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  • What's the best way to communicate the purpose of a string parameter in a public API?

    - by Dave
    According to the guidance published in New Recommendations for Using Strings in Microsoft .NET 2.0, the data in a string may exhibit one of the following types of behavior: A non-linguistic identifier, where bytes match exactly. A non-linguistic identifier, where case is irrelevant, especially a piece of data stored in most Microsoft Windows system services. Culturally-agnostic data, which still is linguistically relevant. Data that requires local linguistic customs. Given that, I'd like to know the best way to communicate which behavior is expected of a string parameter in a public API. I wasn't able to find an answer in the Framework Design Guidelines. Consider the following methods: f(string this_is_a_linguistic_string) g(string this_is_a_symbolic_identifier_so_use_ordinal_compares) Is variable naming and XML documentation the best I can do? Could I use attributes in some way to mark the requirements of the string? Now consider the following case: h(Dictionary<string, object> dictionary) Note that the dictionary instance is created by the caller. How do I communicate that the callee expects the IEqualityComparer<string> object held by the dictionary to perform, for example, a case-insensitive ordinal comparison?

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  • When should I implement globalization and localization in C#?

    - by Geo Ego
    I am cleaning up some code in a C# app that I wrote and really trying to focus on best practices and coding style. As such, I am running my assembly through FXCop and trying to research each message it gives me to decide what should and shouldn't be changed. What I am currently focusing on are locale settings. For instance, the two errors that I have currently are that I should be specifying the IFormatProvider parameter for Convert.ToString(int), and setting the Dataset and Datatable locale. This is something that I've never done, and never put much thought into. I've always just left that overload out. The current app that I am working on is an internal app for a small company that will very likely never need to run in another country. As such, it is my opinion that I do not need to set these at all. On the other hand, doing so would not be such a big deal, but it seems like it is unneccessary and could hinder readability to a degree. I understand that Microsoft's contention is to use it if it's there, period. Well, I'm technically supposed to call Dispose() on every object that implements IDisposable, but I don't bother doing that with Datasets and Datatables, so I wonder what the practice is "in the wild."

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  • Hibernate NamingStrategy implementation that maintains state between calls

    - by Robert Petermeier
    Hi, I'm working on a project where we use Hibernate and JBoss 5.1. We need our entity classes to be mapped to Oracle tables that follow a certain naming convention. I'd like to avoid having to specify each table and column name in annotations. Therefore, I'm currently considering implementing a custom implementation of org.hibernate.cfg.NamingStrategy. The SQL naming conventions require the name of columns to have a suffix that is equivalent to a prefix of the table name. If there is a table "T100_RESOURCE", the ID column would have to be named "RES_ID_T100". In order to implement this in a NamingStrategy, the implementation would have to maintain state, i.e. the current class name it is creating the mappings for. It would rely on Hibernate to always call classToTableName() before propertyToColumnName() and to determine all column names by calling propertyToColumnName() before the next call to classToTableName() Is it safe to do that or are there situations where Hibernate will mix things up? I am not thinking of problems through multiple threads here (which can be solved by keeping the last class name in a ThreadLocal) but also of Hibernate deliberately calling this out of order in certain circumstances. For example Hibernate asking for mappings of three properties of class A, then one of class B, then again more attributes of class A.

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  • Paperclip: Stay put on edit

