single threaded - Page 534

What are best practices for managing related Cabal packages?

- by Norman Ramsey

I'm working on a dataflow-based optimization library written in Haskell. It now seems likely that the library is going to have to be split into two pieces: A core piece with minimal build dependencies; call it hoopl-core. A full piece, call it hoopl, which may have extra dependencies on packages like a prettyprinter, QuickCheck, and so on. The idea is that the Glasgow Haskell Compiler will depend only on hoopl-core, so that it won't be too difficult to bootstrap the compiler. Other compilers will get the extra goodies in hoopl. Package hoopl will depend on hoopl-core. The Debian package tools can build multiple packages from a single source tree. Unfortunately Cabal has not yet reached that level of sophistication. But there must be other library or application designers out there who have similar issues (e.g., one package for a core library, another for a command-line interface, another for a GUI interface). What are current best practices for building and managing multiple related Haskell packages using Cabal?

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How can I stop an auto-generated Linq to SQL class from loading ALL data?

- by Gary McGill

I have an ASP.NET MVC project, much like the NerdDinner tutorial example. (I'm using MVC 2, but followed the NerdDinner tutorial in order to create it). As per the instructions in part 3 of the tutorial, I've created a Linq-to-SQL model of my database by creating a "Linq to SQL Classes" (.dbml) surface, and dropping my database tables onto it. The designer has automatically added relationships between the generated classes based on my database tables. Let's say that my classes are as per the NerdDinner example, so I have Dinner and RSVP tables, where each Dinner record is associated with many RSVP records - hence in the generated classes, the Dinner object has a RSVPs property which is a list of RSVP objects. My problem is this: it appears (and I'd be gladly proved wrong on this) that as soon as I access a Dinner object, it's loading all of the corresponding RSVP objects, even if I don't use the RSVPs member. First question: is this really the default behavior for the generated classes? In my particular situation, the object graph contains many more tables (which have an order of magnitude more records), and so this is disastrous behaviour - I'd be loading tons of data when all I want to do is show the details of a single parent record. Second question: are there any properties exposed through the designer UI that would let me modify this behavior? (I can't find any). Third question: I've seen a description of how to control the loading of related records in a DataContext by using a DataShape object associated with the DataContext. Is that what I'm meant to do, and if so are there any tutorials like the NerdDinner one that would show not only how to do it, but also suggest a 'pattern' for normal use?

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CQRS - The query side

- by mattcodes

A lot of the blogsphere articles related to CQRS (command query repsonsibility) seperation seem to imply that all screens/viewmodels are flat. e.g. Name, Age, Location Of Birth etc.. and thus the suggestion that implementation wise we stick them into fast read source etc.. single table per view mySQL etc.. and pull them out with something like primitive SqlDataReader, kick that nasty nhibernate ORM etc.. However, whilst I agree that domain models dont mapped well to most screens, many of the screens that I work with are more dimensional, and Im sure this is pretty common in LOB apps. So my question is how are people handling screen where by for example it displays a summary of customer details and then a list of their orders with a [more detail] link etc.... I thought about keeping with the straight forward SQL query to the Query Database breaking off the outer join so can build a suitable ViewModel to View but it seems like overkill? Alternatively (this is starting to feel yuck) in CustomerSummaryView table have a text/big (whatever the type is in your DB) column called Orders, and the columns for the Order summary screen grid are seperated by , and rows by |. Even with XML datatype it still feeel dirty. Any thoughts on an optimal practice?

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Show NotifyIcon Context Menu and Control Its Position?

- by Shawn O'Hern

I'm trying to show a context menu when I left-click a NotifyIcon. Just calling NotifyIcon.ContextMenuStrip.Show() doesn't work very well. A solution has been posted here before that calls a secret method using Reflection: Dim mi As System.Reflection.MethodInfo = GetType(NotifyIcon).GetMethod("ShowContextMenu", Reflection.BindingFlags.Instance Or Reflection.BindingFlags.NonPublic) mi.Invoke(Icon, Nothing) This works great, except that I also need to control where the menu is shown. I want to wait for the SystemInformation.DoubleClickTime to elapse between receiving the NotifyIcon.MouseUp event and displaying the menu, so that I can handle single-clicks and double-clicks separately. But invoking the ShowContextMenu method displays the menu at the current mouse position when ShowContextMenu is called, not when the icon was actually clicked. Which means that if the mouse moved during the DoubleClickTime, the menu will be displayed in a different part of the screen. So if I can control where the menu is shown, I can just save the mouse coordinates when I receive the MouseUp event, and then I can ensure that the menu is displayed near the icon. Is there a way to do this? Thanks in advance.

