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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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• 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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• 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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• 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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• 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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• 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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• 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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• 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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• 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 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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• 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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• 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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• Internet Radio Station for University

  - by ryan

  I am trying to help my University Student Radio station rethink the setup of the way they stream music, but I have some questions regarding the use of Ubuntu to stream music. Currently, the radio station uses two windows machines: one of which is used to stream the radio station and serve the website, and the other is used by rotating djs to select songs and create playlists. The computer used by djs feeds mono into the sound card of the server and the server streams the feed online. -Ideally I would like to maintain a two-computer setup: One computer as server, and another that is used to select and play music by rotating djs. -I would like to use Ubuntu for the server. -I would like to use Windows for the other machine. -The server should be able to stream song information. First, is there a way to somehow get the song information from an analog feed? Second, what is the best streaming server for radio? I have encountered shoutcast, icecast, and darwin, but I don't know where to begin in attempting to gauge them. Finally, if anyone has any tips or pointers about small internet radio station management/ setup they would be appreciated as this is my first radio station, and I am eager to hear of past experiences.

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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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• TypeError: Error #1009 - (Null reference error) With Flash.

  - by Wind Chimez

  I am not an expert in flash, but i do work with AS and tweak Flash projects , though not having deep expertise in it. Currently i need to revamp a flash website done by one another guy, and the code base given to me, upon execution is throwing the following error. "--- TypeError: Error #1009: Cannot access a property or method of a null object reference. at NewSite_fla::MainTimeline/__setProp_ContactOutP1_ContactOut_Contents_0() at NewSite_fla::MainTimeline/frame1() --" The structure of the project is like, it has the different sections split into different movie clips. There is no single main timeline, but click actions on different areas of seperate movie clips will take them between one another. All the AS logic of event handling are written inline in FLA , no seperate Document class exists. Preloader Movie clip is the first one getting loaded. As i understood the error is getting thrown initially itself, and it is not happening due to any Action script logic written inline, because it is throwing error even before hitting the first inline AS code. I am not able to figure Out what exactly it causing the problem, or where to resolve it. I setup the stuff online, for reference if anybody want to take a look at it, and here is the link.You need to have flash debugger turned ON in your browser, if need to see the exception getting triggered. http://tinyurl.com/2alvlfx I really got stuck at this point. Any help will be great.I had not seen the particular solution i am looking for anywhere yet, though Error #1009 is common.

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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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• Is it possible to update old database from dbml file ? (C#, .Net 4, Linq, SQL Server)

  - by Emil

  Hi all, I began recently a new job, a very interesting project (C#,.Net 4, Linq, VS 2010 and SQL Server). And immediately I got a very exciting challenge: I must implement either a new tool or integrate the logic when program start, or whatever, but what must happen is the following: the customers have previous application and database (full with their specific data). Now a new version is ready and the customer gets the update. In the mean time we made some modification on DB (new table, columns, maybe an old column deleted, or whatever). I’m pretty new in Linq and also SQL databases and my first solution can be: I check the applications/databases version and implement all the changes step by step comparing all tables, columns, keys, constrains, etc. (all this new information I have in my dbml and the old I asked from the existing DB). And I’ll do this each time the version changed. But somehow I feel, this is NOT a smart solution so I look for a general solution of this problem. Is there a way to update customers DB from the dbml file? To create a new one is not a problem (CreateDatabase with DataContext), is there any update/alter database methods? I guess I’m not the only one who search for such a solution (I found nothing in internet – or I looked for bad keywords). How did you solve this problem? I look also for an external tool, but first for a solution with C#, Linq or something similar. For any idea thank you in advance! Best regards, Emil

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• Finding intersection of two spheres

  - by Onkar Deshpande

  Hi, Consider the following problem - I am given 2 links of length L0 and L1. P0 is the point that the first link starts at and P1 is the point that I want the end of second link to be at in 3-D space. I am supposed to write a function that should take in these 3-D points (P0 and P1) as inputs and should find all configurations of the links that put the second link's end point at P1. My understanding of how to go about it is - Each link L0 and L1 will create a sphere S0 and S1 around itself. I should find out the intersection of those two spheres (which will be a circle) and print all points that are on the circumference of that circle. I saw gmatt's first reply on the http://stackoverflow.com/questions/1406375/finding-intersection-points-between-3-spheres but could not understand it properly since the images did not show up. I also saw a formula for finding out the intersection at mathworld[dot]wolfram[dot]com/Sphere-SphereIntersection[dot]html . I could find the radius of intersection by the method given on mathworld. Also I can find the center of that circle and then use the parametric equation of circle to find the points. The only doubt that I have is will this method work for the points P0 and P1 mentioned above ? Please comment and let me know your thoughts.

