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  • How to submit Nothing as a route value to ASP MVC

    - by Adam
    I have a route with several optional parameters. These are possible search terms in different fields. So, for example, if I have fields key, itemtype and text then I have in global.asax: routes.MapRoute( _ "Search", _ "Admin.aspx/Search/{Key}/{ItemType}/{Text}", _ New With {.controller = "Admin", .action = "Search" .Key = Nothing, .ItemType = Nothing, .Text = Nothing} _ ) My action takes optional parameters: Function Search(Optional ByVal Key As String = Nothing, _ Optional ByVal ItemType As Integer = 0, _ Optional ByVal Text As String = Nothing, _ Optional ByVal OtherText As String = Nothing) It then checks if the Key and Text strings have a non-null (and non-empty) value and adds search terms to the db request as needed. However, is it possible to send in a null value for, for example, Key but still send in a value for Text? If so, what does the URL look like? (Admin.aspx/Search//0/Foo doesn't work :) ) I know I can handle this using a parameter array instead, but wondered if this was possible using the sort of route described? I could of course define some other value as equivalent to null (for example, a space/%20) but is there any way to send a null value in the URL? I'm suspecting not, but thought I'd see if anyone knew of one. I'm using ASP MVC 2 for this project.

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  • Lookup table size reduction

    - by Ryan
    Hello: I have an application in which I have to store a couple of millions of integers, I have to store them in a Look up table, obviously I cannot store such amount of data in memory and in my requirements I am very limited I have to store the data in an embebedded system so I am very limited in the space, so I would like to ask you about recommended methods that I can use for the reduction of the look up table. I cannot use function approximation such as neural networks, the values needs to be in a table. The range of the integers is not known at the moment. When I say integers I mean a 32 bit value. Basically the idea is use some copmpression method to reduce the amount of memory but without losing many precision. This thing needs to run in hardware so the computation overhead cannot be very high. In my algorithm I have to access to one value of the table do some operations with it and after update the value. In the end what I should have is a function which I pass an index to it and then I get a value, and after I have to use another function to write a value in the table. I found one called tile coding http://www.cs.ualberta.ca/~sutton/book/8/node6.html, this one is based on several look up tables, does anyone know any other method?. Thanks.

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  • JQuery error in IE, works with FF. Maybe a problem with live.

    - by olve
    Hello. I have an ASP.net MVC2 application. In wich I'm using JQuery to alter all table rows so I can click anywhere in any row to trigger a click event on a link in the clicked row. The tables is created using MVC's built in partialview ajax. Here is my JQuery script. <script type="text/javascript"> $(document).ready(function () { $('table tr').live('click',function (event) { $('#asplink', this).trigger('click'); }) .live('mouseenter',function (event) { this.bgColor = 'lightblue'; }) .live('mouseleave', function (event) { this.bgColor = 'white'; }); }); </script> And this is the first part of the partial view code that creates the table. <% foreach (var item in Model.JobHeaderData) { %> <tr> <td> <a id="asplink" href="http://localhost/sagstyring/EditJob.asp?JobDataID=<%: item.JobDataId %>&JobNumId=<%: item.JobNumID%>&JobNum=<%: item.JobNumID%>&DepId=1&User_Id=<%:ViewData["UserId"]%>" onclick="window.open(this.href,'Rediger sag <%: item.JobNumID %> ', 'status=0, toolbar=0, location=0, menubar=0, directories=0, resizeable=0, scrollbars=0, width=900, height=700'); return false;">Rediger</a> </td> In firefox this works perfectly. In IE, JQuery crashes when I click on a row. If I debug the page in IE. I get this. Out of stack space In jquery-1.4.1.js line 1822 // Trigger the event, it is assumed that "handle" is a function var handle = jQuery.data( elem, "handle" ); if ( handle ) { handle.apply( elem, data ); } I'm no eagle at javascript, so I'm pretty much stuck.

