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  • is the + in += on a Map a prefix operator of =?

    - by Steve
    In the book "Programming in Scala" from Martin Odersky there is a simple example in the first chapter: var capital = Map("US" -> "Washington", "France" -> "Paris") capital += ("Japan" -> "Tokyo") The second line can also be written as capital = capital + ("Japan" -> "Tokyo") I am curious about the += notation. In the class Map, I didn't found a += method. I was able to the same behaviour in an own example like class Foo() { def +(value:String) = { println(value) this } } object Main { def main(args: Array[String]) = { var foo = new Foo() foo = foo + "bar" foo += "bar" } } I am questioning myself, why the += notation is possible. It doesn't work if the method in the class Foo is called test for example. This lead me to the prefix notation. Is the + a prefix notation for the assignment sign (=)? Can somebody explain this behaviour?

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  • NHibernate - Is ITransaction.Commit really necessary?

    - by user365383
    Hi I've just start studying NHibernate 2 days ago, and i'm looking for a CRUD method that i've writed based on an tutorial. My insert method is: using (ISession session = Contexto.OpenSession()) using (ITransaction transaction = session.BeginTransaction()) { session.Save(noticia); transaction.Commit(); session.Close(); } The complete code of "Contexto" is here: http://codepaste.net/mrnoo5 My question is: Do i really need to use ITransaction transaction = session.BeginTransaction() and transaction.Commit();? I'm asking this because i've tested run the web app without those two lines, and i've sucefully inserted new records. If possible, can someone explain me too the porpuse of Itransaction and the method Commit? Thanks

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  • Empty R environment becomes large file when saved

    - by user1052019
    I'm getting behaviour I don't understand when saving environments. The code below demonstrates the problem. I would have expected the two files (far-too-big.RData, and right-size.RData) to be the same size, and also very small because the environments they contain are empty. In fact, far-too-big.R ends up the same size as bigfile.RData. I get the same results using 2.14.1 and 2.15.2, both on WinXP 5.1 SP3. Can anyone explain why this is happening? Thanks. a <- matrix(runif(1000000, 0, 1), ncol=1000) save(a, file="c:/temp/bigfile.RData") test <- function() { load("c:/temp/bigfile.RData") test <- new.env() save(test, file="c:/temp/far-too-big.RData") test1 <- new.env(parent=globalenv()) save(test1, file="c:/temp/right-size.RData") } test()

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  • oomla.. GoDaddy.. FileZilla ... :S

    - by user282659
    have created a a website in my localhost computer using Joomla Now I want to launch the site into the web.. So I brought a domain from GoDaddy.com .. Im a newbie into this and I was using This Tutorial in order to set up the website... Now Im Stuck in the Step 08 Which asks to upload some files into the web host directory... I used FileZilla as my FTP Client .. When I give the host name and the password, Port number as 21 and try to login it says.. Connection Timed Out.. and says.. Could Not Connect to server . Plase explain m on how to use the FileZilla.. And Solve th above problem ..

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  • How to understand the functional programming code for converting IP string to a number?

    - by zfz
    In a python discusion, I saw a way to convert IP string to a integer in functional progamming way. Here is the Link . The function is implemented in a single line. def ipnumber(ip): return reduce(lambda sum, chunk: sum <<8 | chunk, map(int, ip.split("."))) However, I have few ideas of funcional programming. Could anybody explain the function in detail? I've some knowledg of "map" and "reduce". But I don't konw what "|" and "chunk" mean here? Thanks.

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  • Sharing base object with inheritance

    - by max
    I have class Base. I'd like to extend its functionality in a class Derived. I was planning to write: class Derived(Base): def __init__(self, base_arg1, base_arg2, derived_arg1, derived_arg2): super().__init__(base_arg1, base_arg2) # ... def derived_method1(self): # ... Sometimes I already have a Base instance, and I want to create a Derived instance based on it, i.e., a Derived instance that shares the Base object (doesn't re-create it from scratch). I thought I could write a static method to do that: b = Base(arg1, arg2) # very large object, expensive to create or copy d = Derived.from_base(b, derived_arg1, derived_arg2) # reuses existing b object but it seems impossible. Either I'm missing a way to make this work, or (more likely) I'm missing a very big reason why it can't be allowed to work. Can someone explain which one it is? [Of course, if I used composition rather than inheritance, this would all be easy to do. But I was hoping to avoid the delegation of all the Base methods to Derived through __getattr__.]

