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• How does loop address alignment affect the speed on Intel x86_64?

  - by Alexander Gololobov

  I'm seeing 15% performance degradation of the same C++ code compiled to exactly same machine instructions but located on differently aligned addresses. When my tiny main loop starts at 0x415220 it's faster then when it is at 0x415250. I'm running this on Intel Core2 Duo. I use gcc 4.4.5 on x86_64 Ubuntu. Can anybody explain the cause of slowdown and how I can force gcc to optimally align the loop? Here is the disassembly for both cases with profiler annotation: 415220 576 12.56% |XXXXXXXXXXXXXX 48 c1 eb 08 shr $0x8,%rbx 415224 110 2.40% |XX 0f b6 c3 movzbl %bl,%eax 415227 0.00% | 41 0f b6 04 00 movzbl (%r8,%rax,1),%eax 41522c 40 0.87% | 48 8b 04 c1 mov (%rcx,%rax,8),%rax 415230 806 17.58% |XXXXXXXXXXXXXXXXXXX 4c 63 f8 movslq %eax,%r15 415233 186 4.06% |XXXX 48 c1 e8 20 shr $0x20,%rax 415237 102 2.22% |XX 4c 01 f9 add %r15,%rcx 41523a 414 9.03% |XXXXXXXXXX a8 0f test $0xf,%al 41523c 680 14.83% |XXXXXXXXXXXXXXXX 74 45 je 415283 ::Run(char const*, char const*)+0x4b3 41523e 0.00% | 41 89 c7 mov %eax,%r15d 415241 0.00% | 41 83 e7 01 and $0x1,%r15d 415245 0.00% | 41 83 ff 01 cmp $0x1,%r15d 415249 0.00% | 41 89 c7 mov %eax,%r15d 415250 679 13.05% |XXXXXXXXXXXXXXXX 48 c1 eb 08 shr $0x8,%rbx 415254 124 2.38% |XX 0f b6 c3 movzbl %bl,%eax 415257 0.00% | 41 0f b6 04 00 movzbl (%r8,%rax,1),%eax 41525c 43 0.83% |X 48 8b 04 c1 mov (%rcx,%rax,8),%rax 415260 828 15.91% |XXXXXXXXXXXXXXXXXXX 4c 63 f8 movslq %eax,%r15 415263 388 7.46% |XXXXXXXXX 48 c1 e8 20 shr $0x20,%rax 415267 141 2.71% |XXX 4c 01 f9 add %r15,%rcx 41526a 634 12.18% |XXXXXXXXXXXXXXX a8 0f test $0xf,%al 41526c 749 14.39% |XXXXXXXXXXXXXXXXXX 74 45 je 4152b3 ::Run(char const*, char const*)+0x4c3 41526e 0.00% | 41 89 c7 mov %eax,%r15d 415271 0.00% | 41 83 e7 01 and $0x1,%r15d 415275 0.00% | 41 83 ff 01 cmp $0x1,%r15d 415279 0.00% | 41 89 c7 mov %eax,%r15d

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• What algorithm should i follow to retrieve data in the prescribed format?

  - by Prateek

  I have to retrieve data from a database in which tables are consisting of fields like "ttc, rm, atc and lta" namely. Actually these values are stored on daily basis with a 15 min interval like From_time to_time ttc rm atc lta 00:00 00:15 45 10 35 25, 00:15 00:30 35 10 25 25 and so on .. These values are stored for every day of every month and i want it to be previewed in the prescribed format then what algorithm should i follow. I am confused about how to do comparisons for a format like below mentioned. The format is at this link https://drive.google.com/a/itbhu.ac.in/file/d/0B_J0Ljq64i4Za2J1V0lvbDZ4eGc/edit?usp=sharing To be specific once again, my question is, I have to prepare a report from the retrieved data which is being stored in the databases as explained above. But the report which is going to be prepared will be of entire month. So, to say the least, there may be cases that for two particular days the value of "ttc" would be same for some time so i want it to be listed together (as shown in format). And the confusing part is any of the values "ttc", "rm", "atc", "lta" can be same for any particular interval. So what algorithm should i follow for such comparisons. And if still any query with question, u can ask your doubt. Thanks

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• Find items with belongs_to associations in Rails?

