Search Results

Search found 11672 results on 467 pages for 'formal methods'.

Page 48/467 | < Previous Page | 44 45 46 47 48 49 50 51 52 53 54 55  | Next Page >

  • When is it better to use a method versus a property for a class definition?

    - by ccomet
    Partially related to an earlier question of mine, I have a system in which I have to store complex data as a string. Instead of parsing these strings as all kinds of separate objects, I just created one class that contains all of those objects, and it has some parser logic that will encode all properties into strings, or decode a string to get those objects. That's all fine and good. This question is not about the parser itself, but about where I should house the logic for the parser. Is it a better choice to put it as a property, or as a method? In the case of a property, say public string DataAsString, the get accessor would house the logic to encode all of the data into a string, while the set accessor would decode the input value and set all of the data in the class instance. It seems convenient because the input/output is indeed a string. In the case of a method, one method would be Encode(), which returns the encoded string. Then, either the constructor itself would house the logic for the decoding a string and require the string argument, or I write a Decode(string str) method which is called separately. In either case, it would be using a method instead of a property. So, is there a functional difference between these paths, in terms of the actual running of the code? Or are they basically equivalent and it then boils down to a choice of personal preference or which one looks better? And in that kind of question... which would look cleaner anyway?

    Read the article

  • Returning IEnumerable<T> vs IQueryable<T>

    - by stackoverflowuser
    what is the difference between returning iqueryable vs ienumerable. IQueryable<Customer> custs = from c in db.Customers where c.City == "<City>" select c; IEnumerable<Customer> custs = from c in db.Customers where c.City == "<City>" select c; Will both be deferred execution? When should one be preferred over the other?

    Read the article

  • Fast ArgumentNullException with attributes. It is possible?

    - by Fraga
    Hi. Is there any fast way to verify null arguments via attributes or something? Convert this: public void Method(type arg1,type arg2,type arg3) { if (arg1== null) throw new ArgumentNullException("arg1"); if (arg2== null) throw new ArgumentNullException("arg2"); if (arg3== null) throw new ArgumentNullException("arg3"); //Business Logic } Into something like this: [VerifyNullArgument("arg1","arg2","arg3")] public void Method(type arg1,type arg2,type arg3) { //Business Logic } Ideas? thanks guys.

    Read the article

  • Good working habits to observe in project development?

    - by Will Marcouiller
    As my development experience grows, I see fit to stick to best practices from here and there to build somehow my own working practices while observing the conventions, etc. I'm currently working on a project which my goals is to graduate the security access model from an environment's Active Directory to another environment's automatically. I don't know for any of you, but as far as I'm concerned, I meet some real difficulties sticking to only one way, then develop. I mean, I learn something new everyday while visiting SO, and recently wanted to get acquainted with generics. On the other hand, I better know the Façade pattern which proved to be very practical in transactional programming in process systems. This seems to be less practical for desktop application as there are plenty of variables to consider in a desktop application that you don't have to care in transactional programming, as you're playing only with information data. As for my current project, I have: Groups; Organizational Units; Users. Which are all considered an entry in the Active Directory. This points out to be a good candidate for generics, as also approached this way by Bart de Smett's Linq to AD on CodePlex. He has a DirectorySource<T>, and to manage let's say groups, then he instantiate a source with the proper type: var groups = new DirectorySource<Group>(); This seems to be very a good way of doing. Despite, I seem to go from one pattern to another and I don't seem to be able to strictly stick to one. While I'm aware that one must not stay with only one way of doing, since each pattern statisfies certain advantages, while also illustrating disadvantages under some usage conditions, I seem to want to develop with both patterns having a singleton Façade class with the underlying factories which represent the sub systems: GroupsFactory; UsersFactory; OrganizationalUnitsFactory. Each of the factories offers the possible operations for their respective entity (group, user, OU). To make a very long story short, I often have plenty of ideas while developping and this causes me some trouble, as I go from an idea to another feeling completely lost after a while. Yet I understand the advantages and disavantages, I have no trouble choosing from one pattern to another depending on the situation. Nevertheless, when it comes to programming itself, if I'm not part of a team, I feel sometimes like I can't do anything good. That is, because I can't stand not doing something "perfect" the first time. The role I play within the project is both: the project manager and the programmer. I am more comfortable in the project manager role, architectural role, analytical role than the developer's. Has any of you some good habbits to observe in project development? Thanks to you all! =)

    Read the article

  • Lisp, OCaml or what for Runge Kutta?

