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  • Javascript Closures, Callbacks, This and That

    - by nazbot
    I am having some trouble getting a callback function to work. Here is my code: SomeObject.prototype.refreshData = function() { var read_obj = new SomeAjaxCall("read_some_data", { }, this.readSuccess, this.readFail); } SomeObject.prototype.readSuccess = function(response) { this.data = response; this.someList = []; for (var i = 0; i < this.data.length; i++) { var systemData = this.data[i]; var system = new SomeSystem(systemData); this.someList.push(system); } this.refreshList(); } Basically SomeAjaxCall is making an ajax request for data. If it works we use the callback 'this.readSuccess' and if it fails 'this.readFail'. I have figured out that 'this' in the SomeObject.readSuccess is the global this (aka the window object) because my callbacks are being called as functions and not member methods. My understanding is that I need to use closures to keep the 'this' around, however, I have not been able to get this to work. If someone is able show me what I should be doing I would appreciate it greatly. I am still wrapping my head around how closures work and specifically how they would work in this situation. Thanks!

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  • MSMQ - Message Queue Abstraction and Pattern

    - by Maxim Gershkovich
    Hi All, Let me define the problem first and why a messagequeue has been chosen. I have a datalayer that will be transactional and EXTREMELY insert heavy and rather then attempt to deal with these issues when they occur I am hoping to implement my application from the ground up with this in mind. I have decided to tackle this problem by using the Microsoft Message Queue and perform inserts as time permits asynchronously. However I quickly ran into a problem. Certain inserts that I perform may need to be recalled (ie: retrieved) immediately (imagine this is for POS system and what happens if you need to recall the last transaction - one that still hasn’t been inserted). The way I decided to tackle this problem is by abstracting the MessageQueue and combining it in my data access layer thereby creating the illusion of a single set of data being returned to the user of the datalayer (I have considered the other issues that occur in such a scenario (ie: essentially dirty reads and such) and have concluded for my purposes I can control these issues). However this is where things get a little nasty... I’ve worked out how to get the messages back and such (trivial enough problem) but where I am stuck is; how do I create a generic (or at least somewhat generic) way of querying my message queue? One where I can minimize the duplication between the SQL queries and MessageQueue queries. I have considered using LINQ (but have very limited understanding of the technology) and have also attempted an implementation with Predicates which so far is pretty smelly. Are there any patterns for such a problem that I can utilize? Am I going about this the wrong way? Does anyone have an of their own ideas about how I can tackle this problem? Does anyone even understand what I am talking about? :-) Any and ALL input would be highly appreciated and seriously considered… Thanks again.

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  • What is the difference between .get() and .fetch(1)

    - by AutomatedTester
    I have written an app and part of it is uses a URL parser to get certain data in a ReST type manner. So if you put /foo/bar as the path it will find all the bar items and if you put /foo it will return all items below foo So my app has a query like data = Paths.all().filter('path =', self.request.path).get() Which works brilliantly. Now I want to send this to the UI using templates {% for datum in data %} <div class="content"> <h2>{{ datum.title }}</h2> {{ datum.content }} </div> {% endfor %} When I do this I get data is not iterable error. So I updated the Django to {% for datum in data.all %} which now appears to pull more data than I was giving it somehow. It shows all data in the datastore which is not ideal. So I removed the .all from the Django and changed the datastore query to data = Paths.all().filter('path =', self.request.path).fetch(1) which now works as I intended. In the documentation it says The db.get() function fetches an entity from the datastore for a Key (or list of Keys). So my question is why can I iterate over a query when it returns with fetch() but can't with get(). Where has my understanding gone wrong?

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  • 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?

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  • Windows Server 2008 R2 File Permissions

    - by Fly_Trap
    I’m having some problems understanding some particular file permissions behaviour. Here are the steps to reproduce: Log into the server using the default Administrator account Create a text file (testfile.txt) in C:\ProgramData containing some arbitrary text Create a new user account and make it a member of the Administrators group Log in using new account and open C:\ProgramData\testfile.txt Edit the text and try to save Upon clicking save I’m presented with the save as dialog, which indicates that i do not have the necessary permissions to edit the file. This seems odd considering that the new user account is a member of Administrators. When I view the permissions of the file I can see the there are three groups listed, System, Administrators and Users. SYSTEM and Administrators have full permissions, however, Users only has the Read & Execute and Read permissions checked. It would appear that when I open the testfile.txt from the new users account, it opens in the context of the Users group, despite being a member of Administrators, is this correct? It would certainly explain the behaviour. The reason that this is an issue for me is that if I deploy an application via 'Run as Administrator', will normal users be able to edit the text files I install to ProgramData. Is this behaviour confined to Windows server or is it the same in Vista and Win7.