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• Entity framework memory leak after detaching newly created object

  - by Tom Peplow

  Hi, Here's a test: WeakReference ref1; WeakReference ref2; TestRepositoryEntitiesContainer context; int i = 0; using (context = GetContext<TestRepositoryEntitiesContainer>()) { context.ObjectMaterialized += (o, s) => i++; var item = context.SomeEntities.Where(e => e.SomePropertyToLookupOn == "some property").First(); context.Detach(item); ref1 = new WeakReference(item); var newItem = new SomeEntity {SomePropertyToLookupOn = "another value"}; context.SomeEntities.AddObject(newItem); ref2 = new WeakReference(newItem); context.SaveChanges(); context.SomeEntities.Detach(newItem); newItem = null; item = null; } context = null; GC.Collect(); Assert.IsFalse(ref1.IsAlive); Assert.IsFalse(ref2.IsAlive); First assert passes, second fails... I hope I'm missing something, it is late... But it appears that detaching a fetched item will actually release all handles on the object letting it be collected. However, for new objects something keeps a pointer and creates a memory leak. NB - this is EF 4.0 Anyone seen this before and worked around it? Thanks for your help! Tom

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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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• 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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• 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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• emacs: x-popup-menu max size constraints?

  - by Cheeso

  I'm working on an intellisense or code-completion capability for C#. So far, so good. Right now I have basic completion working. There are 2 ways to request completion. The first cycles through all the potential matches. The second presents a popup menu of the matches. It works for types: And also for local variables: I'm confronting two problems with x-popup-menu: the popup menu can expand to consume all available screen space, when the number of choices is large. Literally it can obscure the entire screen. The silly thing is, it's scrollable. First it expands to consume all available space, then it also becomes scrollable. Is there a way I can limit the maximum size of x-popup-menu? To specify the position of the popup menu, I pass in a position, and x-popup-menu uses that as the *middle*, not the left, of the top line of the menu. Why middle? who knows. What this means is, if I specify (40 . 60) for the location of the menu, and the menu happens to be 100 pixels wide, the menu will extend beyond the left border of the emacs window. You can see this in the 2nd image above. If I knew how wide the popup would be before specifying the position, I could compensate. But I don't. Is there a workaround? Is there a way to get x-popup-menu to take its position as the LEFT rather than the middle.

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• How can I choose different hints for different joins for a single table in a query hint?

  - by RenderIn

  Suppose I have the following query: select * from A, B, C, D where A.x = B.x and B.y = C.y and A.z = D.z I have indexes on A.x and B.x and B.y and C.y and D.z There is no index on A.z. How can I give a hint to this query to use an INDEX hint on A.x but a USE_HASH hint on A.z? It seems like hints only take the table name, not the specific join, so when using a single table with multiple joins I can only specify a single strategy for all of them. Alternative, suppose I'm using a LEADING or ORDERED hint on the above query. Both of these hints only take a table name as well, so how can I ensure that the A.x = B.x join takes place before the A.z = D.z one? I realize in this case I could list D first, but imagine D subsequently joins to E and that the D-E join is the last one I want in the entire query. A third configuration -- Suppose I want the A.x join to be the first of the entire query, and I want the A.z join to be the last one. How can I use a hint to have a single join from A to take place, followed by the B-C join, and the A-D join last?

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• Which non-clustered index should I use?

  - by Junior Mayhé

  Here I am studying nonclustered indexes on SQL Server Management Studio. I've created a table with more than 1 million records. This table has a primary key. CREATE TABLE [dbo].[Customers]( [CustomerId] [int] IDENTITY(1,1) NOT NULL, [CustomerName] [varchar](100) NOT NULL, [Deleted] [bit] NOT NULL, [Active] [bit] NOT NULL, CONSTRAINT [PK_Customers] PRIMARY KEY CLUSTERED ( [CustomerId] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] This is the query I'll be using to see what execution plan is showing: SELECT CustomerName FROM Customers Well, executing this command with no additional non-clustered index, it leads the execution plan to show me: I/O cost = 3.45646 Operator cost = 4.57715 Now I'm trying to see if it's possible to improve performance, so I've created a non-clustered index for this table: 1) First non-clustered index CREATE NONCLUSTERED INDEX [IX_CustomerID_CustomerName] ON [dbo].[Customers] ( [CustomerId] ASC, [CustomerName] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO Executing again the select against Customers table, the execution plan shows me: I/O cost = 2.79942 Operator cost = 3.92001 It seems better. Now I've deleted this just created non-clustered index, in order to create a new one: 2) First non-clustered index CREATE NONCLUSTERED INDEX [IX_CustomerIDIncludeCustomerName] ON [dbo].[Customers] ( [CustomerId] ASC ) INCLUDE ( [CustomerName]) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] GO With this new non-clustered index, I've executed the select statement again and the execution plan shows me the same result: I/O cost = 2.79942 Operator cost = 3.92001 So, which non-clustered index should I use? Why the costs are the same on execution plan for I/O and Operator? Am I doing something wrong or this is expected? thank you

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