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• Multi-table Update(MySQL)

  - by smokinguns

  Hey all, I have a question regarding multi-table update(MySQL). Consider table t1 and t2. The PKEY for t1 is 'tid' which is a foreign Key in t2. There is a field "qtyt2" in t2 which depends on a field called "qtyt1" in table t1. Consider the foll SQL statement: UPDATE t2,t1 SET t2.qtyt2=IF(( t2.qtyt2- t1.qtyt1 )<0,0,( t2.qtyt2- t1.qtyt1 ) ), t1.qtyt1 ="Some value.." where t2.tid="some value.." AND t2.tid=t1.tid In this example qtyt2 depends on qtyt1 for update and the latter itself is updated.Now the result should return 2 if two rows are updated. Is there a guarantee that the fields will be updated in the order in which they appear in the statement( first qtyt2 will be set and then qtyt1).Is it possible that qtyt1 will be set first and then qtyt2? Is the order of tables in the statement important (UPDATE t2, t1 or UPDATE t1,t2)? I found that if I wrote "UPDATE t1,t2" then only t1 would get updated, but on changing the statement to "UPDATE t2,t1" everything worked correctly.

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• F# passing an operator with arguments to a function

  - by dan

  Can you pass in an operation like "divide by 2" or "subtract 1" using just a partially applied operator, where "add 1" looks like this: List.map ((+) 1) [1..5];; //equals [2..6] // instead of having to write: List.map (fun x-> x+1) [1..5] What's happening is 1 is being applied to (+) as it's first argument, and the list item is being applied as the second argument. For addition and multiplication, this argument ordering doesn't matter. Suppose I want to subtract 1 from every element (this will probably be a common beginners mistake): List.map ((-) 1) [1..5];; //equals [0 .. -4], the opposite of what we wanted 1 is applied to the (-) as its first argument, so instead of (list_item - 1), I get (1 - list_item). I can rewrite it as adding negative one instead of subtracting positive one: List.map ((+) -1) [1..5];; List.map (fun x -> x-1) [1..5];; // this works too I'm looking for a more expressive way to write it, something like ((-) _ 1), where _ denotes a placeholder, like in the Arc language. This would cause 1 to be the second argument to -, so in List.map, it would evaluate to list_item - 1. So if you wanted to map divide by 2 to the list, you could write: List.map ((/) _ 2) [2;4;6] //not real syntax, but would equal [1;2;3] List.map (fun x -> x/2) [2;4;6] //real syntax equivalent of the above Can this be done or do I have to use (fun x -> x/2)? It seems that the closest we can get to the placeholder syntax is to use a lambda with a named argument.

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• Why do I have to unserialize this serialized value twice? (wordpress/bbpress maybe_serialize)

  - by 55skidoo

  What am I doing wrong here? I'm serializing a value, storing it in a database (table bb_meta), retrieving it... OK so far... but then I have to unserialize it twice. Shouldn't I be able to just unserialize once? This seems to work, but I'm wondering what point about serialization I'm missing here. //check database to see if user has ever visited before. $querystring = $bbdb->prepare( "SELECT `meta_value` FROM `$bbdb->meta` WHERE `object_type` = %s AND `object_id` = %s AND `meta_key` = %s LIMIT 1", $bbtype, $bb_this_thread, $bbuser ); $bb_last_visits = $bbdb->get_row($querystring, OBJECT); //if $bb_last_visits is empty, add time() as the metavalue using bb_update_meta if (empty($bb_last_visits)) { $first_visit = time(); echo 'serialized first visit: ' . $bb_this_visit_time_serialized = serialize(array($bb_this_thread => $first_visit)); bb_update_meta( $bb_this_thread, $bbuser, $bb_this_visit_time_serialized, $bbtype ); //add to database, bb_meta table echo '$bb_last_visits was empty. Setting first visit time as ' . $bb_this_visit_time_serialized . '<br>'; } else { //else, test by unserializing the data for use. echo 'last visit time already set: '; echo $bb_last_visits->meta_value; echo '<br>'; //fatal error - echo 'unserialized: ' . $bb_last_visits_unserialized = unserialize($bb_last_visits[0]->meta_value); echo '<br>'; echo 'unserialize: ' . $unserialized_visits = unserialize($bb_last_visits->meta_value); echo '<br>'; echo 'hmm, need to unserialize again??: '; echo $unserialized_unserialized_visits = unserialize($unserialized_visits); echo '<br>'; echo 'hey look, it\'s an array value I can finally use now. phew: ' . $unserialized_unserialized_visits[$bb_this_thread]; }

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• Strategies for serializing an object for auditing/logging purpose in .NET?

