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  • calling constructor of the class in the destructor of the same class

    - by dicaprio
    Experts !! I know this question is one of the lousy one , but still I dared to open my mind , hoping I would learn from all. I was trying some examples as part of my routine and did this horrible thing, I called the constructor of the class from destructor of the same class. I don't really know if this is ever required in real programming , I cant think of any real time scenarios where we really need to call functions/CTOR in our destructor. Usually , destructor is meant for cleaning up. If my understanding is correct, why the compiler doesn't complain ? Is this because it is valid for some good reasons ? If so what are they ? I tried on Sun Forte, g++ and VC++ compiler and none of them complain about it. using namespace std; class test{ public: test(){ cout<<"CTOR"<<endl; } ~test() {cout<<"DTOR"<<endl; test(); }};

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  • Performing measures within the execution of a c++ code every t milliseconds

    - by user506901
    Given a while loop and the function ordering as follows: int k=0; int total=100; while(k<total){ doSomething(); if(approx. t milliseconds elapsed) { measure(); } ++k; } I want to perform 'measure' every t-th milliseconds. However, since 'doSomething' can be close to the t-th millisecond from the last execution, it is acceptable to perform the measure after approximately t milliseconds elapsed from the last measure. My question is: how could this be achieved? One solution would be to set timer to zero, and measure it after every 'doSomething'. When it is withing the acceptable range, I perform measures, and reset. However, I'm not which c++ function I should use for such a task. As I can see, there are certain functions, but the debate on which one is the most appropriate is outside of my understanding. Note that some of the functions actually take into account the time taken by some other processes, but I want my timer to only measure the time of the execution of my c++ code (I hope that is clear). Another thing is the resolution of the measurements, as pointed out below. Suppose the medium option of those suggested.

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  • Entity Framework does not map 2 columns from a SqlQuery calling a stored procedure

    - by user1783530
    I'm using Code First and am trying to call a stored procedure and have it map to one of my classes. I created a stored procedure, BOMComponentChild, that returns details of a Component with information of its hierarchy in PartsPath and MyPath. I have a class for the output of this stored procedure. I'm having an issue where everything except the two columns, PartsPath and MyPath, are being mapped correctly with these two properties ending up as Nothing. I searched around and from my understanding the mapping bypasses any Entity Framework name mapping and uses column name to property name. The names are the same and I'm not sure why it is only these two columns. The last part of the stored procedure is: SELECT t.ParentID ,t.ComponentID ,c.PartNumber ,t.PartsPath ,t.MyPath ,t.Layer ,c.[Description] ,loc.LocationID ,loc.LocationName ,CASE WHEN sup.SupplierID IS NULL THEN 1 ELSE sup.SupplierID END AS SupplierID ,CASE WHEN sup.SupplierName IS NULL THEN 'Scinomix' ELSE sup.SupplierName END AS SupplierName ,c.Active ,c.QA ,c.IsAssembly ,c.IsPurchasable ,c.IsMachined ,t.QtyRequired ,t.TotalQty FROM BuildProducts t INNER JOIN [dbo].[BOMComponent] c ON c.ComponentID = t.ComponentID LEFT JOIN [dbo].[BOMSupplier] bsup ON bsup.ComponentID = t.ComponentID AND bsup.IsDefault = 1 LEFT JOIN [dbo].[LookupSupplier] sup ON sup.SupplierID = bsup.SupplierID LEFT JOIN [dbo].[LookupLocation] loc ON loc.LocationID = c.LocationID WHERE (@IsAssembly IS NULL OR IsAssembly = @IsAssembly) ORDER BY t.MyPath and the class it maps to is: Public Class BOMComponentChild Public Property ParentID As Nullable(Of Integer) Public Property ComponentID As Integer Public Property PartNumber As String Public Property MyPath As String Public Property PartsPath As String Public Property Layer As Integer Public Property Description As String Public Property LocationID As Integer Public Property LocationName As String Public Property SupplierID As Integer Public Property SupplierName As String Public Property Active As Boolean Public Property QA As Boolean Public Property IsAssembly As Boolean Public Property IsPurchasable As Boolean Public Property IsMachined As Boolean Public Property QtyRequired As Integer Public Property TotalQty As Integer Public Property Children As IDictionary(Of String, BOMComponentChild) = New Dictionary(Of String, BOMComponentChild) End Class I am trying to call it like this: Me.Database.SqlQuery(Of BOMComponentChild)("EXEC [BOMComponentChild] @ComponentID, @PathPrefix, @IsAssembly", params).ToList() When I run the stored procedure in management studio, the columns are correct and not null. I just can't figure out why these won't map as they are the important information in the stored procedure. The types for PartsPath and MyPath are varchar(50).

