Search Results

Search found 53261 results on 2131 pages for 'system state'.

Page 805/2131 | < Previous Page | 801 802 803 804 805 806 807 808 809 810 811 812  | Next Page >

  • What's your experience with Flash drives?

    - by Jon Ericson
    EMC is marketing Solid State Flash Drives and my project is thinking about moving that direction in the future. Does anyone have any experience with replacing traditional disk storage with flash drives? Besides price, have you experienced any downsides to the technology?

    Read the article

  • Please help get this msdn function working to create an auto complete method

    - by Phil
    Here is a method from msdn to provide data to an autocomplete extender / textbox: <System.Web.Services.WebMethodAttribute(), System.Web.Script.Services.ScriptMethodAttribute()> _ Public Shared Function GetCompletionList(ByVal prefixText As String, ByVal count As Integer, ByVal contextKey As String) As String() ' Create array of movies Dim movies() As String = {"Star Wars", "Star Trek", "Superman", "Memento", "Shrek", "Shrek II"} ' Return matching movies Return From m In movies(6) Where _ (m.StartsWith(prefixText, StringComparison.CurrentCultureIgnoreCase)) Select m).Take(count).ToArray() End Function The errors are: m.StartsWith - ('Startswith' is not a member of 'Char') Select m - ('Select Case' must end with a matching end select) .Take(count).ToArray() - (End of statement expected) Can you please let me know how to get this function working? Thanks

    Read the article

  • The Reason of Service Termination

    - by Mariusz
    I use a service application I created in Delphi. My problem is that it is sometimes terminated by the operating system and I don't know why this happens. When I go the the system events, I can find a piece of information like this one: Event ID: 7034, The [...] service terminated unexpectedly. It has done this [...] time(s). I know you can't give me an answer why this happens, but could you please give me a clue what to pay attention to to find the reason of that behaviour? For instance what kind of exceptions could make the OS close an application. Thank you in advance.

    Read the article

  • Can parser combination be made efficient?

    - by Jon Harrop
    Around 6 years ago, I benchmarked my own parser combinators in OCaml and found that they were ~5× slower than the parser generators on offer at the time. I recently revisited this subject and benchmarked Haskell's Parsec vs a simple hand-rolled precedence climbing parser written in F# and was surprised to find the F# to be 25× faster than the Haskell. Here's the Haskell code I used to read a large mathematical expression from file, parse and evaluate it: import Control.Applicative import Text.Parsec hiding ((<|>)) expr = chainl1 term ((+) <$ char '+' <|> (-) <$ char '-') term = chainl1 fact ((*) <$ char '*' <|> div <$ char '/') fact = read <$> many1 digit <|> char '(' *> expr <* char ')' eval :: String -> Int eval = either (error . show) id . parse expr "" . filter (/= ' ') main :: IO () main = do file <- readFile "expr" putStr $ show $ eval file putStr "\n" and here's my self-contained precedence climbing parser in F#: let rec (|Expr|) (P(f, xs)) = Expr(loop (' ', f, xs)) and shift oop f op (P(g, xs)) = let h, xs = loop (op, g, xs) loop (oop, f h, xs) and loop = function | ' ' as oop, f, ('+' | '-' as op)::P(g, xs) | (' ' | '+' | '-' as oop), f, ('*' | '/' as op)::P(g, xs) | oop, f, ('^' as op)::P(g, xs) -> let h, xs = loop (op, g, xs) let op = match op with | '+' -> (+) | '-' -> (-) | '*' -> (*) | '/' -> (/) | '^' -> pown loop (oop, op f h, xs) | _, f, xs -> f, xs and (|P|) = function | '-'::P(f, xs) -> let f, xs = loop ('~', f, xs) P(-f, xs) | '('::Expr(f, ')'::xs) -> P(f, xs) | c::xs when '0' <= c && c <= '9' -> P(int(string c), xs) My impression is that even state-of-the-art parser combinators waste a lot of time back tracking. Is that correct? If so, is it possible to write parser combinators that generate state machines to obtain competitive performance or is it necessary to use code generation?

