giving me an error that says Illegal start of expression and also java 50 error ';' expected. I am not sure why is this coming up and I am a little confused as to whether I am doing something I am not supposed to and how to correct it. Sorry about the double posting, this is the right message. Need some help from you guys to figure this out. Thanks in advanced!

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• How to make every word in the text clickable and send it to the script

  - by fakson

  I have a text for example "The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog. The quick brown fox jumps over the lazy dog." When i click on word i must get data from XML or from mysql about this word. How i can make every word active for click and send it to another script for example: I click on dog, and in new window i get information about dog? on fox about fox? every word must be clickable Any ideas, links or examples? Using php, mysql, jquery, ajax

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• word frequency problem

  - by davit-datuashvili

  hi in programming pearls i have meet following problem question is this:print words in decreasing frequency or as i understand probllem is this suppose there is given string array let call it s words i have taken randomly it does not matter String s[]={"cat","cat","dog","fox","cat","fox","dog","cat","fox}; and we see that string cat occurs 4 times fox 3 times and dog 2 times so result will be such cat fox dog i have following code in java mport java.util.*; public class string { public static void main(String[] args){ String s[]={"fox","cat","cat","fox","dog","cat","fox","dog","cat"}; Arrays.sort(s); int counts; int count[]=new int[s.length]; for (int i=0;i } } or i have sorted array and create count array where i write number of each word in array problem is that somehow index of integer array element and string array element is not same how to do such that print words according tu maximum elements of integer array? please help me

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• How does polymorphism work in Python?

  - by froadie

  I'm new to Python... and coming from a mostly Java background, if that accounts for anything. I'm trying to understand polymorphism in Python. Maybe the problem is that I'm expecting the concepts I already know to project into Python. But I put together the following test code: class animal(object): "empty animal class" class dog(animal): "empty dog class" myDog = dog() print myDog.__class__ is animal print myDog.__class__ is dog From the polymorphism I'm used to (e.g. java's instanceof), I would expect both of these statements to print true, as an instance of dog is an animal and also is a dog. But my output is: False True What am I missing?

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• redirect an old URL using web.config

  - by Dog

  i'm still very new to using URL rewrites and redirects and i'm having some problems on something i thought was quite simple... i've just rebuilt a website and want to redirect the old URLs to the new ones... for example : http://www.mydomain.com/about.asp?lang=1 should now be http://www.mydomain.com/content.asp?id=100230&title=about&langid=1 unfortunately, everything i've tried is giving me errors or simply does nothing. here is one rule i tried : <rule name="redirectoldabout" enabled="true" stopProcessing="true"> <match url="( .*)" negate="true" /> <conditions> <add input="{HTTP_HOST}" pattern="^mydomain\.com/about\.asp\?lang=1$" /> </conditions> <action type="Redirect" url="http://www.mydomain.com/content.asp?id=100230&title=about&langid=1" redirectType="Permanent" /> but i get an error back : HTTP Error 500.19 - Internal Server Error The requested page cannot be accessed because the related configuration data for the page is invalid. any suggestions as to what i'm doing wrong? thanks dog

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• partial string matching - R

  - by DonDyck

  I need to write a query in R to match partial string in column names. I am looking for something similar to LIKE operator in SQL. For e.g, if I know beginning, middle or end part of the string I would write the query in format: LIKE 'beginning%middle%' in SQL and it would return matching strings. In pmatch or grep it seems I can only specify 'beginning' , 'end' and not the order. Is there any similar function in R that I am looking for? For example, say I am looking in the vector: y<- c("I am looking for a dog", "looking for a new dog", "a dog", "I am just looking") Lets say I want to write a query which picks "looking for a new dog" and I know start of the string is "looking" and end of string is "dog". If I do a grep("dog",y) it will return 1,2,3. Is there any way I can specify beginning and end in grep?

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• How to store array data in MySQL database using PHP & MySQL?

