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• How to break out from nested doseqs

  - by fizbin

  Hi, I have a question regarding nested doseq loops. In the start function, once I find an answer I set the atom to true, so that the outer loop validation with :while fails. However it seems that it doesn't break it, and the loops keep on going. What's wrong with it? I am also quite confused with the usage of atoms, refs, agents (Why do they have different names for the update functions when then the mechanism is almost the same?) etc. Is it okay to use an atom in this situation as a flag? Obviously I need a a variable like object to store a state. (def pentagonal-list (map (fn [a] (/ (* a (dec (* 3 a))) 2)) (iterate inc 1))) (def found (atom false)) (defn pentagonal? [a] (let [y (/ (inc (Math/sqrt (inc (* 24 a)))) 6) x (mod (* 10 y) 10)] (if (zero? x) true false))) (defn both-pent? [a b] (let [sum (+ b a) diff (- a b)] (if (and (pentagonal? sum) (pentagonal? diff)) true false))) (defn start [] (doseq [x pentagonal-list :while (false? @found)] (doseq [y pentagonal-list :while (<= y x)] (if (both-pent? x y) (do (reset! found true) (println (- x y)))))))

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• Java : Inner class of an interface (from google guice)

  - by bsreekanth

  Hello, I was going through the source of google guice, and found an unfamiliar piece of code. It would be great learning if someone can clarify it. I have very basic understanding of inner classes, as they keep the implementation details close to the public interface. Otherwise the inner class may pollute the namespace. Now, I see the below lines at public static final Scope SINGLETON = new Scope() { public <T> Provider<T> scope(final Key<T> key, final Provider<T> creator) { return new Provider<T>() { ......... } It assign an inner class instance to the static variable, but Scope is an interface defined as (at) public interface Scope Is it possible to instantiate the interface?? or is it a succinct syntax for an anonymous implementation of an interface?? If anyone can explain what the author is intended by multiple nested classes above (Scope and Provider), and why it make sense to implement this way, it would help me to understand. thanks.

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• understanding and implementing Boids

  - by alphablender

  So I'm working on porting Boids to Brightscript, based on the pseudocode here: http://www.kfish.org/boids/pseudocode.html I'm trying to understand the data structures involved, for example is Velocity a single value, or is it a 3D value, ie velocity={x,y,z} It seems as if the pseudocode seems to mix this up where sometimes it has an equation that incudes both vectors and single-value items: v1 = rule1(b) v2 = rule2(b) v3 = rule3(b) b.velocity = b.velocity + v1 + v2 + v3 If Velocity is a tripartite value then this would make sense, but I'm not sure. So my first question here is, is this the correct datastructure for a single boid based on the Pseudocode on that page: boid={position:{px:0,py:0,pz:0},velocity:{x:0,y:0,z:0},vector:{x:0,y:0,z:0},pc:{x:0,y:0,z:0},pv:{x:0,y:0,z:0}) where pc=perceived center, pv= perceived velocity I"ve implemented a vector_add, vector_sub, vector_div, and vector boolean functions. The reason I'm starting from this pseudocode is I've not been able to find anything else that is as readable, but it still leaves me with lots of questions as the data structures are not explicitly defined for each variable. (edit) here's a good example of what i'm talking about: IF |b.position - bJ.position| < 100 THEN if b.position - b[j].position are both 3D coordinates, how can they be considered "less than 100" unless they are < {100,100,100} ? Maybe that is what I need to do here, use a vector comparison function?

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• Implementing comparision operators via 'tuple' and 'tie', a good idea?