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Code Golf: Easter Spiral

- by friol

What's more appropriate than a Spiral for Easter Code Golf sessions? Well, I guess almost anything. The Challenge The shortest code by character count to display a nice ASCII Spiral made of asterisks ('*'). Input is a single number, R, that will be the x-size of the Spiral. The other dimension (y) is always R-2. The program can assume R to be always odd and = 5. Some examples: Input 7 Output ******* * * * *** * * * * ***** * Input 9 Output ********* * * * ***** * * * * * * *** * * * * * ******* * Input 11 Output *********** * * * ******* * * * * * * * *** * * * * * * * * ***** * * * * * ********* * Code count includes input/output (i.e., full program). Any language is permitted. My easily beatable 303 chars long Python example: import sys; d=int(sys.argv[1]); a=[d*[' '] for i in range(d-2)]; r=[0,-1,0,1]; x=d-1;y=x-2;z=0;pz=d-2;v=2; while d>2: while v>0: while pz>0: a[y][x]='*'; pz-=1; if pz>0: x+=r[z]; y+=r[(z+1)%4]; z=(z+1)%4; pz=d; v-=1; v=2;d-=2;pz=d; for w in a: print ''.join(w); Now, enter the Spiral...

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How Does a COM Program Locate a .NET DLL Registered for COM Interop?

- by Eric J.

One customer wants to consume our .NET DLLs from VB6. They are designed to support reverse interop and all works fine... except: There are two separate VB6 programs in two different directories. It seems it's necessary to do one of: Copy the .NET DLL into both directories, or Install the .NET DLL in the GAC This is the customer's observation and also supported by the RegAsm documentation: After registering an assembly using Regasm.exe, you can install it in the global assembly cache so that it can be activated from any COM client. If the assembly is only going to be activated by a single application, you can place it in that application's directory. I'm confused on this point. First point of confusion: As far as I understand, the COM runtime locates the DLL using the Prog ID / Class ID. When I look in the registry at the Class ID entry, I see the full path to the .NET DLL in the CodeBase key. Why is it that a COM program using the Prog ID / Class ID doesn't locate the .NET DLL using the CodeBase? Second point of confusion: The GAC is specific to .NET. How is it involved in resolving COM references?

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How can I stop an auto-generated Linq to SQL class from loading ALL data?

- by Gary McGill

DUPLICATE of http://stackoverflow.com/questions/2433422/how-can-i-stop-an-auto-generated-linq-to-sql-class-from-loading-all-data post answers there! I have an ASP.NET MVC project, much like the NerdDinner tutorial example. (I'm using MVC 2, but followed the NerdDinner tutorial in order to create it). As per the instructions in part 3 of the tutorial, I've created a Linq-to-SQL model of my database by creating a "Linq to SQL Classes" (.dbml) surface, and dropping my database tables onto it. The designer has automatically added relationships between the generated classes based on my database tables. Let's say that my classes are as per the NerdDinner example, so I have Dinner and RSVP tables, where each Dinner record is associated with many RSVP records - hence in the generated classes, the Dinner object has a RSVPs property which is a list of RSVP objects. My problem is this: it appears (and I'd be gladly proved wrong on this) that as soon as I access a Dinner object, it's loading all of the corresponding RSVP objects, even if I don't use the RSVPs member. First question: is this really the default behavior for the generated classes? In my particular situation, the object graph contains many more tables (which have an order of magnitude more records), and so this is disastrous behaviour - I'd be loading tons of data when all I want to do is show the details of a single parent record. Second question: are there any properties exposed through the designer UI that would let me modify this behavior? (I can't find any). Third question: I've seen a description of how to control the loading of related records in a DataContext by using a DataShape object associated with the DataContext. Is that what I'm meant to do, and if so are there any tutorials like the NerdDinner one that would show not only how to do it, but also suggest a 'pattern' for normal use?

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The "first past the post election" query problem

- by MPelletier

This problem may seem like school work, but it isn't. At best it is self-imposed school work. I encourage any teachers to take is as an example if they wish. "First past the post" elections are single-round, meaning that whoever gets the most votes win, no second rounds. Suppose a table for an election. CREATE TABLE ElectionResults ( DistrictHnd INTEGER NOT NULL, PartyHnd INTEGER NOT NULL, CandidateName VARCHAR2(100) NOT NULL, TotalVotes INTEGER NOT NULL, PRIMARY KEY DistrictHnd, PartyHnd); The table has two foreign keys: DistrictHnd points to a District table (lists all the different electoral districts) and PartyHnd points to a Party table (lists all the different political parties). I won't bother with other tables here, joining them is trivial. This is just a wee bit of context. The question: What SQL query will return a table listing the DistrictHnd, PartyHnd, CandidateName and TotalVotes of the winners (max votes) in each District? This does not suppose any particular database system. If you wish to stick to a particular implementation of SQL, go the way of SQLite and MySQL. If you can devise a better schema (or an easier one), that is acceptable too. Criteria: simplicity, portability to other databases.