  - by Cyn

  I'm new to php and mysql and I'm trying to learn how to store the following array data from three different arrays friend[], hair_type[], hair_color[] using MySQL and PHP an example would be nice. Thanks Here is the HTML code. <input type="text" name="friend[]" id="friend[]" /> <select id="hair_type[]" name="hair_type[]"> <option value="Hair Type" selected="selected">Hair Type</option> <option value="Straight">Straight</option> <option value="Curly">Curly</option> <option value="Wavey">Wavey</option> <option value="Bald">Bald</option> </select> <select id="hair_color[]" name="hair_color[]"> <option value="Hair Color" selected="selected">Hair Color</option> <option value="Brown">Brown</option> <option value="Black">Black</option> <option value="Red">Red</option> <option value="Blonde">Blonde</option> </select> <input type="text" name="friend[]" id="friend[]" /> <select id="hair_type[]" name="hair_type[]"> <option value="Hair Type" selected="selected">Hair Type</option> <option value="Straight">Straight</option> <option value="Curly">Curly</option> <option value="Wavey">Wavey</option> <option value="Bald">Bald</option> </select> <select id="hair_color[]" name="hair_color[]"> <option value="Hair Color" selected="selected">Hair Color</option> <option value="Brown">Brown</option> <option value="Black">Black</option> <option value="Red">Red</option> <option value="Blonde">Blonde</option> </select> Here is the MySQL tables below. CREATE TABLE friends_hair ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, hair_id INT UNSIGNED NOT NULL, user_id INT UNSIGNED NOT NULL, PRIMARY KEY (id) ); CREATE TABLE hair_types ( id INT UNSIGNED NOT NULL AUTO_INCREMENT, friend TEXT NOT NULL, hair_type TEXT NOT NULL, hair_color TEXT NOT NULL, PRIMARY KEY (id) );

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• The relative effort of SharePoint 2010 vs. 2007

  - by erobillard

  SharePoint 2007 was the best demo-ware ever. It’s like going to the pet store and seeing a great dog that does backflips all kinds of tricks – and it really is a smart dog and it does all those tricks – but when you get it home you realize that what you need is a dog that gets the paper. SharePoint 2007 can be trained, but is fundamentally a platform where Microsoft's priority was to get the infrastructure right – to make it trainable and extensible. Because it was great demo-ware it caught on like...(read more)

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• Breaking through the class sealing