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  • Plot vectors with labels in matlab

    - by mad
    I have a Nx62 matrix with N 62-D vectors and a NX1 vector with the labels for the vectors. I am trying to plot these vectors with their labels because I want to see the behavior of these classes when plotted in a 62-dimensional space. The vectors belong to three classes according to the labels of a NX1 vector cited before. How to to that in matlab? when i do plot(vector,classes) the result is very weird to analyse, how to put labels in the graph? The code i am using to get the labels, vectors and plotting is the following: %labels is a vector with labels, vectors is a matrix where each line is a vector [labels,vectors]=libsvmread('features-im1.txt'); when I plot a three dimensional vector is simple a=[1,2,3] plot(a) and then I get the result but now i have a set of vectors and a set of labels, and i want to see the distribution of them, i want to plot each of these labels but also want to identify their classes. How to do that in matlab? EDIT: This code is almost working. The problem is the fact that for each vector and class the plot will assign a color. I just want three colors and three labels, one per class. [class,vector]=libsvmread('features-im1.txt'); %the plot doesn't allow negative and 0 values in the label class=class+2; labels = {'class -1','class 0','class 1'}; h = plot(vector); legend(h,labels{class})

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  • Hibernate: Walk millions of rows and don't leak memory

    - by Autocracy
    The below code functions, but Hibernate never lets go of its grip of any object. Calling session.clear() causes exceptions regarding fetching a joined class, and calling session.evict(currentObject) before retrieving the next object also fails to free the memory. Eventually I exhaust my heap space. Checking my heap dumps, StatefulPersistenceContext is the garbage collector's root for all references pointing to my objects. public class CriteriaReportSource implements JRDataSource { private ScrollableResults sr; private Object currentObject; private Criteria c; private static final int scrollSize = 10; private int offset = 1; public CriteriaReportSource(Criteria c) { this.c = c; advanceScroll(); } private void advanceScroll() { // ((Session) Main.em.getDelegate()).clear(); this.sr = c.setFirstResult(offset) .setMaxResults(scrollSize) .scroll(ScrollMode.FORWARD_ONLY); offset += scrollSize; } public boolean next() { if (sr.next()) { currentObject = sr.get(0); if (sr.isLast()) { advanceScroll(); } return true; } return false; } public Object getFieldValue(JRField jrf) throws JRException { Object retVal = null; if(currentObject == null) { return null; } try { retVal = PropertyUtils.getProperty(currentObject, jrf.getName()); } catch (Exception ex) { Logger.getLogger(CriteriaReportSource.class.getName()).log(Level.SEVERE, null, ex); } return retVal; } }

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  • Can I flow divs down the page instead of across it?

    - by Brabster
    If I have a collection of div elements, I can use CSS to have them flow across the page and overflow onto the next line. Here's a simple example: <html> <head> <title>Flowing Divs</title> <style type="text/css"> .flow { float: left; margin: 4em 8em; } </style> </head> <body> <div class="container"> <div class="flow">Div 1</div> <div class="flow">Div 2</div> <div class="flow">Div 3</div> <div class="flow">Div 4</div> <div class="flow">Div 5</div> <div class="flow">Div 6</div> <div class="flow">Div 7</div> <div class="flow">Div 8</div> </div> </body> </html> Is it possible to have the divs flow down the page instead of across it, so that they would flow down columns not along lines, but still occupy the same space as they would if they flowed across? So for the example above, if they flowed into two lines of four divs, could I get the first column to contain Div1 and Div2 instead of Div1 and Div5?