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Database migration pattern for Java?

- by Eno

Im working on some database migration code in Java. Im also using a factory pattern so I can use different kinds of databases. And each kind of database im using implements a common interface. What I would like to do is have a migration check that is internal to the class and runs some database schema update code automatically. The actual update is pretty straight forward (I check schema version in a table and compare against a constant in my app to decide whether to migrate or not and between which versions of schema). To make this automatic I was thinking the test should live inside (or be called from) the constructor. OK, fair enough, that's simple enough. My problem is that I dont want the test to run every single time I instantiate a database object (it runs a query so having it run on every construction is not efficient). So maybe this should be a class static method? I guess my question is, what is a good design pattern for this type of problem? There ought to be a clean way to ensure the migration test runs only once OR is super-efficient.

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one page has more than one url. search engines give penalty please help me out.

- by Ali Demirtas

Hi I am using prestashop as the cart for my website. I have a problem; the website used to be in dynamic urls. I enabled friendly url writing. The problem is that one page has more than one url. You can access a same page from the dynamic url and static url. In fact a single page has 9 different urls. This obviously creates problems for seo as search engiones penalize my website for this. What can I do to solve this problem? I have no knowledge of programming. Here is the htaccess for the website. Any sample code or help is really appreciated. URL rewriting module activation RewriteEngine on URL rewriting rules RewriteRule ^([a-z0-9]+)-([a-z0-9]+)(-[_a-zA-Z0-9-]*)/([_a-zA-Z0-9-]*).jpg$ /img/p/$1-$2$3.jpg [L,E] RewriteRule ^([0-9]+)-([0-9]+)/([_a-zA-Z0-9-]*).jpg$ /img/p/$1-$2.jpg [L,E] RewriteRule ^([0-9]+)(-[_a-zA-Z0-9-]*)/([_a-zA-Z0-9-]).jpg$ /img/c/$1$2.jpg [L,E] RewriteRule ^lang-([a-z]{2})/([a-zA-Z0-9-])/([0-9]+)-([a-zA-Z0-9-]).html(.)$ /product.php?id_product=$3&isolang=$1$5 [L,E] RewriteRule ^lang-([a-z]{2})/([0-9]+)-([a-zA-Z0-9-]).html(.)$ /product.php?id_product=$2&isolang=$1$4 [L,E] RewriteRule ^lang-([a-z]{2})/([0-9]+)-([a-zA-Z0-9-])(.)$ /category.php?id_category=$2&isolang=$1 [QSA,L,E] RewriteRule ^([a-zA-Z0-9-])/([0-9]+)-([a-zA-Z0-9-]).html(.*)$ /product.php?id_product=$2$4 [L,E] RewriteRule ^([0-9]+)-([a-zA-Z0-9-]).html(.)$ /product.php?id_product=$1$3 [L,E] RewriteRule ^([0-9]+)-([a-zA-Z0-9-])(.)$ /category.php?id_category=$1 [QSA,L,E] RewriteRule ^content/([0-9]+)-([a-zA-Z0-9-])(.)$ /cms.php?id_cms=$1 [QSA,L,E] RewriteRule ^([0-9]+)__([a-zA-Z0-9-])(.)$ /supplier.php?id_supplier=$1$3 [QSA,L,E] RewriteRule ^([0-9]+)_([a-zA-Z0-9-])(.)$ /manufacturer.php?id_manufacturer=$1$3 [QSA,L,E] RewriteRule ^lang-([a-z]{2})/(.*)$ /$2?isolang=$1 [QSA,L,E] Catch 404 errors ErrorDocument 404 /404.php Options +FollowSymLinks RewriteEngine on RewriteCond %{HTTP_HOST} ^.com [NC] RewriteRule ^(.)$ http://www.*.com/$1 [L,R=301] Options +FollowSymLinks RewriteEngine on index.php to / RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /.index.php\ HTTP/ RewriteRule ^(.)index.php$ /$1 [R=301,L] Header set Cache-Control: "no-store, no-cache, must-revalidate, pre-check=0, post-check=0, max-age=0"

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Navigation view system with webview problem with touches!