    - by EricR
    When a user edits something in my application, they're forced to re-upload their image via paperclip even if they aren't changing it. Failing to do so will cause an error, since I validate_presence_of :image. This is quite annoying. How can I make it so Paperclip won't update its attributes if a user simply doesn't supply a new image on an edit? The photo controller is fresh out of Rails' scaffold generator. The rest of the source code is provided below. models/accommodation.rb class Accommodation < ActiveRecord::Base attr_accessible :photo validates_presence_of :photo has_one :photo has_many :notifications belongs_to :user accepts_nested_attributes_for :photo, :allow_destroy => true end controllers/accommodation_controller.rb class AccommodationsController < ApplicationController def index @accommodations = Accommodation.all end def show @accommodation = Accommodation.find(params[:id]) rescue ActiveRecord::RecordNotFound flash[:error] = "Accommodation not found." redirect_to :home end def new @accommodation = current_user.accommodations.build @accommodation.build_photo end def create @accommodation = current_user.accommodations.build(params[:accommodation]) if @accommodation.save flash[:notice] = "Successfully created your accommodation." redirect_to @accommodation else @accommodation.build_photo render :new end end def edit @accommodation = Accommodation.find(params[:id]) @accommodation.build_photo rescue ActiveRecord::RecordNotFound flash[:error] = "Accommodation not found." redirect_to :home end def update @accommodation = Accommodation.find(params[:id]) if @accommodation.update_attributes(params[:accommodation]) flash[:notice] = "Successfully updated accommodation." redirect_to @accommodation else @accommodation.build_photo render :edit end end def destroy @accommodation = Accommodation.find(params[:id]) @accommodation.destroy flash[:notice] = "Successfully destroyed accommodation." redirect_to :inkeep end end models/photo.rb class Photo < ActiveRecord::Base attr_accessible :image, :primary belongs_to :accommodation has_attached_file :image, :styles => { :thumb=> "100x100#", :small => "150x150>" } end

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  • What's the proper approach for writing multi-path "story" flows?

    - by Basiclife
    Hi, I wonder if you can help me. I'm writing a game (2d) which allows players to take multiple routes, some of which branch/merge - perhaps even loop. Each section of the game will decide which section is loaded next. I'm calling each section an IStoryElement - And I'm wondering how best to link these elements up in a way that is easily changed/configured and at the same time, graphable I'm going to have an engine/factory assembly which will load the appropriate StoryElement(s) based on various config options. I initially planned to give each StoryElement a NextElement() As IStoryElement property and a Completed() event. When the vent fires, the engine reads the NextElement property to find the next StoryElement. The downside to this is that if I ever wanted to graph all the routes through the game, I would be unable to - I couldn't determine all possible targets for each StoryElement. I considered a couple of other solutions but they all feel a little clunky - eg Do I need an additional layer of abstraction? ie StoryElementPlayers or similar - Each one would be responsible for stringing together multiple StoryElement perhaps a Series and a ChoicePlayer with each responsible for graphing its own StoryElement - But this will just move the problem up a layer. In short, I need some way of emulating a simple but dynamic workflow (but I'd rather not actually use WWF). Is there a pattern for something this simple? All the ones I've managed to find relate to more advanced control flow (parallel processing, etc.)

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  • class modifier issues in C# with "private" classes

    - by devoured elysium
    I had a class that had lots of methods: public class MyClass { public bool checkConditions() { return checkCondition1() && checkCondition2() && checkCondition3(); } ...conditions methods public void DoProcess() { FirstPartOfProcess(); SecondPartOfProcess(); ThirdPartOfProcess(); } ...process methods } I identified two "vital" work areas, and decided to extract those methods to classes of its own: public class MyClass { private readonly MyClassConditions _conditions = new ...; private readonly MyClassProcessExecution = new ...; public bool checkConditions() { return _conditions.checkConditions(); } public void DoProcess() { _process.DoProcess(); } } In Java, I'd define MyClassConditions and MyClassProcessExecution as package protected, but I can't do that in C#. How would you go about doing this in C#? Setting both classes as inner classes of MyClass? I have 2 options: I either define them inside MyClass, having everything in the same file, which looks confusing and ugly, or I can define MyClass as a partial class, having one file for MyClass, other for MyClassConditions and other for MyClassProcessExecution. Defining them as internal? I don't really like that much of the internal modifier, as I don't find these classes add any value at all for the rest of my program/assembly, and I'd like to hide them if possible. It's not like they're gonna be useful/reusable in any other part of the program. Keep them as public? I can't see why, but I've let this option here. Any other? Name it! Thanks

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  • Binding a value to one of two possibilities in Guice