    - by Eelvex
    Which language would you propose for solving a system with: first order differential equations complex variables N-dimensions using 4th order Runge Kutta or the like. Speed matters a lot but would sacrifice for: Elegant (clean and short) code Flexibility + scalability I'm mostly between a Lisp and OCaml but any other suggestion is welcomed. Thanks!

    Read the article

  • Ruby module_function, invoking module's private method, invoked in class method style on module shows error

    - by Jignesh
    test_module.rb module MyModule def module_func_a puts "module_func_a invoked" private_b end module_function :module_func_a private def private_b puts "private_b invoked" end end class MyClass include MyModule def test_module module_func_a end end Invoking module function from class c = MyClass.new c.test_module Output 1: $ ruby test_module.rb module_func_a invoked private_b invoked Invoking module function on module in class method style ma = MyModule.module_func_a Output 2: module_func_a invoked test_module.rb:5:in `module_func_a': undefined local variable or method `private_b' for MyModule:Module (NameError) from test_module.rb:31 As can be seen from the Output 1 and Output 2 when including the module in a class, no issue occurs when a module's private method gets invoked from a module function while in case when directly invoking the module function on the module in class method style the module's private method, invoked from module function, is not found. Can anybody make me understand the reason behind above behavior and whether invoking module function (which in turn invokes module's private method) on module in class method style is possible or not? If possible, then what rectifications are required in my code to do the same? Thanks, Jignesh

    Read the article

  • Rails NoMethodError in loop when method exists

    - by Kevin Whitaker
    Good day all. I'm running into a bit of a problem getting a script running on my production environment, even though it works just fine on my dev box. I've verified that all the requisite gems and such are the same version. I should mention that the script is intended to be run with the script/runner command. Here is a super-condensed version of what I'm trying to do, centered around the part that's broken: def currentDeal marketTime = self.convertToTimeZone(Time.new) deal = Deal.find(:first, :conditions = ["start_time ? AND market_id = ? AND published = ?", marketTime, marketTime, self.id, 1]) return deal end markets = Market.find(all) markets.each do |market| deal = market.currentDeal puts deal.subject end Now convertToTimeZone is a method attached to the model. So, this code works just fine on my dev machine, as stated. However, attempting to run it on my production machine results in: undefined method `subject' for nil:NilClass (NoMethodError) If, however, I go into the console on the production box and do this: def currentDeal marketTime = self.convertToTimeZone(Time.new) deal = Deal.find(:first, :conditions = ["start_time ? AND market_id = ? AND published = ?", marketTime, marketTime, self.id, 1]) return deal end market = Market.find(1) deal = market.currentDeal puts deal.subject It returns the correct value, no problem. So what is going on? This is on rails v 2.3.5, on both machines. Thanks for any help

    Read the article

  • Fatal error: Function name must be a string in.. PHP error

    - by Jonesy
    Hi I have a class called User and a method called insertUser(). function insertUser($first_name, $last_name, $user_name, $password, $email_address, $group_house_id) { $first_name = mysql_real_escape_string($first_name); $last_name = mysql_real_escape_string($last_name); $user_name = mysql_real_escape_string($user_name); $password = mysql_real_escape_string($password); $email_address = mysql_real_escape_string($email_address); $query = "INSERT INTO Users (FirstName,LastName,UserName,Password,EmailAddress, GroupHouseID) VALUES ('$first_name','$last_name','$user_name','$password','$email_address','$group_house_id')"; $mysql_query($query); } And I call it like this: $newUser = new User(); $newUser->insertUser($first_name, $last_name, $user_name, $email, $password, $group_house_id); When I run the code I get this error: Fatal error: Function name must be a string in /Library/WebServer/Documents/ORIOnline/includes/class_lib.php on line 33 Anyone know what I am doing wronly? Also, this is my first attempt at OO PHP. Cheers, Jonesy

    Read the article

  • Does Java support default parameter values?

    - by gnavi
    I came across some Java code that had the following structure: public MyParameterizedFunction(String param1, int param2) { this(param1, param2, false); } public MyParameterizedFunction(String param1, int param2, boolean param3) { //use all three parameters here } I know that in C++ I can assign a parameter a default value. For example: void MyParameterizedFunction(String param1, int param2, bool param3=false); Does Java support this kind of syntax? Are there any reasons why this two step syntax is preferable?

