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Pair-wise iteration in C# or sliding window enumerator

- by f3lix

If I have an IEnumerable like: string[] items = new string[] { "a", "b", "c", "d" }; I would like to loop thru all the pairs of consecutive items (sliding window of size 2). Which would be ("a","b"), ("b", "c"), ("c", "d") My solution was is this public static IEnumerable<Pair<T, T>> Pairs(IEnumerable<T> enumerable) { IEnumerator<T> e = enumerable.GetEnumerator(); e.MoveNext(); T current = e.Current; while ( e.MoveNext() ) { T next = e.Current; yield return new Pair<T, T>(current, next); current = next; } } // used like this : foreach (Pair<String,String> pair in IterTools<String>.Pairs(items)) { System.Out.PrintLine("{0}, {1}", pair.First, pair.Second) } When I wrote this code, I wondered if there are already functions in the .NET framework that do the same thing and do it not just for pairs but for any size tuples. IMHO there should be a nice way to do this kind of sliding window operations. I use C# 2.0 and I can imagine that with C# 3.0 (w/ LINQ) there are more (and nicer) ways to do this, but I'm primarily interested in C# 2.0 solutions. Though, I will also appreciate C# 3.0 solutions.

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Script working with mysql and php into a textarea and back

- by Tribalcomm

I am trying to write a custom script that will keep a list of strings in a textarea. Each line of the textarea will be a row from a table. The problem I have is how to work the script to allow for adding, updating, or deleting rows based on a submit. So, for instance, I currently have 3 rows in the database: john sue mark I want to be able to delete sue and add richard and it will delete the row with sue and insert a row for richard. My code so far is as follows: To query the db and list it in the textarea: $basearray = mysql_query("SELECT name FROM mytable ORDER BY name"); <textarea name="names" cols=6 rows=12>'); <?php foreach($basearray as $base){ echo $base->name."\n"; } ?> </textarea> After the submit, I have: <?php $namelist = $_REQUEST[names]; $newarray = explode("\n", $namelist); foreach($newarray as $name) { if (!in_array($name, $basearray)) { mysql_query(DELETE FROM mytable WHERE word='$name'"); } elseif (in_array($name, $basearray)) { ; } else { mysql_query("INSERT INTO mytable (name) VALUES ("$name")"); } } ?> Please tell me what I am doing wrong. I am not getting any functions to work when I edit the contents of the textarea. Thanks!

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Get directory path by fd

- by tylerl

I've run into the need to be able refer to a directory by path given its file descriptor in Linux. The path doesn't have to be canonical, it just has to be functional so that I can pass it to other functions. So, taking the same parameters as passed to a function like fstatat(), I need to be able to call a function like getxattr() which doesn't have a f-XYZ-at() variant. So far I've come up with these solutions; though none are particularly elegant. The simplest solution is to avoid the problem by calling openat() and then using a function like fgetxattr(). This works, but not in every situation. So another method is needed to fill the gaps. The next solution involves looking up the information in proc: if (!access("/proc/self/fd",X_OK)) { sprintf(path,"/proc/self/fd/%i/",fd); } This, of course, totally breaks on systems without proc, including some chroot environments. The last option, a more portable but potentially-race-condition-prone solution, looks like this: DIR* save = opendir("."); fchdir(fd); getcwd(path,PATH_MAX); fchdir(dirfd(save)); closedir(save); The obvious problem here is that in a multithreaded app, changing the working directory around could have side effects. However, the fact that it works is compelling: if I can get the path of a directory by calling fchdir() followed by getcwd(), why shouldn't I be able to just get the information directly: fgetcwd() or something. Clearly the kernel is tracking the necessary information. So how do I get to it?

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loading child swf as3

- by RichW

Hi, I've been given an fla to make some changes too. Basically its a fairly long timeline animation with sound. So far I've successfully added a few button functions for sound etc.. but one has got me stumped. One of the buttons needs to load a child swf. I'm using the code below but I'm recieving an error - 'Error #1009: Cannot access a property or method of a null object reference'. I believe this may be refferring to an object that isn't set yet but I have no idea which one it is: Code: var mcExt:MovieClip = new MovieClip(); var ldr:Loader = new Loader(); ldr.contentLoaderInfo.addEventListener(Event.COMPLETE, swfLoaded); ldr.load(new URLRequest("Downloads.swf")); function swfLoaded(e:Event):void { mcExt = MovieClip(ldr.contentLoaderInfo.content); ldr.contentLoaderInfo.removeEventListener(Event.COMPLETE, swfLoaded); mcExt.x = 50; mcExt.y = 50; addChild(mcExt); } Any help on what is going wrong would be greatly appreciated! Thanks