  - by Jason Crease

  Do you understand 'sealing' in C#?  Somewhat?  Anyway, here's the lowdown. I've done this article from a C# perspective, but I've occasionally referenced .NET when appropriate. What is sealing a class? By sealing a class in C#, you ensure that you ensure that no class can be derived from that class.  You do this by simply adding the word 'sealed' to a class definition: public sealed class Dog {} Now writing something like " public sealed class Hamster: Dog {} " you'll get a compile error like this: 'Hamster: cannot derive from sealed type 'Dog' If you look in an IL disassembler, you'll see a definition like this: .class public auto ansi sealed beforefieldinit Dog extends [mscorlib]System.Object Note the addition of the word 'sealed'. What about sealing methods? You can also seal overriding methods.  By adding the word 'sealed', you ensure that the method cannot be overridden in a derived class.  Consider the following code: public class Dog : Mammal { public sealed override void Go() { } } public class Mammal { public virtual void Go() { } } In this code, the method 'Go' in Dog is sealed.  It cannot be overridden in a subclass.  Writing this would cause a compile error: public class Dachshund : Dog { public override void Go() { } } However, we can 'new' a method with the same name.  This is essentially a new method; distinct from the 'Go' in the subclass: public class Terrier : Dog { public new void Go() { } } Sealing properties? You can also seal seal properties.  You add 'sealed' to the property definition, like so: public sealed override string Name {     get { return m_Name; }     set { m_Name = value; } } In C#, you can only seal a property, not the underlying setters/getters.  This is because C# offers no override syntax for setters or getters.  However, in underlying IL you seal the setter and getter methods individually - a property is just metadata. Why bother sealing? There are a few traditional reasons to seal: Invariance. Other people may want to derive from your class, even though your implementation may make successful derivation near-impossible.  There may be twisted, hacky logic that could never be second-guessed by another developer.  By sealing your class, you're protecting them from wasting their time.  The CLR team has sealed most of the framework classes, and I assume they did this for this reason. Security.  By deriving from your type, an attacker may gain access to functionality that enables him to hack your system.  I consider this a very weak security precaution. Speed.  If a class is sealed, then .NET doesn't need to consult the virtual-function-call table to find the actual type, since it knows that no derived type can exist.  Therefore, it could emit a 'call' instead of 'callvirt' or at least optimise the machine code, thus producing a performance benefit.  But I've done trials, and have been unable to demonstrate this If you have an example, please share! All in all, I'm not convinced that sealing is interesting or important.  Anyway, moving-on... What is automatically sealed? Value types and structs.  If they were not always sealed, all sorts of things would go wrong.  For instance, structs are laid-out inline within a class.  But what if you assigned a substruct to a struct field of that class?  There may be too many fields to fit. Static classes.  Static classes exist in C# but not .NET.  The C# compiler compiles a static class into an 'abstract sealed' class.  So static classes are already sealed in C#. Enumerations.  The CLR does not track the types of enumerations - it treats them as simple value types.  Hence, polymorphism would not work. What cannot be sealed? Interfaces.  Interfaces exist to be implemented, so sealing to prevent implementation is dumb.  But what if you could prevent interfaces from being extended (i.e. ban declarations like "public interface IMyInterface : ISealedInterface")?  There is no good reason to seal an interface like this.  Sealing finalizes behaviour, but interfaces have no intrinsic behaviour to finalize Abstract classes.  In IL you can create an abstract sealed class.  But C# syntax for this already exists - declaring a class as a 'static', so it forces you to declare it as such. Non-override methods.  If a method isn't declared as override it cannot be overridden, so sealing would make no difference.  Note this is stated from a C# perspective - the words are opposite in IL.  In IL, you have four choices in total: no declaration (which actually seals the method), 'virtual' (called 'override' in C#), 'sealed virtual' ('sealed override' in C#) and 'newslot virtual' ('new virtual' or 'virtual' in C#, depending on whether the method already exists in a base class). Methods that implement interface methods.  Methods that implement an interface method must be virtual, so cannot be sealed. Fields.  A field cannot be overridden, only hidden (using the 'new' keyword in C#), so sealing would make no sense.

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• Functional programming compared to OOP with classes

  - by luckysmack

  I have been interested in some of the concepts of functional programming lately. I have used OOP for some time now. I can see how I would build a fairly complex app in OOP. Each object would know how to do things that object does. Or anything it's parents class does as well. So I can simply tell Person().speak() to make the person talk. But how do I do similar things in functional programming? I see how functions are first class items. But that function only does one specific thing. Would I simply have a say() method floating around and call it with an equivalent of Person() argument so I know what kind of thing is saying something? So I can see the simple things, just how would I do the comparable of OOP and objects in functional programming, so I can modularize and organize my code base? For reference, my primary experience with OOP is Python, PHP, and some C#. The languages that I am looking at that have functional features are Scala and Haskell. Though I am leaning towards Scala. Basic Example (Python): Animal(object): def say(self, what): print(what) Dog(Animal): def say(self, what): super().say('dog barks: {0}'.format(what)) Cat(Animal): def say(self, what): super().say('cat meows: {0}'.format(what)) dog = Dog() cat = Cat() dog.say('ruff') cat.say('purr')

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• CMD Command to create folder for each file and move file into folder

  - by Tom

  I need a command that can be run from the command line to create a folder for each file (based on the file-name) in a directory and then move the file into the newly created folders. Example : Starting Folder: Dog.jpg Cat.jpg The following command works great at creating a folder for each filename in the current working directory. for %i in (*) do md "%~ni" Result Folder: \Dog\ \Cat\ Dog.jpg Cat.jpg I need to take this one step further and move the file into the folder. What I want to achieve is: \Dog\Dog.jpg \Cat\Cat.jpg Can someone help me with one command to do all of this?