- by Gonçalo Falcão

Hello i have search everything and i didn't figure this out! I have a tab bar controller with 5 navigation controlls, in one of the navigation control, i have a view, with a table view inside, and when i click that item i push a new view, that view have view -webview -view i create that second view(is transperant) because i need to handle a single tap to hide my toolbar and navigation bar, and the webview was eating all the touches! I put that view and implement on the view controller -(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{ UITouch* touch = [touches anyObject]; if(touch.tapCount == 2){ [NSObject cancelPreviousPerformRequestsWithTarget:self]; } [[wv.subviews objectAtIndex:0] touchesBegan:touches withEvent:event]; [super touchesBegan:touches withEvent:event]; } -(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{ [[wv.subviews objectAtIndex:0] touchesMoved:touches withEvent:event]; [super touchesMoved:touches withEvent:event]; } -(void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{ UITouch* touch = [touches anyObject]; if(touch.tapCount == 1){ [self performSelector:@selector(hideBars) withObject:nil afterDelay:0.3]; } [[wv.subviews objectAtIndex:0] touchesEnded:touches withEvent:event]; [super touchesEnded:touches withEvent:event]; } -(void) touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event{ [[wv.subviews objectAtIndex:0] touchesCancelled:touches withEvent:event]; [super touchesCancelled:touches withEvent:event]; } wv is my UIWebView IBOutlet now i can get the the touches in my controller and send them to my webview. So i thought everything was working, i'm able to scroll, but now when i have links i'm not able to click them. And the webview is detecting the links i have made that test. So any other way to implements this to get the touches in the links, or i should change this workaround to hide the toolbars so i can have the full functionability of the webview? Thks for the help in advance.

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using alias parameters in window command prompt

- by freshWoWer

Source:http://jpsoft.com/help/index.htm?alias.htm Aliases can use command line parameters or parameters like those in batch files. The command line parameters are numbered from %0 to %511. (%0 contains the alias name.) For example, the following alias will change directories, perform a command, and return to the original directory: alias in pushd %1 & %2$ & popd when i run the above, my command prompt gives error saying %1 * Unable to read value of alias * '%2' is not recognized as an internal or external command, operable program or batch file. 'popd`' is not recognized as an internal or external command, operable program or batch file. if you use double quote instead, alias in "pushd %1 & dir & popd" it doesn't interprets the %1 when you execute the alias C:\abc\defalias Dumping all defined aliases for CMD.EXE. in =pushd %1 & dir & popd alias def wont work ---------EDIT------------ let me try some sample output with a simple echo alias D:\abc\defalias /? Usage: ALIAS [-v] [-p programName] [-f filespec] [ ] [-v] means verbose output. [-d] means delete aliases. [-p programName] specifies which image file name these alias definitions are for. Default is CMD.EXE [-f filespec] specifies a file which contains the alises. C:\Office\dev15alias out 'echo %1' %1' * Unable to read value of alias * C:\Office\dev15alias out backtick echo %1 backtick %1` * Unable to read value of alias * C:\Office\dev15alias out "echo %1" C:\Office\dev15alias Dumping all defined aliases for CMD.EXE. out =echo %1 C:\Office\dev15out abc %1 C:\Office\dev15alias out echo %1 %1 * Unable to read value of alias * C:\Office\dev15out abc ECHO is on. Problem is, both single quote and back tick produces error, while double quote wont treat %1 as variable parameter

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dlopen / dlsym with as little linking as possible

- by johannes

I have an application which can make use of plugins which are loaded at runtime using dlopen. Each of the plugins defines a function toretrieve the plugin information which is defined using a common structure. Something like that: struct plugin { char *name; char *app_version; int app_verion_id; char *plugin_version; int plugin_version_id; /* ... */ }; struct plugin p = { "sample plugin",APP_VERION,APP_VERSION_ID,"1.2.3",10203 }; struct plugin *get_plugin() { return &p; } This works well and plugins can be loaded. Now i want to build a small tool to read these properties without linking the whole application. For doing that I have some code like this: void *handle; struct plugin *plugin; struct plugin *(get_plugin*)(); handle = dlopen(filename, RTLD_LAZY); if (!handle) { /*...return; ...*/ } get_plugin = dlym(handle, "get_plugin"); if (!get_plugin) { /*...return; ...*/ } plugin = get_plugin(); printf("Plugin: %s\n", plugin->name); This works nice for simple plugins. The issue is that many plugins reference further symbols from the application, which are resolved even though RTLD_LAZY was set. (like global variables from the application which are used to initialize plugin-global things) So the dlopen() call fails with an error like fatal: relocation error: file sample_plugin.so: symbol application_some_symbol: referenced symbol not found. As I just want to have access to the single simple structure I was wondering how I can prevent the linker from doing that much of his work.

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how i print the values from NSArray objects in CGContextShowTextAtpoint()?