  - by Jiho Han

  Let's say I have an application that processes messages. Messages are just objects in this case that implements IMessage interface which is just a marker. In this app, if a message fails to process, then I want to log it, first of all for auditing and troubleshooting purposes. Secondly I might want to use it for re-processing. Ideally, I want the message to be serialized into a format that is human-readable. The first candidate is XML although there are others like JSON. If I were to serialize the messages as XML, I want to know whether the message object is XML-serializable. One way is to reflect on the type and to see if it has a parameter-less constructor and the other is to require IXmlSerializable interface. I'm not too happy with either of these approaches. There is a third option which is to try to serialize it and catch exceptions. This doesn't really help - I want to, in some way, stipulate that IMessage (or a derived type) should be xml-serializable. The reflection route has obvious disadvantages such as security, performance, etc. IXmlSerializable route locks down my messages to one format, when in the future, I might want to change the serialization format to be JSON. The other thing is even the simplest objects now must implement ReadXml and WriteXml methods. Is there a route that involves the least amount of work that lets me serialize an arbitrary object (as long as it implements the marker interface) into XML but not lock future messages into XML?

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• ContentControl + RenderTargetBitmap + empty image

  - by Kellls

  Im trying to create some chart images without ever displaying those charts on the screen. I'v been at this for quite a while and tried a lot of different things but nothing seems to work. The code works perfectly if I display the chart in a window first, but if I don't display it in a window, the bitmap is just white with a black border (no idea why). I have tried adding the chart to a border before rendering and giving the border a green borderBrush. In the bitmap, I see the green borderBrush then the black border and white background but no chart. I don't know where the black border is coming from as the chart is not contained in a black border. I have tried adding the chart to a window without calling window.Show() and again just the black boarder and white background. However if I call window.Show() the bitmap contains the chart. I have tried using a drawingVisual as explained here, same result. Here is the code (not including adding the element to a border or window): private static BitmapSource CreateElementScreenshot(FrameworkElement element, int dpi) { if (!element.IsMeasureValid) { Size size = new Size(element.Width, element.Height); element.Measure(size); element.Arrange(new Rect(size)); } element.UpdateLayout(); var scale = dpi/96.0; var renderTargetBitmap = new RenderTargetBitmap ( (int)(scale * element.RenderSize.Width),(int)(scale * element.RenderSize.Height),dpi,dpi,PixelFormats.Default ); // this is waiting for dispatcher to perform measure, arrange and render passes element.Dispatcher.Invoke(((Action)(() => renderTargetBitmap.Render(element))), DispatcherPriority.Render); return renderTargetBitmap; } Note: The chart is a ContentControl. Is there anyway I can get the chart to render without displaying it in a window first?

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• Where to put data management rules for complex data validation in ASP.NET MVC?

  - by TheRHCP

  Hello, I am currently working on an ASP.NET MVC2 project. This is the first time I am working on a real MVC web application. The ASP.NET MVC website really helped me to get started really fast, but I still have some obscure knowledge concerning datamodel validation. My problem is that I do not really know where to manage my filled datamodel when it comes to complex validation rules. For example, validating a string field with a Regex is quite easy and I know that I just have to decorate my field with a specific attribute, so data management rules are implemented in the model. But if I have multiple fields that I need to validate which each other, for example multiple datetime that need to be correctly set following a specific time rule, where do I need to validate them? I know that I could create my own validation attributes, but sometimes validation ask a specific validation path which is to complex to be validated using attributes. This first question also leads me to a related question which is, is it right to validate a model in the controller? Because for the moment that is the only way I found for complex validation. But I find this a bit dirty and I feel it does not really fit a the controller role and much harder to test (multiple code path). Thanks.