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  • question on find value in array

    - by davit-datuashvili
    i have seen a few days ago such problem there is given two array find elements which are common of these array one of the solution was sort big array and then use binary search algorithm and also there is another algorithm- brute-force algorithm for (int i=0;i<array1.length;i++){ for (int j=0;j<array2.length;j++){ if (array1[i]==array2[j]){ //code here } } it's complexity is O(array1.length*array2.length); and i am interested the first method's complexity is also same yes? because we should sort array first and then use search method binary search algorithm's complexity is log_2(n) so it means that total time will be array.length*log_2(n) and about sort? please explain me which is better

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  • Rails: How to have dynamic association

    - by Aaron Dufall
    I'll use an example to explain what behaviour I would like to achieve. If you had a project management app and you added a task, but not all the contributors are users of the app. So when you adding contributors to the task you can enter a user name or email address. Here is the part that I'm finding a little tricky. The task model has many contributors which are linked through the user model, but from this point on I want to achieve 2 things. Store the non members email(this would obviously be quite simple) If that email address was to create an account it would then link that user to the task and remove the temporally saved email. This way, when that user creates an account all the related tasks will already be associated with their email. Is this something that i could achieve with a polymorphic association? or is there something else I should be looking at?

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  • 1120: Why can't it access the variable?

    - by Oden
    I'm new at as3, maybe thats the reason why i don't understand, why the setInterval causes an error. <mx:Script> <![CDATA[ import flash.utils.setInterval; import mx.controls.Alert; [Bindable] public var MyInt:int = 500; setInterval(function():void{ ++MyInt; },1000); ]]> </mx:Script> I have a label where the value of MyInt gets visible, the bind works perfect, i've tested it several ways, and i i create a button it grows the number, but if i use the setInterval function i get an error: Access of undefined property myInt. Why? What does cause this? Please explain it, so I can avoid errors like this. Thanks

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  • Caveates on the html options of <pre> <code> [on hold]

    - by user2935199
    Over at html syntax to display literal string i asked about displaying a literal. When i tried : http://sdrv.ms/1bEsPWz (as the posted sample will not display, i need to show a picture, as i don't have 10 xxx, i can't insert a picture, I am only left with a skydrive reference) In english, the and syntax was tried but it failed to show all content inside the block. It only showed the "is equal to - pre sample " part. I thought - did not care what was inside ? Can some explain how to make a truely literal block display ? I have my reasons why i don't want to have the " syntax in the html. Thanks

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  • Why does this C program compile?

    - by AdmiralJonB
    I've just come across someone's C code that I'm confused as to why it is compiling. There are two points I don't understand. First, the function prototype has no parameters compared to the actual function definition. Secondly, the parameter in the function definition doesn't have an type. #include <stdio.h> int func(); int func(param) { return param; } int main() { int bla = func(10); printf("%d",bla); } Could someone please explain to me why this works? I've tested it in a couple of compilers and it works fine.

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  • How to change active culture on Windows Phone 7

    - by Sam
    [Update] I see I need the full example to explain. In my Windows Phone 7 App, I got a page containing a TextBox bound to a Decimal "Amount": <TextBox Text="{Binding Amount,Mode=TwoWay}" InputScope="CurrencyAmount"/> The phone settings are set to German. In german localization, a value like 1234.56m would be formatted 1.234,56 (unlike the US, where it should be 1,234.56). Problem is, when I enter a value like 1.234,56 in the textbox, the content will be interpreted for US, resulting in 1.23456m, when it should have been 1234.56m. So, how do I get the binding on the WP7 to use the current phone culture instead of a generic US one? In Germany people expect to enter a colon for decimals instead of a dot.

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  • Why do you sometimes need to write <typename T> instead of just <T> ?