- by Rajendra Bhole

Hi, I developing an application in which i want to print the values on a line interval, for that i used NSArray with multiple objects and those object i passing into CGContextShowTextAtPoint() method. The code is. CGContextMoveToPoint(ctx, 30.0, 200.0); CGContextAddLineToPoint(ctx, 30.0, 440.0); NSArray *hoursInDays = [[NSArray alloc] initWithObjects:@"0",@"1",@"3",@"4",@"5",@"6",@"7",@"8",@"9",@"10",@"11",@"12", nil]; int intHoursInDays = 0; for(float y = 400.0; y >= 200.0; y-=18, intHoursInDays++) { CGContextSetRGBStrokeColor(ctx, 2.0, 2.0, 2.0, 1.0); CGContextMoveToPoint(ctx, 28, y); CGContextAddLineToPoint(ctx, 32, y); CGContextSelectFont(ctx, "Helvetica", 12.0, kCGEncodingMacRoman); CGContextSetTextDrawingMode(ctx, kCGTextFill); CGContextSetRGBFillColor(ctx, 0, 255, 255, 1); CGAffineTransform xform = CGAffineTransformMake( 1.0, 0.0, 0.0, -1.0, 0.0, 0.0); CGContextSetTextMatrix(ctx, xform); NSString *arrayDataForYAxis = [hoursInDays objectAtIndex:intHoursInDays]; CGContextShowTextAtPoint(ctx, 10.0, y+20, [arrayDataForYAxis UTF8String], strlen((char *)arrayDataForYAxis)); CGContextStrokePath(ctx); } The above code is executed but it given me output is {oo, 1o,2o,...........11}, i want the output is {0,1,2,3...........11,12}. The above code given me one extra character "o" after single digit.I think the problem i meet near the parameters type casting of 5th parameter inside the method of CGContextShowTextAtpoint CGContextShowTextAtpoint(). How i resolve the problem of type casting for printing the objects of NSSArray in CGContextShowTextAtpoint() method??????????????

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Bloated PDF created by TCPDF

- by Yogi Yang 007

In a web app developed in PHP we are generating Quotations and Invoices (which are very simple and of single page) using TCPDF lib. The lib is working just great but it seems to generate very large PDF files. For example in our case it is generating PDF files as large as 4 MB (+/- a few KB). How to reduce this bloating of PDF files generated by TCPDF? Here is code snippet that I am using ob_start(); include('quote_view_bag_pdf.php'); //This file is valid HTML file with PHP code to insert data from DB $quote = ob_get_contents(); //Capture the content of 'quote_view_bag_pdf.php' file and store in variable ob_end_clean(); //Code to generate PDF file for this Quote //This line is to fix a few errors in tcpdf $k_path_url=''; require_once('tcpdf/config/lang/eng.php'); require_once('tcpdf/tcpdf.php'); // create new PDF document $pdf = new TCPDF(); // remove default header/footer $pdf->setPrintHeader(false); $pdf->setPrintFooter(false); // add a page $pdf->AddPage(); // print html formated text $pdf->writeHtml($quote, true, 0, true, 0); //Insert Variables contents here. //Build Out File Name $pdf_out_file = "pdf/Quote_".$_POST['quote_id']."_.pdf"; //Close and output PDF document $pdf->Output($pdf_out_file, 'F'); $pdf->Output($pdf_out_file, 'I'); /////////////// enter code here Hope this code fragment will give some idea?

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Right Click Context Menu Script for iFrame

- by Ramiz Uddin

The context of the problem is related to an application which is based on single-page Ajax application which consists of three different panels (iframes). The layout of the page is as follows: _________________________________________________ | | | Frame A | FRAME C |__________________| | | | Frame B | | | | | | | | | | | | | | | The problem is with the context menu (right-click menu) in Frame C. The position of the context menu is not perfectly positioned with the mouse click. Particularly, if you drag and increase the size of the Frame C window. Code snippet: var rightedge = parent.frames["FrameC"].frameElement.clientWidth-event.clientX; var bottomedge = parent.frames["FrameC"].frameElement.clientHeight-event.clientY; if (rightedge < document.getElementById('Menu').offsetWidth) menuCoorX = parent.frames["FrameC"].frameElement.scrollLeft + event.clientX - document.getElementById('Menu').offsetWidth; else menuCoorX = parent.frames["FrameC"].frameElement.scrollLeft + event.clientX; if (bottomedge < document.getElementById('Menu').offsetHeight) menuCoorY = parent.frames["FrameC"].frameElement.scrollTop + event.clientY - document.getElementById('Menu').offsetHeight; else menuCoorY = parent.frames["FrameC"].frameElement.scrollTop + event.clientY; Currently, we need it to work only for IE (7 and 8). Please, help! Thanks.