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• Recursive Perl detail need help

  - by Catarrunas

  Hi everybody, i think this is a simple problem, but i'm stuck with it for some time now! I need a fresh pair of eyes on this. The thing is i have this code in perl: #!c:/Perl/bin/perl use CGI qw/param/; use URI::Escape; print "Content-type: text/html\n\n"; my $directory = param ('directory'); $directory = uri_unescape ($directory); my @contents; readDir($directory); foreach (@contents) { print "$_\n"; } #------------------------------------------------------------------------ sub readDir(){ my $dir = shift; opendir(DIR, $dir) or die $!; while (my $file = readdir(DIR)) { next if ($file =~ m/^\./); if(-d $dir.$file) { #print $dir.$file. " ----- DIR\n"; readDir($dir.$file); } push @contents, ($dir . $file); } closedir(DIR); } I've tried to make it recursive. I need to have all the files of all of the directories and subdirectories, with the full path, so that i can open the files in the future. But my output only returns the files in the current directory and the files in the first directory that it finds. If i have 3 folders inside the directory it only shows the first one. Ex. of cmd call: "perl readDir.pl directory=C:/PerlTest/" Thanks

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• A copy of ApplicationController has been removed from the module tree but is still active

  - by Matchu

  Whenever two concurrent HTTP requests go to my Rails app, the second always returns the following error: A copy of ApplicationController has been removed from the module tree but is still active! From there it gives an unhelpful stack trace to the effect of "we went through the standard server stuff, ran your first before_filter on ApplicationController (and I checked; it's just whichever filter runs first)", then offers the following: /home/matchu/rails/torch/vendor/rails/activesupport/lib/active_support/dependencies.rb:414:in `load_missing_constant' /home/matchu/rails/torch/vendor/rails/activesupport/lib/active_support/dependencies.rb:96:in `const_missing' which I'm assuming is a generic response and doesn't really say much. Google seems to tell me that people developing Rails Engines will encounter this, but I don't do that. All I've done is upgrade my Rails app from 2.2 (2.1?) to 2.3. What are some possible causes for this error, and how can I go about tracking down what's really going on? I know this question is vague, so would any other information be helpful? More importantly: I tried doing a test run in a "production" environment just now, and the error doesn't seem to persist. Does this only affect development, then, and need I not worry too much?

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• Ruby: what is the pitfall in this simple code excerpt that tests variable existence

  - by zipizap

  I'm starting with Ruby, and while making some test samples, I've stumbled against an error in the code that I don't understand why it happens. The code pretends to tests if a variable finn is defined?() and if it is defined, then it increments it. If it isn't defined, then it will define it with value 0 (zero). As the code threw an error, I started to decompose it in small pieces and run it, to better trace where the error was comming from. The code was run in IRB irb 0.9.5(05/04/13), using ruby 1.9.1p378 First I certify that the variable finn is not yet defined, and all is ok: ?> finn NameError: undefined local variable or method `finn' for main:Object from (irb):134 from /home/paulo/.rvm/rubies/ruby-1.9.1-p378/bin/irb:15:in `<main>' >> Then I certify that the following inline-condition executes as expected, and all is ok: ?> ((defined?(finn)) ? (finn+1):(0)) => 0 And now comes the code that throws the error: ?> finn=((defined?(finn)) ? (finn+1):(0)) NoMethodError: undefined method `+' for nil:NilClass from (irb):143 from /home/paulo/.rvm/rubies/ruby-1.9.1-p378/bin/irb:15:in `<main>' I was expecting that the code would not throw any error, and that after executing the variable finn would be defined with a first value of 0 (zero). But instead, the code thows the error, and finn get defined but with a value of nil. >> finn => nil Where might the error come from?!? Why does the inline-condition work alone, but not when used for the finn assignment? Any help apreciated :)

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• Why might stable_sort be affecting my hashtable values?

