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  • Why should "miter" joints be slower than others?

    - by Hanno Fietz
    I'm having a graphics problem on drawing lines in Flash Player, where two lines drawn on top of each other with different thickness don't align properly if I use any other JointStyle than MITER. For pictures of the effect, and for the graphics oriented part of the question, see my post over on doctype. However, there's also a second angle on this problem, which is: why should drawing the "mitered" joints be so much slower than others? This seems to be a problem since at least FP 8, but I couldn't find any detailed info on what the problem might be. Is this just an ordinary bug that didn't get fixed yet, or is there something inherently slower about drawing these joints? For example, they seem to have something to do with square roots, but I seriously lack understanding of what this joint style thing is all about, technically. It just looks like some minor detail a graphic designer might worry about. I'm asking because I'm wondering if I can do something to mitergate, er, mitigate, the problem.

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  • Overloading on return type ???

    - by Green Hyena
    scala> val shares = Map("Apple" -> 23, "MicroSoft" -> 50, "IBM" -> 17) shares: scala.collection.immutable.Map[java.lang.String,Int] = Map(Apple -> 23, MicroSoft -> 50, IBM -> 17) scala> val shareholders = shares map {_._1} shareholders: scala.collection.immutable.Iterable[java.lang.String] = List(Apple, MicroSoft, IBM) scala> val newShares = shares map {case(k, v) => (k, 1.5 * v)} newShares: scala.collection.immutable.Map[java.lang.String,Double] = Map(Apple -> 34.5, MicroSoft -> 75.0, IBM -> 25.5) From this example it seems like the map method is overloaded on return type. Overloading on return type is not possible right? Would somebody please explain what's going on here?

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  • How to handle ViewData type casting in MVC

    - by Wondering
    Hi All, I am new to MVC and facing one issue. I have a xml file and i am retrieving its value using Linq to xml and assigning it to ViewData. Controller.cs var res=from x in doc.Descendants("person") select new { Fname=x.Element("fname").Value, Lname=x.Element("lname").Value }; ViewData["Persons"]=res; in View I am trying <% foreach (var item in ViewData["Persons"]) { %> <li> <%= item.Fname %> </li> <% } %> but foreach (var item in ViewData["Persons"] is giving type casting error..what should be the exact type csting so that i can retrive values in the format item.Fname. Thanks.

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  • Problem when trying to define Show for my Point3D type in Haskell

    - by devoured elysium
    I am trying to define Show for my Point3D type: type Point3D = (Integer, Integer, Integer) instance Show Point3D where show (x,y,z) = "<" ++ (show x) ++ "," ++ (show y) ++ "," ++ (show z) ++ ">" yet I must be missing something in the sintax, as I am always getting an error: Illegal instance declaration for `Show Point3D' (All instance types must be of the form (T t1 ... tn) where T is not a synonym. Use -XTypeSynonymInstances if you want to disable this.) In the instance declaration for `Show Point3D' What am I doing wrong?

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  • Collection type generated by for with yield

    - by Jesper
    When I evaluate a for in Scala, I get an immutable IndexedSeq (a collection with array-like performance characteristics, such as efficient random access): scala> val s = for (i <- 0 to 9) yield math.random + i s: scala.collection.immutable.IndexedSeq[Double] = Vector(0.6127056766832756, 1.7137598183155291, ... Does a for with a yield always return an IndexedSeq, or can it also return some other type of collection class (a LinearSeq, for example)? If it can also return something else, then what determines the return type, and how can I influence it? I'm using Scala 2.8.0.RC3.

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  • Declaring a data type dynamically in C++

    - by Bobby
    I want to be able to do the following: I have an array of strings that contain data types: string DataTypeValues[20] = {"char", "unsigned char", "short", "int"}; Then later, I would like to create a variable of one of the data types at runtime. I won't know at compile time what the correct data type should be. So for example, if at runtime I determined a variable x needed to be of type int: DataTypeValues[3] x = 100; Obviously this won't work, so how could I do something like this?

