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  • create a new model instance version instead of update

    - by pablo
    Hi, I have a model with a version field - autocreate timestamp. When a model instance is being saved I want to create a new instance with a new timestamp instead of updating the old model instance. Is it possible? I thought of overriding the model save() method but I don't know how to create a new instance without creating a infinite save() loop. Thanks

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  • Why can I not access this class member in python?

    - by Peter Smit
    I have the following code class Transcription(object): WORD = 0 PHONE = 1 STATE = 2 def __init__(self): self.transcriptions = [] def align_transcription(self,model,target=Transcription.PHONE): pass The important part here is that I would like to have a class member as default value for a variable. This however gives the following error: NameError: name 'Transcription' is not defined Why is this not possible and what is the right (pythonic) way to do something like this.

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  • How to initialize List<E> in empty class constructor?

    - by Nazgulled
    Hi, The following code obviously doesn't work because List<E> is abstract: public class MyList { private List<E> list; public MyList() { this.list = new List<E>(); } } How can I initialize MyList class with an empty constructor if I need the list variable to be a LinkedList or a ArrayList depending on my needs?

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  • Cannot extend a class located in another file, PHP

    - by NightMICU
    I am trying to set up a class with commonly used tasks, such as preparing strings for input into a database and creating a PDO object. I would like to include this file in other class files and extend those classes to use the common class' code. However, when I place the common class in its own file and include it in the class it will be used in, I receive an error that states the second class cannot be found. For example, if the class name is foo and it is extending bar (the common class, located elsewhere), the error says that foo cannot be found. But if I place the code for class bar in the same file as foo, it works. Here are the classes in question - Common Class abstract class coreFunctions { protected $contentDB; public function __construct() { $this->contentDB = new PDO('mysql:host=localhost;dbname=db', 'username', 'password'); } public function cleanStr($string) { $cleansed = trim($string); $cleansed = stripslashes($cleansed); $cleansed = strip_tags($cleansed); return $cleansed; } } Code from individual class include $_SERVER['DOCUMENT_ROOT'] . '/includes/class.core-functions.php'; $mode = $_POST['mode']; if (isset($mode)) { $gallery = new gallery; switch ($mode) { case 'addAlbum': $gallery->addAlbum($_POST['hash'], $_POST['title'], $_POST['description']); } } class gallery extends coreFunctions { private function directoryPath($string) { $path = trim($string); $path = strtolower($path); $path = preg_replace('/[^ \pL \pN]/', '', $path); $path = preg_replace('[\s+]', '', $path); $path = substr($path, 0, 18); return $path; } public function addAlbum($hash, $title, $description) { $title = $this->cleanStr($title); $description = $this->cleanStr($description); $path = $this->directoryPath($title); if ($title && $description && $hash) { $addAlbum = $this->contentDB->prepare("INSERT INTO gallery_albums (albumHash, albumTitle, albumDescription, albumPath) VALUES (:hash, :title, :description, :path)"); $addAlbum->execute(array('hash' => $hash, 'title' => $title, 'description' => $description, 'path' => $path)); } } } The error when I try it this way is Fatal error: Class 'gallery' not found in /home/opheliad/public_html/admin/photo-gallery/includes/class.admin_photo-gallery.php on line 10

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  • Is it a bad programming practise to have "Public" members inside an "Internal" class?

    - by Amby
    I mean, won;t it be more specific and appropriate if i "only" keep "protected","internal" and "private" members (field,method,property,event) in a class which is declared as "internal" ? I have seen this practice ( having "public" members in an "internal" class) in various code so just wanted to know is it a bad practice or does it has some benefit or advantage. [Only concerned about C#] Thanks for your interest.

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  • C++, class as parameter to a method, not template.

    - by ra170
    So, I came across an interesting method signature that I don't quite understand, it went along the lines of: void Initialize(std::vector< std::string > & param1, class SomeClassName * p); what I don't understand is the "class" keyword being used as the parameter, why is it there? Is it necessary to specify or it is purely superficial?

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  • Is it a bad programming practice to have "Public" members inside an "Internal" class?

    - by Amby
    I mean, won;t it be more specific and appropriate if i "only" keep "protected","internal" and "private" members (field,method,property,event) in a class which is declared as "internal" ? I have seen this practice ( having "public" members in an "internal" class) in various code so just wanted to know is it a bad practice or does it has some benefit or advantage. [Only concerned about C#] Thanks for your interest.

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  • HAproxy - Redirect issue - Uri Variables ?

    - by Justin
    I'm using haproxy 1.5dev3 and I was wondering if there is any possible way to grab uri variables from a request to reappend the query on the end of a redirect url? What I'm trying to do is redirect from: http://www.domain.com/page/example.htm?id=1234567 to: http://www.domain.com/frame/newpage.cfm?id=1234567 redirect prefix doesn't work properly as it tries to append /page/example.htm to the end of the redirect url. Can I do some sort of rewrite to accomplish this? It would be awesome if you could use uri and queries as variables for redirection/pool selection like on F5. Please help...Thanks!

