Search Results

Search found 4999 results on 200 pages for 'derived instances'.

Page 173/200 | < Previous Page | 169 170 171 172 173 174 175 176 177 178 179 180  | Next Page >

  • Any problems with this C++ const reference accessor interface idiom?

    - by mskfisher
    I was converting a struct to a class so I could enforce a setter interface for my variables. I did not want to change all of the instances where the variable was read, though. So I converted this: struct foo_t { int x; float y; }; to this: class foo_t { int _x; float _y; public: foot_t() : x(_x), y(_y) { set(0, 0.0); } const int &x; const float &y; set(int x, float y) { _x = x; _y = y; } }; I'm interested in this because it seems to model C#'s idea of public read-only properties. Compiles fine, and I haven't seen any problems yet. Besides the boilerplate of associating the const references in the constructor, what are the downsides to this method? Any strange aliasing issues? Why haven't I seen this idiom before?

    Read the article

  • returning reference to a vector from a method and using its public members

    - by memC
    dear experts, I have a vector t_vec that stores references to instances of class Too. The code is shown below. In the main , I have a vector t_vec_2 which has the same memory address as B::t_vec. But when I try to access t_vec_2[0].val1 it gives error val1 not declared. Could you please point out what is wrong? Also, if you know of a better way to return a vector from a method, please let me know! Thanks in advance. class Too { public: Too(); ~Too(){}; int val1; }; Too::Too(){ val1 = 10; }; class B { public: vector<Too*> t_vec; Too* t1; vector<Too*>& get_tvec(); B(){t1 = new Too();}; ~B(){delete t1;}; }; vector<Too*>& B::get_tvec(){ t_vec.push_back(t1); return t_vec; } int main(){ B b; b = B(); vector<Too*>& t_vec_2 = b.get_tvec(); // Getting error std::cout << "\n val1 = " << t_vec_2[0].val1; return 0; }

    Read the article

  • Contrary to Python 3.1 Docs, hash(obj) != id(obj). So which is correct?

    - by Don O'Donnell
    The following is from the Python v3.1.2 documentation: From The Python Language Reference Section 3.3.1 Basic Customization: object.__hash__(self) ... User-defined classes have __eq__() and __hash__() methods by default; with them, all objects compare unequal (except with themselves) and x.__hash__() returns id(x). From The Glossary: hashable ... Objects which are instances of user-defined classes are hashable by default; they all compare unequal, and their hash value is their id(). This is true up through version 2.6.5: Python 2.6.5 (r265:79096, Mar 19 2010 21:48:26) ... ... >>> class C(object): pass ... >>> c = C() >>> id(c) 11335856 >>> hash(c) 11335856 But in version 3.1.2: Python 3.1.2 (r312:79149, Mar 21 2010, 00:41:52) ... ... >>> class C: pass ... >>> c = C() >>> id(c) 11893680 >>> hash(c) 743355 So which is it? Should I report a documentation bug or a program bug? And if it's a documentation bug, and the default hash() value for a user class instance is no longer the same as the id() value, then it would be interesting to know what it is or how it is calculated, and why it was changed in version 3.

    Read the article

  • Update Web Reference in Visual Studio

    - by NeilD
    Hi, I have inherited a web site project that makes use of a number of WCF Web Services hosted on a BizTalk server. We have two environments that I need to deploy this project to, with different URLs for the different BizTalk servers. i.e. In the Staging environment, I need to point the services at xx.xx.xx.101 In the Live environment, I need to point them at xx.xx.xx.102, or whatever. Currently, we've got all of the URLs stored in keys in the web.config file, so that we can change them dynamically... Unfortunately this isn't working! If I change the URL in the web.config to something other than what the project was compiled with, I get an error when calling the service: Server did not recognize the value of HTTP Header SOAPAction: xx.xx.xx.101\ServiceName\MethodName I'm told that the only way they've known to deploy this is to update the web.config URLs, change all of the web references in Visual Studio to match, click on "update web reference" for each reference in Visual Studio, and then compile. It's driving me mad! I've written a pre-build NAnt script to go through and replace all instances of the URL found anywhere in the project directory, and even that isn't making any difference. There must be something else being pulled down from the service when I click the "update reference", but I'm new to working with web services, and so I'm not sure what. Does anyone have any ideas? Is there a way to do this programatically? Thanks.