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  • Setting the default stack size on Linux globally for the program

    - by wowus
    So I've noticed that the default stack size for threads on linux is 8MB (if I'm wrong, PLEASE correct me), and, incidentally, 1MB on Windows. This is quite bad for my application, as on a 4-core processor that means 64 MB is space is used JUST for threads! The worst part is, I'm never using more than 100kb of stack per thread (I abuse the heap a LOT ;)). My solution right now is to limit the stack size of threads. However, I have no idea how to do this portably. Just for context, I'm using Boost.Thread for my threading needs. I'm okay with a little bit of #ifdef hell, but I'd like to know how to do it easily first. Basically, I want something like this (where windows_* is linked on windows builds, and posix_* is linked under linux builds) // windows_stack_limiter.c int limit_stack_size() { // Windows impl. return 0; } // posix_stack_limiter.c int limit_stack_size() { // Linux impl. return 0; } // stack_limiter.cpp int limit_stack_size(); static volatile int placeholder = limit_stack_size(); How do I flesh out those functions? Or, alternatively, am I just doing this entirely wrong? Remember I have no control over the actual thread creation (no new params to CreateThread on Windows), as I'm using Boost.Thread.

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  • PHP Resize image down and crop using imagemagick

    - by mr12086
    I'm trying to downsize image uploaded by users at the time of upload. This is no problem but I want to get specific with sizes now. I'm looking for some advice on an algorithm im struggling to produce that will take any shape image - square or rectangle of any widths/heights and downsize it. This image needs to be downsized to a target box size (this changes but is stored in a variable).. So it needs to downsize the image so that both the width and height are larger than the width and height of the target maintaining aspect ratio. but only just.. The target size will be used to crop the image so there is no white space around the edges etc. I'm looking for just the algorithm behind creating the correct resize based on different dimension images - I can handle the cropping, even resizing in most cases but it fails in a few so i'm reaching out. I'm not really asking for PHP code more pseudo. Either is fine obviously. Thanks Kindly.

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  • Have you considered doing revenue sharing to fund development of a mobile app? How would you do it?

    - by Brennan
    I am looking to build multiple mobile apps which leverage existing content and resources by enabling these mobile apps with web services. I will duplication much of the same features which are also in place and add more features that are possible on a mobile device like address book, maps and calendar integration to make the service much more useful. To fund these projects I see that I have 2 options. First I could simply quote them for the project based on my hourly rate and the estimate in hours that I will take the to complete the job. That may be a high number. The second option would be to do shared revenue with ads placed in the app. I could then take a percentage of any revenue that is generated from the app. There is also a hybrid where I might charge for a percentage of the estimated quote and then take a percentage of the revenue sharing. So my question is how much should I propose for the revenue sharing? Should it be 30%? Or maybe I should make it 70% up to a point that a certain dollar amount is reached? And should the revenue sharing agreement be for 12 months, 24 months or more? Should I include in the proposal an agreement that they will help promote this app with their content and resources? Ultimately this system will benefit both sides because it extends their reach into the mobile space instead of where they are currently with just print and web. I have tried to find some examples with a few Google searches but I keep hitting content about the Google and Apple revenue sharing models. I would like to get some solid examples that are working to compare against so that my proposal do build these apps is not completely off base.

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  • Guid Primary /Foreign Key dilemma SQL Server

    - by Xience
    Hi guys, I am faced with the dilemma of changing my primary keys from int identities to Guid. I'll put my problem straight up. It's a typical Retail management app, with POS and back office functionality. Has about 100 tables. The database synchronizes with other databases and receives/ sends new data. Most tables don't have frequent inserts, updates or select statements executing on them. However, some do have frequent inserts and selects on them, eg. products and orders tables. Some tables have upto 4 foreign keys in them. If i changed my primary keys from 'int' to 'Guid', would there be a performance issue when inserting or querying data from tables that have many foreign keys. I know people have said that indexes will be fragmented and 16 bytes is an issue. Space wouldn't be an issue in my case and apparently index fragmentation can also be taken care of using 'NEWSEQUENTIALID()' function. Can someone tell me, from there experience, if Guid will be problematic in tables with many foreign keys. I'll be much appreciative of your thoughts on it...