  - by Xeo

  (Note: tuple and tie can be taken from Boost or C++11.) When writing small structs with only two elements, I sometimes tend to choose a std::pair, as all important stuff is already done for that datatype, like operator< for strict-weak-ordering. The downsides though are the pretty much useless variable names. Even if I myself created that typedef, I won't remember 2 days later what first and what second exactly was, especially if they are both of the same type. This gets even worse for more than two members, as nesting pairs pretty much sucks. The other option for that is a tuple, either from Boost or C++11, but that doesn't really look any nicer and clearer. So I go back to writing the structs myself, including any needed comparision operators. Since especially the operator< can be quite cumbersome, I thought of circumventing this whole mess by just relying on the operations defined for tuple: Example of operator<, e.g. for strict-weak-ordering: bool operator<(MyStruct const& lhs, MyStruct const& rhs){ return std::tie(lhs.one_member, lhs.another, lhs.yet_more) < std::tie(rhs.one_member, rhs.another, rhs.yet_more); } (tie makes a tuple of T& references from the passed arguments.) Edit: The suggestion from @DeadMG to privately inherit from tuple isn't a bad one, but it got quite some drawbacks: If the operators are free-standing (possibly friends), I need to inherit publicly With casting, my functions / operators (operator= specifically) can be easily bypassed With the tie solution, I can leave out certain members if they don't matter for the ordering Are there any drawbacks in this implementation that I need to consider?

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• How to output multiple rows from an SQL query using the mysqli object

  - by Jonathan

  Assuming that the mysqli object is already instantiatied (and connected) with the global variable $mysql, here is the code I am trying to work with. class Listing { private $mysql; function getListingInfo($l_id = "", $category = "", $subcategory = "", $username = "", $status = "active") { $condition = "`status` = '$status'"; if (!empty($l_id)) $condition .= "AND `L_ID` = '$l_id'"; if (!empty($category)) $condition .= "AND `category` = '$category'"; if (!empty($subcategory)) $condition .= "AND `subcategory` = '$subcategory'"; if (!empty($username)) $condition .= "AND `username` = '$username'"; $result = $this->mysql->query("SELECT * FROM listing WHERE $condition") or die('Error fetching values'); $this->listing = $result->fetch_array() or die('could not create object'); foreach ($this->listing as $key => $value) : $info[$key] = stripslashes(html_entity_decode($value)); endforeach; return $info; } } there are several hundred listings in the db and when I call $result-fetch_array() it places in an array the first row in the db. however when I try to call the object, I can't seem to access more than the first row. for instance: $listing_row = new Listing; while ($listing = $listing_row-getListingInfo()) { echo $listing[0]; } this outputs an infinite loop of the same row in the db. Why does it not advance to the next row? if I move the code: $this->listing = $result->fetch_array() or die('could not create object'); foreach ($this->listing as $key => $value) : $info[$key] = stripslashes(html_entity_decode($value)); endforeach; if I move this outside the class, it works exactly as expected outputting a row at a time while looping through the while statement. Is there a way to write this so that I can keep the fetch_array() call in the class and still loop through the records?

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• Using parameterized function calls in SELECT statements. MS SQL Server

  - by geekzlla

  I have taken over some code from a previous developer and have come across this SQL statement that calls several SQL functions. As you can see, the function calls in the select statement pass a parameter to the function. How does the SQL statement know what value to replace the variable with? For the below sample, how does the query engine know what to replace nDeptID with when it calls, fn_SelDeptName_DeptID(nDeptID)? nDeptID IS a column in table Note. SELECT STATEMENT: SELECT nCustomerID AS [Customer ID], nJobID AS [Job ID], dbo.fn_SelDeptName_DeptID(nDeptID) AS Department, nJobTaskID AS JobTaskID, dbo.fn_SelDeptTaskDesc_OpenTask(nJobID, nJobTaskID) AS Task, nStandardNoteID AS StandardNoteID, dbo.fn_SelNoteTypeDesc(nNoteID) AS [Note Type], dbo.fn_SelGPAStandardNote(nStandardNoteID) AS [Standard Note], nEntryDate AS [Entry Date], nUserName as [Added By], nType AS Type, nNote AS Note FROM Note WHERE nJobID = 844261 xORDER BY nJobID, Task, [Entry Date] ====================== Function fn_SelDeptName_DeptID: ALTER FUNCTION [dbo].[fn_SelDeptName_DeptID] (@iDeptID int) RETURNS varchar(25) -- Used by DataCollection for Job Tracking -- if the Deptartment isnt found return an empty string BEGIN -- Return the Department name for the given DeptID. DECLARE @strDeptName varchar(25) IF @iDeptID = 0 SET @strDeptName = '' ELSE BEGIN SET @strDeptName = (SELECT dName FROM Department WHERE dDeptID = @iDeptID) IF (@strDeptName IS NULL) SET @strDeptName = '' END RETURN @strDeptName END ========================== Thanks in advance.