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C# Taking a element off each time (stack)

- by Sef

Greetings, Have a question considering a program that stimulates a stack.(not using any build in stack features or any such) stack2= 1 2 3 4 5 //single dimension array of 5 elements By calling up a method "pop" the stack should look like the following: Basically taking a element off each time the stack is being "called" up again. stack2= 1 2 3 4 0 stack2= 1 2 3 0 0 stack2= 1 2 0 0 0 stack2= 1 0 0 0 0 stack2= 0 0 0 0 0 - for (int i = 1; i <= 6; i++) { number= TryPop(s2); //use number ShowStack(s2, "s2"); } Basically I already have code that fills my array with values (trough a push method). The pop method should basically take the last value and place it on 0. Then calls up the next stack and place the following on 0 (like shown above in stack2). The current pop method that keeps track of the top index (0 elements = 0 top, 1 element = 1 top etc..). Already includes a underflow warning if this goes on 0 or below (which is correct). public int Pop() { if(top <= 0) { throw new Exception("Stack underflow..."); } else { for (int j = tabel.Length - 1; j >= 0; j--) { //...Really not sure what to do here. } } return number; }/*Pop*/ Since in the other class I already have a loop (for loop shown above) that simulates 6 times the s2 stack. (first stack: 1 2 3 4 0, second stack 1 2 3 0 0 and so on.) How exactly do I take a element off each time? Either I have the entire display on 0 or the 0 in the wrong places / out of index errors. Thanks in advance!

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Custom model validation of dependent properties using Data Annotations

- by Darin Dimitrov

Since now I've used the excellent FluentValidation library to validate my model classes. In web applications I use it in conjunction with the jquery.validate plugin to perform client side validation as well. One drawback is that much of the validation logic is repeated on the client side and is no longer centralized at a single place. For this reason I'm looking for an alternative. There are many examples out there showing the usage of data annotations to perform model validation. It looks very promising. One thing I couldn't find out is how to validate a property that depends on another property value. Let's take for example the following model: public class Event { [Required] public DateTime? StartDate { get; set; } [Required] public DateTime? EndDate { get; set; } } I would like to ensure that EndDate is greater than StartDate. I could write a custom validation attribute extending ValidationAttribute in order to perform custom validation logic. Unfortunately I couldn't find a way to obtain the model instance: public class CustomValidationAttribute : ValidationAttribute { public override bool IsValid(object value) { // value represents the property value on which this attribute is applied // but how to obtain the object instance to which this property belongs? return true; } } I found that the CustomValidationAttribute seems to do the job because it has this ValidationContext property that contains the object instance being validated. Unfortunately this attribute has been added only in .NET 4.0. So my question is: can I achieve the same functionality in .NET 3.5 SP1? UPDATE: It seems that FluentValidation already supports clientside validation and metadata in ASP.NET MVC 2. Still it would be good to know though if data annotations could be used to validate dependent properties.

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displaying music current time & duration from AVFoundation

- by msb

I have a view-based iphone application that has a single play-pause button that plays an mp3 file. At the time of invoking my doPlayPauseButton() method, I 'd like to show the current time and total duration of this mp3 through the AVAudioPlayer instance I've created, called myAudioPlayer. I have placed two labels at the UI and i'm trying to assign the currentTime and duration properties to these label when the playing begins but my attempts have failed. Here's my play/pause loop, any help would be appreciated: -(IBAction) doPlayPauseButton:(UIButton *)theButton { if(myAudioPlayer.playing) { [myActivityIndicatorView stopAnimating]; myActivityIndicatorView.hidden = YES; //I think I need a myAudioPlayer.currentTime call of some sort for my labels. [myAudioPlayer pause]; [theButton setTitle:@"Play" forState:UIControlStateNormal]; [myTimer invalidate]; } else { [myActivityIndicatorView startAnimating]; myActivityIndicatorView.hidden = NO; myTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:@selector(doTimer) userInfo:nil repeats:YES]; [myAudioPlayer play]; [theButton setTitle:@"Pause" forState:UIControlStateNormal];

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How to make comment reply query in MYSQL?

- by Prashant

I am having comment reply (only till one level) functionality. All comments can have as many as replies but no replies can have their further replies. So my database table structure is like below Id ParentId Comment 1 0 this is come sample comment text 2 0 this is come sample comment text 3 0 this is come sample comment text 4 1 this is come sample comment text 5 0 this is come sample comment text 6 3 this is come sample comment text 7 1 this is come sample comment text In the above structures, commentid, 1 (has 2 replies) and 3 (1 reply) has replies. So to fetch the comments and their replies, one simple method is first I fetch all the comments having ParentId as 0 and then by running a while loop fetch all the replies of that particular commentId. But that seems to be running hundreds of queries if I'll have around 200 comments on a particular record. So I want to make a query which will fetch Comments with their replies sequentially as following; Id ParentId Comment 1 0 this is come sample comment text 4 1 this is come sample comment text 7 1 this is come sample comment text 2 0 this is come sample comment text 3 0 this is come sample comment text 6 3 this is come sample comment text 5 0 this is come sample comment text I also have a comment date column in my comment table, if anyone wants to use this with comment query. So finally I want to fetch all the comments and their replies by using one single mysql query. Please tell me how I can do that? Thanks