  - by dannymcc

  Hi Everyone, I have a model called Kase each "Case" is assigned to a contact person via the following code: class Kase < ActiveRecord::Base validates_presence_of :jobno has_many :notes, :order => "created_at DESC" belongs_to :company # foreign key: company_id belongs_to :person # foreign key in join table belongs_to :surveyor, :class_name => "Company", :foreign_key => "appointedsurveyor_id" belongs_to :surveyorperson, :class_name => "Person", :foreign_key => "surveyorperson_id" I was wondering if it is possible to list on the contacts page all of the kases that that person is associated with. I assume I need to use the find command within the Person model? Maybe something like the following? def index @kases = Person.Kase.find(:person_id) or am I completely misunderstanding everything again? Thanks, Danny EDIT: If I use: @kases= @person.kases I can successfully do the following: <% if @person.kases.empty? %> No Cases Found <% end %> <% if @person.kases %> This person has a case assigned to them <% end %> but how do I output the "jobref" field from the kase table for each record found?

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• Entity Framework and differences between Contains between SQL and objects using ToLower

  - by John Ptacek

  I have run into an "issue" I am not quite sure I understand with Entity Framework. I am using Entity Framework 4 and have tried to utilize a TDD approach. As a result, I recently implemented a search feature using a Repository pattern. For my test project, I am implementing my repository interface and have a set of "fake" object data I am using for test purposes. I ran into an issue trying to get the Contains clause to work for case invariant search. My code snippet for both my test and the repository class used against the database is as follows: if (!string.IsNullOrEmpty(Description)) { items = items.Where(r => r.Description.ToLower().Contains(Description.ToLower())); } However, when I ran my test cases the results where not populated if my case did not match the underlying data. I tried looking into what I thought was an issue for a while. To clear my mind, I went for a run and wondered if the same code with EF would work against a SQL back end database, since SQL will explicitly support the like command and it executed as I expected, using the same logic. I understand why EF against the database back end supports the Contains clause. However, I was surprised that my unit tests did not. Any ideas why other than the SQL server support of the like clause when I use objects I populate in a collection instead of against the database server? Thanks! John

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• Query notation for the sitecore 'source' field in template builder

  - by M.R.

  I am trying to set the the source field of a template using the query notation (or xpath - whichever works), but none of them seems to be working. My content tree is a multisite content tree: France --Page 1 ----Page1A -------Page1AA --Page 2 --Page 3 --METADATA ----Regions US --Page 1 ----Page1A -------Page1AA --Page 2 --Page 3 --METADATA ----Regions Each site has its own METADATA folder, and I want it so that when adding a page inside each of the main country nodes, I want the values to reflect whatever is in the METADATA of that site. I have two different fields for now - a droplink and a treelistex field. So I thought I can just get the parent item that is a country site, and get the metadata folder for that. When I put the following query in both the fields, I get different results: query:./ancestor::*[@@templatename='CountryHome']/METADATA/Regions/* For the droplink field, I get only the first Region (one item) For the treelistex field, I get the entire content tree I then tried to modify the query a little bit and took the 'query' notation out ./ancestor::*[@@templatename='CountryHome']/METADATA/Regions/* If I go to the developer center/xpath builder, and set the context node to any item underneath the main country site, it returns me exactly what I need, but when I put this in the source, I get the entire content tree in both the cases. Help!

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• how to prevent divs from overlapping when using no-wrap across table cells

  - by pedalpete

  I'm trying to create an events calendar which has a somewhat 'gantt' chart like bar representing the times of an event, along with the time listed. I've uploaded a page showing the problem As you can see, the problem is that in the 3rd cell, the event div is being overlapped by the previous event div which goes outside the boundary of the cell. The event from the 2nd cell SHOULD expand beyond the cell border, but what I'm trying to get to happen is that WHEN the event from the 2nd cell expands into the 3rd cell, the event on the 3rd cell starts a new line. I believe the problem exists because of the nowrap on the time, but I want the time and in some cases the bar to cross the cell boundary when the time goes from one day to another. All that works now, but I'm having a problem with events overlapping when an event goes from one day to another. I've tried all sorts of :even cells having a different padding, etc. but all these solutions seem to bring up more problems. Is there a way get the no-wrap to force a new long when it crosses into the next cell? or any other solution to this issue?