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• Page_Load or Page_Init

  - by balexandre

  Let's take a really simple example on using jQuery to ajaxify our page... $.load("getOrders.aspx", {limit: 25}, function(data) { // info as JSON is available in the data variable }); and in the ASP.NET (HTML part) page (only one line) <%@ Page Language="C#" AutoEventWireup="true" CodeFile="getOrders.aspx.cs" Inherits="getOrders" %> and in the ASP.NET (Code Behind) page public partial class getOrders : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { string lmt = Request["limit"]; List<Orders> ords = dll.GetOrders(limit); WriteOutput( Newtonsoft.Json.JsonConvert.SerializeObject(ords) ); } private void WriteOutput(string s) { Response.Clear(); Response.Write(s); Response.Flush(); Response.End(); } } my question is Should it be protected void Page_Load(object sender, EventArgs e) or protected void Page_Init(object sender, EventArgs e) So we can save some milliseconds as we don't actually need to process the events for the page, or will Page_Init lack of some sorting of a method by the time it is called? P.S. Currently works fine in both methods, but I just want to understand the ins and outs of choosing one method over the other

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• multi-threading in MFC

  - by kiddo

  Hello all,in my application there is a small part of function,in which it will read files to get some information,the number of filecount would be utleast 50,So I thought of implementing threading.Say if the user is giving 50 files,I wanted to separate it as 5 *10, 5 thread should be created,so that each thread can handle 10 files which can speed up the process.And also from the below code you can see that some variables are common.I read some articles about threading and I am aware that only one thread should access a variable/contorl at a me(CCriticalStiuation can be used for that).For me as a beginner,I am finding hard to imlplement what I have learned about threading.Somebody please give me some idea with code shown below..thanks in advance file read function:// void CMyClass::GetWorkFilesInfo(CStringArray& dataFilesArray,CString* dataFilesB, int* check,DWORD noOfFiles,LPWSTR path) { CString cFilePath; int cIndex =0; int exceptionInd = 0; wchar_t** filesForWork = new wchar_t*[noOfFiles]; int tempCheck; int localIndex =0; for(int index = 0;index < noOfFiles; index++) { tempCheck = *(check + index); if(tempCheck == NOCHECKBOX) { *(filesForWork+cIndex) = new TCHAR[MAX_PATH]; wcscpy(*(filesForWork+cIndex),*(dataFilesB +index)); cIndex++; } else//CHECKED or UNCHECKED { dataFilesArray.Add(*(dataFilesB+index)); *(check + localIndex) = *(check + index); localIndex++; } } WorkFiles(&cFilePath,dataFilesArray,filesForWork, path, cIndex); dataFilesArray.Add(cFilePath); *(check + localIndex) = CHECKED; }

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• In C, when do structure names have to be included in structure initializations and definitions?

  - by Tyler

  I'm reading The C Programming Language by K&R and in the section on structures I came across these code snippets: struct maxpt = { 320, 200 }; and /* addpoints: add two points */ struct addpoint(struct point p1, struct point p2) { p1.x += p2.x; p1.y += p2.y; return p1; } In the first case, it looks like it's assigning the values 320 and 200 to the members of the variable maxpt. But I noticed the name of the struct type is missing (shouldn't it be "struct struct_name maxpt = {320, 200}"? In the second case, the function return type is just "struct" and not "struct name_of_struct". I don't get why they don't include the struct names - how does it know what particular type of structure it's dealing with? My confusion is compounded by the fact that in previous snippets they do include the structure name, such as in the return type for the following function, where it's "struct point" and not just "struct". Why do they include the name in some cases and not in others? /* makepoint: make a point from x and y components */ struct point makepoint(int x, int y) { struct point temp; temp.x = x; temp.y = y; return temp; }

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• How to move positions within an array?

