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  • In Scala 2.8 collections, why was the Traversable type added above Iterable?

    - by Seth Tisue
    I know that to be Traversable, you need only have a foreach method. Iterable requires an iterator method. Both the Scala 2.8 collections SID and the "Fighting Bitrot with Types" paper are basically silent on the subject of why Traversable was added. The SID only says "David McIver... proposed Traversable as a generalization of Iterable." I have vaguely gathered from discussions on IRC that it has to do with reclaiming resources when traversal of a collection terminates? The following is probably related to my question. There are some odd-looking function definitions in TraversableLike.scala, for example: def isEmpty: Boolean = { var result = true breakable { for (x <- this) { result = false break } } result } I assume there's a good reason that wasn't just written as: def isEmpty: Boolean = { for (x <- this) return false true }

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  • how to control textbox type to double in visual basic?

    - by fema
    Hi, I'd like to make a textbox that accepts only numbers, but not integer, but rather double. I've read here about e.Handled = Not Char.IsDigit(e.KeyChar) and it works, but again, it can be used only for integer, since it declines decimal point. Another thing I've read here is If Not Double.TryParse(TextBox2.Text, value) Then .... and it would work fine, except that it allows only decimal comma instead of point. I don't know whether it's because of my location settings (Hungary, we use commas instead of points), but I don't have any other idea how to solve my problem, and the SQL server I send my data uses decimal point. Thanks in advance.

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  • In Java, how do I set a return type if an exception occurs?

    - by beagleguy
    hey all, I'm new to Java and was wondering if I define a method to return a database object like import java.sql.*; public class DbConn { public Connection getConn() { Connection conn; try { Class.forName("com.mysql.jdbc.Driver").newInstance(); if(System.getenv("MY_ENVIRONMENT") == "development") { String hostname = "localhost"; String username = "root"; String password = "root"; } conn = DriverManager.getConnection("jdbc:mysql:///mydb", username, password); return conn; } catch(Exception e) { throw new Exception(e.getMessage()); } } } if the connection fails when I try to create it what should I return? eclipse is telling me I have to return a Connection object but if it fails I'm not sure what to do. thanks!

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  • how to make a javascript number keypad popup

    - by user2434653
    i have a website with 3 pages. each page has a form with two input fields. i am trying to make a popup number-keypad that will populate what ever input field called it. below is that base code i keep coming back to. <html> <head><title>test</title></head> <body> <script> function num(id) { return document.getElementById(id); } </script> <form action="/unitPage" method="POST" style=" text-align:center;"> Prefix: <input id="num" name"prefix" type="text" onfocus="num('keypad').style.display='inline-block';"/> Number: <input id="num" name"number" type="text" pattern="[0-9]{6}" onfocus="num('keypad').style.display='inline-block';"/> </form> <div id="keypad" style="display:none; background:#AAA; vertical-align:top;"> <input type="button" value="7" onclick="num('num').value+=7;"/> <input type="button" value="8" onclick="num('num').value+=8;"/> <input type="button" value="9" onclick="num('num').value+=9;"/><br/> <input type="button" value="4" onclick="num('num').value+=4;"/> <input type="button" value="5" onclick="num('num').value+=5;"/> <input type="button" value="6" onclick="num('num').value+=6;"/><br/> <input type="button" value="1" onclick="num('num').value+=1;"/> <input type="button" value="2" onclick="num('num').value+=2;"/> <input type="button" value="3" onclick="num('num').value+=3;"/><br/> <input type="button" value="X" onclick="num('keypad').style.display='none'"/> <input type="button" value="0" onclick="num('num').value+=0;"/> <input type="button" value="&larr;" onclick="num('num').value=num('num').value.substr(0,num('num').value.length-1);"/> </div> </body> </html> is there a way of making one number key pad that i call from any page or do i need to make the above for each input? thanks

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  • Hover image - part of forms appears untill hover another How?