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  • Read Java in as Hex

    - by James
    Hi, I have tried to solve this but I keep coming up with stuff that is no help I'm sure this is easy (when you know how of course ;) ) What I would like to do is read in a file using a byte stream like below: while((read = in.read()) != -1){ //code removed to save space Integer.toHexString(read); System.out.println(read); } When it prints out the Hex to the screen it will print out numbers fine e.g 31 13 12 0 but when it comes to a hex code that should be 01 31 it will print 0 131. I want to read it in to a variable like you would see in a hex editor i.e 00 11 21 31 no single numbers as i need to scan the whole file and look for patterns which I know how to do I'm just stuck on this :/ so in short i need a variabe to contain the two hex characters i.e int temp = 01 not int temp = 0 , I hope this all makes sense, I'm a little confused as it's 3am! If anyone knows how to do this I would be most greatful, p.s thanks for the help in advance this site has saved me loads of research and have learnt a lot! Many thanks.

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  • Concatenate 2 text elements on a line with full-width border using CSS only

    - by Michael Horne
    Okay, I'm a newbie to CSS3, so please be gentle. ;-) I'm working with some Wordpress code (Woocommerce plugin, to be exact), and I'm trying to format a line of code in a sidebar so that 2 separate text items (one in an <a, the other in a <span are all on the same line, the full width of the column, and with a bottom border. It looks something like this (except the bottom border on each text do not go all the way across the enclosing sidebar box): http://www.dalluva.com/temp/browse-catalog.JPG (sorry, I'm new and can't post inline images yet) Here's the code fragment I'm trying to live with (i.e. I don't want to change it): <div class="widget"> ... <ul class="product-categories"> <li class="cat-item"> <a href="http://localhost/dalluva/shop/product-category/books/">Books</a> <span class="count">(5)</span> </li> ... And here's the CSS I have now: .widget ul li a { border-bottom: 1px solid #e9e9e9; line-height:1.0; padding: 5px 0 5px 22px; display: inline-block; } .widget ul li span { border-bottom: 1px solid #e9e9e9; line-height: 1.0; padding: 5px 0 5px 0; display: inline-block; } The output in the image above looks right for this CSS code, but when I change the 'span' CSS to include a width:100%, it causes the span element to wrap to the next line, looking like this: http://www.dalluva.com/temp/browse-catalog-2.JPG I've played with white-space:nowrap, overflow:hidden, etc, but I can't seem to find a way to have both the <a and the <span text on the same line with the border extending the full width of the column. Any suggestions on getting the desired effect through CSS only? Thanks. Michael

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  • Linux C debugging library to detect memory corruptions

    - by calandoa
    When working sometimes ago on an embedded system with a simple MMU, I used to program dynamically this MMU to detect memory corruptions. For instance, at some moment at runtime, the foo variable was overwritten with some unexpected data (probably by a dangling pointer or whatever). So I added the additional debugging code : at init, the memory used by foo was indicated as a forbidden region to the MMU; each time foo was accessed on purpose, access to the region was allowed just before then forbidden just after; a MMU irq handler was added to dump the master and the address responsible of the violation. This was actually some kind of watchpoint, but directly self-handled by the code itself. Now, I would like to reuse the same trick, but on a x86 platform. The problem is that I am very far from understanding how is working the MMU on this platform, and how it is used by Linux, but I wonder if any library/tool/system call already exist to deal with this problem. Note that I am aware that various tools exist like Valgrind or GDB to manage memory problems, but as far as I know, none of these tools car be dynamically reconfigured by the debugged code. I am mainly interested for user space under Linux, but any info on kernel mode or under Windows is also welcome!