    Read the article

  • Hide All But First Matching Element

    - by Batfan
    I am using jquery to sort through multiple paragraphs. Currently I have it set to show only paragraphs that start with a current letter. But now, I would like to consolidate further. If the text between the paragraph tags has multiple instances, I would like all but the first hidden. This is what I have so far but, it is not working. var letter = '<?php echo(strlen($_GET['letter']) == 1) ? $_GET['letter'] : ''; ?>' function finish(){ jQuery('p').each(function(){ if(jQuery(this).text().substr(0,1).toUpperCase() == letter){ jQuery(this).addClass('current-series'); jQuery(this).html(letter + '<span class="hidden">'+jQuery(this).text().slice(1)+ '</span>'); } else{ jQuery(this).hide();} }) } Update: Sorry guys, I know this is kind of hard to explain. Here's a basic example: The selected letter is B The values returned are: Ball Ball Ball Boy Brain Bat Bat Each of these values is in a paragraph tag. Is there a way to consolidate to this? Ball Boy Brain Bat

    Read the article

  • GWT Deserialisation of Persistent Entities (JPA)

    - by slartidan
    Hi everyone, I am currently developing Java/GWT-application which is hosted on a weblogic application server. I am using EJB3.0 with EclipseLink as persistence layer. Sadly my GWT has problems to deserialize persistent entities. It might be helpful for you to know, that I have the EclipseLink-Library in my classpath (including javax.persistence.Entity) am not recieving the persistence objects from a database or persistence-manager - I am creating the objects with standard java code use Eclipse IDE for Java EE Developers for development and deploying and I am compiling my GWT code with the GWT-Plugin (GWT 2.1.0) - my source code is split up in several projects am pretty sure, that the problems occures on client side, since the HTTP response of my server is the same in my working and in my not working example tried to patch javax.persistence.Entity and tried to include several libraries which included javax.persistence.Entity but nothing was helping In my server provides a list of instances of class SerialClass; the interface looks like this: public interface GreetingService extends RemoteService { List<SerialClass> greetServer(); } My onModuleLoad()-Method gets those instances and creates a browser-popup with the information: public void onModuleLoad() { GreetingServiceAsync server = (GreetingServiceAsync) GWT.create(GreetingService.class); server.greetServer(new AsyncCallback<List<SerialClass>>() { public void onFailure(Throwable caught) { } public void onSuccess(List<SerialClass> result) { String resultString = ""; try { for (SerialClass serial : result) { if (serial == null) { resultString += "null "; } else { resultString += ">" + serial.id + "< "; } } } catch (Throwable t) { Window.alert("failed to process"); } Window.alert("success:" + resultString); } }); } My server is looking like this: public class GreetingServiceImpl extends RemoteServiceServlet implements GreetingService { public List<SerialClass> greetServer() throws IllegalArgumentException { List<SerialClass> list = new ArrayList<SerialClass>(); for (int i = 0; i < 100; i++) { list.add(new SerialClass()); } return list; } } Case 1 = everything works fine I am using this SerialClass (either without any annotation, or with any annotation other than Entity - for example javax.persistence.PersistenceContext works fine): //@Entity public class SerialClass implements Serializable, IsSerializable { public int id = 4711; } The popup contains (as expected): success:>4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< >4711< The data sent over HTTP looks like this: //OK[4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,100,1,["java.util.ArrayList/3821976829","serial.shared.SerialClass/10650133"],0,6] Case 2 = its not working at all I am using this SerialClass: @Entity public class SerialClass implements Serializable, IsSerializable { public int id = 4711; } My popup contains (THIS IS MY PROBLEM): success:>2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null >2< null The data sent over HTTP looks like this (exactly the same!): //OK[4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,4711,2,100,1,["java.util.ArrayList/3821976829","serial.shared.SerialClass/10650133"],0,6] There is no suspicious logging output - neither on server, nor on client. All HTTP-responses have return code 200. My current workaround I am going to try to create transfer objects as a copy of my SerialClass - those transfer objects will look exactly the same, but will not have the @Entity annotation. Alternatively I could try to use the RequestFactory (thanks to @Hilbrand for the hint). I really don't know how to solve that problem and I'm really thankful about any suggestions, hints, tips, links, etc.