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  • Storing a jpa entity where only the timestamp changes results in updates rather than inserts (desire

    - by David Schlenk
    I have a JPA entity that stores a fk id, a boolean and a timestamp: @Entity public class ChannelInUse implements Serializable { @Id @GeneratedValue private Long id; @ManyToOne @JoinColumn(nullable = false) private Channel channel; private boolean inUse = false; @Temporal(TemporalType.TIMESTAMP) private Date inUseAt = new Date(); ... } I want every new instance of this entity to result in a new row in the table. For whatever reason no matter what I do it always results in the row getting updated with a new timestamp value rather than creating a new row. Even tried to just use a native query to run an insert but channel's ID wasn't populated yet so I gave up on that. I've tried using an embedded id class consisting of channel.getId and inUseAt. My equals and hashcode for are: public boolean equals(Object obj){ if(this == obj) return true; if(!(obj instanceof ChannelInUse)) return false; ChannelInUse ciu = (ChannelInUse) obj; return ( (this.inUseAt == null ? ciu.inUseAt == null : this.inUseAt.equals(ciu.inUseAt)) && (this.inUse == ciu.inUse) && (this.channel == null ? ciu.channel == null : this.channel.equals(ciu.channel)) ); } /** * hashcode generated from at, channel and inUse properties. */ public int hashCode(){ int hash = 1; hash = hash * 31 + (this.inUseAt == null ? 0 : this.inUseAt.hashCode()); hash = hash * 31 + (this.channel == null ? 0 : this.channel.hashCode()); if(inUse) hash = hash * 31 + 1; else hash = hash * 31 + 0; return hash; } } I've tried using hibernate's Entity annotation with mutable=false. I'm probably just not understanding what makes an entity unique or something. Hit the google pretty hard but can't figure this one out.

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  • Entity Framework POCO objects

    - by Dan
    I'm struggling with understanding Entity Framework and POCO objects. Here's what I'm trying to achieve. 1) Separate the DAL from the Business Layer by having my business layer use an interface to my DAL. Maybe use Unity to create my context. 2) Use Entity Framework inside my DAL. I have a Domain model with objects that reside in my business layer. I also have a database full of tables that doesn't really represent my domain model. I setup Entity Framework and generated POCO objects by using the ADO.NET POCO Generator extension. This gave me an object for each table in my database. Now I want to be able to say context.GetAll<User>(); and have it return a list of my User objects. The User object is in my business layer. Is that possible? Does that make sense or am I totally off and should start over? I'm guessing I need to use the repository pattern to achieve this, but I'm not sure. Can anyone help?

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  • CSS3PIE issues in IE6 and 8

    - by Gordon
    I'm using CSS3PIE to apply some rounded corners to elements in Internet Explorer that will get them by stylesheet in other browsers. I've run into some issues with it though. In IE8, I discovered that any element that had the PIE behaviour would behave strangely. The container would jump a few pixels to the right, but the content would stay in its original position, giving the appearance that the content had all shifted left relative to its container. This would be especially problematic on elements with no or small amounts of padding. I was able to hack my way around the problem in IE8 by using X-UA-Compatible, but I'd rather avoid this solution if at all possible. I don't have access to IE9 for testing but my understanding hacks like PIE aren't necessary and it would be wasteful to force a compatibility mode in a browser that doesn't need it. I have worse issues in IE6, with the PIE layout breaking down completely on a list that is set up to use display:inline; zoom:1; list items (to simulate inline-block, which works in IE8 and the other browsers). Here the borders of the list items get rendered in completely the wrong place. So ideally, I'd like to have PIE work properly in IE6, and in IE8 without having to resort to compatibility mode. As far as IE6 goes, a graceful fallback where PIE is just not applied will do. IE7 is the only browser where the page displays as intended. I can't provide an example page just at the moment unfortunately, I can add one later though. Follow up: Here are some screen grabs made with IE Tester. I'm hoping they will make things a little more clear for everybody. As you can see, IE7 is fine. However, in IE8, the containers are offset to the left relative to their content, and in IE6 the list elements (with the rounded 1 pixel border) are a complete mess! Full size versions for IE8, IE7 and IE6 are also available