    - by Kelvin Chung
    Suppose I have a value for which I have a default, which can be overridden if System.getProperty("foo") is set. I have one module for which I have bindConstant().annotatedWith(Names.named("Default foo")).to(defaultValue); I'm wondering what the best way of implementing a module for which I want to bind something annotated with "foo" to System.getProperty("foo"), or, if it does not exist, the "Default foo" binding. I've thought of a simple module like so: public class SimpleIfBlockModule extends AbstractModule { @Override public void configure() { requireBinding(Key.get(String.class, Names.named("Default foo"))); if (System.getProperties().containsKey("foo")) { bindConstant().annotatedWith(Names.named("foo")).to(System.getProperty("foo")); } else { bind(String.class).annotatedWith(Names.named("foo")).to(Key.get(String.class, Names.named("Default foo"))); } } } I've also considered creating a "system property module" like so: public class SystemPropertyModule extends PrivateModule { @Override public void configure() { Names.bindProperties(binder(), System.getProperties()); if (System.getProperties().contains("foo")) { expose(String.class).annotatedWith(Names.named("foo")); } } } And using SystemPropertyModule to create an injector that a third module, which does the binding of "foo". Both of these seem to have their downsides, so I'm wondering if there is anything I should be doing differently. I was hoping for something that's both injector-free and reasonably generalizable to multiple "foo" attributes. Any ideas?

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  • NotApplicable marker with display pattern

    - by Jeff Barger
    Ok, so I'm pretty new to Cocoa, especially Bindings, but here's what I'm trying to do. I've got a Core Data model consisting of two entities: Category and Item. Category has a to-many relationship to Item called children, and Item has a relationship to Category called parent. Item has two attributes that Category does not have: quantity and desiredQuantity. What I'd like to do is display the tree in an NSOutlineView with two columns. One column is bound to the name of either the Category or the Item. I want to the second column to display something along the lines of 2 of 5 for the Item rows and nothing at all for the Category rows. When I use a display pattern, the Category rows end up showing of I noticed that if I don't use a display pattern for the second column, and instead just bind its Value to either the quantity or the desiredQuantity, the Category rows show nothing; its only if I try to use the display pattern. How can I make it display nothing for the Category rows and still use the display pattern? Or can I? Edit: I guess I didn't explain what the NotApplicable marker has to do with anything - Category does have properties for quantity and desiredQuantity, but they just return NSNotApplicableMarker.

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  • after assembling jar - No Persistence provider for EntityManager named ....

    - by alabalaa
    im developing a standalone application and it works fine when starting it from my ide(intellij idea), but after creating an uberjar and start the application from it javax.persistence.spi.PersistenceProvider is thrown saying "No Persistence provider for EntityManager named testPU" here is my persistence.xml which is placed under meta-inf directory: <persistence-unit name="testPU" transaction-type="RESOURCE_LOCAL"> <provider>org.hibernate.ejb.HibernatePersistence</provider> <class>test.model.Configuration</class> <properties> <property name="hibernate.connection.username" value="root"/> <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/> <property name="hibernate.connection.password" value="root"/> <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/test"/> <property name="hibernate.show_sql" value="true"/> <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLInnoDBDialect"/> <property name="hibernate.c3p0.timeout" value="300"/> <property name="hibernate.hbm2ddl.auto" value="update"/> </properties> </persistence-unit> and here is how im creating the entity manager factory: emf = Persistence.createEntityManagerFactory("testPU"); im using maven and tried the assembly plug-in with the default configuration fot it, i dont have much experience with assembling jars and i dont know if im missing something, so if u have any ideas ill be glad to hear them

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  • NHibernate + Cannot insert the value NULL into...

    - by mybrokengnome
    I've got a MS-SQL database with a table created with this code CREATE TABLE [dbo].[portfoliomanager]( [idPortfolioManager] [int] NOT NULL PRIMARY KEY IDENTITY, [name] [varchar](45) NULL ) so that idPortfolioManager is my primary key and also auto-incrementing. Now on my Windows WPF application I'm using NHibernate to help with adding/updating/removing/etc. data from the database. Here is the class that should be connecting to the portfoliomanager table namespace PortfolioManager { [Class(Table="portfoliomanager",NameType=typeof(PortfolioManagerClass))] public class PortfolioManagerClass { [Id(Name = "idPortfolioManager")] [Generator(1, Class = "identity")] public virtual int idPortfolioManager { get; set; } [NHibernate.Mapping.Attributes.Property(Name = "name")] public virtual string name { get; set; } public PortfolioManagerClass() { } } } and some short code to try and insert something PortfolioManagerClass portfolio = new PortfolioManagerClass(); Portfolio.name = "Brad's Portfolios"; The problem is, when I try running this, I get this error: {System.Data.SqlClient.SqlException: Cannot insert the value NULL into column 'idPortfolioManager', table 'PortfolioManagementSystem.dbo.portfoliomanager'; column does not allow nulls. INSERT fails. The statement has been terminated... with an outer exception of {"could not insert: [PortfolioManager.PortfolioManagerClass][SQL: INSERT INTO portfoliomanager (name) VALUES (?); select SCOPE_IDENTITY()]"} I'm hoping this is the last error I'll have to solve with NHibernate just to get it to do something, it's been a long process. Just as a note, I've also tried setting Class="native" and unsaved-value="0" with the same error. Thanks! Edit: Ok removing the 1, from Generator actually allows the program to run (not sure why that was even in the samples I was looking at) but it actually doesn't get added to the database. I logged in to the server and ran the sql server profiler tool and I never see the connection coming through or the SQL its trying to run, but NHibernate isn't throwing an error anymore. Starting to think it would be easier to just write SQL statements myself :(