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• What MS technology to use for HTTP service returning XML?

  - by Borek

  I need to create a service that: accepts HTTP requests (with query string or HTTP POST parameters) does some processing on the requests (checking if the request is valid, authentication etc.) reads data from a custom store (another HTTP call in our case) returns the result as custom XML (defined with XSD) I'm trying to think of various MS technologies that could help me and how good they would be for this scenario (pretty standard one I guess). The tasks above are relatively separate, this is what comes to mind: HTTP front-end: ASP.NET Web Forms ASP.NET MVC (seems more appropriate here as I won't need server controls, view state etc.) WCF? Don't know much about it or how well it would suit my task. Custom logic on the server: this will probably be a generic C# code in all cases (sometimes "plugged into" or called from MVC controllers or some equivalent place in other technologies) Reading data from internal data stores: As said, this is another HTTP server in our case. Options that come to mind: Just read the data using something like WebClient (Just theoretically) implement a LINQ provider (Just even more theoretically) implement an EF provider Output the data as custom XML: Linq2XML Serialization? Is it flexible enough? Does WCF provide some tools for this? Some "OXM" - Object/XML mapper if there is something like that for .NET I may be wrong in many of my assumptions, this is just a quick list that comes to mind after a quick research. Some general notes / questions: Testing is important Solution with a clear domain model would be much preferred over the one without Can Entity Framework actually help somewhere in my scenario? If so, where and how? Would WCF be an appropriate technology for this? I don't know much about it.

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• How to Avoid PHP Object Nesting/Creation Limit?

  - by Will Shaver

  I've got a handmade ORM in PHP that seems to be bumping up against an object limit and causing php to crash. Here's a simple script that will cause crashes: <? class Bob { protected $parent; public function Bob($parent) { $this->parent = $parent; } public function __toString() { if($this->parent) return (string) "x " . $this->parent; return "top"; } } $bobs = array(); for($i = 1; $i < 40000; $i++) { $bobs[] = new Bob($bobs[$1 -1]); } ?> Even running this from the command line will cause issues. Some boxes take more than 40,000 objects. I've tried it on Linux/Appache (fail) but my app runs on IIS/FastCGI. On FastCGI this causes the famous "The FastCGI process exited unexpectedly" error. Obviously 20k objects is a bit high, but it crashes with far fewer objects if they have data and nested complexity. Fast CGI isn't the issue - I've tried running it from the command line. I've tried setting the memory to something really high - 6,000MB and to something really low - 24MB. If I set it low enough I'll get the "allocated memory size xxx bytes exhausted" error. I'm thinking that it has to do with the number of functions that are called - some kind of nesting prevention. I didn't think that my ORM's nesting was that complicated but perhaps it is. I've got some pretty clear cases where if I load just ONE more object it dies, but loads in under 3 seconds if it works.

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• DSL to generate test data

  - by queen3

  There're several ways to generate data for tests (not only unit tests), for example, Object Mother, builders, etc. Another useful approach is to write test data as plain text: product: Main; prices: 145, 255; Expire: 10-Apr-2011; qty: 2; includes: Sub product: Sub; prices: 145, 255; Expire: 10-Apr-2011; qty: 2 and then parse it into C# objects. This is easy to use in unit tests (because deep inner collections can be written in single line), this is even more convenient to use in FitNesse-like system (because this DSL naturally fits into wiki), and so on. So I use this and write parser, but it's tedious to write each time. I'm not a big expert in DSL/language parsers, but I think they can help here. What would be the right one to use? I only heard about: DSL (I mean, any DSL) Boo (that I think can do DSL) ANTLR but I don't even know which one to pick and where to start. So the question: is it reasonable to use some kind of DSL to generate test data? What would you suggest to do so? Are there any existing cases?