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  • DNS protocol message example

    - by virtual-lab
    hello there, I am trying to figure out how to send out DNS messages from an application socket adapter to a DNSBL. I spent the last two days understanding the basics, including experimenting with WireShark to catch an example of message exchanged. Now I would like to query the DNS without using dig or host command (I'm using Ubuntu); how can I perform this action at low level, without the help of these tools in wrapping the request in a proper DNS message format? How the message should be post it? Hex or String? Thanks in advance for any help. Regards Alessandro Ilardo Comment added I am investigating on JDev and Oracle SOA. The platform provides a Socket Adapter which simply apply a transformation (XSLT) and send the message straight to the socket. How the payload parameters (ex. the host I'm looking up) are wrapped within the message is left to the developer. So basically I have an idea on how the all DNS message is structured, but rather than put everything on JDev stright away I'd like to make some tests on my own just to make sure I got a valid message format. So, I am not using any specific language (I don't even understand why they moved my question from serverfault) and I don't want to use any tools which would hide part of the message, such as the header. I know they work well btw. I guess this stuff has something to do with packet injection. Someone suggested me to use telnet, but I've only used for SMTP or HTTP, I haven't got a clue on how it works for DNS request. Does it make more sense now?

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  • Android lifecycle of thread-based game

    - by ehehhh
    I ran into a bit of trouble while trying to get my game to work correctly after being put to the background by the user or a phone call for example. My app has a SurfaceView class called GameView, which has the onDraw() method to do all the necessary drawing for my game and two threads - one for calling the onDraw() and one for doing the necessary calculations for the game's logic. I succesfully implemented onPause() and onResume(). (I paused both threads when back button was pressed and resumed them after user cancelled in the AlertDialog.) Now I would like to have the game paused the same way when onStop() gets called. I put both threads on pause and saved my characters location in the savedInstanceState, but when I start my app again, no method gets called (I checked with Logcat). I believe onRestart() should be called first, then onStart() and then onResume(), but none of that happens. What am I doing wrong? (Didn't include any code, because it seems to be a problem of me not understanding the lifecycle, not a problem in code. If it seems necessary, I'll post the parts you request.)

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  • Freestanding ARM C++ Code - empty .ctors section

    - by Matthew Iselin
    I'm writing C++ code to run in a freestanding environment (basically an ARM board). It's been going well except I've run into a stumbling block - global static constructors. To my understanding the .ctors section contains a list of addresses to each static constructor, and my code simply needs to iterate this list and make calls to each function as it goes. However, I've found that this section in my binary is in fact completely empty! Google pointed towards using ".init_array" instead of ".ctors" (an EABI thing), but that has not changed anything. Any ideas as to why my static constructors don't exist? Relevant linker script and objdump output follows: .ctors : { . = ALIGN(4096); start_ctors = .; *(.init_array); *(.ctors); end_ctors = .; } .dtors : { . = ALIGN(4096); start_dtors = .; *(.fini_array); *(.dtors); end_dtors = .; } -- 2 .ctors 00001000 8014c000 8014c000 00054000 2**2 CONTENTS, ALLOC, LOAD, DATA <snip> 8014d000 g O .ctors 00000004 start_ctors <snip> 8014d000 g O .ctors 00000004 end_ctors I'm using an arm-elf targeted GCC compiler (4.4.1).

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  • problem with two key ranges in couchdb

    - by Duasto
    I'm having problem getting the right results in my coordinate system. To explain my system, I have this simple database that have x_axis, y_axis and name columns. I don't need to get all the data, I just need to display some part of it. For example, I have a coordinate system that have 10:10(meaning from x_axis -10 to 10 and from y_axis -10 to 10) and I want to display only 49 coordinates. In sql query I can do it something like this: "select * from coordinate where x_axis = -3 and x_axis <= 3 and y_axis = -3 y_axis <= 3" I tried this function but no success: "by_range": { "map": "function(doc) { emit([doc.x_axis, doc.y_axis], doc) }" } by_range?startkey=[-3,-3]&endkey=[3,3] I got a wrong results of: -3x-3 -3x-2 -3x-1 -3x0 -3x1 -3x2 -3x3 <-- should not display this part -- -3x4 -3x5 -3x6 -3x7 -3x8 -3x9 -3x10 <-- end of should not display this part -- ..... up to 3x3 to give you a better understanding of my project here is the screenshot of that I want to be made: Oops they don't allowed new poster to post an image img96(dot)imageshack(dot)us/img96/5382/coordinates(dot)jpg <<< just change the "(dot)" to "."