    Read the article

  • Segmentation fault on instationation of more than 1 object

    - by ECE
    I have a class called "Vertex.hpp" which is as follows: #include <iostream> #include "Edge.hpp" #include <vector> using namespace std; /** A class, instances of which are nodes in an HCTree. */ class Vertex { public: Vertex(char * str){ *name=*str; } vector<Vertex*> adjecency_list; vector<Edge*> edge_weights; char *name; }; #endif When I instantiate an object of type Vector as follows: Vertex *first_read; Vertex *second_read; in.getline(input,256); str=strtok(input," "); first_read->name=str; str=strtok(NULL, " "); second_read->name=str; A segmentation fault occurs when more than 1 object of type Vector is instantiated. Why would this occur if more than 1 object is instantiated, and how can i allow multiple objects to be instantiated?

    Read the article

  • Issue with creating index organized table

    - by mtim
    I'm having a weird problem with index organized table. I'm running Oracle 11g standard. i have a table src_table SQL> desc src_table; Name Null? Type --------------- -------- ---------------------------- ID NOT NULL NUMBER(16) HASH NOT NULL NUMBER(3) ........ SQL> select count(*) from src_table; COUNT(*) ---------- 21108244 now let's create another table and copy 2 columns from src_table set timing on SQL> create table dest_table(id number(16), hash number(20), type number(1)); Table created. Elapsed: 00:00:00.01 SQL> insert /*+ APPEND */ into dest_table (id,hash,type) select id, hash, 1 from src_table; 21108244 rows created. Elapsed: 00:00:15.25 SQL> ALTER TABLE dest_table ADD ( CONSTRAINT dest_table_pk PRIMARY KEY (HASH, id, TYPE)); Table altered. Elapsed: 00:01:17.35 It took Oracle < 2 min. now same exercise but with IOT table SQL> CREATE TABLE dest_table_iot ( id NUMBER(16) NOT NULL, hash NUMBER(20) NOT NULL, type NUMBER(1) NOT NULL, CONSTRAINT dest_table_iot_PK PRIMARY KEY (HASH, id, TYPE) ) ORGANIZATION INDEX; Table created. Elapsed: 00:00:00.03 SQL> INSERT /*+ APPEND */ INTO dest_table_iot (HASH,id,TYPE) SELECT HASH, id, 1 FROM src_table; "insert" into IOT takes 18 hours !!! I have tried it on 2 different instances of Oracle running on win and linux and got same results. What is going on here ? Why is it taking so long ?

    Read the article

  • Drupal view filter to show only one of a certain item

    - by Joel
    I'm fairly new to Drupal, and am using Node Import to take a TSV file and turn it into nodes. I'm hitting a problem, though, with automating updates to the nodes. Again, I'd like to take a Tab Separated Values text file, and load it into my site via Node Import (or whatever else anyone might suggest) and then only show updated Nodes. Here's a specific example: I have a Node with the following info: StoreId Name Address Phone Contact 01 Name1 Address1 Phone1 Contact1 02 Name2 Address2 Phone2 Contact2 etc. The info pulls into the nodes just fine (Thank you Node Import!), but we also want to process updates to the nodes. So far I have two ideas... figure out how to delete duplicate (previous) instances of the same StoreID, or just save the node with the duplicate StoreID (and new other info) and just display the most current version. In Views, I can get it to show the nodes and everything, but I can't figure out how to only display the most recent version of each StoreID. A view of views would work, but I can't seem to get that to work, either. Any ideas or other approaches I could take? Thanks in advance for the help!