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• Looking for detailed explanation of Hibernate UserType methods for mutable objects

  - by Tom

  I am creating a custom UserType class in Hibernate. The specific case is for an HL7v3 clinical document (I work in health IT). It is a mutable object and most of the documentation around the Hibernate UserType interface seems to center around immutable types. I want a better understanding of how and when the interface methods are used, specifically: assemble - why two parameters (one Serializable, one Object)? What is the use case for this method? disassemble - should I just implement this method to return a serializable form (e.g. String representation)? When and how is this method invoked? equals - is this for update? read? contention? dirty reads? What are the consequences of simply returning false in most cases? replace - I really don't understand where the three Object parameters come from, when this method is invoked, and what Hibernate expects to return, or how that return value is used. Any pointers would be appreciated. I've searched and read all I can find on the subject, but have not found much documentation at all explaining how these methods are used for mutable objects.

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• Mono WCF NetTcp service takes only one client at a time

  - by vene

  While trying to build a client-server WCF application in Mono we ran into some issues. Reducing it to just a bare example we found that the service only accepts one client at a time. If another client attempts to connect, it hangs until the first one disconnects. Simply changing to BasicHttpBinding fixes it but we need NetTcpBinding for duplex communication. Also the problem does not appear if compiled under MS .NET. EDIT: I doubt (and hope not) that Mono doesn't support what I'm trying to do. Mono code usually throws NotImplementedExceptions in such cases as far as I noticed. I am using Mono v2.6.4 This is how the service is opened in our basic scenario: public static void Main (string[] args) { var binding = new NetTcpBinding (); binding.Security.Mode = SecurityMode.None; var address = new Uri ("net.tcp://localhost:8080"); var host = new ServiceHost (typeof(Hello)); host.AddServiceEndpoint (typeof(IHello), binding, address); ServiceThrottlingBehavior behavior = new ServiceThrottlingBehavior () { MaxConcurrentCalls = 100, MaxConcurrentSessions = 100, MaxConcurrentInstances = 100 }; host.Description.Behaviors.Add (behavior); host.Open (); Console.ReadLine (); host.Close (); } The client channel is obtained like this: var binding = new NetTcpBinding (); binding.Security.Mode = SecurityMode.None; var address = new EndpointAddress ("net.tcp://localhost:8080/"); var client = new ChannelFactory<IHello> (binding, address).CreateChannel (); As far as I know this is a Simplex connection, isn't it? The contract is simply: [ServiceContract] public interface IHello { [OperationContract] string Greet (string name); } Service implementation has no ServiceModel tags or attributes. I'll update with details as required.

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• Detecting Connection Speed / Bandwidth in .net/WCF

  - by Mystagogue

  I'm writing both client and server code using WCF, where I need to know the "perceived" bandwidth of traffic between the client and server. I could use ping statistics to gather this information separately, but I wonder if there is a way to configure the channel stack in WCF so that the same statistics can be gathered simultaneously while performing my web service invocations. This would be particularly useful in cases where ICMP is disabled (e.g. ping won't work). In short, while making my regular business-related web service calls (REST calls to be precise), is there a way to collect connection speed data implicitly? Certainly I could time the web service round trip, compared to the size of data used in the round-trip, to give me an idea of throughput - but I won't know how much of that perceived bandwidth was network related, or simply due to server-processing latency. I could perhaps solve that by having the server send back a time delta, representing server latency, so that the client can compute the actual network traffic time. If a more sophisticated approach is not available, that might be my answer...

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• A monkey could do this better - Access to and availability of private member functions in C++