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  • Using delegate Types vs methods

    - by Grant Sutcliffe
    I see increasing use of the delegate types offered in the System namespace (Action; Predicate etc). As these are delegates, my understanding is that they should be used where we have traditionally used delegates in the past (asynchronous calls; starting threads, event handling etc). Is it just preference or is it considered practice to use these delegate types in scenarios such as the below; rather than using calls to methods we have declared (or anonymous methods): public void MyMethod { Action<string> action = delegate(string userName { try { XmlDocument profile = DataHelper.GetProfile(userName); UpdateMember(profile); } catch (Exception exception) { if (_log.IsErrorEnabled) _log.ErrorFormat(exception.Message); throw (exception); } }; GetUsers().ForEach(action); } At first, I found the code less intuitive to follow than using declared or anonymous methods. I am starting to code this way, and wonder what the view are in this regard. The example above is all within a method. Is this delegate overuse.

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  • Why should I abstract my data layer?

    - by Gazillion
    OOP principles were difficult for me to grasp because for some reason I could never apply them to web development. As I developed more and more projects I started understanding how some parts of my code could use certain design patterns to make them easier to read, reuse, and maintain so I started to use it more and more. The one thing I still can't quite comprehend is why I should abstract my data layer. Basically if I need to print a list of items stored in my DB to the browser I do something along the lines of: $sql = 'SELECT * FROM table WHERE type = "type1"';' $result = mysql_query($sql); while($row = mysql_fetch_assoc($result)) { echo '<li>'.$row['name'].'</li>'; } I'm reading all these How-Tos or articles preaching about the greatness of PDO but I don't understand why. I don't seem to be saving any LoCs and I don't see how it would be more reusable because all the functions that I call above just seem to be encapsulated in a class but do the exact same thing. The only advantage I'm seeing to PDO are prepared statements. I'm not saying data abstraction is a bad thing, I'm asking these questions because I'm trying to design my current classes correctly and they need to connect to a DB so I figured I'd do this the right way. Maybe I'm just reading bad articles on the subject :) I would really appreciate any advice, links, or concrete real-life examples on the subject!

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  • What do you call a set of Javascript closures that share a common context?

    - by Ed Stauff
    I've been trying to learn closures (in Javascript), which kind of hurts my brain after way too many years with C# and C++. I think I now have a basic understanding, but one thing bothers me: I've visited lots of websites in this Quest for Knowledge, and nowhere have I seen a word (or even a simple two-word phrase) that means "a set of Javascript closures that share a common execution context". For example: function CreateThingy (name, initialValue) { var myName = name; var myValue = initialValue; var retObj = new Object; retObj.getName = function() { return myName; } retObj.getValue = function() { return myValue; } retObj.setValue = function(newValue) { myValue = newValue; } return retObj; }; From what I've read, this seems to be one common way of implementing data hiding. The value returned by CreateThingy is, of course, an object, but what would you call the set of functions which are properties of that object? Each one is a closure, but I'd like a name I can used to describe (and think about) all of them together as one conceptual entity, and I'd rather use a commonly accepted name than make one up. Thanks! -- Ed

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  • Why does reusing arrays increase performance so significantly in c#?