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  • Forward Shibboleth Environment Variables to Tomcat via Apache

    - by Deepak Singh Rawat
    I am using Shibbolethv2.3 with Apache web server and Tomcat application server. I am using Apache as a reverse proxy using mod_proxy.so. I am not able to forward the Shibboleth environment variables from Apache to Tomcat. I am able to forward the attributes in the headers but as already mentioned in the wiki this approach is not safe. I have tried forwarding the environment variables by the following directive : SetEnv AJP_username ${username} then at the Java side I can access the attribute by : request.getAttribute("username"); The strange thing here is that, I get a different value instead of the one set by Shibboleth. I get the Windows account name as a result. If I use any other attribute name, I get a null value. I have searched a lot and have run out of options. Please guide me towards the right solution. My setup details : Shibboleth version : 2.3 OS : Windows XP SP3 Webserver : Apache 2.2 Application Server : Tomcat 6 Proxy module : mod_proxy.so

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  • How can I tell if my Amazon Windows instance was an SQL Server AMI?

    - by Aligma
    I want to purchase some reserved instances, because I have several instances already created and running 24 hours a day. When I go to purchase a Windows instance, I can see 3 options, Windows Windows with SQL Server Standard Windows with SQL server Web I don't know which of these was used to create the original instance. Is there a way I can find out? My assumptions: the instance type is is important because as far as I understand, the way to purchase a reserved instance is to first have a running instance, and then purchase a matching reserved instance. The reserved instance is not itself a new machine, but a kind of contract between you and Amazon to pay for an instance for 1 or 3 years, at a discounted rate. The contracted, reserved instance will "offset" one matching running instance where they have the same size and platform. Please feel free to correct me if these assumptions are incorrect.

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  • non-privileged normal user passing environment variables to /bin/login [closed]

    - by AAAAAAAA
    Suppose that in FreeBSD (or linux maybe) there is a non-privileged normal user (non-superuser). And there is a telnet standalone (I know that telnet is usually run under inetd) running under (owned by) this user. (Suppose that there was no original, root-owned telnet running.) This telnet server is programmed so that it does not check ld_* environment variables before passing it to /bin/login owned by root that has setuid set up. The question would be: 1. Will this telnet work? 2. If it does work, will it even be able to pass environment variables to /bin/login?

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  • C#/.NET Little Wonders: The Nullable static class