  - by zebraman

  I have defined a struct ABC to contain an int ID, string NAME, string LAST_NAME; My procedure is this: Read in a line from an input file. Parse each line into first name and last name and insert into the ABC struct. Also, the struct's ID is given by the number of the input line. Then, push_back the struct into a vector masterlist. I am also hashing these to a hashtable defined as vector< vector , using first name and last name as keywords. That is, If my data is: Garfield Cat Snoopy Dog Cat Man Then for the keyword cash hashes to a vector containing Garfield Cat and Cat Man. I insert the structs into the hashtable using push_back again. The problem is, when I call stable_sort on my masterlist, my hashtable is affected for some reason. I thought it might be happening since the songs are being ordered differently, so I tried making a copy of the masterlist and sorting it and it still affects the hashtable though the original masterlist is unaffected. Any ideas why this might be happening?

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• Deserializing a FileStream on Client using WCF

  - by Grandpappy

  I'm very new to WCF, so I apologize in advance if I misstate something. This is using .NET 4.0 RC1. Using WCF, I am trying to deserialize a response from the server. The base response has a Stream as its only MessageBodyMember. public abstract class StreamedResponse { [MessageBodyMember] public Stream Stream { get; set; } public StreamedResponse() { this.Stream = Stream.Null; } } The derived versions of this class are actually what's serialized, but they don't have a MessageBodyMember attribute (they have other base types such as int, string, etc listed as MessageHeader values). [MessageContract] public class ChildResponse : StreamedResponse { [DataMember] [MessageHeader] public Guid ID { get; set; } [DataMember] [MessageHeader] public string FileName { get; set; } [DataMember] [MessageHeader] public long FileSize { get; set; } public ChildResponse() : base() { } } The Stream is always a FileStream, in my specific case (but may not always be). At first, WCF said FileStream was not a known type, so I added it to the list of known types and now it serializes. It also appears, at first glance, to deserialize it on the client's side (it's the FileStream type). The problem is that it doesn't seem to be usable. All the CanRead, CanWrite, etc are false, and the Length, Position, etc properties throw exceptions when being used. Same with ReadByte(). What am I missing that would keep me from getting a valid FileStream?

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• C# : changing listbox row color?

  - by Meko

  HI. I am trying to changing backround colorof some rows on listbox.I have 2 list that one has all names and it shown on listbox.And second list has some same value with first list.I want to show that when clicking button it will search in listbox and in second list then will change color where found value. I may search in list box like for (int i = 0; i < listBox1.Items.Count; i++) { for (int j = 0; j < students.Count; j++) if (listBox1.Items[i].ToString().Contains(students[j].ToString())) { } } But I don't know which method to change appearances of row.Any help? *EDIT: * HI I made my code like private void ListBox1_DrawItem(object sender, DrawItemEventArgs e) { e.DrawBackground(); Graphics g = e.Graphics; Brush myBrush = Brushes.Black; Brush myBrush2 = Brushes.Red; g.FillRectangle(new SolidBrush(Color.Silver), e.Bounds); e.Graphics.DrawString(listBox1.Items[e.Index].ToString(), e.Font, myBrush, e.Bounds, StringFormat.GenericDefault); for (int i = 0; i < listBox1.Items.Count; i++) { for (int j = 0; j < existingStudents.Count; j++) if (listBox1.Items[i].ToString().Contains(existingStudents[j])) { e.Graphics.DrawString(listBox1.Items[i].ToString(), e.Font, myBrush2, e.Bounds, StringFormat.GenericDefault); } } e.DrawFocusRectangle(); } Now it draws my list on listbox.But when I click button first it shows only student that in list with red color but when I click on listbox it again draws all elements.I want that it will show all element ,when I click button it will show all elements and founded element in list with red color.Whre is my mistake?