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  • problems with Haskell's Number Types

    - by mindeavor.
    I have the following haskell code: fac n = product [1..n] taylor3s w0 f f' f'' t h = w1 : taylor3s w1 f f' f'' (t+h) h where hp i = h^i / fac i w1 = w0 + (hp 1) * f t w0 + (hp 2) * f' t w0 + (hp 3) * f'' t w0 taylor_results = take 4 $ taylor3s 1 f f' f'' 1 0.25 where f t x = t^4 - 4*x/t f' t x = 4*t^3 - 4*(f t x)/t + 4*x/t^2 f'' t x = 12*t^2 - 4*(f' t x)/t + 8*(f t x)/t^2 - 8*x/t^3 taylor_results is supposed to be a use case of taylor3s. However, there is something wrong with the number type inferencing. When I try to compile, this is the error I get: practice.hs:93:26: Ambiguous type variable `a' in the constraints: `Integral a' arising from a use of `taylor3s' at practice.hs:93:26-51 `Fractional a' arising from a use of `f' at practice.hs:93:37 Possible cause: the monomorphism restriction applied to the following: taylor_results :: [a] (bound at practice.hs:93:0) Probable fix: give these definition(s) an explicit type signature or use -XNoMonomorphismRestriction Can someone help me with understanding what the problem is?

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  • How to detect if a form input element of type file is empty

    - by Ankur
    I have some code which reads a file through a form field of type file <input type="file" ... /> I want to give the user another option of providing a url to a file rather than having to upload it as many are already online. How can I detect when this field is empty on the server side. I am using Apache Commons FileUpload FileItemStream item = iter.next(); name = item.getFieldName(); stream = item.openStream(); if(!item.isFormField()){ if(item.toString()!=""){ .... I need to detect when item is empty. The above code doesn't work, nor does using: if(item.equals(null)){ ....

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  • Is a server an infinite loop running as a background process?

    - by Tony
    Is a server essentially a background process running an infinite loop listening on a port? For example: while(1){ command = read(127.0.0.1:xxxx); if(command){ execute(command); } } When I say server, I obviously am not referring to a physical server (computer). I am referring to a MySQL server, or Apache, etc. Full disclosure - I haven't had time to poke through any source code. Actual code examples would be great!

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  • How to know any request type with comet in tomcat 6

    - by Alvin
    Hi, I want to create a chat application in Tomcat 6.0, but before allowing any user for chatting I want to authenticate a user or registering its account to the database by passing request to the servlets at the comet Event type Begin. But I don't know how to know about the request type. How can I know a user has already been logged in, or he is making a request for registering his account. How can I know this by implementing CometProcessor interface? Is there any better way to do that task?

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  • data type trouble in php

    - by user225269
    I don't know why but the data type in this code makes a trouble when the id in the url starts with the number zero like this: http://localhost/exp/update.php?id=03A43 In this case the id is 03A43. And my query looks like this: mysql_select_db("school", $con); $result = mysql_query("SELECT * FROM student WHERE IDNO=".(int)$_GET['id']); ?> There is no problem in the design if the id does not start with the number zero. What might be the proper data type for numbers beginning in zero?

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  • Java Sql Udate error, data type missmatch

    - by codo
    I have created a table in ms access. I have set the data type of ID to Auto Number in MS-access. In java when I try to update a record. the netBeans IDE gives me the error of " data type missmatch in criteria expression". But when I changed the ID number that was not in the table already it works well. The code is below. String sql = "Update table1 set price ='" + txtPrice.getText() + "', quantity='" + txtQuantity.getText() + "', description='" + txtDescription.getText() + "' where id= " + txtid.getText() + ""; try { pst = conn.prepareStatement(sql); pst.executeUpdate(); JOptionPane.showMessageDialog(null, "Updated"); UpdateJTable(); } catch (Exception e) { JOptionPane.showMessageDialog(null, e); }

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  • using AutoCompleteTextField in wicket without String as the generic type

    - by Manuel
    Hi! This question follows this: handling to onchange event of AutoCompleteTextField in wicket I'm trying to use the AutoCompleteTextField with a custom class as the generic type, and to add an AjaxFormComponentUpdatingBehavior. What I mean is I want to have a AutoCompleteTextField<SomeClass> myAutoComplete = ...; and after that add a AjaxFormComponentUpdatingBehavior: myAutoComplete.add(new AjaxFormComponentUpdatingBehavior("onchange") { @Override protected void onUpdate(AjaxRequestTarget target) { System.out.println( "Value: "+getValue() ); } }); The problem is that for some reason, adding that behavior makes the form try to set the model object with a String (even though the AutoCompleteTextField has a generic type of SomeClass), causing a ClassCastException when the onchange event fires. Is there a way to use AutoCompleteTextField without it being AutoCompleteTextField<String>? I couldn't find any example. Thanks for your time! and thanks to the user biziclop for his help in this matter.