    Read the article

  • sql server modify error

    - by Jaspal
    hi, i m not able to modify table in SQL server. i m new to databases. use work go alter table employee modify id varchar(20) error message is- Msg 102, Level 15, State 1, Line 1 Incorrect syntax near 'modify' here is an screenshot thanks

    Read the article

  • How do I rewrite a plist if its data types are immutable?

    - by dugla
    I am getting comfortable with using plists for initializing my app. I now want to save app state back to the plist used to initialize the app and I find myself stuck. At application startup I ingest the plist into an NSDictionary which is immutable. I now want to update the NSDictionary by replacing old values with new values for existing keys and write to the plist via [NSDictionary writeToFile:atomically]. How do I get around the immutability of NSDictionary? Thanks, Doug

    Read the article

  • Get Cell RSSI(Network Signal Strength) on Android 1.5

    - by Brandon
    Is there any way to retrieve the current cellular Signal Strength (RSSI) on Android 1.5? I know there's a way to listen for signal strength updates through the TelephonyManager, but this seems to only give a "state," not a numeric value. Is using the RSSI field on a neighboring cell fairly accurate? I'm guessing not, but I'm running out of ideas.

    Read the article

  • Intercepting touch events on activity and button on Android

    - by hgpc
    I have an Android activity with an ImageButton. I would like to execute some logic when the button is clicked and show a different image for the pressed state, but also receive the touch event on the activity. By default only the button receives the touch event. If I set the clickable attribute of the button to false then only the activity receives the touch event. What's the best way to receive the touch event in both the activity and the button?

    Read the article

  • PHP: How to process SOAP response to get a tag value?

    - by understack
    I've a SOAP response in a var $soap_response like this: <SOAP-ENV:Envelope SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/" xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:clr="http://schemas.microsoft.com/soap/encoding/clr/1.0"> <SOAP-ENV:Header> <h3:__MethodSignature xsi:type="SOAP-ENC:methodSignature" SOAP-ENC:root="1" xmlns:h3="http://schemas.microsoft.com/clr/soap/messageProperties" xmlns:a2="http://schemas.microsoft.com/clr/ns/System.Collections">xsd:string a2:Hashtable</h3:__MethodSignature> </SOAP-ENV:Header> <SOAP-ENV:Body> <i4:ReturnDataSetResponse id="ref-1" xmlns:i4="http://schemas.microsoft.com/clr/nsassem/TOIServerAppl.clsRSchedule/TOIServerAppl"> <return href="#ref-6"/> </i4:ReturnDataSetResponse> <a3:DataSet id="ref-6" xmlns:a3="http://schemas.microsoft.com/clr/nsassem/System.Data/System.Data%2C%20Version%3D1.0.5000.0%2C%20Culture%3Dneutral%2C%20PublicKeyToken%3Db77a5c561934e089"> <XmlSchema id="ref-7"><![CDATA[<?xml version="1.0" encoding="utf-16"?> <xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata"> <xs:element name="NewDataSet" msdata:IsDataSet="true"> <xs:complexType> <xs:choice maxOccurs="unbounded"> <xs:element name="Table"> <xs:complexType> <xs:sequence> <xs:element name="id" type="xs:long" msdata:targetNamespace="" minOccurs="0" /> </xs:sequence> </xs:complexType> </xs:element> </xs:choice> </xs:complexType> </xs:element> </xs:schema>]]> </XmlSchema> <XmlDiffGram id="ref-8"> <id>4437031</id> </XmlDiffGram> </a3:DataSet> </SOAP-ENV:Body> </SOAP-ENV:Envelope> How can I extract id value from <id>4437031</id>? simplexml_load_string($soap_response); returns empty object array. I've seen someplaces that I might have to replace all those namespaces to make it work?

    Read the article

  • c++ class member functions selected by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched stackoverflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instatiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state info was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice?

    Read the article

  • more details in Jboss console ?