    Read the article

  • After calling a COM-dll component, C# exceptions are not caught by the debugger

    - by shlomil
    I'm using a COM dll provided to me by 3rd-party software company (I don't have the source code). I do know for sure they used Java to implement it because their objects contain property names like 'JvmVersion'. After I instantiated an object introduced by the provided COM dll, all exceptions in my C# program cannot be caught by the VS debugger and every time an exception occurs I get the default Windows Debugger Selection dialog (And that's while executing my program in debug mode under a full VisualStudio debugging environment). To illustrate: throw new Exception("exception 1"); m_moo = new moo(); // Component taken from the COM-dll throw new Exception("exception 2"); Exception 1 will be caught by VS and show the "yellow exception window". Exception 2 will open a dialog titled "Visual Studio Just-In-Time Debugger" containing the text "An unhandled win32 exception occurred in myfile.vshost.exe[1348]." followed by a list of the existing VS instances on my system to select from. I guess the instantiation of "moo" object overrides C#'s exception handler or something like that. Am I correct and is there a way to preserve C#'s exception handler?

    Read the article

  • Fast serialization/deserialization of structs

    - by user256890
    I have huge amont of geographic data represented in simple object structure consisting only structs. All of my fields are of value type. public struct Child { readonly float X; readonly float Y; readonly int myField; } public struct Parent { readonly int id; readonly int field1; readonly int field2; readonly Child[] children; } The data is chunked up nicely to small portions of Parent[]-s. Each array contains a few thousands Parent instances. I have way too much data to keep all in memory, so I need to swap these chunks to disk back and forth. (One file would result approx. 2-300KB). What would be the most efficient way of serializing/deserializing the Parent[] to a byte[] for dumpint to disk and reading back? Concerning speed, I am particularly interested in fast deserialization, write speed is not that critical. Would simple BinarySerializer good enough? Or should I hack around with StructLayout (see accepted answer)? I am not sure if that would work with array field of Parent.children. UPDATE: Response to comments - Yes, the objects are immutable (code updated) and indeed the children field is not value type. 300KB sounds not much but I have zillions of files like that, so speed does matter.

    Read the article

  • How would I compare two Lists(Of <CustomClass>) in VB?

    - by Kumba
    I'm working on implementing the equality operator = for a custom class of mine. The class has one property, Value, which is itself a List(Of OtherClass), where OtherClass is yet another custom class in my project. I've already implemented the IComparer, IComparable, IEqualityComparer, and IEquatable interfaces, the operators =, <>, bool and not, and overriden Equals and GetHashCode for OtherClass. This should give me all the tools I need to compare these objects, and various tests comparing two singular instances of these objects so far checks out. However, I'm not sure how to approach this when they are in a List. I don't care about the list order. Given: Dim x As New List(Of OtherClass) From {New OtherClass("foo"), New OtherClass("bar"), New OtherClass("baz")} Dim y As New List(Of OtherClass) From {New OtherClass("baz"), New OtherClass("foo"), New OtherClass("bar")} Then (x = y).ToString should print out True. I need to compare the same (not distinct) set of objects in this list. The list shouldn't support dupes of OtherClass, but I'll have to figure out how to add that in later as an exception. Not interested in using LINQ. It looks nice, but in the few examples I've played with, adds a performance overhead in that bugs me. Loops are ugly, but they are fast :) A straight code answer is fine, but I'd like to understand the logic needed for such a comparison as well. I'm probably going to have to implement said logic more than a few times down the road.

    Read the article

  • How to run stored procedures and ad-hoc scripts asynchronously with "loosely" connected SQL Server 2

    - by sanga
    Is there a way to initiate a script against an instance of SQL server when it is not connected then have it run on the instance the next time it connects? This needs to happen without any intervention from me. Background situation if you are interested: We have about 120 machines each with their own instance of SQL Server 2000. Most of them are laptops. We have merge replication set up with each one. From time to time, there is a need to delete "rogue" guids from some tables in some instances that overwrite legitimate records on the main publisher as well as perform administrative tasks via stored procedure or adhoc sql statements. The problem is there is no telling when each machine is going to be connected to the network. Some folks turn their machines completely off at the end of the day. Others disconnect their machines and take them on business trips, home for the weekend etc. Did I mention that about 35 of these machines are in utility trucks and "attempt" to sync over a wireless connection. Thanks in advance for any assistance or suggestions. Sanga