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• operator<< overload,

  - by mr.low

  //using namespace std; using std::ifstream; using std::ofstream; using std::cout; class Dog { friend ostream& operator<< (ostream&, const Dog&); public: char* name; char* breed; char* gender; Dog(); ~Dog(); }; im trying to overload the << operator. I'm also trying to practice good coding. But my code wont compile unless i uncomment the using namespace std. i keep getting this error and i dont know. im using g++ compiler. Dog.h:20: error: ISO C++ forbids declaration of ‘ostream’ with no type Dog.h:20: error: ‘ostream’ is neither function nor member function; cannot be declared friend. if i add line using std::cout; then i get this error. Dog.h:21: error: ISO C++ forbids declaration of ‘ostream’ with no type. Can somebody tell me the correct way to overload the << operator with out using namespace std;

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• Can't contravariance be solved with interfaces?

  - by Sir Psycho

  Hi, I'm at the point where I'm starting to grasp contravariance, although I'm trying to work out what the advantage is when an interface can be used instead. Obviously I'm missing something. Here is the c#4 example class Dog : Animal { public Dog(string name) : base(name) { } } class Animal { string _name; public Animal(string name) { _name = name; } public void Walk() { Console.WriteLine(_name + " is walking"); } } Action<Animal> MakeItMove = (ani) => { ani.Walk(); }; Action<Dog> MakeItWalk = MakeItMove; MakeItWalk(new Dog("Sandy")); Same example which works in earlier versions on c# class Dog : Animal { public Dog(string name) : base(name) { } } class Animal : IAnimal { string _name; public Animal(string name) { _name = name; } public void Walk() { Console.WriteLine(_name + " is walking"); } } interface IAnimal { void Walk(); } Action<IAnimal> MakeItMove = (ani) => { ani.Walk(); }; Action<IAnimal> MakeItWalk = MakeItMove; MakeItWalk(new Dog("Sandy")); These may not be the best examples, but I still can't seem to 'get it'. Is the in keywork defined on the action delegate simply a short hand syntax way like lamda is to delegates?

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• Django's post_save signal behaves weirdly with models using multi-table inheritance

  - by hekevintran

  Django's post_save signal behaves weirdly with models using multi-table inheritance I am noticing an odd behavior in the way Django's post_save signal works when using a model that has multi-table inheritance. I have these two models: class Animal(models.Model): category = models.CharField(max_length=20) class Dog(Animal): color = models.CharField(max_length=10) I have a post save callback called echo_category: def echo_category(sender, **kwargs): print "category: '%s'" % kwargs['instance'].category post_save.connect(echo_category, sender=Dog) I have this fixture: [ { "pk": 1, "model": "animal.animal", "fields": { "category": "omnivore" } }, { "pk": 1, "model": "animal.dog", "fields": { "color": "brown" } } ] In every part of the program except for in the post_save callback the following is true: from animal.models import Dog Dog.objects.get(pk=1).category == u'omnivore' # True When I run syncdb and the fixture is installed, the echo_category function is run. The output from syncdb is: $ python manage.py syncdb --noinput Installing json fixture 'initial_data' from '~/my_proj/animal/fixtures'. category: '' Installed 2 object(s) from 1 fixture(s) The weird thing here is that the dog object's category attribute is an empty string. Why is it not 'omnivore' like it is everywhere else? As a temporary (hopefully) workaround I reload the object from the database in the post_save callback: def echo_category(sender, **kwargs): instance = kwargs['instance'] instance = sender.objects.get(pk=instance.pk) print "category: '%s'" % instance.category post_save.connect(echo_category, sender=Dog) This works but it is not something I like because I must remember to do it when the model inherits from another model and it must hit the database again. The other weird thing is that I must do instance.pk to get the primary key. The normal 'id' attribute does not work (I cannot use instance.id). I do not know why this is. Maybe this is related to the reason why the category attribute is not doing the right thing?

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