    - by worldpython
    Dear all, I am new to JBOSS 4.2. when I start the server on CentOS 5.4(final). it give me simple log in its console. How I can show deployment errors, messages that wars print in Jboss log ? Thanks in advance 15:46:24,207 INFO [Server] Server Log Dir: /home/mebada/jad/jboss-4.2.3.GA/server /nops01/log 15:46:24,207 INFO [Server] Server Temp Dir: /home/mebada/jad/jboss-4.2.3.GA/server /nops01/tmp 15:46:24,208 INFO [Server] Root Deployment Filename: jboss-service.xml 15:46:25,849 INFO [ServerInfo] Java version: 1.6.0,Sun Microsystems Inc. 15:46:25,849 INFO [ServerInfo] Java VM: OpenJDK Client VM 1.6.0-b09,Sun Microsystems Inc. 15:46:25,849 INFO [ServerInfo] OS-System: Linux 2.6.18-164.el5,i386 15:46:26,674 INFO [Server] Core system initialized 15:46:41,567 INFO [WebService] Using RMI server codebase: http://127.0.0.1:8083/ 15:46:41,569 INFO [Log4jService$URLWatchTimerTask] Configuring from URL: resource:jboss-log4j.xml

    Read the article

  • How do I get the XAML compiler to use textual content property on custom classes?

    - by Duncan
    Given a simple C# class definition like: [System.Windows.Markup.ContentProperty("PropertyOne")] public class SimpleBase { public string PropertyOne { get; set; } public string PropertyTwo { get; set; } } why is it not possible to omit the sys:string tags around the word Test in the xaml below. <custom:SimpleBase x:Class="TestType" xmlns:custom="clr-namespace:ConsoleApplication1;assembly=" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:sys="clr-namespace:System;assembly=mscorlib"> <sys:String>Test</sys:String> </custom:SimpleBase> Somehow the compiler correctly converts text to string for the type String, why doesn't it work for my custom type? The context can be found on my blog: http://www.deconflations.com/?tag=xaml

    Read the article

  • Save object states in .data or attr - Performance vs CSS?

    - by Neysor
    In response to my answer yesterday about rotating an Image, Jamund told me to use .data() instead of .attr() First I thought that he is right, but then I thought about a bigger context... Is it always better to use .data() instead of .attr()? I looked in some other posts like what-is-better-data-or-attr or jquery-data-vs-attrdata The answers were not satisfactory for me... So I moved on and edited the example by adding CSS. I thought it might be useful to make a different Style on each image if it rotates. My style was the following: .rp[data-rotate="0"] { border:10px solid #FF0000; } .rp[data-rotate="90"] { border:10px solid #00FF00; } .rp[data-rotate="180"] { border:10px solid #0000FF; } .rp[data-rotate="270"] { border:10px solid #00FF00; } Because design and coding are often separated, it could be a nice feature to handle this in CSS instead of adding this functionality into JavaScript. Also in my case the data-rotate is like a special state which the image currently has. So in my opinion it make sense to represent it within the DOM. I also thought this could be a case where it is much better to save with .attr() then with .data(). Never mentioned before in one of the posts I read. But then i thought about performance. Which function is faster? I built my own test following: <!DOCTYPE HTML> <html> <head> <title>test</title> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script> <script type="text/javascript"> function runfirst(dobj,dname){ console.log("runfirst "+dname); console.time(dname+"-attr"); for(i=0;i<10000;i++){ dobj.attr("data-test","a"+i); } console.timeEnd(dname+"-attr"); console.time(dname+"-data"); for(i=0;i<10000;i++){ dobj.data("data-test","a"+i); } console.timeEnd(dname+"-data"); } function runlast(dobj,dname){ console.log("runlast "+dname); console.time(dname+"-data"); for(i=0;i<10000;i++){ dobj.data("data-test","a"+i); } console.timeEnd(dname+"-data"); console.time(dname+"-attr"); for(i=0;i<10000;i++){ dobj.attr("data-test","a"+i); } console.timeEnd(dname+"-attr"); } $().ready(function() { runfirst($("#rp4"),"#rp4"); runfirst($("#rp3"),"#rp3"); runlast($("#rp2"),"#rp2"); runlast($("#rp1"),"#rp1"); }); </script> </head> <body> <div id="rp1">Testdiv 1</div> <div id="rp2" data-test="1">Testdiv 2</div> <div id="rp3">Testdiv 3</div> <div id="rp4" data-test="1">Testdiv 4</div> </body> </html> It should also show if there is a difference with a predefined data-test or not. One result was this: runfirst #rp4 #rp4-attr: 515ms #rp4-data: 268ms runfirst #rp3 #rp3-attr: 505ms #rp3-data: 264ms runlast #rp2 #rp2-data: 260ms #rp2-attr: 521ms runlast #rp1 #rp1-data: 284ms #rp1-attr: 525ms So the .attr() function did always need more time than the .data() function. This is an argument for .data() I thought. Because performance is always an argument! Then I wanted to post my results here with some questions, and in the act of writing I compared with the questions Stack Overflow showed me (similar titles) And true enough, there was one interesting post about performance I read it and run their example. And now I am confused! This test showed that .data() is slower then .attr() !?!! Why is that so? First I thought it is because of a different jQuery library so I edited it and saved the new one. But the result wasn't changing... So now my questions to you: Why are there some differences in the performance in these two examples? Would you prefer to use data- HTML5 attributes instead of data, if it represents a state? Although it wouldn't be needed at the time of coding? Why - Why not? Now depending on the performance: Would performance be an argument for you using .attr() instead of data, if it shows that .attr() is better? Although data is meant to be used for .data()? UPDATE 1: I did see that without overhead .data() is much faster. Misinterpreted the data :) But I'm more interested in my second question. :) Would you prefer to use data- HTML5 attributes instead of data, if it represents a state? Although it wouldn't be needed at the time of coding? Why - Why not? Are there some other reasons you can think of, to use .attr() and not .data()? e.g. interoperability? because .data() is jquery style and HTML Attributes can be read by all... UPDATE 2: As we see from T.J Crowder's speed test in his answer attr is much faster then data! which is again confusing me :) But please! Performance is an argument, but not the highest! So give answers to my other questions please too!