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  • Sending JSON content type in from JavaScript objects ( jQuery ajax )

    - by smartnut007
    I am having trouble sending JavaScript objects as a http request that only accepts json content-type. i.e "application/json" or "text/json" But, I am not sure why data2 ( stringified json ) works fine But, data1 ( json object ) does throws 400 ( Bad Request ). i.e I am not sure jQuery does not serialize the json object to a valid json string for the server to process. var data1 = ({ rating : 3 }); //does not work var data2 = '{ "rating" : 3}'; //works fine $.ajax({ url : "/rate", data : data1, type : "POST", contentType: "application/json", success: function(json){ console.log("Ajax Return :"+json); } });

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  • Parent key of type encoded string?

    - by user246114
    Hi, How do we create a parent key which is an encoded string? Example: class Parent { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String mEncKey; } class Child { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) @Extension(vendorName="datanucleus", key="gae.encoded-pk", value="true") private String mEncKey; // In the doc examples, they have Key as the type here. @Persistent @Extension(vendorName="datanucleus", key="gae.parent-pk", value="true") private String mParentEncKey; } yeah I'm not sure how to make mParentEncKey an encoded string type, because the 'key' label is already being used? I would need something like?: key="gae.parent-pk.encoded-pk" not sure - is that possible? Thanks

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  • do you call them functions, procedures or methods?

    - by lowlyintern
    consider a standard c# 'function' public void foo() { //some code } In c or c++ this is called a 'function' - even if taking no parameters and returning no value. In another language maybe it would be a 'procedure'. In object orientation speak it would be called a 'method' if a class member. What would be the correct term to use in c#?

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  • PHP find if file data is an image

    - by Christian Sciberras
    Imagine I have some file data in a variable $data. I need to determine whether it is an image or not. No need for details such as corrupt images etc. Firs thought would be getting the file mime type by looking at the magic number and then see whether "image" is in the mime type. No such luck, even if I have a "file extension to mime type" script, I don't have a reliable way to get mime from magic number. My next option was to have a reasonable list of image file magic numbers and consult them. However, it relatively difficult to find such magic numbers (gif for instance has different magic numbers, some of which could pretty rare - if memory serves me right). A better idea would be some linux program which can do this kind of thing. Any ideas? I'm running RHEL and PHP 5.3. I've got root access - ie able to install stuff if needed. - Chris.

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  • What areas of computer science are particularly relevant to mobile development?

    - by MalcomTucker
    This isn't a platform specific question - rather I'm interested in the general platform independent areas of computer science that are particularly relevant to mobile applications development. For example, things like compression techniques, distributed synchronisation algorithims etc.. what theoretical concepts have you found relevant, useful or enabling when building mobile apps?

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  • Floating point computer - Trouble with getting back correct results

    - by Francisco P.
    Having trouble with a challenge. Let's say I have a theoretical, base 10, floating point calculator with the following characteristics Only 3 digits for mantissa 1 digit for exponent Sign for mantissa and exponent How would this machine compute the following? 300 + \sum_{i=1}^{100} 0.2 The correct result is 320. The machine's result is 300. But why? Can't get where the 20 goes goes missing... Thanks for your time.

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  • How to change a vairable type in C#?

    - by Mosho Mulan
    I wanted to use something like this: if(x==5) { var mydb= ........ ; } else { var mydb = ........ ; } but it didn't work because I can't declare a variable inside if statement. So I tried to do this: var mydb; if (x==5) { mydb= ............. ; } else { mydb=.............; } but id didn't work either because I had to initialize the variable (mydb). So the question is: I don't necessarily know the type of the variable, can I declare it anyway and then change the type inside the if statement?

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  • Single C++/CLI method to wrap many type specific C functions

    - by T33C
    I am wrapping a C library using C++/CLI so that the C library can be used easily from C# in a C#'ish way. Some of the functions in this library are for putting a value into a container. There are no generics in C so there exists a function per type CLIB_SetBool(BOOL value), CLIB_SetInt(int value), CLIB_SetString(char* string) and so on. To make it easier to use from C#, I have created a single Set function which takes a System::Object. I have two related questions: With my method how would you use a switch statement on the type of System::Object to call the correct CLIB_Setxxxx function. [typeid is only for unmanaged code and I can't seem to use GetType.] Is there a better way to wrap these functions like using a Generic? [I started using template specialisation but then realised that C# doesn't see templates.] Thanks.

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