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  • Interchange structured data between Haskell and C

    - by Eonil
    First, I'm a Haskell beginner. I'm planning integrating Haskell into C for realtime game. Haskell does logic, C does rendering. To do this, I have to pass huge complexly structured data (game state) from/to each other for each tick (at least 30 times per second). So the passing data should be lightweight. This state data may laid on sequential space on memory. Both of Haskell and C parts should access every area of the states freely. In best case, the cost of passing data can be copying a pointer to a memory. In worst case, copying whole data with conversion. I'm reading Haskell's FFI(http://www.haskell.org/haskellwiki/FFICookBook#Working_with_structs) The Haskell code look specifying memory layout explicitly. I have a few questions. Can Haskell specify memory layout explicitly? (to be matched exactly with C struct) Is this real memory layout? Or any kind of conversion required? (performance penalty) If Q#2 is true, Any performance penalty when the memory layout specified explicitly? What's the syntax #{alignment foo}? Where can I find the document about this? If I want to pass huge data with best performance, how should I do that? *PS Explicit memory layout feature which I said is just C#'s [StructLayout] attribute. Which is specifying in-memory position and size explicitly. http://www.developerfusion.com/article/84519/mastering-structs-in-c/ I'm not sure Haskell has matching linguistic construct matching with fields of C struct.

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  • Do you have health checks in your web app or web site?

    - by Pekka
    I have built PHP based "health check" scripts for several projects, but they were always custom-made for the occasion and not written for abstraction as an independent product. I would like to know whether such a solution exists. What I meam by "health check" is a protected web page that functions much like a suite of unit tests, but on a more operational level, showing red/yellow/green statuses for things like Are the cache directories writable? Is the PHP version correct, are required extensions installed? Is the configuration file protected from writing? Is the database server reachable? Do the key tables exist in the database? Is there enough disk space available? Is the site's front page reachable and renders fully ( = no PHP errors)? Do the project's libraries' MD5 checksums match the original ones? Do you do this - or parts of it - in your applications and web sites? Are there any standardized tools for this that bring along all the functionality to perform the tests (ideally as plugins), and just need to be configured accordingly? Is there a way to set this up using one of the Unit Testing frameworks available for PHP (preferably PHPUnit)? If so, do you know any resources / tutorials outlining how?

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  • Varchar columns: Nullable or not.

    - by NYSystemsAnalyst
    The database development standards in our organization state the varchar fields should not allow null values. They should have a default value of an empty string (""). I know this makes querying and concatenation easier, but today, one of my coworkers questioned me about why that standard only existed for varchar types an not other datatypes (int, datetime, etc). I would like to know if others consider this to be a valid, defensible standard, or if varchar should be treated the same as fields of other data types? I believe this standard is valid for the following reason: I believe that an empty string and null values, though technically different, are conceptually the same. An empty, zero length string is a string that does not exist. It has no value. However, a numeric value of 0 is not the same as NULL. For example, if a field called OutstandingBalance has a value of 0, it means there are $0.00 remaining. However, if the same field is NULL, that means the value is unknown. On the other hand, a field called CustomerName with a value of "" is basically the same as a value of NULL because both represent the non-existence of the name. I read somewhere that an analogy for an empty string vs. NULL is that of a blank CD vs. no CD. However, I believe this to be a false analogy because a blank CD still phyically exists and still has physical data space that does not have any meaningful data written to it. Basically, I believe a blank CD is the equivalent of a string of blank spaces (" "), not an empty string. Therefore, I believe a string of blank spaces to be an actual value separate from NULL, but an empty string to be the absense of value conceptually equivalent to NULL. Please let me know if my beliefs regarding variable length strings are valid, or please enlighten me if they are not. I have read several blogs / arguments regarding this subject, but still do not see a true conceptual difference between NULLs and empty strings.