  - by Jade Mulholland

  A program that simply moves array elements. Two variables: userInputVariable and blankSpaceVariable. I have a 2D array named table. Defined as table[userInputVariable + 1][6] I am printing out this array in a table format, and the far left column is numbered by whatever number the user entered at the beginning of the program. I then ask the user where they would like to enter a blank space within the array. This blank space acts like a divider for all the other information in the array. For example, if the user enters 10 at the start for the userInputVariable, and then enters 5 for the blank space. Once printed, the numbers should go like this: 1, 2, 3, 4, --, 5, 6, 7, 8, 9, 10. My plan has been to create a for loop and try to move all the numbers in the array back a position starting from the blank space variable. What I currently have, but does not work: for (int i = blankSpaceVariable; i < table.length - 1; i++) { table[i] = table[i + 1]; } table[blankSpaceVariable] = "--"; With my current code, the numbers go like this: 1, 2, 3, 4, 6, 7, 8, 9, 10 Tried completing this a few different ways also, but the other info within my 2D array didn't move with the numbers. So I thought that this approach can hopefully move all the info within my 2D array down, and make way for a blank section. All help is greatly appreciated!

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• How to iteratively generate k elements subsets from a set of size n in java?

  - by Bea Metitiri

  Hi, I'm working on a puzzle that involves analyzing all size k subsets and figuring out which one is optimal. I wrote a solution that works when the number of subsets is small, but it runs out of memory for larger problems. Now I'm trying to translate an iterative function written in python to java so that I can analyze each subset as it's created and get only the value that represents how optimized it is and not the entire set so that I won't run out of memory. Here is what I have so far and it doesn't seem to finish even for very small problems: public static LinkedList<LinkedList<Integer>> getSets(int k, LinkedList<Integer> set) { int N = set.size(); int maxsets = nCr(N, k); LinkedList<LinkedList<Integer>> toRet = new LinkedList<LinkedList<Integer>>(); int remains, thresh; LinkedList<Integer> newset; for (int i=0; i<maxsets; i++) { remains = k; newset = new LinkedList<Integer>(); for (int val=1; val<=N; val++) { if (remains==0) break; thresh = nCr(N-val, remains-1); if (i < thresh) { newset.add(set.get(val-1)); remains --; } else { i -= thresh; } } toRet.add(newset); } return toRet; } Can anybody help me debug this function or suggest another algorithm for iteratively generating size k subsets? EDIT: I finally got this function working, I had to create a new variable that was the same as i to do the i and thresh comparison because python handles for loop indexes differently.

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• How to use the values from session variables in jsp pages that got saved using @Scope("session") in the mvc controllers

  - by droidsites

  Doing a web site using spring mvc. I added a SignupController to handle all the sign up related requests. Once user signup I am adding that to a session using @Scope("session"). Below is the SignupController code, SignupController.java @Controller @Scope("session") public class SignupController { @Autowired SignupServiceInter signUpService; private static final Logger logger = Logger.getLogger(SignupController.class); private String sessionUser; @RequestMapping("/SignupService") public ModelAndView signUp(@RequestParam("userid") String userId, @RequestParam("password") String password,@RequestParam("mailid") String emailId){ logger.debug(" userId:"+userId+"::Password::"+password+"::"); String signupResult; try { signUpService.registerUser(userId, password,emailId); sessionUser = userId; //adding the sign up user to the session return new ModelAndView("userHomePage","loginResult","Success"); //Navigate to user Home page if everything goes right } catch (UserExistsException e) { signupResult = e.toString(); return new ModelAndView("signUp","loginResult", signupResult); //Navigate to signUp page back if user does not exist } } } I am using "sessionUser" variable to store the signed up User Id. My understanding is that when I use @Scope("session") for the controller all the instance variables will added to HttpSession. So by that understanding I tried to access this "SessionUser" in userHomePage.jsp as, userHomepage.jsp Welcome to <%=session.getAttribute("sessionUser")%> But it throws null. So my question is how to use the values from session variables in jsp pages that got saved using @Scope("session") in the mvc controllers. Note: My work around is that pass that signed User Id to jsp page through ModelAndView, but it seems passing the value like these among the pages takes me back to managing state among pages using QueryStrings days.