    - by Willem
    In my code, I perform a large number of tasks, each requiring a large array of memory to temporarily store data. I have about 500 tasks. At the beginning of each task, I allocate memory for an array : double[] tempDoubleArray = new double[M]; M is a large number depending on the precise task, typically around 2000000. Now, I do some complex calculations to fill the array, and in the end I use the array to determine the result of this task. After that, the tempDoubleArray goes out of scope. Profiling reveals that the calls to construct the arrays are time consuming. So, I decide to try and reuse the array, by making it static and reusing it. It requires some additional juggling to figure out the minimum size of the array, requiring an extra pass through all tasks, but it works. Now, the program is much faster (from 80 sec to 22 sec for execution of all tasks). double[] tempDoubleArray = staticDoubleArray; However, I'm a bit in the dark of why precisely this works so well. Id say that in the original code, when the tempDoubleArray goes out of scope, it can be collected, so allocating a new array should not be that hard right? I ask this because understanding why it works might help me figuring out other ways to achieve the same effect, and because I would like to know in what cases allocation gives performance issues.

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  • Looking for a good C++/.net book

    - by Michael Minerva
    I have recently started to feel that I need to greatly improve my C++ skills especially in the realm of .net. I graduated from a good four year university with a degree in computer science about 9 months ago and I have since been doing full time contract work for a small software company in my local area. Most of my work has been done using Java/lisp/cocoa/XML and before that most of my programming in my senior year was in java/C#. I did a decent amount of C++ in my Sophomore year and in my free time before that but I feel that my general knowledge of C++/.net is very lacking for the opportunities that are now coming my way. Can anyone recommend a good book that could help me get up too speed? I feel I do not need a very basic introduction to C++ but something that covers the fundamentals of .net would be good for me. So basically what I need is a book or books that would be good for a .net novice and a C++ developer who is just beyond novice. Also, a book that would help bein an interview by giving me a conversional understanding of C++ would be great. Thanks a lot!.

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  • Linear Interpolation. How to implement this algorithm in C ? (Python version is given)

    - by psihodelia
    There exists one very good linear interpolation method. It performs linear interpolation requiring at most one multiply per output sample. I found its description in a third edition of Understanding DSP by Lyons. This method involves a special hold buffer. Given a number of samples to be inserted between any two input samples, it produces output points using linear interpolation. Here, I have rewritten this algorithm using Python: temp1, temp2 = 0, 0 iL = 1.0 / L for i in x: hold = [i-temp1] * L temp1 = i for j in hold: temp2 += j y.append(temp2 *iL) where x contains input samples, L is a number of points to be inserted, y will contain output samples. My question is how to implement such algorithm in ANSI C in a most effective way, e.g. is it possible to avoid the second loop? NOTE: presented Python code is just to understand how this algorithm works. UPDATE: here is an example how it works in Python: x=[] y=[] hold=[] num_points=20 points_inbetween = 2 temp1,temp2=0,0 for i in range(num_points): x.append( sin(i*2.0*pi * 0.1) ) L = points_inbetween iL = 1.0/L for i in x: hold = [i-temp1] * L temp1 = i for j in hold: temp2 += j y.append(temp2 * iL) Let's say x=[.... 10, 20, 30 ....]. Then, if L=1, it will produce [... 10, 15, 20, 25, 30 ...]

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  • Clarification/explanation of RegisterClientScriptInclude method

    - by mpminnich
    I've been looking on the Internet for a fairly clear explanation of the different methods of registering javascript in an asp.net application. I think I have a basic understating of the difference between registerStartupScript and registerClientScriptBlock (the main difference being where in the form the script is inserted). I'm not sure I understand what the RegisterClientScriptInclude method does or when it is used. From what I can gather, it is used to register an external .js file. Does this then make any and all javascript functions in that file available to the aspx page it was registered on? For example, if it was registered in the onLoad event of a master page, would all pages using that master page be able to use the javascript functions in the .js file? What problems would arise when trying to use document.getElementById in this case, if any? Also, when it is necessary/advantageous to use multiple .js files and register them separately? I appreciate any help you can give. If you know of any really good resources I can use to get a thorough understanding of this concept, I'd appreciate it!