    Read the article

  • Nhibernate + Gridview + TargetInvocationException

    - by Scott
    For our grid views, we're setting the data sources as a list of results from an Nhibernate query. We're using lazy loading, so the objects are actually proxied... most of the time. In some instances the list will consist of types of Student and Composition_Aop_Proxy_jklasjdkl31231, which implements the same members as the Student class. We've still got the session open, so the lazy loading would resolve fine, if GridView didn't throw an error about the different types in the gridview. Our current workaround is to clone the object, which results in fetching all of the data that can be lazily loaded, even though most of it won't be accessed.. ever. This, however, converts the proxy into an actual object and the grid view is happy. The performance implications kind of scare me as we're getting closer to rolling the code out as is. I've tried evicting the object after a save, which should ensure that everything is a proxy, but this doesn't seem like a good idea either. Does anyone have any suggestions/workarounds?

    Read the article

  • Android game logic problem

    - by semajhan
    I'm currently creating a game and have a problem which I think I know why it is occurring but not entirely sure and even if I knew, don't know how to solve. I have a 2D array 10 x 10 and have a "player" class that takes up a tile. Now, I have created 2 instances of the player and move them around via swiping. Around the edges I have put "walls" that the player cannot walk through and everything works fine, until I remove a wall. Once I remove a wall and move the character/player to the edge of the screen, the player cannot go any further. The problem occurs here, where the second instance of the player is not at the edge of the screen but say 2 tiles from the first instance of "player" who is at the edge. If I try moving them further into the direction of the edge, I understand that the first instance of player wouldn't move or do anything but the second instance of player should still move, but it won't. This is the code that executed when the user swipes: if (player.getArrayX() - 1 != player2.getArrayX()) { player.moveLeft(); } else if (player.getArrayX() - 1 == player2.getArrayX() && player.getArrayY() != player2.getArrayY()) { player.moveLeft(); } if (player2.getArrayX() - 1 != player.getArrayX()) { player2.moveLeft(); } else if (player2.getArrayX() - 1 == player.getArrayX() && player2.getArrayY() != player.getArrayY()) { player2.moveLeft(); } In the player class I have: public void moveLeft() { if (alive) { switch (levelMaster.getLevel1(getArrayX() - 1, getArrayY())) { case 0: break; case 1: subX(); // basically moves player left setArrayX(getArrayX() - 1); // shifts x coord of player 1 within tilemap Log.d("semajhan", "x: " + getArrayX()); break; case 9: subX(); setArrayX(getArrayX() - 1); setAlive(false); break; } } } Any help on the matter or further insight would be greatly appreciated, thanks.

    Read the article

  • Java constructor using generic types

    - by Beer Me
    I'm having a hard time wrapping my head around Java generic types. Here's a simple piece of code that in my mind should work, but I'm obviously doing something wrong. Eclipse reports this error in BreweryList.java: The method breweryMethod() is undefined for the type <T> The idea is to fill a Vector with instances of objects that are a subclass of the Brewery class, so the invocation would be something like: BreweryList breweryList = new BreweryList(BrewerySubClass.class, list); BreweryList.java package com.beerme.test; import java.util.Vector; public class BreweryList<T extends Brewery> extends Vector<T> { public BreweryList(Class<T> c, Object[] j) { super(); for (int i = 0; i < j.length; i++) { T item = c.newInstance(); // breweryMethod() is an instance method // of Brewery, of which <T> is a subclass (right?) c.breweryMethod(); // "The method breweryMethod() is undefined // for the type <T>" } } } Brewery.java package com.beerme.test; public class Brewery { public Brewery() { super(); } protected void breweryMethod() { } } BrewerySubClass.java package com.beerme.test; public class BrewerySubClass extends Brewery { public BrewerySubClass() { super(); } public void brewerySubClassMethod() { } } I'm sure this is a complete-generics-noob question, but I'm stuck. Thanks for any tips!

    Read the article

  • Add a value to an element in a list of sets

    - by Kapelson
    Hello. I'm using python, and I have a list of sets, constructed like this: list = [set([])]*n ...where n is the number of sets I want in the list. I want to add a value to a specific set in the list. Say, the second set. I tried list[1].add(value) But this instead adds the value to each set in the list. This behaviour is pretty non-intuitive to me. Through further tests, I think I've found the problem: the list apparently contains 10 instances of the same set, or ten pointers to the same set, or something. Constructing the list through repeated calls of list.append(set([])) allowed me to use the syntax above to add elements to single sets. So my question is this: what exactly is going on in my first list-construction technique? It is clear I don't understand the syntax so well. Also, is there a better way to intialize an n-element list? I've been using this syntax for a while and this is my first problem with it.