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  • Best practices for creating a logger library using log4net. Is

    - by VolleyBall Player
    My goal is to create a log4net library that can be shared across multiple projects. In my solution which is in .net 4.0, I created a class library called Logger and referenced it from web project. Now I created a logger.config in the class library and put all the configuration in the logger.config file. I then used [assembly: log4net.Config.XmlConfigurator(Watch = true, ConfigFile = "Logger.config")] When I run the web app nothing is getting logged. So I added this line of code in web.config <add key="log4net.Internal.Debug" value="true"/> which gave me debugging info and error information Failed to find configuration section 'log4net' in the application's .config file. Check your .config file for the and elements. The configuration section should look like: I moved the configuration from logger.config to web.config and everything seems to work fine. I don't want the log4net configuration in web.config but have it logger.config as a cleaner approach. The goal is to make other projects use this library and not have to worry about configuration in every project. Now the question is, How do I do this? What am I doing wrong? Any suggestion with code example will be beneficial to everyone. FYI, I am using structure map IOC to reslove the logger before logging to it.

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  • Binary serialization and deserialization without creating files (via strings)

    - by the_V
    Hi, I'm trying to create a class that will contain functions for serializing/deserializing objects to/from string. That's what it looks like now: public class BinarySerialization { public static string SerializeObject(object o) { string result = ""; if ((o.GetType().Attributes & TypeAttributes.Serializable) == TypeAttributes.Serializable) { BinaryFormatter f = new BinaryFormatter(); using (MemoryStream str = new MemoryStream()) { f.Serialize(str, o); str.Position = 0; StreamReader reader = new StreamReader(str); result = reader.ReadToEnd(); } } return result; } public static object DeserializeObject(string str) { object result = null; byte[] bytes = System.Text.Encoding.ASCII.GetBytes(str); using (MemoryStream stream = new MemoryStream(bytes)) { BinaryFormatter bf = new BinaryFormatter(); result = bf.Deserialize(stream); } return result; } } SerializeObject method works well, but DeserializeObject does not. I always get an exception with message "End of Stream encountered before parsing was completed". What may be wrong here?

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  • Using C# to parse a SOAP Response

    - by Gavin
    I am trying to get the values for faultcode, faultstring, and OrderNumber from the SOAP below <SOAP:Envelope xmlns:SOAP="http://schemas.xmlsoap.org/soap/envelope/"> <SOAP:Body> <faultcode>1234</faultcode> <faultstring>SaveOrder:SetrsOrderMain:Cannot change OrderDate if GLPeriod is closed, new OrderDate is 3/2/2010:Ln:1053</faultstring> <detail> <SOAP:Envelope xmlns:SOAP="http://schemas.xmlsoap.org/soap/envelope/"> <SOAP:Body UserGUID="test"> <m:SaveOrder xmlns:m="http://www.test.com/software/schema/" UserGUID="test"> <Order OrderNumber="1234-1234-123" Caller="" OrderStatus="A" xmlns="http://www.test.com/software/schema/"> Here is my code in C# XDocument doc = XDocument.Load(HttpContext.Current.Server.MapPath("XMLexample.xml")); var errorDetail = new EcourierErrorDetail { FaultCode = from fc in doc.Descendants("faultcode") select fc.Value, FaultString = from fs in c.Descendants("faultstring") select fs.Value, OrderNumber = from o in doc.Descendants("detail").Elements("Order").Attributes("OrderNumber") select o.Value }; return errorDetail; I am able to get the values for both faultcode and faultstring but not the OrderNumber. I am getting "Enumeration yielded no results." Can anyone help? Thanks.