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  • CSS overflow detection in JavaScript

    - by ring0
    In order to display a line of text (like in a forum), and end that line with "..." if the text would overflow the line (not truncating using the CSS overflow property), there are a number of ways. I'm still seeking the best solution. For instance, Adding in CSS a "..." as a background-image is a possibility, but it would appear all the time, and this is not a good solution. Some sites just count the characters and if over - say - 100, truncates the string to keep only 100 (or 97) chars and add a "..." at the end. But fonts are usually not proportional, so the result is not pretty. For instance the space - in pixels - taken by "AAA" and "iii" is clearly different "AAA" and "iii" via a proportional font have the same width There is another idea to get the exact size in pixels of the string: create in Javascript a DIV insert the text in it (via innerHTML for instance) measure the width (via .offsetWidth) which is not implemented yet. However, I wonder if there could be any browser compatibility problem? Did any one tried this solution? Other recommendations would be welcome.

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  • How to change size of Android ScrollView

    - by user611923
    I have a layout like this (abstracted): Scrollview - fill_parent LinearLayout - wrap_content ImageView 1 - wrap_content ImageView 2 - ... ImageView 3 ... In the course of user interaction some images are replaced by larger or smaller ones, shortening or lenghtening the area to be scrolled. And that is the problem. The Scrollview (SV) does not know about the change, so either it scrolls over a lot of empty space at the bottom, or cuts off a picture or two at the bottom. Question 1: Can I somehow make the SV readapt to the changed hight of the LiearLayout (LL)? Question 2: I can obtain the current size through getHight on the LL. But supplyong it to the SV via changed LayoutParams does not work - of course, that would only change the height of the SV on the screen. Is there a way to put the changed height of the LL into the SV in the code, somehow? Question 3: I havn't tried it yet. Would creating the SV, LL and its children in code and then adding/removing children of changed size as required, make the SV adapt to the changes? And last question: Is there a better aüpproach, except using ListViews?

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  • xsl transform: problem with Ampersand URL parameters

    - by Rac123
    I'm having issues with transforming XSL with parameters in a URL. I'm at a point that I can't change the C# code anymore, only can make changes to xsl file. C# code: string xml = "<APPLDATA><APPID>1052391</APPID></APPLDATA>"; XmlDocument oXml = new XmlDocument(); oXml.LoadXml(xml); XslTransform oXslTransform = new XslTransform(); oXslTransform.Load(@"C:\Projects\Win\ConsoleApps\XslTransformTest\S15033.xsl"); StringWriter oOutput = new StringWriter(); oXslTransform.Transform(oXml, null, oOutput) XSL Code: <body> <xsl:variable name="app"> <xsl:value-of select="normalize-space(APPLDATA/APPID)" /> </xsl:variable> <div id="homeImage" > <xsl:attribute name="style"> background-image:url("https://server/image.gif?a=10&amp;Id='<xsl:value-of disable-output-escaping="yes" select="$app" />'") </xsl:attribute> </div> </body> </html> URL transformed: https://server/image.gif?a=10&Id='1052391' URL Expected: https://server/image.gif?a=10&Id='1052391' How do I fix this? The output (oOutput.ToString()) is being used in an email template so it's taking the URL transformed literally. When you click on this request (with the correct server name of course), the 403 (Access forbidden) error is being thrown.

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  • C++: is it safe to work with std::vectors as if they were arrays?

    - by peoro
    I need to have a fixed-size array of elements and to call on them functions that require to know about how they're placed in memory, in particular: functions like glVertexPointer, that needs to know where the vertices are, how distant they are one from the other and so on. In my case vertices would be members of the elements to store. to get the index of an element within this array, I'd prefer to avoid having an index field within my elements, but would rather play with pointers arithmetic (ie: index of Element *x will be x - & array[0]) -- btw, this sounds dirty to me: is it good practice or should I do something else? Is it safe to use std::vector for this? Something makes me think that an std::array would be more appropriate but: Constructor and destructor for my structure will be rarely called: I don't mind about such overhead. I'm going to set the std::vector capacity to size I need (the size that would use for an std::array, thus won't take any overhead due to sporadic reallocation. I don't mind a little space overhead for std::vector's internal structure. I could use the ability to resize the vector (or better: to have a size chosen during setup), and I think there's no way to do this with std::array, since its size is a template parameter (that's too bad: I could do that even with an old C-like array, just dynamically allocating it on the heap). If std::vector is fine for my purpose I'd like to know into details if it will have some runtime overhead with respect to std::array (or to a plain C array): I know that it'll call the default constructor for any element once I increase its size (but I guess this won't cost anything if my data has got an empty default constructor?), same for destructor. Anything else?