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• How to change the picture of CustomButtonField on click event?

  - by Ujjal boruah Vinod

  I have posted this question previously but the answer is not appropiate. The solution provided just change the picture when the custombutton has focus and unfocus. Suppose in my application I need to change the picture if the user clicks on the customButton, n i m doing this by calling the same screen (ie UiApplication.getUiApplication().pushScreen(new Screen2(b));) . Screen2 is the screen which holds the customButton. On the click evevt i m pushing the same screen by passing aint variable pic_status that determines which picture to be drawn in the CustomButton in the new screen. Is there any way to update the picture in the CustomButtonField on click event without pushing the same Screen again and again. //code in Screen2 public void fieldChanged(Field field, int context) { if(field == bf1) { if(pic_status == 0) { pic_status=1; } UiApplication.getUiApplication().pushScreen(new Screen2(pic_status)); } //code in CustomButtonField CustomButtonField(String label,int pic_status,long style) { super(style); this.label = label; this.labelHeight = getFont().getHeight(); this.labelWidth = getFont().getAdvance(label); this.notice = s; if(pic_status ==0) { currentPicture1 = onPicture; currentPicture2 = onPicture; } if(pic_status ==1) { currentPicture1 = clickPicture; currentPicture2 = onPicture; } if( pic_status==2 ) { currentPicture1 = onPicture; currentPicture2 = clickPicture; } } I need a way to update the customButtonField text and picture on the buttonClick event not on focus/unfocus event without pushing the same Screen again and again. If my above description of problem is not satisfactory, plz add a comment n i can give more details explanation of my problem?

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• Difference between the address space of parent process and its child process in Linux?

  - by abbas1707

  Hi, I am confused about it. I have read that when a child is created by a parent process, child gets a copy of its parent's address space. What it means here by copy? If i use code below, then it prints same addresses of variable 'a' which is on heap in all cases. i.e in case of child and parent. So what is happening here? #include <sys/types.h> #include <stdio.h> #include <unistd.h> #include <stdlib.h> int main () { pid_t pid; int *a = (int *)malloc(4); printf ("heap pointer %p\n", a); pid = fork(); if (pid < 0) { fprintf (stderr, "Fork Failed"); exit(-1); } else if (pid == 0) { printf ("Child\n"); printf ("in child heap pointer %p\n", a); } else { wait (NULL); printf ("Child Complete\n"); printf ("in parent heap pointer %p\n", a); exit(0); } }

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• Need help: input int from console and pass it into method in different class and do math

  - by christophe

  i'm a beginner, Need help, Please!!! I want to read optional number "a" from console and then store it in variable to use as passing to a different class (different .java file). and pint the sum separetely by optional inputting. How do i code the 2 classes? thanks /* * DemoApp.java */ public class DemoApp { public static void main(String[] args) { Scanner input = new Scanner(System.in); int a; System.out.println("Input one of the following 3 numbers: 100, 200, 300"); System.out.print("Enter: "); a = input.nextInt(); TestApplication testapp = new TestApplication(); testapp.test(a); } } /* * TestApplication.java * */ public class TestApplication { private int a; public void test(int a) { this.a = a; // TODO: where to get the "a"? (entered by users from console) System.out.println("The number_a was passed in: "+a); } protected void printNum() throws Exception { int num; switch (a) { case 100: num = num + 10; break; case 200: num = num + 20; break; case 300: num = num + 30; break; default: // TODO: unexpected number input. throw(); break; } System.out.println("I got a sum number"+num); } }

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• How do I stop events from bubbling/multiple events with animated mouseovers?