    - by StackedCrooked
    I was reading the Wikipedia article on SFINAE and encountered following code sample: struct Test { typedef int Type; }; template < typename T > void f( typename T::Type ) {} // definition #1 template < typename T > void f( T ) {} // definition #2 void foo() { f< Test > ( 10 ); //call #1 f< int > ( 10 ); //call #2 without error thanks to SFINAE } Now I've actually written code like this before, and somehow intuitively I knew that I needed to type "typename T" instead of just "T". However, it would be nice to know the actual logic behind it. Anyone care to explain?

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  • How to decide between a method or event?

    - by Wil
    I read something ages ago I think by Jon Skeet (which I can't find now) saying that in IL, all events get converted to methods... it was before I understood C# and did not understand it all, but if that is (or even if it isn't) the gist of it.... In a purely hypothetical situation, I was wondering if someone could explain or point me to a resource that says when to use an event over a method? Basically, If I want to have a big red/green status picture which is linked to a Bool field, and I wanted to change it based on the value of the bool, should I: a) Have a method called Changepicture which is linked to the field and changes the state of the bool and the picture. b) Have a get/set part to the field and stick an event in the set part. c) Have a get/set part to the field and stick a method in the set part. d) Other?

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  • Is apparent NULL pointer dereference in C actually pointer arithmetic?

    - by karthik A
    hey ive got this piece of code. It dereferences a null pointer here. But then there is an and with unsigned int. I really dont understand the whole part. Can someone explain the output.?? struct hi { long a; int b; long c; }; int main() { struct hi ob={3,4,5}; struct hi *ptr=&ob; int num= (unsigned int) & (((struct hi *)0)->b); printf("%d",num); printf("%d",*(int *)((char *)ptr + (unsigned int) & (((struct hi *)0)->b))); } The output I get is 44. But how does it work?

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  • PHP using count() with array

    - by seb
    Hi there, Im trying to get the amount of elements in an array using the count() function, the result is a bit puzzling to me, considere the following example. Assume that the user ID provided is wrong, and therefore had no matches, wouldnt then the result of the count function be 0? yet it is 1. can you explain to me why? thanks $q = mysql_query("select password from users where user_name = '" . $userID . "'"); $check = mysql_fetch_array($q); $result = count($check); echo "RESULT:" . $result;

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  • I can get access to object's properties if method is called from anonymous function, but I can't do

    - by Kirzilla
    Hello, $.Comment = function() { this.alertme = "Alert!"; } $.Comment.prototype.send = function() { var self = this; $.post( self.url, { 'somedata' : self.somedata }, function(data) { //using anonymous function to call object's method self.callback(data); } ); } $.Comment.prototype.callback = function(data) { alert(this.alertme); } This code works great when I'm calling $.Comment.send(), but this code won't work... $.Comment.prototype.send = function() { var self = this; $.post( self.url, { 'somedata' : self.somedata }, self.callback //using direct access to method ); } Please, could you explain me why? Thank you

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  • Null Pointer Exception with an array of bitsets

    - by p0ny
    could someone explain to me why the following results in a Null pointer Exception? And how to set a value for bitarray[0]? BitSet[] bitarray; bitarray= new BitSet[10]; bitarray[0].set(1); Also, why something like this work and not result in a pointer exception? BitSet[] bitarray = new BitSet[10]; BitSet bits = new BitSet(32); bits.set(1); bitarray[0] = bits; Thanks

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  • Replacing Text in a Toggled Anchor with JQuery

    - by willmcneilly
    Hi I'm trying to change the text in an anchor on toggle. I'm doing this way at the moment but have found that once the anchor markup has replaced the toggle no longer works. Can someone please explain why this is happening and a solution? Many thanks. $('a#toggleHeader').toggle(function() { $('#header-wrapper').slideUp(); $(this).replaceWith('< href=\"#\" id="toggleHeader">Show Header</>'); //Note:I've move the anchor because I can only post one anchor as a new user },function(){ $('#header-wrapper').slideDown(); $(this).replaceWith('<a href=\"#\" id="toggleHeader">Hide Header</a>'); });

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  • Database Documentation with `SQL Doc 2`

    - by mehdi lotfi
    I use SQL Doc 2 for documentation my database. But this tools not support following expect : Add diagrams in documentation. Add Additional description for each object such as tables, columns and etc. Customize output format. Add custom link for each object. Add Analyze business description of created tables, columns and etc Some time need to explain records of each table such as records of literal tables. How Can support above request in SQL Doc 2? Do exists a tools for documentation database with above request?