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  • help on developing enterprise level software solutions

    - by wefwgeweg
    there is a specific niche which I would like to target by providing a complete enterprise level software solution.... the problem is, where do i begin ? meaning, i come from writing just desktop software on VB/ASP .net/PHP/mysql and suddenly unfamiliar terms popup like Oracle, SAP Business Information Warehouse, J2EE.... obviously, something is pointing towards Java, is it common for software suites, or solutions to be developed 100% on Java technology and standards? Are there any other platform to build enterprise level software on ? i am still lacking understanding what exactly is "Enterprise level" ? what is sufficient condition to call a software that sells for $199 and then suddenly it's $19,999 for "enterprise" package. I dont understand why there is such a huge discrepancy between "standard" and "enterprise" versions of software. Is it just attempting to bag large corporations on a spending spree ? so why does one choose to develop so called "enterprise" softwares ? is it because of the large inflated price tag you can justify with ? i would also like some more enterpreneural resources on starting your own enterprise software company in a niche.... Thank you for reading, i am still trying to find the right questions.

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  • How do I export a package symbol to a namespace in Perl?

    - by Mike
    I'm having trouble understanding how to export a package symbol to a namespace. I've followed the documentation almost identically, but it seems to not know about any of the exporting symbols. mod.pm #!/usr/bin/perl package mod; use strict; use warnings; require Exporter; @ISA = qw(Exporter); @EXPORT=qw($a); our $a=(1); 1; test.pl $ cat test.pl #!/usr/bin/perl use mod; print($a); This is the result of running it $ ./test.pl Global symbol "@ISA" requires explicit package name at mod.pm line 10. Global symbol "@EXPORT" requires explicit package name at mod.pm line 11. Compilation failed in require at ./test.pl line 3. BEGIN failed--compilation aborted at ./test.pl line 3. $ perl -version This is perl, v5.8.4 built for sun4-solaris-64int

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  • Why won't my Setup Project Perform my Custom Registration Process

    - by Jordan S
    I am trying to write an Setup Project/Installer for a class library driver that I wrote in C# using Visual Studio 2008. The driver project has a section of code that looks like this... [ComRegisterFunction] public static void RegisterASCOM(Type t) { Trace.WriteLine("Registration Started."); DoRegistration(true); } In the driver project Properties - "Assembly Information" I have set checked the box that says Make COM-Visible = true. I added a Setup Project to the solution in VS, added the output dll from the driver project so that it installs on the target machine and set the Register property of the dll to "vsdraCOM". So, my understanding is that when the installer runs it SHOULD execute the methods of the dll that are marked with [COMRegisterFunction]. Using SysInternals Debug View I can monitor when the above code snippet is hit by watching for the "Registration started" text to show up in the window. When I build the solution, I can see the text show up so I know the driver is registering properly. The problem is that when I run the installer, I don't think it is doing the registration bit. I see nothing show up in Debug View. And if i try to access my driver via another application I get an error saying it "Cannot create ActiveX object". Why does the registration not occur during the install process? The driver does register for COM but it does NOT call my custom registration method. Does anyone have and suggestions of what I could be missing? Is there another way I can debug this? (I can provide more code if anyone want's to take a look!!)

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  • Database Programming in C#, returning output from Stored Proc