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  • Eclipse PDT "tips" ?

    - by Pascal MARTIN
    Hi ! (Yes, this is a quite opened and general and subjective question -- it's by design, cause I want tips you think are great !) I'm using Eclipse PDT 2.1 to work in PHP, either for small and/or big projects -- I've been doing so for quite some times, now, actually (since before 1.0 stable, if I remember well)... I was wondering if any of you did know "tips" to be more efficient. Let met explain more in details : I know about things like plugins like Aptana (better editor for JS/CSS), Subversive (for SVN access), RSE, Filesync, integrating Xdebug's debugger, ... What I mean by "tips" is more some little things you discovered one day and since use all the time -- and allow you to be more efficient in your PHP projects. Some examples of "tips" that come to my mind, and that already know and use : ctrl+space to open the list of suggestions for functions / variables names ctrl+shift+R (navigate > open resource) to open a popup which show only files which names contain what you type ; ie, quick opening of files this one might be the perfect example : I know this one is not often known by coworkers and they find it as useful as I do ; so, I guess there might be lots of other things like this one I don't know myself ^^ ctrl+M to switch to full-screen view for the editor (instead of double-click on tabs bar) shift+F2 while on a function name, to open it's page if the PHP manual in a browser Attention Mac Users use Command instead Control. I guess you get the point ; but I'm really open to any suggestion (be it eclipse-related in general, of more PHP/PDT-specific) that can help be be more efficient :-) Anyway, thanks in advance for your help !

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  • Fastest Java way to remove the first/top line of a file (like a stack)

    - by christangrant
    I am trying to improve an external sort implementation in java. I have a bunch of BufferedReader objects open for temporary files. I repeatedly remove the top line from each of these files. This pushes the limits of the Java's Heap. I would like a more scalable method of doing this without loosing speed because of a bunch of constructor calls. One solution is to only open files when they are needed, then read the first line and then delete it. But I am afraid that this will be significantly slower. So using Java libraries what is the most efficient method of doing this. --Edit-- For external sort, the usual method is to break a large file up into several chunk files. Sort each of the chunks. And then treat the sorted files like buffers, pop the top item from each file, the smallest of all those is the global minimum. Then continue until for all items. http://en.wikipedia.org/wiki/External_sorting My temporary files (buffers) are basically BufferedReader objects. The operations performed on these files are the same as stack/queue operations (peek and pop, no push needed). I am trying to make these peek and pop operations more efficient. This is because using many BufferedReader objects takes up too much space.

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  • Antlr MismatchedSetException During Interpretation

    - by user1646481
    I am new to Antlr and I have defined a basic grammar using Antlr 3. The grammar compiles and ANTLRWorks generates the Parser and Lexer code without any problems. The grammar can be seen below: grammar i; @header { package i; } module : 'Module1'| 'Module2'; object : 'I'; objectType : 'Name'; filters : EMPTY | 'WHERE' module; table : module object objectType; STRING : ('a'..'z'|'A'..'Z')+; EMPTY : ' '; The problem is that when I interpret the table Parser I get a MismatchedSetException. This is due to having the EMPTY. As soon as I remove EMPTY from the grammar, the interpretation works. I have looked on the Antlr website and some other examples and the Empty space is ' '. I am not sure what to do. I need this EMPTY. As soon as I change the EMPTY to be the following: EMPTY : ''; instead of: EMPTY : ' '; It actually interprets it. However, I am getting the following Exception: Interpreting... [10:57:23] problem matching token at 1:4 NoViableAltException(' '@[1:1: Tokens : ( T__4 | T__5 | T__6 | T__7 | T__8 | T__9 | T__10 | T__11 | T__12 | T__13 | T__14 | T__15 | T__16 );]) [10:57:23] problem matching token at 1:9 NoViableAltException(' '@[1:1: Tokens : ( T__4 | T__5 | T__6 | T__7 | T__8 | T__9 | T__10 | T__11 | T__12 | T__13 | T__14 | T__15 | T__16 );]) When I take out the EMPTY, there are no problems at all. I hope you can help.