    Read the article

  • What is the HEAD in git?

    - by e-satis
    There seems to be a difference between the last commit, the HEAD and the state of the file I can see in my directory. What is HEAD, what can I do with it and what mistake should I avoid?

    Read the article

  • Snow Leopard - PHP 5.3.1 installed... but no PEAR?

    - by Jon Busby
    I've been trying to do some PHP work on my snow leopard machine.. but I've found issues when I need to use PEAR packages (as symfony handles its php plugins with PEAR). I've found some references that state that snow leopard includes PEAR.. but how come I cant find it?! Could someone confirm this.. if if so, where is my pear?

    Read the article

  • Best similarity metric for collaborative filtering?

    - by allclaws
    I'm trying to decide on the best similarity metric for a product recommendation system using item-based collaborative filtering. This is a shopping basket scenario where ratings are binary valued - the user has either purchased an item or not - there is no explicit rating system (eg, 5-stars). Step 1 is to compute item-to-item similarity, though I want to look at incorporating more features later on. Is the Tanimoto coefficient the best way to go for binary values? Or are there other metrics that are appropriate here? Thanks.

    Read the article

  • Learning resources for Linux filesystem, command line, and structure

    - by webworm
    Can anyone suggest some good materials for learning more about the Linux filesystem and command line? I have found myself frequently confused as to what programs go where on the Linux filesystem. I would like to learn how the various directories (var, etc, usr ...) are used and how to use the commandline more effectively. I come from the Windows development world (.NET developer) so I am very familiar with Windows system administration. However, when doing more and more work with PHP I found myself lost in the internals of Linux (specifically Ubuntu). For example I was having problems installing PEAR properly on my Ubuntu system and not understanding why it was installed where it was. All of my interactions with Linux machines is done via SSH so I would like to focus on the command line and the filesystem. Thanks for any suggestions.