    Read the article

  • Preventing ActiveRecord save() on an instance

    - by Craig Walker
    I have an ActiveRecord model object Foo; it represents a standard database row. I want to be able to display modified versions of instances of this object. I'd like to reuse the class itself, as it already has all the hooks & aspects I'll need. (For example: I already have a view that displays the appropriate attributes). Basically I want to clone the model instance, modify some of its properties, and feed it back to the caller (view, test, etc). I do not want these attribute modifications getting back into the database. However, I do want to include the id attribute in the cloned version, as it makes dealing with the route-helpers much easier. Thus, I plan on calling ActiveRecord::Base.clone(), manually setting the ID of the cloned instance, and then making the appropriate attribute changes to the new instance. This has me worried though; one save() on the modified instance and my original data will get clobbered. So, I'm looking to lock down the new instance so that it won't hurt anything else. I'm already planning on calling freeze() (on the understanding that this prevents further modification to the object, though the documentation isn't terribly clear). However, I don't see any obvious way to prevent a save(). What would be the best approach to achieving this?

    Read the article

  • Enterprise Platform in Python, Design Advice

    - by Jason Miesionczek
    I am starting the design of a somewhat large enterprise platform in Python, and was wondering if you guys can give me some advice as to how to organize the various components and which packages would help achieve the goals of scalability, maintainability, and reliability. The system is basically a service that collects data from various outside sources, with each outside source having its own separate application. These applications would poll a central database and get any requests that have been submitted to perform on the external source. There will be a main website and REST/SOAP API that should also have access to the central data service. My initial thought was to use Django for the web site, web service and data access layer (using its built-in ORM), and then the outside source applications can use the web service(s) to get the information they need to process the request and save the results. Using this method would allow me to have multiple instances of the service applications running on the same or different machines to balance out the load. Are there more elegant means of accomplishing this? i've heard of messaging systems such as MQ, would something like that be beneficial in this scenario? My other thought was to use a completely separate data service not based on Django, and use some kind of remoting or remote objects (in they exist in Python) to interact with the data model. The downside here would be with the website which would become much slower if it had to push all of its data requests through a second layer. I would love to hear what other developers have come up with to achieve these goals in the most flexible way possible.

    Read the article

  • Processing a database queue across multiple threads - design advice

    - by rwmnau
    I have a SQL Server table full of orders that my program needs to "follow up" on (call a webservice to see if something has been done with them). My application is multi-threaded, and could have instances running on multiple servers. Currently, every so often (on a Threading timer), the process selects 100 rows, at random (ORDER BY NEWID()), from the list of "unconfirmed" orders and checks them, marking off any that come back successfully. The problem is that there's a lot of overlap between the threads, and between the different processes, and their's no guarantee that a new order will get checked any time soon. Also, some orders will never be "confirmed" and are dead, which means that they get in the way of orders that need to be confirmed, slowing the process down if I keep selecting them over and over. What I'd prefer is that all outstanding orders get checked, systematically. I can think of two easy ways do this: The application fetches one order to check at a time, passing in the last order it checked as a parameter, and SQL Server hands back the next order that's unconfirmed. More database calls, but this ensures that every order is checked in a reasonable timeframe. However, different servers may re-check the same order in succession, needlessly. The SQL Server keeps track of the last order it asked a process to check up on, maybe in a table, and gives a unique order to every request, incrementing its counter. This involves storing the last order somewhere in SQL, which I wanted to avoid, but it also ensures that threads won't needlessly check the same orders at the same time Are there any other ideas I'm missing? Does this even make sense? Let me know if I need some clarification.

    Read the article

  • When using Direct3D, how much math is being done on the CPU?