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• Saving twice don't update my object in JDO

  - by Javi

  Hello I have an object persisted in the GAE datastore using JDO. The object looks like this: public class MyObject implements Serializable, StoreCallback { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String id; @Persistent private String firstId; ... } As usually when the object is stored for the first time a new id value is generated for the identifier. I need that if I don't provide a value for firstId it sets the same value as the id. I don't want to solve it with a special getter which checks for null value in firstId and then return the id value because I want to make queries relating on firstId. I can do it in this way by saving the object twice (Probably there's a better way to do this, but I'll do it in this way until I find a better one). But it is not working. when I debug it I can see that result.firstId is set with the id value and it seems to be persisted, but when I go into the datastore I see that firstId is null (as it was saved the first time). This save method is in my DAO and it is called in another save method in the service annotated with @Transactional. Does anyone have any idea why the second object in not persisted properly? @Override public MyObject save(MyObject obj) { PersistenceManager pm = JDOHelper.getPersistenceManagerFactory("transactions-optional"); MyObject result = pm.makePersistent(obj); if(result.getFirstId() == null){ result.setFirstId(result.getId()); result = pm.makePersistent(result); } return result; } Thanks.

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• Ordered delivery with NetNamedPipeBinding using oneWay calls

  - by Aseem Bansal

  Is it possible to guarantee ordered delivery with oneWay calls using namedPipe binding? I have a WCF service/client communicating using namedPipe binding. The client is exposing a callback contract in which all the methods in the callback are marked as OneWay. Something like this [ServiceContract(CallbackContract = typeof(IMyServiceCallback))] public interface IMyService { [OperationContract] void MyOperation(); } public interface IMyServiceCallback { [OperationContract(IsOneWay=true)] void MyCallback1(); [OperationContract(IsOneWay=true)] void MyCallback2(); } At the server side, the implementation of MyOperation method always calls MyCallback1 first and then MyCallback2 but I am observing that sometimes the client receives the calls in the incorrect order (MyCallback2 first and then MyCallback1). On searching the internet I found that the order is not guaranteed with oneway operation as mentioned here and also there is something called reliableSession which ensure message ordering. All the examples on the internet for reliable session are with TCP binding (and not a single one with NamedPipeBinding) and the tcpBinding also has a property called ReliableSession which is not present on the NetNamedPipeBinding. So I am not sure whether reliable session is expected to work with NetNamedPipeBinding or not. Question: Does reliable session work with namedPipeBinding? If yes, how? If no, Is there any other approach with which I can guarantee ordered delivery?

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• how to access a type defined in one .ml file in another .ml file

  - by user339261

  Hi, I m very new to ocaml and i m facing the problem below, In a.ml a record type t is defined and is also defined transparently in a.mli, i.e. in d interface so that the type definition is available to all other files. a.ml also has a function, func, which returns a list of t. Now in another file, b.ml i m calling func, now obviously ocaml compiler wud nt be able to infer d type of objects stored in d list, for compiler its just a list. so in b.ml, i hav something like dis, let tlist = A.func in let vart = List.hd tlist in printf "%s\n" vart.name (name is a field in record t) Now here i get a compiler error sayin "Unbound record field label name" which makes sense as compiler can't infer d type of vart. my first question: how do I explicitly provide d type of vart as t here? i tried doing "let vart:A.t = " but got the same error. I also tried creating another function to fetch the first element of d list and mentioning return type as A.t, but then i got the "Unbound value A.t". I did this: let firstt = function [] - 0 | x :: _ - A.t x ;; The problem is compiler is unable to recognize A.t (a type) in b.ml but is able to recognize function A.func. If I remove A.t from the b.ml, i don'get any compiler errors. Please help, its urgent work. Thanks in advance! ~Tarun

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• WPF - binding ElementName problem...