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  • asmx web service returning xml instead of json in .net 4.0

    - by Baldy
    i have just upgraded a test copy of my site to asp.net 4.0 and have noticed a strange issue that only arises when i upload the site to my server. the site has an asmx web service that returns json, yet when i run the site on my server it returns xml. it as been working fine in asp.net 3.5 for over a year. the webMethod is decorated with the correct attributes... [WebMethod][ScriptMethod(ResponseFormat = ResponseFormat.Json)] public List<LocationRecentChange> RecentChanges() and on my local machine it returns json. yet on the server (Windows 2008 64bit) it returns xml. you can inspect the response on the test site here... my test site using firebug console you will see a 200 OK response and a bunch of XML, and on my local machine the data returned is the JSON i expect. Here is the javascript that calls the service.. function loadRecentData() { $.ajax({ type: "POST", url: "service/spots.asmx/RecentChanges", data: "{}", contentType: "application/json; charset=utf-8", dataType: "json", success: loadRecentUpdates, failure: function(msg) { //alert(msg); } }); } Any suggestions welcome, this has got me stumped!

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  • How to convert a rectangle to TRBL CSS rect value?

    - by VLostBoy
    I'm not quite sure how to put this, but here goes... The css clip attribute is defined like so: rect(top, right, bottom, left). However, I'm exploring the use of a custom Rectangle 'class' to encapsulate some operations. The rectangle class has the attributes height, width and x, y. The x and y values are encapsulated in a Point object, and the height and width are encapsulated in a Dimension object, the rectangle being a composite of a point (its top-left location) and a dimension (width and height). So far so good. I though it would be pretty simple on the basis of having the rectangles x, y, width and height values to define the css rect attribute in terms of top, right, bottom, left, but I've become hopelessly confused- I've been googling for a while, and I can't seem to find any documentation as to what the TRBL values actually are or what they represent. For example, should I be thinking in terms of co-ordinates, in which case, surely I can describe the rectangle as a css rect using the rectangles x position for Top, x position + width for Right, the rectangles height + y for Bottom and its y position for Left... but thats a load of BS, surely? Also, surely rect is actually an inset, or have I just inverted my understanding of clip? I'd appreciate some advice. What I want to be able to do is (i) Define a rectangle using x, y, width and height (ii)Express the rectangle in TRBL form so that I can manipulate a divs clipping behaviour (iii)Change x, y, width or height and recalculate in terms of TRBL and goto (ii) I appreciate there are some other factors here, and some intermediary transforms to be done, but I've confused myself pretty badly- Can anyone give me some pointers?

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  • How do I put all the types matching a particular C# interface in an IDictionary?

    - by Kevin Brassen
    I have a number of classes all in the same interface, all in the same assembly, all conforming to the same generic interface: public class AppleFactory : IFactory<Apple> { ... } public class BananaFactory : IFactory<Banana> { ... } // ... It's safe to assume that if we have an IFactory<T> for a particular T that it's the only one of that kind. (That is, there aren't two things that implement IFactory<Apple>.) I'd like to use reflection to get all these types, and then store them all in an IDictionary, where the key is typeof(T) and the value is the corresponding IFactory<T>. I imagine eventually we would wind up with something like this: _map = new Dictionary<Type, object>(); foreach(Type t in [...]) { object factoryForType = System.Reflection.[???](t); _map[t] = factoryForType; } What's the best way to do that? I'm having trouble seeing how I'd do that with the System.Reflection interfaces.