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  • servlet connection to DB

    - by underW
    Initially, after reading books on the subject, I firmly believed that the algorithm for working with a database from a servlet is as follows: create a connection - connect to the database - form a request - send the request to the database - get the query results - process them - close connection - OK. Now, with a better understanding of the practical side, I realized that nobody does it that way, and everything happens through a connection pool according to the following algorithm: initialize the servlet - create a connection pool - a request comes from a user - take a free connection from the pool - form a request - send the request to the database - get the query results - process them - return the connection back to the pool - ok. Now I have this problem: We have 100 users, they are divided into 10 groups, each group has it's own username and password to connect to the database. Moreover, each group may have different rights to the database. How am I supposed to use a connection pool in this situation? If I understand correctly, a pool is nothing more than just a group of similar connections with a single login and password. And here I have 10 pairs of username / password. It looks like I cannot use the pool in this situation. What should I do?

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  • Android designing an app to keep me logged into a wifi access point

    - by MrGibbage
    At the gym where I work out, they have an open wifi access point. The way it is set up, once you "connect", you have to navigate to a web page (it is a 1.1.X.X ip address) and click the "I agree" button, after presumably reading the user agreement. The problem is, they have it set up to log you out once an hour, which always happens in the middle of my workout. I have the SSID remembered, so it connects automatically when I come in range, but I get an android notification that further action is needed to fully connect. What I was wondering is if there a work around so that I don't have to click-through every hour? I was thinking of writing an app that could detect when I was in range, or when "half-connected", and then have it somehow complete the registration process. Perhaps this will have to be done by loading the web page in memory and then somehow clicking the "I agree" button. What I would like help with is: 1) what is the terminology involved here? What state is the connection in when I am connected, but I haven't clicked through? What other connection states may apply? If I knew that, I might just be able to research this and come up with a solution. Are these different states "detectable"? It seems like it is since I get a notification that I need to complete the registration process when I am "half-connected". 2) I know there are plugins for desktop browsers that can click buttons (like the keepass plugins, which will log you into a site). How could I replicate this in Android? Ideally I would like to do it internally, in memory, rather than firing up a browser. Possible? Comments? Is my understanding and thought process sound here, or am I overlooking something?

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  • Can it be important to call remove() on an EJB 3 stateless session bean? Perhaps on weblogic?

    - by Michael Borgwardt
    I'm in the process of migrating an EJB 2 application to EJB 3 (and what a satisfying task it is to delete all those deployment descriptors!). It used to run on Weblogic and now runs on Glassfish. The task is going very smoothly, but one thing makes me wary: The current code takes great care to ensure that EJBObject.remove() is called on the bean when it's done its job, and other developers have (unfortunately very vague) memories of "bad things" happening when that was not done. However, with EJB3, the implementation class does not implement EJBObject, so there is no remove() method to be called. And my understanding is that there isn't really any point at all in calling it on stateless session beans, since they are, well, stateless. Could these "bad things" have been weblogic-specific? If not, what else? Should I avoid the full EJB3 lightweightness and keep a remote interface that extends EJBObject? Or just write it off as cargo-cult programming and delete all those try/finally clauses? I'm leaning towards the latter, but now feeling very comfortable with it.

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  • SQL Server find and replace in TEXT field

    - by incubushead
    I have a database in SQL Server 2005 that was brought up from SQL Server 2000 and is still using TEXT type fields instead of varchar(max). I need to find and replace a string of characters in the text field but all of the examples of how to do this that I have found don't seem like they would work for me. It seems the UPDATETEXT command requires that the two parameters "insert_offset" and "delete_length" be set explicitly but the string i am searching for could show up in the text at any point or even at several points in the same cell. My understanding of these two parameters is that the string im searching for will always be in the same place, so that insert_offset is the number of spaces into the text that the UPDATETEXT command will start replacing text. Example: Need to find: &lt;u&gt; and Replace it with: <u> Text field example: *Everyone in the room was <b>&lt;u&gt;tired&lt;/u&gt;.</b><br>Then they woke <b>&lt;u&gt;up&lt;/u&gt;. Can anyone help me out with this? THANKS!