    - by jpavlov
    I am working at gaining an understanding at how to interface stored procedures with applications. My example is simple, but it doesn't display my columns and rows in the command prompt, instead it display System.Data.SqlClient.SqlDataReader. How do I display the rows from my stored procudure? ----Stored Proc-- ALTER PROCEDURE dbo.SelectID AS SELECT * FROM tb_User; ----- Below is the code: using System; using System.Data.SqlClient; using System.IO; namespace ExecuteStoredProc { class Program { static void Main(string[] args) { SqlConnection cnnUserMan; SqlCommand cmmUser; //SqlDataReader drdUser; //Instantiate and open the connection cnnUserMan = new SqlConnection("Data Source=.\\SQLEXPRESS;AttachDbFilename=c:\\Program Files\\Microsoft SQL Server\\MSSQL10.SQLEXPRESS\\MSSQL\\DATA\\UserDB.mdf; Integrated Security=True;Connect Timeout=30;User Instance=True"); cnnUserMan.Open(); //Instantiate and initialize command cmmUser = new SqlCommand("SelectID", cnnUserMan); cmmUser.CommandType = System.Data.CommandType.StoredProcedure; //drdUser = cmmUser.ExecuteReader(); Console.WriteLine(cmmUser.ExecuteReader()); Console.ReadLine(); } } } Thanks.

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  • PHP Session variable isset(..)=1 after session_start()

    - by Nicsoft
    Hello! I guess I am not understanding the scope of session variables, or the session itself, in PHP, hence this question: This is my code if(!session_id()==""){ echo "Getting rid of session"."</br>"; session_destroy(); } echo "Before session_start(): ".isset($_SESSION["first_date_of_week"])."</br>"; session_start(); echo "After session_start(): ".isset($_SESSION["first_date_of_week"])." ".$_SESSION["first_date_of_week"]->format("Y-m-d")."</br>"; The output is: Before session_start(): After session_start(): 1 2011-01-09 How come that when doing the isset(..) on the session variable it is set directly after starting the session, even though I haven't even used it or set it yet? It does, however, still have the same value as before. Also, session_id()="" since the if-clause is never triggered. I never kill the session, how come it is set to ""? I.e. I refresh the page and expects the session to still be alive. Using the isset(..) function is then pretty useless testing if it has been set already... Thanks in advance! /Niklas

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  • Which web framework or technologies would suit me?

    - by Suraj Chandran
    Hi, I had been working on desktop apps and server side(non web) for some time and now I am diving in to web first time. I plan to write a scalable enterprise level app. I have worked with Java, Javascript, Jquery etc. but I absolutely hate jsp. So is there any framework that focuses on developing enterprise level web apps without jsp. I liked Wicket's approach, but I think there is a little lack of support of dynamic html in it and jquery(yes i looked at wiquery). Also I feel making wicket apps scalable would take some sweat. Can Spring MVC, Struts2 etc. help me make with this with just using say Java, JavaScript, and JQuery. Or are there any other options for me like Wicket. Please do forgive if anything above looks insane, I am still working on my understanding with enterprise web apps. NOTE: If you think that I should take a different direction or approach, please do suggest!

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  • directory resource does not create directory

    - by Dan Tenenbaum
    I have a Vagrantfile that provisions a VM by running a chef recipe. The first resource in the chef recipe is: directory "/downloads" do owner "root" group "root" mode "0755" action :create end # check that it worked: raise "/downloads doesn't exist!" unless File.exists? "/downloads" When I run this at work, it works fine. When I run it at home, it fails, the exception is raised when I check to see if /downloads exists. I'm not sure why this is happening. I would expect it to behave identically, since the underlying Vagrant box is the same both at work and at home. I am a chef newb so perhaps there is something I am not understanding about the order in which the resources are run within my recipe? I would expect them to run in sequential order... I also tried putting a notifies call inside the directory block, where I call another execute block :immediately. That works, but inside the second execute block I test to see whether /downloads has been created and it hasn't. Clearly I'm missing something very basic.

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  • How to write a JOIN statement to combine data from disparate tables