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  • AIX specific socket programming query

    - by kumar_m_kiran
    Hi All, Question 1 From SUSE man pages, I get the below details for socket connect options If the initiating socket is connection-mode, then connect() shall attempt to establish a connection to the address specified by the address argument. If the connection cannot be established immediately and O_NONBLOCK is not set for the file descriptor for the socket, connect() shall block for up to an unspecified timeout interval until the connection is established. If the timeout interval expires before the connection is established, connect() shall fail and the connection attempt shall be aborted. If connect() is interrupted by a signal that is caught while blocked waiting to establish a connection, connect() shall fail and set errno to [EINTR], but the connection request shall not be aborted, and the connection shall be established asynchronously. Question : Is the above contents valid for AIX OS (especially the connection time-out, timed wait ...etc)?Because I do not see it in AIX man pages (5.1 and 5.3) Question 2 I have a client socket whose attributes are a. SO_RCVTIMEO ,SO_SNDTIMEO are set for 5 seconds. b. AF_INET and SOCK_STREAM. c. SO_LINGER with linger on and time is 5 seconds. d. SO_REUSEADDR is set. Note that the client socket is not O_NONBLOCK. Question : Now since O_NONBLOCK is not set and SO_RCVTIMEO and SO_SNDTIMEO is set for 5 seconds, does it mean a. connect in NON Blocking or Blocking? b. If blocking, is it timed blocking or "infinite" time blocking? c. If it is infinite, How do I establish a "connect" system call which is O_BLOCKING with timeout to t secs. Sorry if the questions are be very naive. Thanks in advance for your input.

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  • Maven (EJB) project with client and server artifacts

    - by Cornel Masson
    Here's my variation on the "multiple artifacts from Maven build" question: I'm porting from Ant to Maven. My application is an EJB server that is packaged as an EAR, but it also exposes a client JAR for use by other client apps. This jar contains the EJB interfaces, facade class and some helpers. I know that the Maven way is to have one artifact per project (POM); however, both artifacts (server EAR and client JAR) need to be built from the same source tree - server and client share, for example, the EJB and 'home' interfaces. How do I do this in Maven? Do I have one project containing two POMs, say server-pom.xml & client-pom.xml? I was thinking I could also have a parent POM (pom.xml) that can be used to build both client and server with one foul swoop? However, the lifecycles diverge after the 'package' phase, since the server has to go through assembly (tar/gzip), while the client is done after 'package' and can simply be installed into the repository. Any advice/experience on the best way to approach this?

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  • Map inheritance from generic class in Linq To SQL

    - by Ksenia Mukhortova
    Hi everyone, I'm trying to map my inheritance hierarchy to DB using Linq to SQL: Inheritance is like this, classes are POCO, without any LINQ to SQL attributes: public interface IStage { ... } public abstract class SimpleStage<T> : IStage where T : Process { ... } public class ConcreteStage : SimpleStage<ConcreteProcess> { ... } Here is the mapping: <Database Name="NNN" xmlns="http://schemas.microsoft.com/linqtosql/mapping/2007"> <Table Name="dbo.Stage" Member="Stage"> <Type Name="BusinessLogic.Domain.IStage"> <Column Name="ID" Member="ID" DbType="Int NOT NULL IDENTITY" IsPrimaryKey="true" IsDbGenerated="true" AutoSync="OnInsert" /> <Column Name="StageType" Member="StageType" IsDiscriminator="true" /> <Type Name="BusinessLogic.Domain.SimpleStage" IsInheritanceDefault="true"> <Type Name="BusinessLogic.Domain.ConcreteStage" IsInheritanceDefault="true" InheritanceCode="1"/> </Type> </Type> </Table> </Database> In the runtime I get error: System.InvalidOperationException was unhandled Message="Mapping Problem: Cannot find runtime type for type mapping 'BusinessLogic.Domain.SimpleStage'." Neither specifying SimpleStage, nor SimpleStage<T> in mapping file helps - runtime keeps producing different types of errors. DC is created like this: StreamReader sr = new StreamReader(@"MappingFile.map"); XmlMappingSource mapping = XmlMappingSource.FromStream(sr.BaseStream); DataContext dc = new DataContext(@"connection string", mapping); If Linq to SQL doesn't support this, could you, please, advise some other ORM, which does. Thanks in advance, Regards! Ksenia

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  • Best (Java) book for understanding 'under the bonnet' for programming?