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  • Trouble with go tour crawler exercise

    - by David Mason
    I'm going through the go tour and I feel like I have a pretty good understanding of the language except for concurrency. On slide 71 there is an exercise that asks the reader to parallelize a web crawler (and to make it not cover repeats but I haven't gotten there yet.) Here is what I have so far: func Crawl(url string, depth int, fetcher Fetcher, ch chan string) { if depth <= 0 { return } body, urls, err := fetcher.Fetch(url) if err != nil { ch <- fmt.Sprintln(err) return } ch <- fmt.Sprintf("found: %s %q\n", url, body) for _, u := range urls { go Crawl(u, depth-1, fetcher, ch) } } func main() { ch := make(chan string, 100) go Crawl("http://golang.org/", 4, fetcher, ch) for i := range ch { fmt.Println(i) } } The issue I have is where to put the close(ch) call. If I put a defer close(ch) somewhere in the Crawl method, then I end up writing to a closed channel in one of the spawned goroutines, since the method will finish execution before the spawned goroutines do. If I omit the call to close(ch), as is shown in my example code, the program deadlocks after all the goroutines finish executing but the main thread is still waiting on the channel in the for loop since the channel was never closed.

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  • Wicket: Where to add components? Constructor? Or onBeforeRender?

    - by gmallett
    I'm a Wicket newb. This may just be my ignorance of the Wicket lifecycle so please enlighten me! My understanding is that Wicket WebPage objects are instantiated once and then serialized. This has led to a point of confusion for me, see below. Currently I have a template class which I intend to subclass. I followed the example in the Wicket docs demonstrating how to override the template's behavior in the subclass: protected void onBeforeRender() { add(new Label("title", getTitle())); super.onBeforeRender(); } protected String getTitle() { return "template"; } Subclass: protected String getTitle() { return "Home"; } This works very well. What's not clear to me are the "best practices" for this. It seems like onBeforeRender() is called on every request for the page, no? This seems like there would be substantially more processing done on a page if everything is in onBeforeRender(). I could easily follow the example of the other Wicket examples and add some components in the constructor that I do not want to override, but then I've divided by component logic into two places, something I'm hesitant to do. If I add a component that I intend to be in all subclasses, should I add it to the constructor or onBeforeRender()?

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  • Nested IF statements in Excel [Over the 7 allowed limit]

    - by Alks
    hey guys, i am trying to create a spreadsheet which automagically gives a grade to a student based on their marks they got. I've apparently hit excels nested IF statement limit which is 7. here's my if statement: =IF(O5>0.895,"A+",IF(O5>0.845,"A",IF(O5>0.795,"A-",IF(O5>0.745,"B+",IF(O5>0.695,"B",IF(O5>0.645,"B-",IF(O5>0.595,"C+",IF(O5>0.545,"C","D")))))))) I was reading online that I could create a VBA script and assign it that, but I dont know anything about VBA....so if someone could help me write a VBA for this, would be awesome. Its still mising the C- grade and anything lower should be awarded a D mark. This is the grading scheme I am trying to create...: A+ 89.500 - 100.000 Pass with Distinction A 84.500 - 89.490 Pass with Distinction A- 79.500 - 84.490 Pass with Distinction B+ 74.500 - 79.490 Pass with Merit B 69.500 - 74.490 Pass with Merit B- 64.500 - 69.490 Pass with Merit C+ 59.500 - 64.490 Pass C 54.500 - 59.490 Pass C- 49.500 - 54.490 Pass D 0.000 - 49.490 Specified Fail I wouldn't mind going down the VBA route, however my understanding of VB language is absolutely minimal (don't like it)...if this gets too tedious, I was thinking to create a small php/mysql application instead. Cheers :)

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  • Where to turn upon realizing I can't program my way out of a paper bag?

    - by luminarious
    I have no job and just enough money to get by until April or so. While looking for work, I figured I might as well go through with a pet project, a browser based card game. Make it nice and free, collect donations and maybe earn enough for a movie ticket to escape reality for a while. I have dabbled in web development a bit. I can make simple stuff happen with JS/PHP if I follow tutorials. I designed my own art blog's template - http://luminarious.tumblr.com. I can visualise the game working in my head, flowcharts and everything. But then I tried to go deeper with Javascript and almost had an aneurysm before understanding what a closure is. Wether I suck at learning, have ADD or fail epically at productivity, I have not got much done. Coming up with ideas, screen mock-ups and so forth was very enjoyable, but actual implementation.. not so much. In fact, I cry a bit every time I think about the time someone competent could have finished this in. I'd like to excuse myself with my ENTP personality type, but that hardly solves anything. Rather, I'd like to know to get from A (bunch of ideas with little semblance to a web app) to B (something to proudly show others) while being unable to pay anyone? Are there any secret techniques for learning? Is there any way to get mentoring or code review? Is there anyone with too much free time willing to code for me? How to trust someone to not steal my code when I ask for assistance? Is there anything I should have asked instead of any of those?