    - by James Michael Hare
    Once again, in this series of posts I look at the parts of the .NET Framework that may seem trivial, but can help improve your code by making it easier to write and maintain. The index of all my past little wonders posts can be found here. Today we’re going to look at an interesting Little Wonder that can be used to mitigate what could be considered a Little Pitfall.  The Little Wonder we’ll be examining is the System.Nullable static class.  No, not the System.Nullable<T> class, but a static helper class that has one useful method in particular that we will examine… but first, let’s look at the Little Pitfall that makes this wonder so useful. Little Pitfall: Comparing nullable value types using <, >, <=, >= Examine this piece of code, without examining it too deeply, what’s your gut reaction as to the result? 1: int? x = null; 2:  3: if (x < 100) 4: { 5: Console.WriteLine("True, {0} is less than 100.", 6: x.HasValue ? x.ToString() : "null"); 7: } 8: else 9: { 10: Console.WriteLine("False, {0} is NOT less than 100.", 11: x.HasValue ? x.ToString() : "null"); 12: } Your gut would be to say true right?  It would seem to make sense that a null integer is less than the integer constant 100.  But the result is actually false!  The null value is not less than 100 according to the less-than operator. It looks even more outrageous when you consider this also evaluates to false: 1: int? x = null; 2:  3: if (x < int.MaxValue) 4: { 5: // ... 6: } So, are we saying that null is less than every valid int value?  If that were true, null should be less than int.MinValue, right?  Well… no: 1: int? x = null; 2:  3: // um... hold on here, x is NOT less than min value? 4: if (x < int.MinValue) 5: { 6: // ... 7: } So what’s going on here?  If we use greater than instead of less than, we see the same little dilemma: 1: int? x = null; 2:  3: // once again, null is not greater than anything either... 4: if (x > int.MinValue) 5: { 6: // ... 7: } It turns out that four of the comparison operators (<, <=, >, >=) are designed to return false anytime at least one of the arguments is null when comparing System.Nullable wrapped types that expose the comparison operators (short, int, float, double, DateTime, TimeSpan, etc.).  What’s even odder is that even though the two equality operators (== and !=) work correctly, >= and <= have the same issue as < and > and return false if both System.Nullable wrapped operator comparable types are null! 1: DateTime? x = null; 2: DateTime? y = null; 3:  4: if (x <= y) 5: { 6: Console.WriteLine("You'd think this is true, since both are null, but it's not."); 7: } 8: else 9: { 10: Console.WriteLine("It's false because <=, <, >, >= don't work on null."); 11: } To make matters even more confusing, take for example your usual check to see if something is less than, greater to, or equal: 1: int? x = null; 2: int? y = 100; 3:  4: if (x < y) 5: { 6: Console.WriteLine("X is less than Y"); 7: } 8: else if (x > y) 9: { 10: Console.WriteLine("X is greater than Y"); 11: } 12: else 13: { 14: // We fall into the "equals" assumption, but clearly null != 100! 15: Console.WriteLine("X is equal to Y"); 16: } Yes, this code outputs “X is equal to Y” because both the less-than and greater-than operators return false when a Nullable wrapped operator comparable type is null.  This violates a lot of our assumptions because we assume is something is not less than something, and it’s not greater than something, it must be equal.  So keep in mind, that the only two comparison operators that work on Nullable wrapped types where at least one is null are the equals (==) and not equals (!=) operators: 1: int? x = null; 2: int? y = 100; 3:  4: if (x == y) 5: { 6: Console.WriteLine("False, x is null, y is not."); 7: } 8:  9: if (x != y) 10: { 11: Console.WriteLine("True, x is null, y is not."); 12: } Solution: The Nullable static class So we’ve seen that <, <=, >, and >= have some interesting and perhaps unexpected behaviors that can trip up a novice developer who isn’t expecting the kinks that System.Nullable<T> types with comparison operators can throw.  How can we easily mitigate this? Well, obviously, you could do null checks before each check, but that starts to get ugly: 1: if (x.HasValue) 2: { 3: if (y.HasValue) 4: { 5: if (x < y) 6: { 7: Console.WriteLine("x < y"); 8: } 9: else if (x > y) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } 17: } 18: else 19: { 20: Console.WriteLine("x > y because y is null and x isn't"); 21: } 22: } 23: else if (y.HasValue) 24: { 25: Console.WriteLine("x < y because x is null and y isn't"); 26: } 27: else 28: { 29: Console.WriteLine("x == y because both are null"); 30: } Yes, we could probably simplify this logic a bit, but it’s still horrendous!  So what do we do if we want to consider null less than everything and be able to properly compare Nullable<T> wrapped value types? The key is the System.Nullable static class.  This class is a companion class to the System.Nullable<T> class and allows you to use a few helper methods for Nullable<T> wrapped types, including a static Compare<T>() method of the. What’s so big about the static Compare<T>() method?  It implements an IComparer compatible comparison on Nullable<T> types.  Why do we care?  Well, if you look at the MSDN description for how IComparer works, you’ll read: Comparing null with any type is allowed and does not generate an exception when using IComparable. When sorting, null is considered to be less than any other object. This is what we probably want!  We want null to be less than everything!  So now we can change our logic to use the Nullable.Compare<T>() static method: 1: int? x = null; 2: int? y = 100; 3:  4: if (Nullable.Compare(x, y) < 0) 5: { 6: // Yes! x is null, y is not, so x is less than y according to Compare(). 7: Console.WriteLine("x < y"); 8: } 9: else if (Nullable.Compare(x, y) > 0) 10: { 11: Console.WriteLine("x > y"); 12: } 13: else 14: { 15: Console.WriteLine("x == y"); 16: } Summary So, when doing math comparisons between two numeric values where one of them may be a null Nullable<T>, consider using the System.Nullable.Compare<T>() method instead of the comparison operators.  It will treat null less than any value, and will avoid logic consistency problems when relying on < returning false to indicate >= is true and so on. Tweet   Technorati Tags: C#,C-Sharp,.NET,Little Wonders,Little Pitfalls,Nulalble

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  • Any language where every class instance is a class too?

    - by Dokkat
    Taking inspiration from Javascript prototypes, I had the idea of a language where every instance can be used as a class. Before I potentially reinvent the wheel, I would like to ask if there is a language already using this concept: //To declare a Class, extend the base class (in this case, Type) Type(Weapon,{price:0}); //Same syntax to inherit; simply extend the parent: Weapon(Sword,{price:3}); Weapon(Axe,{price:4}); Sword(Katana,{price:7}); Sword(Dagger,{price:3}); //And the same to create an instance: Katana(myKatana,{nickname:"Leon"}); myKatana.price; // 7 myKatana.nickname; // Leon // An operator to return children of a class; Sword_; // [Katana, Dagger] // An operator to return array of descendants; Sword__; // [Katana, Dagger, myKatana] // An operator to return array of parents; Sword^; // Weapon // Arrays can be used as elements Sword__.price += 1; //increases price of Sword's descendants by 1 mySword.price; //8 // And to access specific element (using its name instead of index) var name = "mySword" Katana_[name]; // [mySword] Katana_[name].nickname; // Leon Has this kind of approach been already studied/implemented?

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