    Read the article

  • In an extension method how do a create an object based on the implementation class

    - by Greg
    Hi, In an extension method how do a create an object based on the implementation class. So in the code below I wanted to add an "AddRelationship" extension method, however I'm not sure how within the extension method I can create an Relationship object? i.e. don't want to tie the extension method to this particular implementation of relationship public static class TopologyExtns { public static void AddNode<T>(this ITopology<T> topIf, INode<T> node) { topIf.Nodes.Add(node.Key, node); } public static INode<T> FindNode<T>(this ITopology<T> topIf, T searchKey) { return topIf.Nodes[searchKey]; } public static bool AddRelationship<T>(this ITopology<T> topIf, INode<T> parentNode, INode<T> childNode) { var rel = new RelationshipImp(); // ** How do I create an object from teh implementation // Add nodes to Relationship // Add relationships to Nodes } } public interface ITopology<T> { //List<INode> Nodes { get; set; } Dictionary<T, INode<T> > Nodes { get; set; } } public interface INode<T> { // Properties List<IRelationship<T>> Relationships { get; set; } T Key { get; } } public interface IRelationship<T> { // Parameters INode<T> Parent { get; set; } INode<T> Child { get; set; } } namespace TopologyLibrary_Client { class RelationshipsImp : IRelationship<string> { public INode<string> Parent { get; set; } public INode<string> Child { get; set; } } } public class TopologyImp<T> : ITopology<T> { public Dictionary<T, INode<T>> Nodes { get; set; } public TopologyImp() { Nodes = new Dictionary<T, INode<T>>(); } } thanks

    Read the article

  • private class calling a method from its outer class

    - by oxinabox.ucc.asn.au
    Ok, so I have a class for a "Advanced Data Structure" (in this case a kinda tree) SO I implimented a Iterator as a private class with in it. So the iterator needs to implement a remove function to remove the last retuirned element. now my ADT already impliments a remove function, and in this case there is very little (thinking about it, i think nothing) to be gain by implimenting a different remove function for the iterator. so how do I go about calling the remove from my ADT sketch of my struture: public class ADT { ... private class ADT_Iterator impliments java.util.Itorator{ ... public void remove(){ //where I want to call the ADT's remove function from } ... public void remove( Object paramFoo ) { ... } ... } So just calling remove(FooInstance) won't work (will it?) and this.remove(FooInstance) is the same thing. what do i call? (and changign the name of the ADT's remove function is not an option, as that AD T has to meet an Interace wich I am note at liberty to change) I could make both of them call a removeHelper functon, I guess...

    Read the article

  • Visual Studio Formatting -- Change Method Color

    - by Daniel
    The default appearance of a method for example, ".ToString()" is by default the color black. I want to make it a different color to stand out but I do not see any options that reference this option specifically. I remember one of former collegues showing me his VS IDE years ago and he had it setup this way but I cannot recall what he did. Does anyone have any ideas on how to do this?

    Read the article

  • Runge-Kutta Method with adaptive step

    - by infoholic_anonymous
    I am implementing Runge-Kutta method with adaptive step in matlab. I get different results as compared to matlab's own ode45 and my own implementation of Runge-Kutta method with fixed step. What am I doing wrong in my code? Is it possible? function [ result ] = rk4_modh( f, int, init, h, h_min ) % % f - function handle % int - interval - pair (x_min, x_max) % init - initial conditions - pair (y1(0),y2(0)) % h_min - lower limit for h (step length) % h - initial step length % x - independent variable ( for example time ) % y - dependent variable - vertical vector - in our case ( y1, y2 ) function [ k1, k2, k3, k4, ka, y ] = iteration( f, h, x, y ) % core functionality performed within loop k1 = h * f(x,y); k2 = h * f(x+h/2, y+k1/2); k3 = h * f(x+h/2, y+k2/2); k4 = h * f(x+h, y+k3); ka = (k1 + 2*k2 + 2*k3 + k4)/6; y = y + ka; end % constants % relative error eW = 1e-10; % absolute error eB = 1e-10; s = 0.9; b = 5; % initialization i = 1; x = int(1); y = init; while true hy = y; hx = x; %algorithm [ k1, k2, k3, k4, ka, y ] = iteration( f, h, x, y ); % error estimation for j=1:2 [ hk1, hk2, hk3, hk4, hka, hy ] = iteration( f, h/2, hx, hy ); hx = hx + h/2; end err(:,i) = abs(hy - y); % step adjustment e = abs( hy ) * eW + eB; a = min( e ./ err(:,i) )^(0.2); mul = a * s; if mul >= 1 % step length admitted keepH(i) = h; k(:,:,i) = [ k1, k2, k3, k4, ka ]; previous(i,:) = [ x+h, y' ]; %' i = i + 1; if floor( x + h + eB ) == int(2) break; else h = min( [mul*h, b*h, int(2)-x] ); x = x + keepH(i-1); end else % step length requires further adjustments h = mul * h; if ( h < h_min ) error('Computation with given precision impossible'); end end end result = struct( 'val', previous, 'k', k, 'err', err, 'h', keepH ); end The function in question is: function [ res ] = fun( x, y ) % res(1) = y(2) + y(1) * ( 0.9 - y(1)^2 - y(2)^2 ); res(2) = -y(1) + y(2) * ( 0.9 - y(1)^2 - y(2)^2 ); res = res'; %' end The call is: res = rk4( @fun, [0,20], [0.001; 0.001], 0.008 ); The resulting plot for x1 : The result of ode45( @fun, [0, 20], [0.001, 0.001] ) is:

    Read the article

  • Getting the name of a child class in the parent class (static context)

    - by Benoit Myard
    Hi everybody, I'm building an ORM library with reuse and simplicity in mind; everything goes fine except that I got stuck by a stupid inheritance limitation. Please consider the code below: class BaseModel { /* * Return an instance of a Model from the database. */ static public function get (/* varargs */) { // 1. Notice we want an instance of User $class = get_class(parent); // value: bool(false) $class = get_class(self); // value: bool(false) $class = get_class(); // value: string(9) "BaseModel" $class = __CLASS__; // value: string(9) "BaseModel" // 2. Query the database with id $row = get_row_from_db_as_array(func_get_args()); // 3. Return the filled instance $obj = new $class(); $obj->data = $row; return $obj; } } class User extends BaseModel { protected $table = 'users'; protected $fields = array('id', 'name'); protected $primary_keys = array('id'); } class Section extends BaseModel { // [...] } $my_user = User::get(3); $my_user->name = 'Jean'; $other_user = User::get(24); $other_user->name = 'Paul'; $my_user->save(); $other_user->save(); $my_section = Section::get('apropos'); $my_section->delete(); Obviously, this is not the behavior I was expecting (although the actual behavior also makes sense).. So my question is if you guys know of a mean to get, in the parent class, the name of child class.

    Read the article

  • C# extension method doesn't seem to exist

    - by blahblah
    I can't seem to get the following extension method to be found in another class in the same namespace (MyProject.Util). using System.Collections.Specialized; namespace MyProject.Util { public static class Extensions { public static string Get( this NameValueCollection me, string key, string def ) { return me[key] ?? def; } } } As you can see it's basically another version of foo[bar] ?? baz, but I still don't understand why VS2008 fails to compile telling me that no version of Get takes two arguments. Any ideas?

    Read the article

  • Matlab code help. Backward Euler method.

    - by m0s
    Here is the matlab/freemat code I got to solve ODE numerically using backward Euler method. However the results are inconsistent with my textbook results, and sometimes even ridiculously inconsistent. Please point out what is wrong with the code. I have already asked this question on mathoverflow.com no help there, hope someone here can help. function [x,y]=backEuler(f,xinit,yinit,xfinal,h) %f - this is your y prime %xinit - initial X %yinit - initial Y %xfinal - final X %h - step size n=(xfinal-xinit)/h; %Calculate steps %Inititialize arrays... %1st elements take xinit and yinit corespondigly, the rest fill with 0s x=[xinit zeros(1,n)]; y=[yinit zeros(1,n)]; %Numeric routine for i=1:n x(i+1)=x(i)+h; ynew=y(i)+h*(f(x(i),y(i))); y(i+1)=y(i)+h*f(x(i+1),ynew); end end

    Read the article

  • matlab fit exp2

    - by HelloWorld
    I'm unsuccessfully looking for documentation of fit function using exp2 (sum of 2 exponents). How to operate the function is clear: [curve, gof] = fit(x, y,'exp2'); But since there are multiple ways to fit a sum of exponents I'm trying to find out what algorithm is used. Particularly what happens when I'm fitting one exponent (the raw data) with a bit of noise, how the exponents are spread. I've simulated several cases, and it seems that it "drops" all the weight on the second set of coefficients, but row data analysis often shows different behavior. Does anyone have suggestions of documentation?

    Read the article

  • iPhone: should initWithNibName:bundle: method be deleted from UIViewController class if not used?

    - by Scott Pendleton
    I notice that this method is provided in UIViewController .m files, but is commented out: - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil I had been leaving that method commented out, or even deleting it. But then I looked at this line inside the method: if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) I assume that if it were truly important for self to be set equal to super, then Apple would not have the method be commented out by default. On the other hand, if I do need to do some customization in that method, why do I need to set self = super? What's the best practice, and why?