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  • Performing an action on Parent/Child elements independently.

    - by Matt Weldon
    I have HTML similar to the following in my page <div id="someDiv"> <img src="foo.gif" class="someImg" /> </div> The wrapper div is set up such that when it is clicked, it's background-color changes using the following jQuery code. $("div").click(function(event){ $(this).css("background-color", "blue"); }); I also have some jQuery associated with my img that will do some other function (for the sake of argument I am going to display and alert box) like so: $("img[class=someImg]").click(function(event){ alert("Image clicked"); }); The issue I have come across is that when I click on the img, the event associated with the div is also triggered. I'm pretty sure that this is due to the way that jQuery (or indeed JavaScript) is handling the two DOM elements - clicking the img would require you to also technically click the div, thus triggering both events. Two questions then really: Is my understanding of the DOM/JavaScript flawed in some way or is this actually how things are occurring? Are there any jQuery methods that would allow me to perform actions on a child element without invoking those associated with its parent?

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  • jQuery relative positioned hover

    - by danixd
    I want a link to the next or previous image to appear when hovering over the main image, only I want the next link to appear when hovered over the right hand side, and previous on the left. I have looked at jQuery's .position() and I don't think I am understanding it very well. At the moment all I have is general mouseenter/mouseleave events, which show both links when the image is hovered. jQuery(document).ready(function($) { $('.nav-controls a').hide(); $('#slideshow').mouseenter(function() { $('.nav-controls a').fadeIn(500); }); $('#slideshow').mouseleave(function() { $('.nav-controls a').fadeOut(500); }); }); I'd image it to be something like: jQuery(document).ready(function($) { $('.nav-controls a').hide(); var image = $('#slideshow'); var left = image.position().left(0); var right = image.position().left(50%); left.mouseenter(function() { $('.nav-controls a.previous').fadeIn(500); }); left.mouseleave(function() { $('.nav-controls a.previous').fadeOut(500); }); right.mouseenter(function() { $('.nav-controls a.next').fadeIn(500); }); right.mouseleave(function() { $('.nav-controls a.next').fadeOut(500); }); }); Not sure if I should be using position, if I am using it correctly. Any tips would be great. Edit: I do not want to add unnecessary markup in the form of divs, for the left/right selectors.

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  • PHP classes, parse syntax errors when using 'var' to declare variables

    - by jon
    I am a C# guy trying to translate some of my OOP understanding over to php. I'm trying to make my first class object, and are hitting a few hitches. Here is the beginning of the class: <?php require("Database/UserDB.php"); class User { private var $uid; private var $username; private var $password; private var $realname; private var $email; private var $address; private var $phone; private var $projectArray; public function _construct($username) { $userArray = UserDB::GetUserArray($username); $uid = $userArray['uid']; $username = $userArray['username']; $realname = $userArray['realname']; $email = $userArray['email']; $phone = $userArray['phone']; $i = 1; $projectArray = UserDB::GetUserProjects($this->GetID()); while($projectArray[$i] != null) { $projectArray[$i] = new Project($projectArray[$i]); } UserDB.php is where I have all my static functions interacting with the Database for this User Class. I am getting errors using when I use var, and I'm getting confused. I know I don't HAVE to use var, or declare the variables at all, but I feel it is a better practice to do so. the error is "unexpected T_VAR, expecting T_VARIABLE" When I simply remove var from the declarations it works. Why is this?

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  • What could the negative effects be of attaching to a process as a debugger?