    - by Ben
    What would you say is the best book to buy to understand exactly how programming works under the hood in order to increase performance? I've coded in assembly at university, I studied computer architecture and I obviously did high level programming, but what I really dont understand is things like: -what is happening when I perform a cast -whats the difference in performance if I declare something global as opposed to local? -How does the memory layout for an ArrayList compare with a Vector or LinkedList? -Whats the overhead with pointers? -Are locks more efficient than using synchronized? -Would creating my own array using int[] be faster than using ArrayList -Advantages/disadvantages of declaring a variable volatile I have got a copy of Java Performance Tuning but it doesnt go down very low and it contains rather obvious things like suggesting a hashmap instead of using an ArrayList as you can map the keys to memory addresses etc. I want something a bit more Computer Sciencey, linking the programming language to what happens with the assembler/hardware. The reason im asking is that I have an interview coming up for a job in High Frequency Trading and everything has to be as efficient as possible, yet I cant remember every single possible efficiency saving so i'd just like to learn the fundamentals. Thanks in advance

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  • Multiple "ObjectChangeTracker" getting created, can it be avoided?

    - by user555937
    Hi, We are working on a POC where we have following architecture (MVVM), WPF(Client) + WCF + Model(DataAccess)+ ADO.Net Entity Framework 4.0 (with SQL Server 2008 R2 as DB) All are different projects. In the DataAccess layer we have created different Entity Models(edmx) based on the functionality. The tables under perticular flow are grouped and created different entity models. We are using self tracking entities to and fro to communicate with the WPF client through wcf service. For Single model everything works fine. But when we created a Multiple models then few issues started coming. Mutliple models have few duplicate tables/entities. Two probels are, 1) When we try to access entities from different models mutiple objects "ObjectChangeTracker" are getting created. E.g. CompanyModel(edmx) - Company(Entity) - ObjectChangeTracker, ObjectState ProductModel(edmx) - Customer(Entity) - ObjectChangeTracker1, ObjectState1 OrderModel(edmx) - Oder(Entity) - ObjectChangeTracker2, ObjectState2 Is there any way to avoid this? 2) There are few tables which shared across the Models, E.g. Company(Entity) is used in All above mdoels. During compile time it does not thow any error. But run time It gives error saying "Schema specified is not valid. Errors: The mapping of CLR type to EDM type is ambiguous because multiple CLR types match the EDM type "Company"".. To resolve this, we renamed the entities with some prefix to make them Unique. Is there any other way we can resolve this without changing the name of the entity in the same assembly? Thanks in advance and appreciate if anyone has approach for these issues. Thanks, Kiran

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  • EF in a UserControl can't see the app.config?

    - by Sven
    I just created a user control. This control also makes use of my static Entity Framework class to load two comboboxes. All is well and runs without a problem. Design and runtime are working. Then when I stop the application all the forms that contain my UserControl don't work any more in design time. I just see two errors: Error1: The specified named connection is either not found in the configuration, not intended to be used with the EntityClient provider, or not valid. Error 2: The variable ccArtikelVelden is either undeclared or was never assigned. (ccArtikelVelde is my UserControl) Runtime everything is still working My static EF Repositoy class: public class BSManagerData { private static BSManagerEntities _entities; public static BSManagerEntities Entities { get { if (_entities == null) _entities = new BSManagerEntities(); return _entities; } set { _entities = value; } } } Some logic happening in my UserControl to load the data in the comboboxes: private void LaadCbx() { cbxCategorie.DataSource = (from c in BSManagerData.Entities.Categories select c).ToList(); cbxCategorie.DisplayMember = "Naam"; cbxCategorie.ValueMember = "Id"; } private void cbxCategorie_SelectedIndexChanged(object sender, EventArgs e) { cbxFabrikant.DataSource = from f in BSManagerData.Entities.Fabrikants where f.Categorie.Id == ((Categorie)cbxCategorie.SelectedItem).Id select f; cbxFabrikant.DisplayMember = "Naam"; cbxFabrikant.ValueMember = "Id"; } The only way to make my forms work again, design time, is to comment out the EF part in the UserControl (see above) and rebuild. It's very strange, everything is in the same assembly, same namespace (for the sake of simplicity). Anyone an idea?