  - by Kurucu

  I noticed a lot of JQuery answers on this, but I'm using MooTools... I have a Table of Contents which uses CSS Fixed positioning to keep it off to the left side, except for 20 pixels. The user hovers their cursor over the 20 pixels, which fires the DIV's mouseover event and the ToC slides fully into the page. When the cursor leaves, the ToC slides back to where it was. $('frameworkBreakdown').addEvents({ 'mouseover': function(event){ event = new Event(event); $('frameworkBreakdown').tween('left', 20); event.stop; }, 'mouseout': function(event){ event = new Event(event); $('frameworkBreakdown').tween('left', (10 - $('frameworkBreakdown').getStyle('width').toInt()) ); event.stop; } }); This works well (aside from unrelated issues) except that when I move the mouse on the DIV it starts to jitter, presumably because the contents of the DIV are also firing the event, or the event refires as the mouse tracks over the DIV. How can I stop this behaviour from occuring? Is there a standard method, or do I use some sort of nast global variable that determines whether effects are in action, and thus ignore the event?

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• Trouble with jQuery Form Validation

  - by Sennheiser

  I'm making a form that has the following validation rules: no fields are "required", but if you enter an email, it must be valid, and if you enter a password, it must be at least 6 characters and match the confirm password field value. The form works flawlessly with no validation so I know it's not a PHP or HTML problem. Here's the jQuery code handling the form: $('#success').hide(); $('#pwerror').hide(); $('#emailError').hide(); $('#subSet').live('click',function() { //if any of the fields have a value if($("#chfn").val() != "" || $("#chln").val() != "" || $("#chpw").val() != "" || $("#chpw2").val() != "" || $("#chem").val() != "") { $ev = 1; $pv = 1; //validates an email if there is one, trips the valid variable flag if($("#chem").val() != "") { $("#profSet").validate({ rules: { chem: { email: true }, chpw: { required: false, minlength: 6 }, chpw2: { required: false, minlength: 6, equalTo: $("#chpw").val() } }, messages:{ chpw2: { equalTo: "Passwords must be the same." }, chpw: { minlength: "Password must be at least 6 characters." } } }); if(!($("#profSet").valid())) { $ev = 0; } } //if either password field is filled, start trying to validate it if($("#chpw").val() != "" || $("#chpw2").val() != "") { if(!($("#profSet").valid())) { $pv = 0; } } //if those two were valid if($pv == 1 && $ev == 1) { $.post('php/profSet.php', $('#profSet').serialize(), function(){ $('#profSet').hide(); $('#success').show(); }); } //if either was invalid, the error was already tripped, and this code exits here } }); The problem I'm having now is that the "passwords must be the same" error keeps getting triggered even if both fields are blank, or if they actually are the same. Therefore, the form cannot submit. Any help?

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• PHP shell_exec() - Run directly, or perform a cron (bash/php) and include MySQL layer?

  - by Jimbo

  Sorry if the title is vague - I wasn't quite sure how to word it! What I'm Doing I'm running a Linux command to output data into a variable, parse the data, and output it as an array. Array values will be displayed on a page using PHP, and this PHP page output is requested via AJAX every 10 seconds so, in effect, the data will be retrieved and displayed/updated every 10 seconds. There could be as many as 10,000 characters being parsed on every request, although this is usually much lower. Alternative Idea I want to know if there is a better* alternative method of retrieving this data every 10 seconds, as multiple users (<10) will be having this command executed automatically for them. A cronjob running on the server could execute either bash or php (which is faster?) to grab the data and store it in a MySQL database. Then, any AJAX calls to the PHP output would return values in the MySQL database rather than making a direct call to execute server code every 10 seconds. Why? I know there are security concerns with running execs directly from PHP, and (I hope this isn't micro-optimisation) I'm worried about CPU usage on the server. The server is running a sempron processor. Yes, they do still exist. Having this only execute when the user is on the page (idea #1) means that the server isn't running code that doesn't need to be run. However, is this slow and insecure? Just in case the type of linux command may be of assistance in determining it's efficiency: shell_exec("transmission-remote $host:$port --auth $username:$password -l"); I'm hoping that there are differences in efficiency and level of security with the two methods I have outlined above, and that this isn't just micro-micro-optimisation. If there are alternative methods that are better*, I'd love to learn about these! :)