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  • How to match data between columns to do the comparasion

    - by NCC
    I do not really know how to explain this in a clear manner. Please see attached image I have a table with 4 different columns, 2 are identical to each other (NAME and QTY). The goal is to compare the differences between the QTY, however, in order to do it. I must: 1. sort the data 2. match the data item by item This is not a big deal with small table but with 10 thousand rows, it takes me a few days to do it. Pleas help me, I appreciate. My logic is: 1. Sorted the first two columns (NAME and QTY) 2. For each value of second two columns (NAME and QTY), check if it match with first two column. If true, the insert the value. 3. For values are not matched, insert to new rows with offset from the rows that are in first two columns but not in second two columns

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  • Identifying when there is more than 1 in a group based on grouped field

    - by Brian Cascone
    Sorry for the bad description it is tough to explain in one sentence. I have a dataset that has Cause field (RootCause) and an ID field (GroupID). Both can be many things but I need to identify where a GroupID has a multiple different rootcauses. for example: RootCause GrpId AAA 111 BBB 222 CCC 111 I am looking to be able to identify that GrpId 111 has two different RootCauses. This is what I have so far: Select [RootCause], GrpId, Count(GrpID) as CntGrpId From DB.dbo.Table Where DatatypeField <> '' Group BY [RootCause],GrpId This results set visualy gives me enough information to identify what I am looking for, but i need something better. I am looking to return only the ones that have multiples. Any ideas? Thanks

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  • New replicaset resident memory is larger than the existing sets

    - by eded
    From the mongodb tutorial of how to resync a set, I wipe all the files in /data/db and restart the mongod process to resync the data. Everything looks ok, I get the same number of documents as the existing two sets(primary and one secondary). However, when I check the memory on MMS. it shows me my new resynced set/mongod process has a different memory status value than the other two. For existing twos using db.serverStatus.mem shows like the following: "mem" : { "bits" : 64, "resident" : 239, "virtual" : 66348, "supported" : true, "mapped" : 32865, "mappedWithJournal" : 65730 } however, the new resynced set shows like: "mem" : { "bits" : 64, "resident" : 1239, "virtual" : 52447, "supported" : true, "mapped" : 25700, "mappedWithJournal" : 51400 } the resynced resident memory is 6-10 times more than the existing ones. I wouder if it is normal because all data comes in suddenly during the resyncing?? and even virtual and mapped value are different too. Can anyone explain?? thanks

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  • How to keep a floating div centered on window resize (jQuery/CSS)

    - by Jimbo
    Is there a way (without binding to the window.resize event) to force a floating DIV to re-center itself when the browser window is resized? To help explain, I imagine the pseudocode would look something like: div.left = 50% - (div.width / 2) div.top = 50% - (div.height / 2) UPDATE My query having been answered below, I wanted to post the final outcome of my quest - a jQuery extension method allowing you to center any block element - hope it helps someone else too. jQuery.fn.center = function() { var container = $(window); var top = -this.height() / 2; var left = -this.width() / 2; return this.css('position', 'absolute').css({ 'margin-left': left + 'px', 'margin-top': top + 'px', 'left': '50%', 'top': '50%' }); } Usage: $('#mydiv').center();

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  • Can a method return an NSRange?

    - by Dan Donaldson
    I have a method that returns an NSRange. When I call this method from outside the class I get a compile error. NSRange tmpRange; tmpRange = [phrase rangeInString:searchString forString:theLetter goingForward:YES]; return tmpRange.location == -1; in the .h file: #import <Foundation/Foundation.h> @interface Phrase : NSObject { } - (NSRange) rangeInString:(NSString *) tgt forString:(NSString *) find goingForward:(BOOL) fwd; @end This method is called within the Phrase object by other methods without problems. The compiler says 'incompatible types in assignment'. Can anyone explain this to me? I assume it has to do with returning an NSRange/struct type value generated outside the object, but I don't know why it works in one place and not the other.

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