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Windows console

- by b-gen-jack-o-neill

Hello. Well, I have a simple question, at least I hope its simple. I was interested in win32 console for a while. Our teacher told us, that windows console is just for DOS and real mode emulation purposes. Well, I know it is not true, becouse DOS applications are runned by emulator which only uses console to display output. Another thing I learned is that console is built into Windows since NT. Well. But what I could not find is, how actually are console programs written to use console. I use Visual C++ for programming (well, for learning). So, the only thing I need to do for using console is select console project. I first thought that windows decides wheather it run app in console or tries to run app in window mode. So I created win32 program and tried printf(). Well, I could not compile it. I know that by definition printf() prints text or variables to stdout. I also found that stdout is the console interface for output. But, I could not find what actually stdout is. So, basicly what I want to ask is, where is the difference between console app and win32 app. I thought that windows starts console when it gets command from "console-family" functions. But obvisously it does not, so there must be some code that actually commands windows to create console interface. And the second question is, when the console is created, how does windows recognize which console terminal is used for what app? I mean, what actually is stdout? Is it a area in memory , or some windows routine that is called? Thanks.

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"do it all" page structure and things to watch out for?

- by Andrew Heath

I'm still getting my feet wet in PHP (my 1st language) and I've reached the competency level where I can code one page that handles all sorts of different related requests. They generally have a structure like this: (psuedo code) <?php include 'include/functions.php'; IF authorized IF submit (add data) ELSE IF update (update data) ELSE IF list (show special data) ELSE IF tab switch (show new area) ELSE display vanilla (show default) ELSE "must be registered/logged-in" ?> <HTML> // snip <?php echo $output; ?> // snip </HTML> and it all works nicely, and quite quickly which is cool. But I'm still sorta feeling my way in the dark... and would like some input from the pros regarding this type of page design... is it a good long-term structure? (it seems easily expanded...) are there security risks particular to this design? are there corners I should avoid painting myself into? Just curious about what lies ahead, really...

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MS Query Analyzer / Management Studio replacement?

- by kprobst

I've been using SQL Server since version 6.5 and I've always been a bit amazed at the fact that the tools seem to be targeted to DBAs rather than developers. I liked the simplicity and speed of the Query Analyzer for example, but hated the built-in editor, which was really no better than a syntax coloring-capable Notepad. Now that we have Management Studio the management part seems a bit better but from a developer standpoint the tools is even worse. Visual Studio's excellent text editor... without a way to customize keyboard bindings!? Don't get me started on how unusable is the tree-based management hierarchy. Why can't I re-root the tree on a list of stored procs for example the way the Enterprise Manager used to allow? Now I have a treeview that needs to be scrolled horizontally, which makes it eminently useless. The SQL server support in Visual Studio is fantastic for working with stored procedures and functions, but it's terrible as a general ad hoc data query tool. I've tried various tools over the years but invariably they seem to focus on the management side and shortchange the developer in me. I just want something with basic admin capabilities, good keyboard support and requisite DDL functionality (ideally something like the Query Analyzer). At this point I'm seriously thinking of using vim+sqlcmd and a console... I'm that desperate :) Those of you who work day in and day out with SQL Server and Visual Studio... do you find the tools to be adequate? Have you ever wished they were better and if you have found something better, could you share please? Thanks!

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Emulate domready event with a custom event (mootools)

- by Rob

I need to fire a one time only custom event that functions like the domready event, in that if new events are added after the event has occurred they are fired immediately. This is for some code that cannot execute until certain data and resources are initialized, so I want to do something like this: // I am including a script (loadResources.js) to load data and other resources, // when loadResources.js is done doing it's thing it will fire resourcesAreLoaded with: window.fireEvent('resourcesAreLoaded'); window.addEvent('resourcesAreLoaded', function() { // this is fine }); $('mybutton').addEvent('click', function() { window.addEvent('resourcesAreLoaded', function() { // this is not fine, because resourcesAreLoaded has already fired // by the time the button is clicked }); }); If possible I would like resourcesAreLoaded to function like domready, and execute the code immediately if the event has already fired: window.addEvent('testIsReady', function() { alert('firing test'); }); window.fireEvent('testIsReady'); window.addEvent('test', function() { // this will never execute unless I call fireEvent('testIsReady') again alert('test 2'); }); window.addEvent('domready', function() { alert('domready is firing'); }); window.addEvent('domready', function() { setTimeout(function() { alert('domready has already fired, so this is executed immediately'); }, 500); });