    - by I_like_traffic_lights
    Background A client of mine has a major problem. They have a CRM system, which was created by a single person over a period of 9 years. Unfortunatelly, a few weeks ago, this person died. I believe the company has learned their lesson, and they have started a project of rewriting the CRM system to a modern platform. I have been hired to create a solution in the meantime to make adaptations to the CRM system. I have given up understanding the code, as this would take too long. My solution, is therefore, to make a window and show this on top of the CRM system, whenever this CRM system is showing. This part works fine, but my major problem is extracting the data from the CRM system. Proposed solution After excluding 6 approaches, including runtime code injection, memory searching, database integration, I have arrived at attaching to the process as a debugger, so I get notified about event, and use this in combination with reading from process memory. This approach seems to work, but I am worried about possible side-effects of this approach. Question What are the dangers of using this in a production environment, where there are 250 employees utilizing the system. Needless to say, I cannot risk reducing the already shaky stability of the system.

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  • How can I get 100% test coverage in a Perl module that uses DBI?

    - by BrianH
    I am a bit new to the Devel::Cover module, but have found it very useful in making sure I am not missing tests. A problem I am running into is understanding the report from Devel::Cover. I've looked at the documentation, but can't figure out what I need to test to get 100% coverage. Here is the output from the cover report: line err stmt bran cond sub pod time code ... 36 sub connect_database { 37 3 3 1 1126 my $self = shift; 38 3 100 24 if ( !$self->{dsn} ) { 39 1 7 croak 'dsn not supplied - cannot connect'; 40 } 41 *** 2 33 21 $self->{dbh} = DBI->connect( $self->{dsn}, q{}, q{} ) 42 || croak "$DBI::errstr"; 43 1 11 return $self; 44 } ... line err % l !l&&r !l&&!r expr ----- --- ------ ------ ------ ------ ---- 41 *** 33 1 0 0 'DBI'->connect($$self{'dsn'}, '', '') || croak("$DBI::errstr") And here is and example of my code that tests this specific line: my $database = MyModule::Database->new( { dsn => 'Invalid DSN' }); throws_ok( sub { $database->connect_database() }, qr/Can't connect to data source/, 'Test connection exception (invalid dsn)' ); This test passes - the connect does throw an error and fulfills my "throws_ok" test. I do have some tests that test for a successful connection, which is why I think I have 33% coverage, but if I'm reading it correctly, cover thinks I am not testing the "|| croak" part of the statement. I thought I was, with the "throws_ok" test, but obviously I am missing something. Does anyone have advice on how I can test my DBI-connect line successfully? Thanks!

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  • Good C++ array class for dealing with large arrays of data in a fast and memory efficient way?

    - by Shane MacLaughlin
    Following on from a previous question relating to heap usage restrictions, I'm looking for a good standard C++ class for dealing with big arrays of data in a way that is both memory efficient and speed efficient. I had been allocating the array using a single malloc/HealAlloc but after multiple trys using various calls, keep falling foul of heap fragmentation. So the conclusion I've come to, other than porting to 64 bit, is to use a mechanism that allows me to have a large array spanning multiple smaller memory fragments. I don't want an alloc per element as that is very memory inefficient, so the plan is to write a class that overrides the [] operator and select an appropriate element based on the index. Is there already a decent class out there to do this, or am I better off rolling my own? From my understanding, and some googling, a 32 bit Windows process should theoretically be able address up to 2GB. Now assuming I've 2GB installed, and various other processes and services are hogging about 400MB, how much usable memory do you think my program can reasonably expect to get from the heap? I'm currently using various flavours of Visual C++.

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  • Name lookup for names not dependent on template parameter in VC++2008 Express. Is it a bug?

    - by Maciej H
    While experimenting a bit with C++ templates I managed to produce this simple code, for which the output is different, than I expected according to my understanding of C++ rules. void bar(double d) { std::cout << "bar(double) function called" << std::endl; } template <typename T> void foo(T t) { bar(3); } void bar(int i) { std::cout << "bar(int) function called" << std::endl; } int main() { foo(3); return 0; } When I compile this code is VC++2008 Express function bar(int) gets called. That would be the behaviour I would expect if bar(3);in the template body was dependent on the template parameter. But it's not. The rule I found here says "The C++ standard prescribes that all names that are not dependent on template parameters are bound to their present definitions when parsing a template function or class". Am I wrong, that "present definition" of bar when parsing the template function foo is the definition of void bar(double d);? Why it's not the case if I am wrong. There are no forward declarations of bar in this compilation unit.

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