    - by Mac
    Im trying to make part of my form/questionnaire appears when hover on image and stay active untill hover another image next to it. and repeat it on 7 images. Of course I need the cheched checkboxes to stay after they'll be hidden so you can come back to them by hover the image and for ex. correct answers and so on.. I was using a j code: <script type="text/javascript"> $("#Oobj51").hover(function(){ $('#Oobj58').show(); },function(){ $('#Oobj58').hide(); }); </script> it works to another elements on my page but not to the form. how can i do it maybe with css class or another j code. Thanks! Parts of html: (let's say I want to hover on "Oobj56" and make "Oobj58" appears and stay as I said before...) <div id="Oobj56"> <button type="submit" class="przed6" onmouseover="this.className='po6'" onmouseout="this.className='przed6'" /> </div> <div id="Oobj57"> <button type="submit" class="przed7" onmouseover="this.className='po7'" onmouseout="this.className='przed7'" /> </div> <div id="Oobj60"> <form action="mailto:" method="post" enctype="text/plain"> <div id="Oobj59"> <input type="text" input size="8" name="imie" placeholder="imie"> <input type="text" input size="11" name="numer" placeholder="numer telefonu"> <br><br> <select name="miasto"> <option selected="Miasto">Miasto</option> <option>Wroclaw</option> <option>Warszawa</option> <option>Kraków</option> <option>Trójmiasto</option> <option>Poznan</option> <option>Szczecin</option> <option>Torun</option> <option>Lódz</option> <option>Bydgoszcz</option> <option>Lublin</option> <option>Katowice</option> </select> <select name="wiek"> <option selected="selected">Wiek</option> <option> <15 </option> <option>15-19</option> <option>20-24</option> <option>25-29</option> <option>30-34</option> <option>35-39</option> <option>40-44</option> <option>45-49</option> <option>50-54</option> <option>55-59</option> <option>60-64</option> <option>65-69</option> <option>70-74</option> <option> >75 </option> </select> <select name="plec"> <option selected="selected">Plec</option> <option>Mezczyzna</option> <option>Kobieta</option> </select></div> <div id="Oobj58"> <script language="JavaScript"> function toggle(source) { checkboxes = document.getElementsByName('sport'); for(var i=0, n=checkboxes.length;i<n;i++) { checkboxes[i].checked = source.checked; } } </script> <input type="checkbox" onClick="toggle(this)" /><br> <input type="checkbox" name="sport" value="gym" />silownia<br /> <input type="checkbox" name="sport" value="fitness" />fitness<br /> <input type="checkbox" name="sport" value="noga" />pilka nozna<br /> <input type="checkbox" name="sport" value="kosz" />koszykówka<br /> <input type="checkbox" name="sport" value="siata" />siatkówka<br /> <input type="checkbox" name="sport" value="ameryka" />football amerykanski<br /> <input type="checkbox" name="sport" value="konie" />jezdziectwo konne<br /> <input type="checkbox" name="sport" value="basen" />basen/sporty wodne<br /> <input type="checkbox" name="sport" value="zima" />sporty zimowe<br /> </div> <div id="Oobj15"> <input type="submit" style="font-family: Open Sans;" value="Wyslij" class="wyslij" /> </div></form> </div>

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  • Simple 'database' in c++