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Multiuser login into winforms application

- by schoetbi

Hi there, i have a winforms app in C# that needs access control for certain forms. That means, the application is running under the same (default) user at system startup, but certain forms need to be secured, so that only certain windows users could have access to the additional functions after identifying themself with username and password. For that step windows authentication should be used. Now the tricky part. Although the application was started under a "normal" user I would like the superusers to "login" into the special form without restarting the entiere application. My question now is. Is this possible (i.e. create one thread with the credentials of an administrator). Or do I need to setup another appdomain for that? Please give me a hint wather the user of a running application could be changed somehow. Thank you. EDIT I replaced administrators by "certain users" since the privileged user could be just another ordinary user that is granted access to the special functionality by the configuration of the installation.

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Sorting Arrays by More the One Value, and Prioritizing the Sort based on Column data.

- by Mark Tomlin

I'm looking for a way to sort an array (we call this a row), with an array of values (that I'll call columns). Each row has columns that must be sorted based on the priority of: timetime, lapcount & timestamp. Each column cotains this information: split1, split2, split3, laptime, lapcount, timestamp. laptime if in hundredths of a second. (1:23.45 or 1 Minute, 23 Seconds & 45 Hundredths is 8345.) Lapcount is a simple unsigned tiny int, or unsigned char. timestamp is unix epoch. The lowest laptime should be at the get a better standing in this sort. Should two peoples laptimes equal, then timestamp will be used to give the better standing in this sort. Should two peoples timestamp equal, then the person with less of a lapcount get's the better standing in this sort. By better standing, I mean closer to the top of the array, closer to the index of zero where it a numerical array. I think the array sorting functions built into php can do this with a callback, I was wondering what the best approch was for a weighted sort like this would be.

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Sorting Arrays by More the One Value, and Prioritizing the Sort based on Column data.

- by Mark Tomlin

I'm looking for a way to sort an array, based on the information in each row, based on the information in certain cells, that I'll call columns. Each row has columns that must be sorted based on the priority of: timetime, lapcount & timestamp. Each column cotains this information: split1, split2, split3, laptime, lapcount, timestamp. laptime if in hundredths of a second. (1:23.45 or 1 Minute, 23 Seconds & 45 Hundredths is 8345.) Lapcount is a simple unsigned tiny int, or unsigned char. timestamp is unix epoch. The lowest laptime should be at the get a better standing in this sort. Should two peoples laptimes equal, then timestamp will be used to give the better standing in this sort. Should two peoples timestamp equal, then the person with less of a lapcount get's the better standing in this sort. By better standing, I mean closer to the top of the array, closer to the index of zero where it a numerical array. I think the array sorting functions built into php can do this with a callback, I was wondering what the best approch was for a weighted sort like this would be.

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Why is OpenSubKey() returning null on my Win 7 64 bit system?

- by BrMcMullin

Has anyone seen OpenSubKey() and other Microsoft.Win32 registry functions return null on 64 bit systems when 32 bit registry keys are under Wow6432node in the registry? I'm working on a unit testing framework that makes a call to OpenSubKey() from the .net library. My dev system is a Win 7 64 bit environment with VS 2008 SP1 and the Win 7 SDK installed. The application we're unit testing is a 32 bit application, so the registry is virtualized under HKLM\Software\Wow6432node. When we call: Registry.LocalMachine.OpenSubKey( @"Software\MyCompany\MyApp\" ); Null is returned, however explicitly stating to look here works: Registry.LocalMachine.OpenSubKey( @"Software\Wow6432node\MyCompany\MyApp\" ); From what I understand this function should be agnostic to 32 bit or 64 bit environments and should know to jump to the virtual node. Even stranger is the fact that the exact same call inside a compiled and installed version of our application is running just fine on the same system and is getting the registry keys necessary to run; which are also being placed in HKLM\Software\Wow6432node. Any suggestions? Thanks in advance!

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how to manage a "resource" array efficiently

- by Haiyuan Zhang

The senario of my question is that one need to use a fixed size of array to keep track of certain number of "objects" . The object here can be as simply as a integer or as complex as very fancy data structure. And "keep track" here means to allocate one object when other part of the app need one instance of object and recyle it for future allocation when one instance of the object is returned .Finally ,let me use c++ to put my problme in a more descriptive way . #define MAX 65535 /* 65535 just indicate that many items should be handled . performance demanding! */ typedef struct { int item ; }Item_t; Item_t items[MAX] ; class itemManager { private : /* up to you.... */ public : int get() ; /* get one index to a free Item_t in items */ bool put(int index) ; /* recyle one Item_t indicate by one index in items */ } how will you implement the two public functions of itemManager ? it's up to you to add any private member .