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Maintain order of messages via proxies to app servers

- by David Turner

Hi, I am receiving messages from a 3rd party via a http post, and it is important that the order the messages hit our infrastructure is maintained through the load balancers and proxies until it hits our application server. Quick Diagram. (proxies in place due to security requirements.) [ACE load balancer] - [2 proxies] - [Application Servers] or maybe [ACE load balancer] - [2 proxies] - [ACE load balancer] - [Application Servers] My idea was that I would setup the load balancers in active-passive mode, to force all messages to use one proxy, and then both the proxies would hit a second load balancer that would be configured in active passive to hit one application server. Whilst the above is not ideal, it does give me resilience, and once the message is in my app servers, I enter a stateless world, and load balance across both nodes of my cluster. However, I am concerned that even a single proxy could send messages out of order, perhaps if 2 messages are recived very close together, message 2 might get processed faster than message 1. Is this possible? Likely? Is there a simple open source proxy (MOD_PROXY?) that can be easily configured to just pass messages through it, and to guarantee to send the messages through in the order they are received. If so which, and finally links to how I should configure it would be great. In fact any links to articles around avoiding "out of order" messages using hardware would be gratefully received. Thanks, ps for those that are interested, the app is a java spring integration application currently on a appliation server.

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trying to use mod_proxy with httpd and tomcat

- by techsjs2012

I been trying to use mod_proxy with httpd and tomcat... I have on VirtualBox running Scientific Linux which has httpd and tomcat 6 on it.. I made two nodes of tomcat6. I followed this guide like 10 times and still cant get the 2nd node of tomcat working.. http://www.richardnichols.net/2010/08/5-minute-guide-clustering-apache-tomcat/ Here is the lines from my http.conf file <Proxy balancer://testcluster stickysession=JSESSIONID> BalancerMember ajp://127.0.0.1:8009 min=10 max=100 route=node1 loadfactor=1 BalancerMember ajp://127.0.0.1:8109 min=10 max=100 route=node2 loadfactor=1 </Proxy> ProxyPass /examples balancer://testcluster/examples <Location /balancer-manager> SetHandler balancer-manager AuthType Basic AuthName "Balancer Manager" AuthUserFile "/etc/httpd/conf/.htpasswd" Require valid-user </Location> Now here is my server.xml from node1 <?xml version='1.0' encoding='utf-8'?>   <Server port="8005" shutdown="SHUTDOWN">  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />  <Listener className="org.apache.catalina.core.JasperListener" />  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />  <Listener className="org.apache.catalina.mbeans.ServerLifecycleListener" /> <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />  <GlobalNamingResources>  <Resource name="UserDatabase" auth="Container" type="org.apache.catalina.UserDatabase" description="User database that can be updated and saved" factory="org.apache.catalina.users.MemoryUserDatabaseFactory" pathname="conf/tomcat-users.xml" /> </GlobalNamingResources>  <Service name="Catalina">         <Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />   <Engine name="Catalina" defaultHost="localhost" jvmRoute="node1">      <Realm className="org.apache.catalina.realm.UserDatabaseRealm" resourceName="UserDatabase"/>  <Host name="localhost" appBase="webapps" unpackWARs="true" autoDeploy="true" xmlValidation="false" xmlNamespaceAware="false">     </Host> </Engine> </Service> </Server> now here is the server.xml file from node2 <?xml version='1.0' encoding='utf-8'?>   <Server port="8105" shutdown="SHUTDOWN">  <Listener className="org.apache.catalina.core.AprLifecycleListener" SSLEngine="on" />  <Listener className="org.apache.catalina.core.JasperListener" />  <Listener className="org.apache.catalina.core.JreMemoryLeakPreventionListener" />  <Listener className="org.apache.catalina.mbeans.ServerLifecycleListener" /> <Listener className="org.apache.catalina.mbeans.GlobalResourcesLifecycleListener" />  <GlobalNamingResources>  <Resource name="UserDatabase" auth="Container" type="org.apache.catalina.UserDatabase" description="User database that can be updated and saved" factory="org.apache.catalina.users.MemoryUserDatabaseFactory" pathname="conf/tomcat-users.xml" /> </GlobalNamingResources>  <Service name="Catalina">         <Connector port="8109" protocol="AJP/1.3" redirectPort="8443" />   <Engine name="Catalina" defaultHost="localhost" jvmRoute="node2">      <Realm className="org.apache.catalina.realm.UserDatabaseRealm" resourceName="UserDatabase"/>  <Host name="localhost" appBase="webapps" unpackWARs="true" autoDeploy="true" xmlValidation="false" xmlNamespaceAware="false">     </Host> </Engine> </Service> </Server> I dont know what it is. but I been trying for days

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Lightweight spinlocks built from GCC atomic operations?