    - by Amarundo
    I have the following 2 procedures that I use as my source for a report. As of now, I'm presenting 2 different tables in my SQL Server Reporting Services 2008 R2 report, because it doesn't let me put them together as they belong to 2 different data sets. I want to present them in a single table, but I have not been successful trying to use JOIN here. How do I do that? NOTE: cName in IAgentQueueStats corresponds to UserId in AgentActivityLog. /*** Aggregate values for Call Center Agents for calls, talk and hold time ***/ /*** The detail/row values is per 30-minute interval ***/ ALTER PROCEDURE [dbo].[sp_IAgentQueueStats_OnlyCalls_Grouped] @p_StartDate datetime, @p_EndDate datetime, @p_Agents varchar(8000) AS SELECT [cName] ,sum([nAnswered]) SumNAnswered ,sum([nAnsweredAcd]) SumNAnsweredAcd ,sum([tTalkAcd]) SumTTalkAcd ,sum([nHoldAcd]) SumNHoldAcd ,sum([tHoldAcd]) SumTHoldAcd ,sum([tAcw]) SumTAcw FROM [I3_IC].[dbo].[IAgentQueueStats] WHERE dIntervalStart between @p_StartDate and DATEADD(s, 86400-1, @p_EndDate) AND CHARINDEX ( cName ,@p_Agents)> 0 AND cReportGroup <> '*' AND cHKey3 = '*' and cHKey4 ='*' AND nEnteredAcd > 0 AND cReportGroup <> 'CCFax Email' GROUP BY cName And here is the second one: /*** Aggregate values for Call Center Agents for status/activity time ***/ /*** The detail/row values is per start-time/end-time ***/ ALTER PROCEDURE [dbo].[sp_AgentActivity_Grouped] @p_StartDate datetime, @p_EndDate datetime, @p_Agents varchar(8000) AS SELECT [UserId],[StatusCategory],SUM([StateDuration]) [StatusDuration] FROM ( SELECT [UserId] ,[StatusGroup] ,[StatusKey] , CASE [StatusKey] WHEN 'Available' THEN 'Productive' WHEN 'Follow Up' THEN 'Productive' WHEN 'Campaign Call' THEN 'Productive' WHEN 'Awaiting Callback' THEN 'Productive' WHEN 'In a Meeting' THEN 'Not Your Fault' WHEN 'Project Work' THEN 'Not Your Fault' WHEN 'At a Training Session'THEN 'Not Your Fault' WHEN 'System Issues' THEN 'Not Your Fault' WHEN 'Test' THEN 'Not Your Fault' WHEN 'At Lunch' THEN 'Non Productive' WHEN 'Available, Forward' THEN 'Non Productive' WHEN 'Available, Follow-Me' THEN 'Non Productive' WHEN 'At Play' THEN 'Non Productive' WHEN 'AcdAgentNotAnswering' THEN 'Non Productive' WHEN 'Do Not Disturb' THEN 'Non Productive' WHEN 'Available, No ACD' THEN 'Non Productive' WHEN 'Away from desk' THEN 'Non Productive' ELSE [StatusKey] END StatusCategory ,stateduration FROM [I3_IC].[dbo].[AgentActivityLog] WHERE [StatusDateTime] between @p_StartDate and DATEADD(s, 86400-1, @p_EndDate) AND CHARINDEX ( [UserId] ,@p_Agents)> 0 AND [StatusKey] not in ('Gone Home','Out of the Office','On Vacation','Out of Town') ) a GROUP BY [UserId],[StatusCategory] ORDER BY [UserId], [StatusCategory] desc BTW, if I take some time to comment/reply on your posts, it's not lack of interest, but of understanding...

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  • Is there a recommended way to communicate scientific/engineering programming to C developers?

    - by ggkmath
    Hi, I have a lot of MATLAB code that needs to get ported to C (execution speed is critical for this work) as part of a back-end process for a web application. When I attempt to outsource this code to a C developer, I assume (correct me if I'm wrong) few C developers also understand MATLAB code (things like indexing and memory management are different, etc.). I wonder if there are any C developers out there that can recommend a procedure for me to follow to best communicate what the code does? For example, should I provide the MATLAB code and explain what it's doing line by line? Or, should I just provide the math/algorithm, explain it in plain English, and let the C developer implement it with this understanding in his/her own way (e.g. can I assume the developer understands how to work with complex math (i.e. imaginary numbers), how to generate histograms, perform an FFT, etc.)? Or, is there a better method? I expect I'm not the first to need to do this, so I wonder if any C developers out there ran into this situation and can share any conventional wisdom how they'd like this task to be transferred? Thanks in advance for any comments.