  - by David

  I am wandering the desert of my brain. I'm trying to write something like the following: class MyClass { // Peripherally Related Stuff public: void TakeAnAction(int oneThing, int anotherThing) { switch(oneThing){ case THING_A: TakeThisActionWith(anotherThing); break; //cases THINGS_NOT_A: }; private: void TakeThisActionWith(int thing) { string outcome = new string; outcome = LookUpOutcome(thing); // Do some stuff based on outcome return; } string LookUpOutcome(int key) { string oc = new string; oc = MyPrivateMap[key]; return oc; } map<int, string> MyPrivateMap; Then in the .cc file where I am actually using these things, while compiling the TakeAnAction section, it [CC, the solaris compiler] throws an an error: 'The function LookUpOutcome must have a prototype' and bombs out. In my header file, I have declared 'string LookUpOutcome(int key);' in the private section of the class. I have tried all sorts of variations. I tried to use 'this' for a little while, and it gave me 'Can only use this in non-static member function.' Sadly, I haven't declared anything static and these are all, putatively, member functions. I tried it [on TakeAnAction and LookUp] when I got the error, but I got something like, 'Can't access MyPrivateMap from LookUp'. MyPrivateMap could be made public and I could refer to it directly, I guess, but my sensibility says that is not the right way to go about this [that means that namespace scoped helper functions are out, I think]. I also guess I could just inline the lookup and subsequent other stuff, but my line-o-meter goes on tilt. I'm trying desperately not to kludge it.

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• Practical rules for premature optimization

  - by DougW

  It seems that the phrase "Premature Optimization" is the buzz-word of the day. For some reason, iphone programmers in particular seem to think of avoiding premature optimization as a pro-active goal, rather than the natural result of simply avoiding distraction. The problem is, the term is beginning to be applied more and more to cases that are completely inappropriate. For example, I've seen a growing number of people say not to worry about the complexity of an algorithm, because that's premature optimization (eg http://stackoverflow.com/questions/2190275/help-sorting-an-nsarray-across-two-properties-with-nssortdescriptor/2191720#2191720). Frankly, I think this is just laziness, and appalling to disciplined computer science. But it has occurred to me that maybe considering the complexity and performance of algorithms is going the way of assembly loop unrolling, and other optimization techniques that are now considered unnecessary. What do you think? Are we at the point now where deciding between an O(n^n) and O(n!) complexity algorithm is irrelevant? What about O(n) vs O(n*n)? What do you consider "premature optimization"? What practical rules do you use to consciously or unconsciously avoid it? This is a bit vague, but I'm curious to hear other peoples' opinions on the topic.

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• Image resizing - sometimes very poor quality?!

  - by eWolf

  I'm resizing some images to the screen resolution of the user; if the aspect ratio is wrong, the image should be cut. My code looks like this: protected void ConvertToBitmap(string filename) { var origImg = System.Drawing.Image.FromFile(filename); var widthDivisor = (double)origImg.Width / (double)System.Windows.Forms.Screen.PrimaryScreen.Bounds.Width; var heightDivisor = (double)origImg.Height / (double)System.Windows.Forms.Screen.PrimaryScreen.Bounds.Height; int newWidth, newHeight; if (widthDivisor < heightDivisor) { newWidth = (int)((double)origImg.Width / widthDivisor); newHeight = (int)((double)origImg.Height / widthDivisor); } else { newWidth = (int)((double)origImg.Width / heightDivisor); newHeight = (int)((double)origImg.Height / heightDivisor); } var newImg = origImg.GetThumbnailImage(newWidth, newHeight, null, IntPtr.Zero); newImg.Save(this.GetBitmapPath(filename), System.Drawing.Imaging.ImageFormat.Bmp); } In most cases, this works fine. But for some images, the result has an extremely poor quality. It looks like the would have been resized to something very small (thumbnail size) and enlarged again.. But the resolution of the image is correct. What can I do? Example orig image: Example resized image: Note: I have a WPF application but I use the WinForms function for resizing because it's easier and because I already need a reference to System.Windows.Forms for a tray icon.

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• Is it safe to use random Unicode for complex delimiter sequences in strings?