    - by DevAno1
    Hello. My task was to create pseudodatabase in c++. There are 3 tables given, that store name(char*), age(int), and sex (bool). Write a program allowing to : - add new data to the tables - show all records - sort tables with criteria : - name increasing/decreasing - age increasing/decreasing - sex Using function templates is a must. Also size of arrays must be variable, depending on the amount of records. I have some code but there are still problems there. Here's what I have: Function tabSize() for returning size of array. But currently it returns size of pointer I guess : #include <iostream> using namespace std; template<typename TYPE> int tabSize(TYPE *T) { int size = 0; size = sizeof(T) / sizeof(T[0]); return size; } How to make it return size of array, not its pointer ? Next the most important : add() for adding new elements. Inside first I get the size of array (but hence it returns value of pointer, and not size it's of no use now :/). Then I think I must check if TYPE of data is char. Or am I wrong ? // add(newElement, table) template<typename TYPE> TYPE add(TYPE L, TYPE *T) { int s = tabSize(T); //here check if TYPE = char. If yes, get the length of the new name int len = 0; while (L[len] != '\0') { len++; } //current length of table int tabLen = 0; while (T[tabLen] != '\0') { tabLen++; } //if TYPE is char //if current length of table + length of new element exceeds table size create new table if(len + tabLen > s) { int newLen = len + tabLen; TYPE newTab = new [newLen]; for(int j=0; j < newLen; j++ ){ if(j == tabLen -1){ for(int k = 0; k < len; k++){ newTab[k] = } } else { newTab[j] = T[j]; } } } //else check if tabLen + 1 is greater than s. If yes enlarge table by 1. } Am I thinking correct here ? Last functions show() is correct I guess : template<typename TYPE> TYPE show(TYPE *L) { int len = 0; while (L[len] == '\0') { len++; } for(int i=0; i<len; i++) { cout << L[i] << endl; } } and problem with sort() is as follows : Ho can I influence if sorting is decreasing or increasing ? I'm using bubble sort here. template<typename TYPE> TYPE sort(TYPE *L, int sort) { int s = tabSize(L); int len = 0; while (L[len] == '\0') { len++; } //add control increasing/decreasing sort int i,j; for(i=0;i<len;i++) { for(j=0;j<i;j++) { if(L[i]>L[j]) { int temp=L[i]; L[i]=L[j]; L[j]=temp; } } } } And main function to run it : int main() { int sort=0; //0 increasing, 1 decreasing char * name[100]; int age[10]; bool sex[10]; char c[] = "Tom"; name[0] = "John"; name[1] = "Mike"; cout << add(c, name) << endl; system("pause"); return 0; }

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  • Using a Form With Variables as Part of a Function

    - by John
    Hello, Could the form below be part of a function? I am wondering if it might not be able to be part of a function since it has variables. Thanks in advance, John echo '<form action="http://www...com/sandbox/comments/comments2.php" method="post"> <input type="hidden" value="'.$_SESSION['loginid'].'" name="uid"> <input type="hidden" value="'.$submissionid.'" name="submissionid"> <input type="hidden" value="'.$submission.'" name="submission"> <input type="hidden" value="'.$url.'" name="url"> <input type="hidden" value="'.$submittor.'" name="submittor"> <input type="hidden" value="'.$submissiondate.'" name="submissiondate"> <input type="hidden" value="'.$countcomments.'" name="countcomments"> <input type="hidden" value="'.$dispurl.'" name="dispurl"> <label class="addacomment" for="title">Add a comment:</label> <textarea class="commentsubfield" name="comment" type="comment" id="comment" maxlength="1000"></textarea> <div class="commentsubbutton"><input name="submit" type="submit" value="Submit"></div> </form> ';

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  • C++: Simple data type for a variable in IF statement?

    - by Jason
    I am new to C++ and am making a simple text RPG, anyway, The scenario is I have a "welcome" screen with choices 1-3, and have a simple IF statement to check them, here: int choice; std::cout << "--> "; std::cin >> choice; if(choice == 1) { //.. That works fine, but if someone enters a letter as selection (instead of 1, 2 or 3) it'll become "-392493492"or something and crash the program. So I came up with: char choice; std::cout << "--> "; std::cin >> choice; if(choice == 1) { //.. This works kinda fine, but when I enter a number it seems to skip the IF statements completely.. Is the char "1" the same as the number 1? I get a compiler errro with this (ISO-CPP or something): if(choice == "1") So how on earth do I see if they entered 1-3 correctly!?

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  • syntax error, unexpected ',', expecting ')' RoR

    - by McDoku
    I am trying to get a collection select from an another model and I keep getting the above error. Looked everywhere, got rails casts but nothing makes sense. _form.rb <%= f.label :city %><br /> <%= f.collection_select (:share ,:city_id, City.all , :id, :name ) %> It highlights 'form' on the error report <h1>New share</h1> <%= render 'form' %> <%= link_to 'Back', shares_path %> Here are my models... class Share include Mongoid::Document field :name, type: String field :type, type: String field :summary, type: String field :description, type: String field :city, type: String embedded_in :city has_many :category end class City include Mongoid::Document embedded_in :share field :name, type: String field :country, type: String attr_accessible :name, :city_id, :id end Searched everywhere and I cannot figure it out. It must be something silly.