    Read the article

  • MVVM Binding Orthogonal Aspects in Views e.g. Application Settings

    - by chibacity
    I have an application which I am developing using WPF\Prism\MVVM. All is going well and I have some pleasing MVVM implementations. However, in some of my views I would like to be able to bind application settings e.g. when a user reloads an application, the checkbox for auto-scrolling a grid should be checked in the state it was last time the user used the application. My view needs to bind to something that holds the "auto-scroll" setting state. I could put this on the view-model, but applications settings are orthogonal to the purpose of the view-model. The "auto-scroll" setting is controlling an aspect of the view. This setting is just an example. There will be quite a number of them and splattering my view-models with properties to represent application settings (so I can bind them) feels decidedly yucky. One view-model per view seems to be de rigeuer... What is best\usual practice here? Splatter my view-models with application settings? Have multiple view-models per view so settings can be represented in their own right? Split views so that controls can bind to an ApplicationSettingsViewModel? = too many views? Something else? Edit 1 To add a little more context, I am developing a UI with a tabbed interface. Each tab will host a single widget and there a variety of widgets. Each widget is a Prism composition of individual views. Some views are common amongst widgets e.g. a file picker view. Whilst each widget is composed of several views, as a whole, conceptually a widget has a single set of user settings e.g. last file selected, auto-scroll enabled, etc. These need to be persisted and retrieved\applied when the application starts again, and the widget views are created. My question is focused on the fact that conceptually a widget has a single set of user settings which is at right-angles to the fact that a widget consists of many views. Each view in the widget has it's own view-model (which works nicely and logically) but if I stick to a one view-model per view, I would have to splatter each view-model with user settings appropriate to it. This doesn't sound right ?!?

    Read the article

  • Codeigniter Routes for filename with extension

    - by thehuby
    I am using codeigniter and its routes system successfully with some lovely regexp, however I have come unstuck on what should be an easy peasy thing in the system. I want to include a bunch of search engine related files (for Google webmaster etc.) plus the robots.txt file, all in a controller. So, I have create the controller and updated the routes file and don't seem to be able to get it working with these files. Here's a snip from my routes file: $route['robots\.txt|LiveSearchSiteAuth\.xml'] = 'search_controller/files'; Within the function I use the URI helper to figure out which content to show. Now I can't get this to match, which points to my regexp being wrong. I'm sure this is a really obvious one but its late and my caffeine tank is empty :)

    Read the article

  • What are people's opinions vis-a-vis my choice of authorization plugins?

    - by brad
    I'm slowly but surely putting together my first rails app (first web-app of any kind in fact - I'm not really a programmer) and it's time to set up a user registration/login system. The nature of my app is such that each user will be completely separated from each other user (except for admin roles). When users log in they will have their own unique index page looking at only their data which they and no-one else can ever see or edit. However, I may later want to add a role for a user to be able to view and edit several other user's data (e.g. a group of users may want to allow their secretary to access and edit their data but their secretary would not need any data of their own). My plan is to use authlogic to create the login system and declarative authorization to control permissions but before I embark on this fairly major and crucial task I thought I would canvas a few opinions as to whether this combo was appropriate for the tasks I envisage or whether there would be a better/simpler/faster/cheaper/awesomer option.

    Read the article

  • Is it possible to overwrite a static method in parent class?

    - by MartinDenny2069
    I have a static method defined in a base class, I want to overwrite this method in its child class, is it possible? I tried this but it did not work as I expected. When I created an instance of class B and invoke its callMe() method, the static foo() method in class A is invoked. public abstract class A { public static void foo() { System.out.println("I am base class"); } public void callMe() { foo(); } } Public class B { public static void foo() { System.out.println("I am child class"); } }

    Read the article

  • How do I use accepts_nested_attributes_for? I cannot use the .build method (!)