    Read the article

  • Kohana Database Library - How to Execute a Query with the Same Parameters More Than Once?

    - by Noah Goodrich
    With the following bit of code: $builder = ORM::factory('branch')->where('institution_id', $this->institution->id)->orderby('name'); I need to first execute: $count = $builder->count_all(); Then I need to execute: $rs = $builder->find_all($limit, $offset); However, it appears that when I execute the first query the stored query parameters are cleared so that a fresh query can be executed. Is there a way to avoid having the parameters cleared or at least copy them easily without having to reach directly into the Database driver object that stores the query parameters and copy them out? We are using Kohana 2.3.4 and upgrading is not an option.

    Read the article

  • What's an easy way to set up object communication in Obj-C?

    - by seaworthy
    I am trying to send a slider value from a controller object to a method of a model object. The later is implemented in the separate file and I have appropriate headers. I think the problem is that I am not sure how to instantiate the receiver in order to produce a working method for the controller. Here is the controller's method. -(IBAction)setValue:(id)slider {[Model setValue:[slider floatValue]];} @implementation Model -(void)setValue:(float)n{ printf("%f",n); } @end What I get is 'Model' may not respond to '+setValue' warning and no output in my console. Any insight is appreciated.

    Read the article

  • ControlCollection extension method optimazation

    - by Johan Leino
    Hi, got question regarding an extension method that I have written that looks like this: public static IEnumerable<T> FindControlsOfType<T>(this ControlCollection instance) where T : class { T control; foreach (Control ctrl in instance) { if ((control = ctrl as T) != null) { yield return control; } foreach (T child in FindControlsOfType<T>(ctrl.Controls)) { yield return child; } } } public static IEnumerable<T> FindControlsOfType<T>(this ControlCollection instance, Func<T, bool> match) where T : class { return FindControlsOfType<T>(instance).Where(match); } The idea here is to find all controls that match a specifc criteria (hence the Func<..) in the controls collection. My question is: Does the second method (that has the Func) first call the first method to find all the controls of type T and then performs the where condition or does the "runtime" optimize the call to perform the where condition on the "whole" enumeration (if you get what I mean). secondly, are there any other optimizations that I can do to the code to perform better. An example can look like this: var checkbox = this.Controls.FindControlsOfType<MyCustomCheckBox>( ctrl => ctrl.CustomProperty == "Test" ) .FirstOrDefault();

    Read the article

  • Predicate<INT> match question

    - by Petr
    Hi, I do not understand how following code works. Specifically, I do not understand using of "return i<3". I would expect return i IF its < than 3. I always though that return just returns value. I could not even find what syntax is it. Second question, it seems to me like using anonymous method (delegate(int i)) but could be possible to write it with normal delegate pointing to method elsewere? Thanks List<int> listOfInts = new List<int> { 1, 2, 3, 4, 5 }; List<int> result = listOfInts.FindAll(delegate(int i) { return i < 3; });

    Read the article

  • What's keeping this timer in scope? The anonymous method?

    - by Andy
    Ok, So I have a method which fires when someone clicks on our Icon in a silverlight application, seen below: private void Logo_MouseLeftButtonUp(object sender, MouseButtonEventArgs e) { e.Handled = true; ShowInfo(true); DispatcherTimer autoCloseTimer = new DispatcherTimer(); autoCloseTimer.Interval = new TimeSpan(0, 0, 10); autoCloseTimer.Tick +=new EventHandler((timerSender,args) => { autoCloseTimer.Stop(); ShowInfo(false); }); autoCloseTimer.Start(); } Whats meant to happen is that the method ShowInfo() opens up a box with the company info in and the dispatch timer auto closes it after said timespan. And this all works... But what I'm not sure about is because the dispatch timer is a local var, after the Logo_MouseLeftButtonUp method finishes, what is there to keep the dispatch timer referenced and not availible for GC collection before the anonymous method is fired? Is it the reference to the ShowInfo() method in the anonymous method? Just feels like some thing I should understand deeper as I can imagine with using events etc it can be very easy to create a leak with something like this. Hope this all makes sense! Andy.

    Read the article

  • SVD factorization

    - by Simon
    How can i use the bidiagonal and diagonal form to compute the SVD factorization. I think my real problem is that i don't understand this concepts.

    Read the article

< Previous Page | 44 45 46 47 48 49 50 51 52 53 54 55  | Next Page >