- by Thomas

I'd like to minimize synchronization and write lock-free code when possible in a project of mine. When absolutely necessary I'd love to substitute light-weight spinlocks built from atomic operations for pthread and win32 mutex locks. My understanding is that these are system calls underneath and could cause a context switch (which may be unnecessary for very quick critical sections where simply spinning a few times would be preferable). The atomic operations I'm referring to are well documented here: http://gcc.gnu.org/onlinedocs/gcc-4.4.1/gcc/Atomic-Builtins.html Here is an example to illustrate what I'm talking about. Imagine a RB-tree with multiple readers and writers possible. RBTree::exists() is read-only and thread safe, RBTree::insert() would require exclusive access by a single writer (and no readers) to be safe. Some code: class IntSetTest { private: unsigned short lock; RBTree<int>* myset; public: // ... void add_number(int n) { // Aquire once locked==false (atomic) while (__sync_bool_compare_and_swap(&lock, 0, 0xffff) == false); // Perform a thread-unsafe operation on the set myset->insert(n); // Unlock (atomic) __sync_bool_compare_and_swap(&lock, 0xffff, 0); } bool check_number(int n) { // Increment once the lock is below 0xffff u16 savedlock = lock; while (savedlock == 0xffff || __sync_bool_compare_and_swap(&lock, savedlock, savedlock+1) == false) savedlock = lock; // Perform read-only operation bool exists = tree->exists(n); // Decrement savedlock = lock; while (__sync_bool_compare_and_swap(&lock, savedlock, savedlock-1) == false) savedlock = lock; return exists; } }; (lets assume it need not be exception-safe) Is this code indeed thread-safe? Are there any pros/cons to this idea? Any advice? Is the use of spinlocks like this a bad idea if the threads are not truly concurrent? Thanks in advance. ;)

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SQL INSTR() using CSV. Need exact match rather than part

- by Alastair Pitts

This is a follow up issue relating to the answer for http://stackoverflow.com/questions/2445029/sql-placeholder-in-where-in-issue-inserted-strings-fail Quick background: We have a SQL query that uses a placeholder value to accept a string, which represents a unique tag/id. Usually, this is only a single tag, but we needed the ability to use a csv string for multiple tags, returning a combined result. In the answer we received from the vendor, they suggested the use of the INSTR function, ala: select * from pitotal where tag IN (SELECT tag from pipoint WHERE INSTR(?, tag) <> 0) and time between 'y' and 't' This works perfectly well 99% of the time, the issue is when the tag is also a subset of 2 parts of the CSV string. Eg the placeholder value is: 'northdom,southdom,eastdom,westdom' and possible tags include: north or northdom What happens, as north is a subset of northdom, is that the two tags are return instead of just northdom, which is actually what we want. I'm not strong on SQL so I couldn't work out how to set it as exact, or split the csv string, so help would be appreciated. Is there a way to split the csv string or make it look for an exact match?

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Capture all display-characters in JavaScript?

- by Jean-Charles

I was given an unusual request recently that I'm having the most difficult time addressing that involves capturing all display-characters when typed into a text box. The set up is as follows: I have a text box that has a maxlength of 10 characters. When the user attempts to type more than 10 characters, I need to notify the user that they're typing beyond the character count limit. The simplest solution would be to specify a maxlength of 11, test the length on every keyup, and truncate back down to 10 characters but this solution seems a bit kludgy. What I'd prefer to do is capture the character before keyup and, depending on whether or not it is a display-character, present the notification to the user and prevent the default action. A white-list would be challenging since we handle a lot of international data. I've played around with every combination of keydown, keypress, and keyup, reading event.keyCode, event.charCode, and event.which, but I can't find a single combination that works across all browsers. The best I could manage is the following that works properly in =IE6, Chrome5, FF3.6, but fails in Opera: NOTE: The following code utilizes jQuery. $(function(){ $('#textbox').keypress(function(e){ var $this = $(this); var key = ('undefined'==typeof e.which?e.keyCode:e.which); if ($this.val().length==($this.attr('maxlength')||10)) { switch(key){ case 13: //return case 9: //tab case 27: //escape case 8: //backspace case 0: //other non-alphanumeric break; default: alert('no - '+e.charCode+' - '+e.which+' - '+e.keyCode); return false; }; } }); }); I'll grant that what I'm doing is likely over-engineering the solution but now that I'm invested in it, I'd like to know of a solution. Thanks for your help!

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