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• Why does the VS2005 debugger not report "base." values properly? (was "Why is this if statement fail

  - by Rawling

  I'm working on an existing class that is two steps derived from System.Windows.Forms.Combo box. The class overrides the Text property thus: public override string Text { get { return this.AccessibilityObject.Value; } set { if (base.Text != value) { base.Text = value; } } } The reason given for that "get" is this MS bug: http://support.microsoft.com/kb/814346 However, I'm more interested in the fact that the "if" doesn't work. There are times where "base.Text != value" is true and yet pressing F10 steps straight to the closing } of the "set" and the Text property is not changed. I've seen this both by just checking values in the debugger, and putting a conditional breakpoint on that only breaks when the "if" statement's predicate is true. How on earth can "if" go wrong? The class between this and ComboBox doesn't touch the Text property. The bug above shouldn't really be affecting anything - it says it's fixed in VS2005. Is the debugger showing different values than the program itself sees? Update I think I've found what is happening here. The debugger is reporting value incorrectly (including evaluating conditional breakpoints incorrectly). To see this, try the following pair of classes: class MyBase { virtual public string Text { get { return "BaseText"; } } } class MyDerived : MyBase { public override string Text { get { string test = base.Text; return "DerivedText"; } } } Put a breakpoint on the last return statement, then run the code and access that property. In my VS2005, hovering over base.Text gives the value "DerivedText", but the variable test has been correctly set to "BaseText". So, new question: why does the debugger not handle base properly, and how can I get it to?

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• Unsure how to come up with a good design

  - by Mewzer

  Hello there, I am having trouble coming up with a good design for a group of classes and was hoping that someone could give me some guidance on best practices. I have kept the classes and member functions generic to make the problem simpler. Essentially, I have three classes (lets call them A, B, and C) as follows: class A { ... int GetX( void ) const { return x; }; int GetY( void ) const { return y; }; private: B b; // NOTE: A "has-a" B int x; int y; }; class B { ... void SetZ( int value ) { z = value }; private: int z; C c; // NOTE: B "has-a" C }; class C { private: ... void DoSomething(int x, int y){ ... }; void DoSomethingElse( int z ){ ... }; }; My problem is as follows: Class A uses its member variables "x" and "y" a lot internally. Class B uses its member variable "z" a lot internally. Class B needs to call C::DoSomething(), but C::DoSomething() needs the values of X and Y in class A passed in as arguments. C::DoSomethingElse() is called from say another class (e.g. D), but it needs to invoke SetZ() in class B!. As you can see, it is a bit of a mess as all the classes need information from one another!. Are there any design patterns I can use?. Any ideas would be much appreciated ....

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• C++ Vector of vectors is messing with me

  - by xbonez

  If I put this code in a .cpp file and run it, it runs just fine: #include <iostream> #include <vector> #include <string> using namespace std; typedef vector<int> row; typedef vector<row> myMatrix; void main() { //cout << endl << "test" << endl; myMatrix mat(2,2); mat[0][1] = 2; cout << endl << mat[0][1] << endl; } But, if I make a .h and a .cpp file with the .h file like this, it gives me boatloads of errors. #ifndef _grid_ #define _grid_ #include<iostream> #include<vector> #include<string> using namespace std; typedef vector<int> row; typedef vector<row> myMatrix; class grid { public: grid(); ~grid(); int getElement(unsigned int ri, unsigned int ci); bool setElement(unsigned int ri, unsigned int ci, unsigned int value); private: myMatrix sudoku_(9,9); }; #endif These are some of the errors I get: warning C4091: 'typedef ' : ignored on left of 'int' when no variable is declared error C4430: missing type specifier - int assumed. Note: C++ does not support default-int

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• How to prevent VC++ 9 linker from linking unnecessary global variables?