  - by ccomet

  Question: In terms of program stability and ensuring that the system will actually operate, how safe is it to use chars like ¦, § or ‡ for complex delimiter sequences in strings? Can I reliable believe that I won't run into any issues in a program reading these incorrectly? I am working in a system, using C# code, in which I have to store a fairly complex set of information within a single string. The readability of this string is only necessary on the computer side, end-users should only ever see the information after it has been parsed by the appropriate methods. Because some of the data in these strings will be collections of variable size, I use different delimiters to identify what parts of the string correspond to a certain tier of organization. There are enough cases that the standard sets of ;, |, and similar ilk have been exhausted. I considered two-char delimiters, like ;# or ;|, but I felt that it would be very inefficient. There probably isn't that large of a performance difference in storing with one char versus two chars, but when I have the option of picking the smaller option, it just feels wrong to pick the larger one. So finally, I considered using the set of characters like the double dagger and section. They only take up one char, and they are definitely not going to show up in the actual text that I'll be storing, so they won't be confused for anything. But character encoding is finicky. While the visibility to the end user is meaningless (since they, in fact, won't see it), I became recently concerned about how the programs in the system will read it. The string is stored in one database, while a separate program is responsible for both encoding and decoding the string into different object types for the rest of the application to work with. And if something is expected to be written one way, is possibly written another, then maybe the whole system will fail and I can't really let that happen. So is it safe to use these kind of chars for background delimiters?

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• How can I create a properly sizing QWebView?

  - by chacham15

  I want to make a QWebView appear expanding to the width and height so that ideally it will have no scroll bars. Some websites may have fixed widths that wont allow this, but I am not concerned with those. In any case, I cannot do as I wish because QWebView implements sizeHint as follows: QSize QWebView::sizeHint() const { return QSize(800, 600); // ####... } This is incorrect on a number of levels. 1. It doesnt at all take into account the size of the actual web page. 2. It doesnt take into account that the height and width are related to each other. (To prove #2 think about text in web pages that wraps to the next line.) As a simple fix I tried to do (where QResizingWebView extends QWebView): QSize QResizingWebView::sizeHint() const{ return this-page()-mainFrame()-contentsSize(); } While this is closer to the result, it also has 2 flaws. 1. It doesnt take into account the relation between the displayed width/height. 2. this->page()->mainFrame()->contentsSize() is inaccurate from what I can tell from my preliminary testing (it has returned heights larger than it should under many cases, although this may be related to #1). Does anyone have any tips to fix this?

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• How do I improve this design for dealing with intersecting date ranges and resolving date range conf

  - by derdo

  I am working on some code that deals with date ranges. I have pricing activities that have a starting-date and an end-date to set a certain price for that range. There are multiple pricing activities with intersecting date ranges. What I ultimately need is the ability to query valid prices for a date range. I pass in (jan1,jan31) and I get back a list that says jan1--jan10 $4 , jan11--jan19 $3 jan20--jan31 $4. There are priorities between pricing activities. Some type of pricing activities have high priority, so they override other pricing activities and for certain type of pricing activities lowest price wins etc. I currently have a class that holds these pricing activities and keeps a resolved pricing calendar. As I add new pricing activities I update the resolved calendar. As I write more tests/code, it started to get very complicated with all the different cases (pricing activities intersecting in different ways). I am ending up with very complicated code where I am resolving a newly added pricing activity. See AddPricingActivity() method below. Can anybody think of a simpler way to deal with this? Could there be similar code somewhere out there? Public class PricingActivity() { DateTime startDate; DateTime endDate; Double price; Public bool StartsBeforeEndsAfter (PricingActivity pAct) { // pAct covers this pricing activity } Public bool StartsMiddleEndsAfter (PricingActivity pAct){ // early part of pAct Itersects with later part of this pricing activity } //more similar methods to cover all the combinations of intersecting } Public Class PricingActivityList() { List<PricingActivity> activities; SortedDictionary<Date, PricingActivity> resolvedPricingCalendar; Public void AddPricingActivity(PricingActivity pAct) { //update the resolvedCalendar //go over each activity and find intersecting ones //update the resolved calendar correctly //depending on the type of the intersection //this part is getting out of hand….. } }

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• Conventions for the behavior of double or triple "click to select text" features?

  - by John Sullivan

  Almost any mature program that involves text implements "double click to select the word" and, in some cases, "triple click to select additional stuff like an entire line" as a feature. I find these features useful but they are often inconsistent between programs. Example - some programs' double clicks do not select the ending space after a word, but most do. Some recognize the - character as the end of a word, others do not. SO likes to select the entire paragraph as I write this post when I triple click it, VS web developer 2005 has no triple click support, and ultra-edit 32 will select one line upon triple clicking. We could come up with innumerable inconsistencies about how double and triple click pattern matching is implemented across programs. I am concerned about how to implement this behavior in my program if nobody else has achieved a convention about how the pattern matching should work. My question is, does a convention (conventions? maybe an MS or Linux convention?) exist that dictates how these features are supposed to behave to the end user? What, if any, are they?