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  • Should this work?

    - by Noah Roberts
    I am trying to specialize a metafunction upon a type that has a function pointer as one of its parameters. The code compiles just fine but it will simply not match the type. #include <iostream> #include <boost/mpl/bool.hpp> #include <boost/mpl/identity.hpp> template < typename CONT, typename NAME, typename TYPE, TYPE (CONT::*getter)() const, void (CONT::*setter)(TYPE const&) > struct metafield_fun {}; struct test_field {}; struct test { int testing() const { return 5; } void testing(int const&) {} }; template < typename T > struct field_writable : boost::mpl::identity<T> {}; template < typename CONT, typename NAME, typename TYPE, TYPE (CONT::*getter)() const > struct field_writable< metafield_fun<CONT,NAME,TYPE,getter,0> > : boost::mpl::false_ {}; typedef metafield_fun<test, test_field, int, &test::testing, 0> unwritable; int main() { std::cout << typeid(field_writable<unwritable>::type).name() << std::endl; std::cin.get(); } Output is always the type passed in, never bool_.

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  • Why would you precede the main() function in C with a data type?

    - by Milktrader
    Many are familiar with the hello world program in C #include <stdio.h> main () { printf ("hello world"); return 0; } Why do some precede the main () function with int as in: int main() Also, I've seen the word 'void' entered inside the () as in: int main(void) It seems like extra typing for nothing, but maybe it's a best practice that pays dividends in other situations? Also, why precede main() with an int if you're returning a character string? If anything, one would expect: char main(void) I'm also foggy about why we return 0 at the end of the function.

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  • How to animate button text? (loading type of animation) - jquery?

    - by AL
    I got something that I want to do and want to see what you guys think and how can it be implemented. I got a form in a page and the form will submit to itself to perform some process (run functions) in a class. Upon clicking the submit button, I want to animate the button text to “SUBMIT .” -> “SUBMIT ..” -> “SUBMIT …” -> “SUBMIT ….” -> “SUBMIT ….” and then back again. Sort of “animate” the button text. Once the whole process is done, the button text will goes back to be “SUBMIT” text again. Please note that I am not looking for image button solution, meaning that I do not want to implement gif animated button image. Anyone done this before or know how this can be done? I have google but seems nothing of this kind to be found. Thanks! AL

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  • How to properly assign a value to the member of a struct that has a class data type?

    - by sasayins
    Hi, Please kindly see below for the codes. Its compiling successfully but the expected result is not working. Im very confused because my initialization of the array is valid, //cbar.h class CBar { public: class CFoo { public: CFoo( int v ) : m_val = v {} int GetVal() { return m_val; } private: int m_val; }; public: static const CFoo foo1; static const CFoo foo2; public: CBar( CFoo foo ) m_barval( foo.GetVal() ){} int GetFooVal() { return m_barval; } private: int m_barval; }; //cbar.cpp const CBar::CFoo foo1 = CBar::CFoo(2); const CBar::CFoo foo2 = CBar::CFoo(3); //main.cpp struct St { CBar::CFoo foo; }; St st[] = { CBar::foo1, CBar::foo2 }; for( int i=0; i<sizeof(st)/sizeof(St); i++ ) { CBar cbar( st[i].foo ); std::cout << cbar.GetFooVal() << std::endl; } But then when I change the St::foo to a pointer. And like assign the address of CBar::foo1 or CBar::foo2, its working, like this, //main.cpp struct St { const CBar::CFoo *foo; }; St st[] = { &CBar::foo1, &CBar::foo2 }; for( int i=0; i<sizeof(st)/sizeof(St); i++ ) { CBar cbar( *st[i].foo ); std::cout << cbar.GetFooVal() << std::endl; } The real problem is. The app should output 2 3 Please advice. Many thanks.

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