  - by sharptooth

  I'm playing with function-level linking in VC++. I've enabled /OPT:REF and /OPT:ICF and the linker is happy to eliminate all unused functions. Not so with variables. The following code is to demonstrate the problem only, I fully understand that actually having code structured that way is suboptimal. //A.cpp SomeType variable1; //B.cpp extern SomeType variable1; SomeType variable2; class ClassInB { //actually uses variable1 }; //C.cpp extern SomeType variable2; class ClassInC { //actually uses variable2; }; All those files are compiled into a static lib. The consumer project only uses ClassInC and links to the static library. Now comes the VC++ 9 linker. First the linker sees that C.obj references variable2 and includes B.obj. B.obj references variable1, so it includes A.obj. Then the unreferenced stuff elimination phase starts. It removes all functions in A.obj and B.obj, but not the variables. Both variable and variable2 are preserved together with their static initializers and deinitializers. That inflates the image size and introduces a delay for running the initializers and deinitializes. The code above is oversimplified, in actual code I really can't move variable2 into C.cpp easily. I could put it into a separate .cpp file, but that looks really dumb. Is there any better option to resolve the problem with Visual C++ 9?

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• Explaining a Ruby code snippet

  - by Michael Foukarakis

  I'm in that uncomfortable position again, where somebody has left me with a code snippet in a language I don't know and I have to maintain it. While I haven't introduced Ruby to myself some parts of it are quite simple, but I'd like to hear your explanations nonetheless. Here goes: words = File.open("lengths.txt") {|f| f.read }.split # read all lines of a file in 'words'? values = Array.new(0) words.each { |value| values << value.to_i } # looked this one up, it's supposed to convert to an array of integers, right? values.sort! values.uniq! diffs = Array.new(0) # this looks unused, unless I'm missing something obvious sum = 0 s = 0 # another unused variable # this looks like it's computing the sum of differences between successive # elements, but that sum also remains unused, or does it? values.each_index { |index| if index.to_i < values.length-1 then sum += values.at(index.to_i + 1) - values.at(index.to_i) end } # could you also explain the syntax here? puts "delta has the value of\n" # this will eventually print the minimum of the original values divided by 2 puts values.at(0) / 2 The above script was supposed to figure out the average of the differences between every two successive elements (integers, essentially) in a list. Am I right in saying this is nowhere near what it actually does, or am I missing something fundamental, which is likely considering I have no Ruby knowledge?

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• Spring MVC - Set an actionURL parameter with Javascript

  - by jeffl8n

  Is it possible to dynamically set a Spring MVC portlet:actionURL portlet:param using javascript? I have tried with the following code, but the id value always comes across as null to the controller. I have verified that setting the portlet:param manually passes the value correctly: <portlet:param name="id" value="2" /> I have also verified the value in the javascript is being set correctly and is not null. (Note: I've changed the variable names, etc. from the original code to simplify it and obfuscate it since it is my employer's code.) JSP: <portlet:actionURL var="modifyURL"> <portlet:param name="do" value="modify" /> <portlet:param name="id" value="${model.id}" /> </portlet:actionURL> ... <form:form action="${modifyURL}" id="modifyForm" modelAttribute="model"> <form:hidden path="id" id="id" /> </form:form> Javascript called when the update URL is clicked: function update() { document.forms[0]["id"].value = selectedId; document.forms[0].submit(); } Controller: @RequestMapping(params = {"do=modify"}) public void modify(@ModelAttribute("model") Model model, @RequestParam(value = "id", required=true) Long id, ActionRequest request, ActionResponse response, SessionStatus sessionStatus, ModelMap modelMap) { ....

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• CSS: position:absolute inside position:relative, but not affecting parent?

  - by JP

  <style> #special p { display:none; } #special:hover p { display:block; } </style> <table> <tr> <td style="width:200px">Things</td> <td style="position:relative; width:220px"> <div style="position:absolute;right:0" id="special"> <img id="shows" /> <p>Variable width upto, say 600px (Will be hidden until this td is :hovered</p> </div> </td> </tr> </table> Can I make this work? Ie, can I make the #special p expand over the top of 'Things'? As I currently have it set up #special won't ever grow outside the 220px wide td. Any ideas?

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