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• DataGrid: dynamic DataTemplate for dynamic DataGridTemplateColumn

  - by Lukas Cenovsky

  I want to show data in a datagrid where the data is a collection of public class Thing { public string Foo { get; set; } public string Bar { get; set; } public List<Candidate> Candidates { get; set; } } public class Candidate { public string FirstName { get; set; } public string LastName { get; set; } ... } where the number of candidates in Candidates list varies at runtime. Desired grid layout looks like this Foo | Bar | Candidate 1 | Candidate 2 | ... | Candidate N I'd like to have a DataTemplate for each Candidate as I plan changing it during runtime - user can choose what info about candidate is displayed in different columns (candidate is just an example, I have different object). That means I also want to change the column templates in runtime although this can be achieved by one big template and collapsing its parts. I know about two ways how to achieve my goals (both quite similar): Use AutoGeneratingColumn event and create Candidates columns Add Columns manually In both cases I need to load the DataTemplate from string with XamlReader. Before that I have to edit the string to change the binding to wanted Candidate. Is there a better way how to create a DataGrid with unknown number of DataGridTemplateColumn? Note: This question is based on dynamic datatemplate with valueconverter

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• How does CDI injection work in MDBs and @Scheduled beans?

  - by Nils-Petter Nilsen

  I'm working on a large Java EE 6 application that is deployed on JBoss 6 Final. My current tasks involve using @Inject consistently instead of @EJB, but I'm running into some problems on some types of beans, specifically @MessageDriven beans and beans with @Scheduled methods. What happens is that if I'm unlucky with the timing (for @Schedule) or if there are messages in the MDBs' queues at startup, instantiation of the beans will fail because the injected resources (which are EJBs themselves) are not bound yet. Because I use @Inject, I'm guessing that the EJB container considers my beans to be ready, since the container itself does not care about @Inject; it probably simply assumes that since there are no @EJB injections, the beans are ready for use. The injected CDI proxies will then fail because the resources to inject aren't actually bound yet. Tiny example: @Stateless @LocalBean public class MySupportingBean { public void doSomething() { ... } } @Singleton public class MyScheduledBean { @Inject private MySupportingBean supportingBean; @Schedule(second = "*/1", hour = "*", minute = "*", persistent = false) public void onTimeout() { supportingBean.doSomething(); } } The above example will probably not fail often because there are only two beans, but the project I'm working on binds lots of EJBs, which will amplify the problem. But it might fail because there is no guarantee that MySupportingBean is bound first, and if onTimeout is invoked before MySupportingBean is bound, then instantiation of MyScheduledBean will fail. If I used @EJB instead, MyScheduledBean wouldn't be bound until the dependency to MySupportingBean was satisfied. Note that the example will not fail in onTimeout itself, but when CDI attempts to inject MySupportingBean. I've read a lot of posts on different forums where many people argue that @Inject is always better. Generally, I agree, but how do they handle @Schedule or @MessageDriven combined with @Inject? In my experience, it comes down to dumb luck whether the beans will work or not in those cases, and the beans will fail arbitrarily, depending on which order the EJBs are deployed in, and when @Schedule or onMessage are invoked.

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• Regular expression for finding non-breaking string names in code and then breaking them up for SQL q

  - by Rob Segal

  I am trying to devlop a regex for finding camel case strings in several code files I am working with so I can break them up into separate words for use in a SQL query. I have strings of the form... EmailAddress FirstName MyNameIs And I want them like this... Email Address First Name My Name Is An example SQL query which I currently have is... select FirstName, MyNameIs from MyTables I need the queries in the form... select FirstName as 'First Name', MyNameIs as 'My Name Is' from MyTables Any time a new capital letter appears that should be a new grouping which I can pick out of the matched string. I currently have the following regex... ([A-Z][a-z]+)+ Which does match the cases I have shown above but when I want to perform a replace I need to define groups. Currently I have tried... (([A-Z])([a-z]+))+ Which sort of works. It will pick out "Address" as the first grouping from "EmailAddress" as opposed to "Email" which is what I was expecting. No doubt there is something I'm misunderstanding here so any help is greatly appreciated.