  - by zvi

  Hello First Sorry for my English. I wanted to ask why ElementName does not work the first case, and work in the second. I give the two sections of code . the firts not work <Button Name="button1" Width="100" > <Button.LayoutTransform> <ScaleTransform x:Name="ttt" ScaleX="3" ScaleY="6"/> </Button.LayoutTransform> <Button.Triggers> <EventTrigger RoutedEvent="Path.Loaded"> <EventTrigger.Actions> <BeginStoryboard> <Storyboard RepeatBehavior="Forever"> <DoubleAnimation Storyboard.Target="{Binding ElementName=ttt}" Storyboard.TargetProperty="ScaleX" From="10" To="5" Duration="0:0:1" /> </Storyboard> </BeginStoryboard> </EventTrigger.Actions> </EventTrigger> </Button.Triggers> Button </Button> But it does work <Button Name="button1" Width="100" > <Button.LayoutTransform> <ScaleTransform x:Name="ttt" ScaleX="3" ScaleY="6"/> </Button.LayoutTransform> <Button.Triggers> <EventTrigger RoutedEvent="Path.Loaded"> <EventTrigger.Actions> <BeginStoryboard> <Storyboard RepeatBehavior="Forever"> <DoubleAnimation Storyboard.Target="{Binding ElementName=button1}" Storyboard.TargetProperty="Width" From="100" To="50" Duration="0:0:1" /> </Storyboard> </BeginStoryboard> </EventTrigger.Actions> </EventTrigger> </Button.Triggers> Button </Button> I know I can use Storyboard.TargetName .

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• rails i18n - translating text with inside.

  - by egarcia

  Hi there! I'd like to i18n a text that looks like this: Already signed up? Log in! Note that there is a link on the text. On this example it points to google - in reality it will point to my app's log_in_path. I've found two ways of doing this, but none of them looks "right". The first way I know involves having this my en.yml: log_in_message: "Already signed up? <a href='{{url}}'>Log in!</a>" And in my view: <p> <%= t('log_in_message', :url => login_path) %> </p> This works, but having the <a href=...</a> part on the en.yml doesn't look very clean to me. The other option I know is using localized views - login.en.html.erb, and login.es.html.erb. This also doesn't feel right since the only different line would be the aforementioned one; the rest of the view (~30 lines) would be repeated for all views. It would not be very DRY. I guess I could use "localized partials" but that seems too cumberstone; I think I prefer the first option to having so many tiny view files. So my question is: is there a "proper" way to implement this?

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• Problem with EDM in ASP.NET MVC

  - by Mannsi

  Hello, I have a question that is pretty similar to this question: http://stackoverflow.com/questions/899734/strongly-typed-asp-net-mvc-with-entity-framework but the solutions for that question don't work for me. Let me start by saying that I don't know a great deal about the subject I am asking about. I have the following code [AcceptVerbs(HttpVerbs.Post)] public ActionResult Edit(PaymentInformation paymentInformationToEdit, int pensionFundID) { var originalPaymentInformation = (from PIs in _db.PaymentInformation where PIs.employeeNumber == paymentInformation.employeeNumber select PIs).First(); var laborUnion = (from LUs in _db.LaborUnion where LUs.laborUnionID = laborUnionID select LUs)First(); paymentInformationToEdit.laborUnion = laborUnion; _db.ApplyProperyChanges(originalPaymentInformation.EntityKey.EntitySetName, paymentInformationToEdit); _db.SaveChanges(); } I get an error when I try for the ApplyProperyChanges saying 'The existing object in the ObjectContext is in the Added state. Changes can only be applied when the existing object is in an unchanged or modified state'. I don't know how to change the state to either, or even if I am doing something fundamentally wrong. Please advice. EDIT: I hope this is the way to go here on stackoverflow. I haven't gotten an answer that solved my problem but Gregoire below posted a possible solution that I didn't understand. I hope this edit bumps my question so somebody will see it and help me. Sorry if this is not the way to go.

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• Laravel 4 showing all field from one to one relationship in

  - by rivai04

  I'm trying to show all field of the chosen row from one to one relationship... Route Route::get('relasi-pasien', function() { $pasien = PasienIri::where('no_ipd', '=', '100')->first(); foreach($pasien->keadaanumum as $temp) { echo'<li> Name : '.$temp->name. 'Tekdar: '.$temp->tekdar. 'Nadi : '.$temp->nadi. '</li>'; } }); Relation at PasienIri's model public function keadaanumum() { return $this->hasOne('KeadaanUmum', 'no_ipd'); } Relation at KeadaanUmum's Model public function pasieniri() { return $this->belongsTo('PasienIri', 'no_ipd'); } When I used that way, it showed error: 'Trying to get property of non-object' But if I just trying to show only one of the field, it works, showing one field: Route::get('relasi-pasien', function() { $pasien = PasienIri::where('no_ipd', '=', '100')->first(); return $pasien->keadaanumum->name; }); anyone could help me to show all field with one to one relationship or I really have to change it to one to many relationship? cause if I change it to one to many relationship, it works

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• How does initializing inherited members inside base class constructor reduce the calls to…?