    - by Angela
    Editing my question for conciseness and to update what I've done: How do I model having multiple Addresses for a Company and assign a single Address to a Contact, and be able to assign them when creating or editing a Contact? Here is my model for Contacts: class Contact < ActiveRecord::Base attr_accessible :first_name, :last_name, :title, :phone, :fax, :email, :company, :date_entered, :campaign_id, :company_name, :address_id, :address_attributes belongs_to :company belongs_to :address accepts_nested_attributes_for :address end Here is my model for Address: class Address < ActiveRecord::Base attr_accessible :street1, :street2, :city, :state, :zip has_many :contacts end I would like, when creating an new contact, access all the Addresses that belong to the other Contacts that belong to the Company. So here is how I represent Company: class Company < ActiveRecord::Base attr_accessible :name, :phone, :addresses has_many :contacts has_many :addresses, :through => :contacts end Here is how I am trying to create a field in the View for _form for Contact so that, when someone creates a new Contact, they pass the address to the Address model and associate that address to the Contact: <% f.fields_for :address, @contact.address do |builder| %> <p> <%= builder.label :street1, "Street 1" %> </br> <%= builder.text_field :street1 %> <p> <% end %> When I try to Edit, the field for Street 1 is blank. And I don't know how to display the value from show.html.erb. At the bottom is my error console -- can't seem to create values in the address table: My Contacts controller is as follows: def new @contact = Contact.new @contact.address.build # I GET AN ERROR HERE: says NIL CLASS @contact.date_entered = Date.today @campaigns = Campaign.find(:all, :order => "name") if params[:campaign_id].blank? else @campaign = Campaign.find(params[:campaign_id]) @contact.campaign_id = @campaign.id end if params[:company_id].blank? else @company = Company.find(params[:company_id]) @contact.company_name = @company.name end end def create @contact = Contact.new(params[:contact]) if @contact.save flash[:notice] = "Successfully created contact." redirect_to @contact else render :action => 'new' end end def edit @contact = Contact.find(params[:id]) @campaigns = Campaign.find(:all, :order => "name") end Here is a snippet of my error console: I am POSTING the attribute, but it is not CREATING in the Address table.... Processing ContactsController#create (for 127.0.0.1 at 2010-05-12 21:16:17) [POST] Parameters: {"commit"="Submit", "authenticity_token"="d8/gx0zy0Vgg6ghfcbAYL0YtGjYIUC2b1aG+dDKjuSs=", "contact"={"company_name"="Allyforce", "title"="", "campaign_id"="2", "address_attributes"={"street1"="abc"}, "fax"="", "phone"="", "last_name"="", "date_entered"="2010-05-12", "email"="", "first_name"="abc"}} Company Load (0.0ms)[0m [0mSELECT * FROM "companies" WHERE ("companies"."name" = 'Allyforce') LIMIT 1[0m Address Create (16.0ms)[0m [0;1mINSERT INTO "addresses" ("city", "zip", "created_at", "street1", "updated_at", "street2", "state") VALUES(NULL, NULL, '2010-05-13 04:16:18', NULL, '2010-05-13 04:16:18', NULL, NULL)[0m Contact Create (0.0ms)[0m [0mINSERT INTO "contacts" ("company", "created_at", "title", "updated_at", "campaign_id", "address_id", "last_name", "phone", "fax", "company_id", "date_entered", "first_name", "email") VALUES(NULL, '2010-05-13 04:16:18', '', '2010-05-13 04:16:18', 2, 2, '', '', '', 5, '2010-05-12', 'abc', '')[0m

    Read the article

  • Is there a general concrete implementation of a KeyedCollection?

    - by CodeSavvyGeek
    The System.Collections.ObjectModel.KeyedCollection class is a very useful alternative to System.Collections.Generic.Dictionary, especially when the key data is part of the object being stored or you want to be able to enumerate the items in order. Unfortunately, the class is abstract, and I am unable to find a general concrete implementation in the core .NET framework. The Framework Design Guidlines book indicates that a concrete implementation should be provided for abstract types (section 4.4 Abstract Class Design). Why would the framework designers leave out a general concrete implementation of such a useful class, especially when it could be provided by simply exposing a constructor that accepts and stores a Converter from the item to its key: public class ConcreteKeyedCollection : KeyedCollection { private Converter getKeyForItem = null; public GenericKeyedCollection(Converter getKeyForItem) { if (getKeyForItem == null) { throw new ArgumentNullException("getKeyForItem"); } this.getKeyForItem = getKeyForItem; } protected override TKey GetKeyForItem(TItem item) { return this.getKeyForItem(item); } }

    Read the article

< Previous Page | 801 802 803 804 805 806 807 808 809 810 811 812  | Next Page >