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  • ListView - Index and Position Behavior upon restart()

    - by tunneling
    I am using a ListView with an ArrayAdapter that holds objects. When I select an item, I am capturing the position and index of the selected item. If I scroll down prior to selection, the position and index represent the location of the item in the list. Selecting that items takes me to another activity. When I use the back button to return to the list, it seems that the ListView get's a new position and index for the visible items. As a result, I can't figure out how to reference the selected item during the restart() of the ListView Activity. I have tried to caputure position and index, but as I've said, they change upon returning to the Activity. Is my understanding of the ListView "redraw" correct? Does it renumber my items based on what's visible? -When in the life cycle is getView() called? Is there a way to force an update to the ListView so that my caputured index still points to the same object? Thanks, Jason

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  • How to change the meaning of pointer access operator

    - by kumar_m_kiran
    Hi All, This may be very obvious question, pardon me if so. I have below code snippet out of my project, #include <stdio.h> class X { public: int i; X() : i(0) {}; }; int main(int argc,char *arv[]) { X *ptr = new X[10]; unsigned index = 5; cout<<ptr[index].i<<endl; return 0; } Question Can I change the meaning of the ptr[index] ? Because I need to return the value of ptr[a[index]] where a is an array for subindexing. I do not want to modify existing source code. Any new function added which can change the behavior is needed. Since the access to index operator is in too many places (536 to be precise) in my code, and has complex formulas inside the index subscript operator, I am not inclined to change the code in many locations. PS : 1. I tried operator overload and came to conclusion that it is not possible. 2. Also p[i] will be transformed into *(p+i). I cannot redefine the basic operator '+'. So just want to reconfirm my understanding and if there are any possible short-cuts to achieve. Else I need fix it by royal method of changing every line of code :) .

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  • VB.NET Two different approaches to generic cross-threaded operations; which is better?

    - by BASnappl
    VB.NET 2010, .NET 4 Hello, I recently read about using SynchronizationContext objects to control the execution thread for some code. I have been using a generic subroutine to handle (possibly) cross-thread calls for things like updating UI controls that utilizes Invoke. I'm an amateur and have a hard time understanding the pros and cons of any particular approach. I am looking for some insight on which approach might be preferable and why. Update: This question is motivated, in part, by statements such as the following from the MSDN page on Control.InvokeRequired. An even better solution is to use the SynchronizationContext returned by SynchronizationContext rather than a control for cross-thread marshaling. Method 1: Public Sub InvokeControl(Of T As Control)(ByVal Control As T, ByVal Action As Action(Of T)) If Control.InvokeRequired Then Control.Invoke(New Action(Of T, Action(Of T))(AddressOf InvokeControl), New Object() {Control, Action}) Else Action(Control) End If End Sub Method 2: Public Sub UIAction(Of T As Control)(ByVal Control As T, ByVal Action As Action(Of Control)) SyncContext.Send(New Threading.SendOrPostCallback(Sub() Action(Control)), Nothing) End Sub Where SyncContext is a Threading.SynchronizationContext object defined in the constructor of my UI form: Public Sub New() InitializeComponent() SyncContext = WindowsFormsSynchronizationContext.Current End Sub Then, if I wanted to update a control (e.g., Label1) on the UI form, I would do: InvokeControl(Label1, Sub(x) x.Text = "hello") or UIAction(Label1, Sub(x) x.Text = "hello") So, what do y'all think? Is one way preferred or does it depend on the context? If you have the time, verbosity would be appreciated! Thanks in advance, Brian

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  • What is the difference between these two linq implementations?

    - by Mahesh Velaga
    I was going through Jon Skeet's Reimplemnting Linq to Objects series. In the implementation of where article, I found the following snippets, but I don't get what is the advantage that we are gettting by splitting the original method into two. Original Method: // Naive validation - broken! public static IEnumerable<TSource> Where<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { if (source == null) { throw new ArgumentNullException("source"); } if (predicate == null) { throw new ArgumentNullException("predicate"); } foreach (TSource item in source) { if (predicate(item)) { yield return item; } } } Refactored Method: public static IEnumerable<TSource> Where<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { if (source == null) { throw new ArgumentNullException("source"); } if (predicate == null) { throw new ArgumentNullException("predicate"); } return WhereImpl(source, predicate); } private static IEnumerable<TSource> WhereImpl<TSource>( this IEnumerable<TSource> source, Func<TSource, bool> predicate) { foreach (TSource item in source) { if (predicate(item)) { yield return item; } } } Jon says - Its for eager validation and then defferring for the rest of the part. But, I don't get it. Could some one please explain it in a little more detail, whats the difference between these 2 functions and why will the validations be performed in one and not in the other eagerly? Conclusion/Solution: I got confused due to my lack of understanding on which functions are determined to be iterator-generators. I assumed that, it is based on signature of a method like IEnumerable<T>. But, based on the answers, now I get it, a method is an iterator-generator if it uses yield statements.

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