  - by flockofcode

  I’ve read that instead of initializing inherited members ( _c1 in our example ) inside derived constructor: class A { public int _c; } class B:A { public B(int c) { _c = c; } } we should initialize them inside base class constructor, since that way we reduce the calls to inherited members ( _c ): class A { public A(int c) { _c = c; } public int _c; } class B:A { public B(int c) : base(c) { } } If _c field is initialized inside base constructor, the order of initialization is the following: 1) First the field initializers of derived class B are called 2) Then field initializers of base class A are called (at this point _c is set to value 0) 3) B’s constructor is called, which in turn calls A’s custom constructor 4) _c field gets set to value of a parameter c ( inside A’s custom constructor ) 5) Once A’s custom constructor returns, B’s constructor executes its code. If _c field is initialized inside B's constructor, the order of initialization is the following: 1) First the field initializers of a derived class B are called 2) Then field initializers of a base class A are called(at this point _c is set to value 0) 3) B’s constructor is called, which in turn calls A’s default constructor 4) Once A’s custom constructor returns, B’s constructor sets _c field to a value of parameter c As far as I can tell, in both cases was _c called two times, so how exactly did we reduce calls to inherited member _c? thanx

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• GET params in ruby-on-rails project - best practices?

  - by Lynn C

  I've inherited a little rails app and I need to extend it slightly. It's actually quite simple, but I want to make sure I'm doing it the right way... If I visit myapp:3000/api/persons it gives me a full list of people in XML format. I want to pass param in the URL so that I can return users that match the login or the email e.g. yapp:3000/api/persons?login=jsmith would give me the person with the corresponding login. Here's the code: def index if params.size > 2 # We have 'action' & 'controller' by default if params['login'] @person = [Person.find(:first, :conditions => { :login => params['login'] })] elsif params['email'] @persons = [Person.find(:first, :conditions => { :email => params['email'] })] end else @persons = Person.find(:all) end end Two questions... Is it safe? Does ActiveRecord protect me from SQL injection attacks (notice I'm trusting the params that are coming in)? Is this the best way to do it, or is there some automagical rails feature I'm not familiar with?

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• Javascript: prototypal inheritance and the prototype property

  - by JanD

  Hi, I have a simple code fragment in JS working with prototype inheritance. function object(o) { function F() {} F.prototype = o; return new F(); } //the following code block has a alternate version var mammal = { color: "brown", getColor: function() { return this.color; } } var myCat = object(mammal); myCat.meow = function(){return "meow";} that worked fine but adding this: mammal.prototype.kindOf = "predator"; does not. ("mammal.prototype is undefined") Since I guessed that object maybe have no prototype I rewrote it, replacing the var mammal={... block with: function mammal() { this.color = "brown"; this.getColor = function() { return this.color; } } which gave me a bunch of other errors: "Function.prototype.toString called on incompatible object" and if I try to call _myCat.getColor() "myCat.getColor is not a function" Now I am totally confused. After reading Crockford, and Flanagan I did not get the solution for the errors. So it would be great if somebody knows... - why is the prototype undefined in the first example (which is foremost concern; I thought the prototype of explicitly set in the object() function) - why get I these strange errors trying to use the mammal function as prototype object in the object() function? Edit by the Creator of the Question: These two links helped a lot too: Prototypes_in_JavaScript on the spheredev wiki explains the way the prototype property works relativily simple. What it lacks is some try-out code examples. Some good examples are provided by Morris John's Article. I personally find the explanations are not that easy as in the first link, but still very good. The most difficult part even after I actually got it is really not to confuse the .prototype propery with the internal [[Prototype]] of an object.