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  • ArgumentOutOfRangeException was unhandled by user code - (ASP .net)

    - by ASr..
    I use a GridView to display the records from the database. Also i've attached a Hyperlink to the GridView using TemplateField. When I try to add "onclick" attribute to the HyperLink inside the RowDateBound event, I get the following error.. GridView1.DataKeys[e.Row.RowIndex].Value = 'GridView1.DataKeys[e.Row.RowIndex]' threw an exception of type 'System.ArgumentOutOfRangeException' Message = "Index was out of range. Must be non-negative and less than the size of the collection.\r\nParameter name: index" This is the coding inside the RowDataBound mentod.. protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e) { if (e.Row.RowType == DataControlRowType.DataRow) { HyperLink HyperLink1 = (HyperLink)e.Row.FindControl("HyperLink1"); //The following line makes the error HyperLink1.Attributes.Add("onclick", "ShowMyModalPopup('" + GridView1.DataKeys[e.Row.RowIndex].Value + "')"); } } This is "ShowMyModalPopup" function in javascript <script type="text/javascript"> function ShowMyModalPopup(userpk) { var modal = $find('ModalPopupExtender1'); modal.show(); WebService.FetchOneUser(userpk,DisplayResult); } </script> Can anyone please explain me why this error occurs.. Many thanks in advance..

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  • Custom ASP.net UserControl List<T> Property, having trouble setting declaratively

    - by Chris McCall
    I'm developing a custom UserControl to inject JQuery hotkeys into a page declaratively on the server side. Here's the control (the important parts anyway): [AspNetHostingPermission(SecurityAction.Demand, Level = AspNetHostingPermissionLevel.Minimal), AspNetHostingPermission(SecurityAction.InheritanceDemand, Level = AspNetHostingPermissionLevel.Minimal), DefaultProperty("HotKeys"), ParseChildren(true, "HotKeys"), ToolboxData("<{0}:HotKeysControl runat=\"server\"> </{0}:HotKeysControl>")] public partial class HotKeysControl : System.Web.UI.WebControls.WebControl { private string crlf = Environment.NewLine; public List<HotKey> _HotKeys; public HotKeysControl() { if (_HotKeys == null) { _HotKeys = new List<HotKey>(); } // if I uncomment this line, script is injected into the page // _HotKeys.Add(new HotKey("ctrl+r","thisControl")); } [ Category("Behavior"), Description("The hotkeys collection"), DesignerSerializationVisibility( DesignerSerializationVisibility.Content), Editor(typeof(HotKeyCollectionEditor), typeof(UITypeEditor)), PersistenceMode(PersistenceMode.InnerDefaultProperty) ] public List<HotKey> HotKeys { set { _HotKeys = value; } get { return _HotKeys; } } Here's the .aspx code: <%@ Register Assembly="MyCompany.ProductName.WebControls" Namespace="MyCompany.ProductName.WebControls" TagPrefix="uc" %> ... <uc:HotKeysControl ID="theHotkeys" runat="server" Visible="false"> <uc:HotKey ControlName="firstControl" KeyCode="ctrl+1" /> <uc:HotKey ControlName="thirdControl" KeyCode="ctrl+2" /> </uc:HotKeysControl> Nothing happens, as if no HotKeys objects are being added to the property collection. What Am I doing wrong? If I uncomment out the line above and "manually" add items, it works. It's something about how I'm declaratively adding hotkeys to the page. Any ideas?

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  • Why does JavaScript's getElementsByClassName provide an object that is NOT an array?

    - by Paragon
    I'm trying to get a list in JavaScript (not using jQuery) of all the elements on the page with a specific class name. I therefore employ the getElementsByClassName() function as follows: var expand_buttons = document.getElementsByClassName('expand'); console.log(expand_buttons, expand_buttons.length, expand_buttons[0]); Note that I have three anchor elements on my page with the class 'expand'. This console.log() outputs [] 0 undefined Next, for kicks, I threw expand_buttons into its own array as follows: var newArray = new Array(expand_buttons); console.log(newArray, newArray.length); This suddenly outputs [NodeList[3]] 1 and I can click through the nodelist and see the attributes of the three 'expand' anchor elements on the page. It's also worth noting that I was able to get my code working in a w3schools test page. It may also be of note that my use of document.getElementsByName actually does output (to the console) an array of elements, but when I ask for its length, it tells me 0. Similarly, if I try to access an array element using array_name[0] as normal, it outputs 'undefined', despite there clearly being an element inside of an array when I print the object to the console. Does anybody have any idea why this might be? I just want to loop through DOM elements, and I'm avoiding jQuery at the moment because I'm trying to practice coding with vanilla JavaScript. Thanks, ParagonRG

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