    - by zirgen
    Context: I'm just starting out. I'm not even touching the Direct3D 11 API, and instead looking at understanding the pipeline, etc. From looking at documentation and information floating around the web, it seems like some calculations are being handled by the application. That, is, instead of simply presenting matrices to multiply to the GPU, the calculations are being done by a math library that operates on the CPU. I don't have any particular resources to point to, although I guess I can point to the XNA Math Library or the samples shipped in the February DX SDK. When you see code like mViewProj = mView * mProj;, that projection is being calculated on the CPU. Or am I wrong? If you were writing a program, where you can have 10 cubes on the screen, where you can move or rotate cubes, as well as viewpoint, what calculations would you do on the CPU? I think I would store the geometry for the a single cube, and then transform matrices representing the actual instances. And then it seems I would use the XNA math library, or another of my choosing, to transform each cube in model space. Then get the coordinates in world space. Then push the information to the GPU. That's quite a bit of calculation on the CPU. Am I wrong? Am I reaching conclusions based on too little information and understanding? What terms should I Google for, if the answer is STFW? Or if I am right, why aren't these calculations being pushed to the GPU as well?

    Read the article

  • Am I doing AS3 reference cleanup correctly?

    - by Ólafur Waage
    In one frame of my fla file (let's call it frame 2), I load a few xml files, then send that data into a class that is initialized in that frame, this class creates a few timers and listeners. Then when this class is done doing it's work. I call a dispatchEvent and move to frame 3. This frame does some things as well, it's initialized and creates a few event listeners and timers. When it's done, I move to frame 2 again. This is supposed to repeat as often as I need so I need to clean up the references correctly and I'm wondering if I'm doing it correctly. For sprites I do this. world.removeChild(Background); // world is the parent stage Background = null; For instances of other classes I do this. Players[i].cleanUp(world); // do any cleanup within the instanced class world.removeChild(PlayersSelect[i]); For event listeners I do this. if(Background != null) { Background.removeEventListener(MouseEvent.CLICK, deSelectPlayer); } For timers I do this. if(Timeout != null) { Timeout.stop(); Timeout.removeEventListener(TimerEvent.TIMER, queueHandler); Timeout.removeEventListener(TimerEvent.TIMER_COMPLETE, queueCompleted); Timeout = null; } And for library images I do this if(_libImage!= null) { s.removeChild(Images._libImage); // s is the stage _libImage= null; } And for the class itself in the main timeline, I do this Frame2.removeEventListener("Done", IAmDone); Frame2.cleanUp(); // the cleanup() does all the stuff above Frame2= null; Even if I do all this, when I get to frame 2 for the 2nd time, it runs for 1-2 seconds and then I get a lot of null reference errors because the cleanup function is called prematurely. Am I doing the cleanup correctly? What can cause events to fire prematurely?

    Read the article

  • OOP design issue: Polymorphism

    - by Graham Phillips
    I'm trying to solve a design issue using inheritance based polymorphism and dynamic binding. I have an abstract superclass and two subclasses. The superclass contains common behaviour. SubClassA and SubClassB define some different methods: SubClassA defines a method performTransform(), but SubClassB does not. So the following example 1 var v:SuperClass; 2 var b:SubClassB = new SubClassB(); 3 v = b; 4 v.performTransform(); would cause a compile error on line 4 as performTransform() is not defined in the superclass. We can get it to compile by casting... (v as SubClassA).performTransform(); however, this will cause a runtime exception to be thrown as v is actually an instance of SubClassB, which also does not define performTransform() So we can get around that by testing the type of an object before casting it: if( typeof v == SubClassA) { (cast v to SubClassA).performTransform(); } That will ensure that we only call performTransform() on v's that are instances of SubClassA. That's a pretty inelegant solution to my eyes, but at least its safe. I have used interface based polymorphism (interface meaning a type that can't be instantiated and defines the API of classes that implement it) in the past, but that also feels clunky. For the above case, if SubClassA and SubClassB implemented ISuperClass that defined performTransform, then they would both have to implement performTransform(). If SubClassB had no real need for a performTransform() you would have to implement an empty function. There must be a design pattern out there that addresses the issue.

    Read the article

  • glDrawArrays() slow on iPad?