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• T-SQL Table Joins - Unique Situation

  - by Dimitri

  Hello Everyone. This is my first time encountering the case like this and don't quite know how to handle. Situation: I have one table tblSettingsDefinition, with fields: ID, GroupID, Name, typeID, DefaultValue. Then I have tblSettingtypes with fields TypeID, Name. And I have final table, tblUserSettings with fields SettingID, SettingDefinitionID, UserID, Value. The whole point of this is to have customizable settings. Setting can be defined for a Group or as global setting (if GroupID is NULL). It will have a default value, but if user modifies the setting, an entry is added to tblUserSettings that stores new value. I want to have a query that grabs user settings by first looking at the tblUserSettings, and if it has records for the given user, grabs them, if not retrieves default settings. But the trick is that no matter if user has settings or not, I need to have fields from other two table retrieved to know the setting's Type, Name etc... (which are stored in those other tables). I'm writing query something like this: SELECT * FROM tblSettingDefinition SD LEFT JOIN tblUserSettings US ON SD.SettingID = US.SettingDefinitionID JOIN tblSettingTypes ST ON SD.TypeID=ST.ID WHERE US.UserID=@UserID OR ((SD.GroupID IS NULL) OR (SD.GroupID=(SELECT GroupID FROM tblUser WHERE ID=@UserID))) but it retrieves settings for all users from tblUserSettings instead of just ones that match current @UserID. And if @UserID has no records in tblUserSettings, still, all user settings are retrieved instead of the defaults from tblSettingDefinition. Hope I made myself clear. Any help would be highly appreciated. Thank you.

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• Can FluentNHibernate be used with .Net4?

  - by stiank81

  I have a WPF application running with .Net3.5 using FluentNHibernate, and all works fine. When I upgraded to VS2010 I ran into some odd problems, but after changing to use x64 variant of SQLite it worked fine again. Now I want to change to use .Net4, but this has turned into a more painful experience then I expected.. First I met a problem which required that I set a [SecurityCritical] attribute. Fine - I fixed this. But the reason this was exposed was because an exception was thrown in the first place. And the exception thrown was the following - when calling FluentConfiguration.BuildConfiguration: FluentConfigurationException unhandled An invalid or incomplete configuration was used while creating a SessionFactory. Check PotentialReasons collection, and InnerException for more detail The inner exception gives us more information: Message = "Could not create the driver from NHibernate.Driver.SQLite20Driver, NHibernate, Version=2.1.2.4000, Culture=neutral, PublicKeyToken=aa95f207798dfdb4." This is what I saw in my own project when moving to VS2010. I have tried changing Fluent to use the x64 variant of SQLite, but this doesn't change anything. Does it sound like it might be related to mixing of 32bit and 64bit assemblies? I see that there are also others that have seen this problem, but I haven't really seen any solution yet. Anyone out there using Fluent with .Net4 and SQLite - on a 64bit machine - successfully? Help! I'm lost...

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• Aggregating, restructuring hourly time series data in R

  - by Advait Godbole

  I have a year's worth of hourly data in a data frame in R: > str(df.MHwind_load) # compactly displays structure of data frame 'data.frame': 8760 obs. of 6 variables: $ Date : Factor w/ 365 levels "2010-04-01","2010-04-02",..: 1 1 1 1 1 1 1 1 1 1 ... $ Time..HRs. : int 1 2 3 4 5 6 7 8 9 10 ... $ Hour.of.Year : int 1 2 3 4 5 6 7 8 9 10 ... $ Wind.MW : int 375 492 483 476 486 512 421 396 456 453 ... $ MSEDCL.Demand: int 13293 13140 12806 12891 13113 13802 14186 14104 14117 14462 ... $ Net.Load : int 12918 12648 12323 12415 12627 13290 13765 13708 13661 14009 ... While preserving the hourly structure, I would like to know how to extract a particular month/group of months the first day/first week etc of each month all mondays, all tuesdays etc of the year I have tried using "cut" without result and after looking online think that "lubridate" might be able to do so but haven't found suitable examples. I'd greatly appreciate help on this issue.

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