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  • Implementing a c/c++ style union as a column in MySQL

    - by user81338
    Friends, I have a strange need and cannot think my way through the problem. The great and mighty Google is of little help due to keyword recycling (as you'll see). Can you help? What I want to do is store data of multiple types in a single column in MySQL. This is the database equivalent to a C union (and if you search for MySQL and Union, you obviously get a whole bunch of stuff on the UNION keyword in SQL). [Contrived and simplified case follows] So, let us say that we have people - who have names - and STORMTROOPERS - who have TK numbers. You cannot have BOTH a NAME and a TK number. You're either BOB SMITH -or- TK409. In C I could express this as a union, like so: union { char * name; int tkNo; } EmperialPersonnelRecord; This makes it so that I am either storing a pointer to a char array or an ID in the type EmperialPersonnelRecord, but not both. I am looking for a MySQL equivalent on a column. My column would store either an int, double, or varchar(255) (or whatever combination). But would only take up the space of the largest element. Is this possible? (of course anything is possible given enough time, money and will - I mean is it possible if I am poor, lazy and on a deadline... aka "out of the box")

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  • Using shared_ptr to implement RCU (read-copy-update)?

    - by yongsun
    I'm very interested in the user-space RCU (read-copy-update), and trying to simulate one via tr1::shared_ptr, here is the code, while I'm really a newbie in concurrent programming, would some experts help me to review? The basic idea is, reader calls get_reading_copy() to gain the pointer of current protected data (let's say it's generation one, or G1). writer calls get_updating_copy() to gain a copy of the G1 (let's say it's G2), and only one writer is allowed to enter the critical section. After the updating is done, writer calls update() to do a swap, and make the m_data_ptr pointing to data G2. The ongoing readers and the writer now hold the shared_ptr of G1, and either a reader or a writer will eventually deallocate the G1 data. Any new readers would get the pointer to G2, and a new writer would get the copy of G2 (let's say G3). It's possible the G1 is not released yet, so multiple generations of data my co-exists. template <typename T> class rcu_protected { public: typedef T type; typedef std::tr1::shared_ptr<type> rcu_pointer; rcu_protected() : m_data_ptr (new type()) {} rcu_pointer get_reading_copy () { spin_until_eq (m_is_swapping, 0); return m_data_ptr; } rcu_pointer get_updating_copy () { spin_until_eq (m_is_swapping, 0); while (!CAS (m_is_writing, 0, 1)) {/* do sleep for back-off when exceeding maximum retry times */} rcu_pointer new_data_ptr(new type(*m_data_ptr)); // as spin_until_eq does not have memory barrier protection, // we need to place a read barrier to protect the loading of // new_data_ptr not to be re-ordered before its construction _ReadBarrier(); return new_data_ptr; } void update (rcu_pointer new_data_ptr) { while (!CAS (m_is_swapping, 0, 1)) {} m_data_ptr.swap (new_data_ptr); // as spin_until_eq does not have memory barrier protection, // we need to place a write barrier to protect the assignments of // m_is_writing/m_is_swapping be re-ordered bofore the swapping _WriteBarrier(); m_is_writing = 0; m_is_swapping = 0; } private: volatile long m_is_writing; volatile long m_is_swapping; rcu_pointer m_data_ptr; };

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