    - by Nick
    Hey guys, I was wondering how to speed up my iPad application using OpenGLES 2.0. At the moment we have every drawable object draw itself with a call to glDrawArrays(). Blend mode is on, we really need it. Without disabling blendmode, how would we improve performance for this app? For instances, if we now draw 1 texture across the whole screen, the app only gets 15FPS, which is really slow I think? Are we doing something terribly wrong? Our drawing code (for each drawable), is as follows: - (void) draw { GLuint textureAvailable = 0; if(texture != nil){ textureAvailable = 1; } glActiveTexture(GL_TEXTURE0); glBindTexture(GL_TEXTURE_2D, texture.name); glVertexAttribPointer(ATTRIB_VERTEX, 2, GL_FLOAT, 0, 0, vertices); glEnableVertexAttribArray(ATTRIB_VERTEX); glVertexAttribPointer(ATTRIB_COLOR, 4, GL_FLOAT, 1, 0, colorsWithMultipliedAlpha); glEnableVertexAttribArray(ATTRIB_COLOR); glVertexAttribPointer(ATTRIB_TEXTUREMAP, 2, GL_FLOAT, 1, 0, textureMapping); glEnableVertexAttribArray(ATTRIB_TEXTUREMAP); //Note that we are NOT using position.z here because that is only used to determine drawing order int *jnUniforms = JNOpenGLConstants::getInstance().uniforms; glUniform4f(jnUniforms[UNIFORM_TRANSLATE], position.x, position.y, 0.0, 0.0); glUniform4f(jnUniforms[UNIFORM_SCALE], scale.x, scale.y, 1.0, 1.0); glUniform1f(jnUniforms[UNIFORM_ROTATION], rotation); glUniform1i(jnUniforms[UNIFORM_TEXTURE_SAMPLE], 0); glUniform2f(jnUniforms[UNIFORM_TEXTURE_REPEAT], textureRepeat.x, textureRepeat.y); glUniform1i(jnUniforms[UNIFORM_TEXTURE_AVAILABLE], textureAvailable); glDrawArrays(GL_TRIANGLE_STRIP, 0, 4); }

    Read the article

  • How to replace auto-implemented c# get body at runtime or compile time?

    - by qstarin
    I've been trying to figure this out all night, but I guess my knowledge of the .Net Framework just isn't that deep and the problem doesn't exactly Google well, but if I can get a nod in the right direction I'm sure I can implement it, one way or another. I'd like to be able to declare a property decorated with a custom attribute as such: public MyClass { [ReplaceWithExpressionFrom(typeof(SomeOtherClass))] public virtual bool MyProperty { get; } } public SomeOtherClass : IExpressionHolder<MyClass, bool> { ... } public interface IExpressionHolder<TArg, TResult> { Expression<Func<TArg, TResult>> Expression { get; } } And then somehow - this is the part I'm having trouble figuring - replace the automatically generated implementation of that getter with a piece of custom code, something like: Type expressionHolderType = LookupAttributeCtorArgTypeInDeclarationOfPropertyWereReplacing(); return ReplaceWithExpressionFromAttribute.GetCompiledExpressionFrom(expressionHolderType)(this); The main thing I'm not sure how to do is replace the automatic implementation of the get. The first thing that came to mind was PostSharp, but that's a more complicated dependency than I care for. I'd much prefer a way to code it without using post-processing attached to the build (I think that's the jist of how PostSharp sinks its hooks in anyway). The other part of this I'm not so sure about is how to retrieve the type parameter passed to the particular instantiation of the ReplaceWithExpressionFrom attribute (where it decorates the property whose body I want to replace; in other words, how do I get typeof(SomeOtherClass) where I'm coding the get body replacement). I plan to cache compiled expressions from concrete instances of IExpressionHolder, as I don't want to do that every time the property gets retrieved. I figure this has just got to be possible. At the very least I figure I should be able to search an assembly for any method decorated with the attribute and somehow proxy the class or just replace the IL or .. something? And I'd like to make the integration as smooth as possible, so if this can be done without explicitly calling a registration or initialization method somewhere that'd be super great. Thanks!

    Read the article

< Previous Page | 169 170 171 172 173 174 175 176 177 178 179 180  | Next Page >