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• Avoiding secondary selects or joins with Hibernate Criteria or HQL query

  - by Ben Benson

  I am having trouble optimizing Hibernate queries to avoid performing joins or secondary selects. When a Hibernate query is performed (criteria or hql), such as the following: return getSession().createQuery(("from GiftCard as card where card.recipientNotificationRequested=1").list(); ... and the where clause examines properties that do not require any joins with other tables... but Hibernate still performs a full join with other tables (or secondary selects depending on how I set the fetchMode). The object in question (GiftCard) has a couple ManyToOne associations that I would prefer to be lazily loaded in this case (but not necessarily all cases). I want a solution that I can control what is lazily loaded when I perform the query. Here's what the GiftCard Entity looks like: @Entity @Table(name = "giftCards") public class GiftCard implements Serializable { private static final long serialVersionUID = 1L; private String id_; private User buyer_; private boolean isRecipientNotificationRequested_; @Id public String getId() { return this.id_; } public void setId(String id) { this.id_ = id; } @ManyToOne @JoinColumn(name = "buyerUserId") @NotFound(action = NotFoundAction.IGNORE) public User getBuyer() { return this.buyer_; } public void setBuyer(User buyer) { this.buyer_ = buyer; } @Column(name="isRecipientNotificationRequested", nullable=false, columnDefinition="tinyint") public boolean isRecipientNotificationRequested() { return this.isRecipientNotificationRequested_; } public void setRecipientNotificationRequested(boolean isRecipientNotificationRequested) { this.isRecipientNotificationRequested_ = isRecipientNotificationRequested; } }

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• Rails running multiple delayed_job - lock tables

  - by pepernik

  Hey. I use delayed_job for background processing. I have 8 CPU server, MySQL and I start 7 delayed_job processes RAILS_ENV=production script/delayed_job -n 7 start Q1: I'm wondering is it possible that 2 or more delayed_job processes start processing the same process (the same record-row in the database delayed_jobs). I checked the code of the delayed_job plugin but can not find the lock directive in a way it should be. I think each process should lock the database table before executing an UPDATE on lock_by column. They lock the record simply by updating the locked_by field (UPDATE delayed_jobs SET locked_by...). Is that really enough? No locking needed? Why? I know that UPDATE has higher priority than SELECT but I think this does not have the effect in this case. My understanding of the multy-threaded situation is: Process1: Get waiting job X. [OK] Process2: Get waiting jobs X. [OK] Process1: Update locked_by field. [OK] Process2: Update locked_by field. [OK] Process1: Get waiting job X. [Already processed] Process2: Get waiting jobs X. [Already processed] I think in some cases more jobs can get the same information and can start processing the same process. Q2: Is 7 delayed_jobs a good number for 8CPU server? Why yes/not. Thx 10x!

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• Different Scala Actor Implementations Overview

  - by Stefan K.

  I'm trying to find the 'right' actor implementation for my thesis. I realized there is a bunch of them and it's a bit confusing to pick one. Personally I'm especially interested in remote actors, but I guess a complete overview would be helpful to many others. This is a pretty general question, so feel free to answer just for the implementation you know about. I know about the following Scala Actor implementations (SAI). Please add the missing ones. Scala 2.7 (difference to) Scala 2.8 Akka (http://www.akkasource.org/) Lift (http://liftweb.net/) Scalaz (http://code.google.com/p/scalaz/) What are the target use-cases for these SAIs (lightweight vs. "heavy" enterprise framework)? do they support remote actors? What shortcomings do remote actors have in the SAIs? How is their performace? How active is there community? How easy are they to get started? How good is the documentation? How easy are they to extend? How stable are they? Which projects are using them? What are their shortcomings? What are their design principles? Are they thread based or event based (receive/ react) or both? Nested receiveS hotswapping the Actor’s message loop

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