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Works in Firefox & Opera, but not in IE8

- by Ai Pragma

1) This issue involves just one html webpage, lets call it "ajax.html".2) I have AJAX functions in this webpage that work in both Firefox and IE8.3) I now attempt generating just the option values of a dropdown list of dates using my ajax functions, and it works in Firefox & Opera, but not IE8.4) The surrounding html code for the dropdown looks like this:<select name="entry_7_single" id="entry_7" onChange="Ajax_PhpResultsWithVar('./secure/db/SummaryCls.php','entry_8','dateval',this.value)"></select>The onchange call refers to an ajax function that successfully(both Firefox & IE8) populates a textarea(entry_8) with a description of an event associated with the date selected in this dropdown. 5) An onload call initiates the ajax function to generate the dropdown list values:<body class="ss-base-body" onLoad="OnLoadWebPage()">6) The js script that calls the ajax function is as follows:function OnLoadWebPage(){ Ajax_PhpResults('./secure/db/GenDateListCls.php','entry_7');}7) Since it works in Firefox, but not IE8, I throw the output of the ajax function into a Firefox large textbox and I get the following:<option selected value="8 JUN 2010">8 JUN 2010</option> <option value="9 JUN 2010">9 JUN 2010</option> <option value="10 JUN 2010">10 JUN 2010</option> <option value="11 JUN 2010">11 JUN 2010</option> 8 ) There are over a hundred generated but you get the gist of what the ajax function generates. Next I will list the PHP function that outputs the above dropdown values://///////////////////////////////////////////////////////////////////////////////////////////////////////<?phpinclude_once 'SPSQLite.class.php';include_once 'misc_funcs.php';class GenDateListCls { var $dbName; var $sqlite; function GenDateListCls() { $this->dbName = 'accrsc.db'; $this->ConstructEventDates(); } function ConstructEventDates() { $this->sqlite = new SPSQLite($this->dbName); $todayarr = getdate(); $today = $todayarr[mday] . " " . substr($todayarr[month],0,3) . " " . $todayarr[year]; $ICalDate = ChangeToICalDate($today); $dateQuery = "SELECT dtstart from events where substr(dtstart,1,8) >= '" . $ICalDate . "';"; $this->sqlite->query($dateQuery); $datesResult = $this->sqlite->returnRows(); foreach (array_reverse($datesResult) as $indx => $row) { $normDate = NormalizeICalDate(substr($row[dtstart],0,8)); if ($indx==0) { ?> <option selected value=<?php echo('"' . $normDate . '"'); ?>><?php echo $normDate; ?></option><?php } else {?> <option value=<?php echo('"' . $normDate . '"'); ?>><?php echo $normDate; ?></option><?php } } $this->sqlite->close(); }}$dateList = new GenDateListCls(); ?>/////////////////////////////////////////////////////////////////////////////////////////////////////////////<<< I appreciate any assistance on this matter. Aipragma >>> My Background: To let you all know, I am a complete newbie to PHP, Ajax, & javascript, and learning it all on my own, no classes. My background is in Linux, Windows, C++, Java, VB,VBA,MS XML, & some html.

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Business Objects - Containers or functional?

- by Walter

Where I work, we've gone back and forth on this subject a number of times and are looking for a sanity check. Here's the question: Should Business Objects be data containers (more like DTOs) or should they also contain logic that can perform some functionality on that object. Example - Take a customer object, it probably contains some common properties (Name, Id, etc), should that customer object also include functions (Save, Calc, etc.)? One line of reasoning says separate the object from the functionality (single responsibility principal) and put the functionality in a Business Logic layer or object. The other line of reasoning says, no, if I have a customer object I just want to call Customer.Save and be done with it. Why do I need to know about how to save a customer if I'm consuming the object? Our last two projects have had the objects separated from the functionality, but the debate has been raised again on a new project. Which makes more sense? EDIT These results are very similar to our debates. One vote to one side or another completely changes the direction. Does anyone else want to add their 2 cents? EDIT Eventhough the answer sampling is small, it appears that the majority believe that functionality in a business object is acceptable as long as it is simple but persistence is best placed in a separate class/layer. We'll give this a try. Thanks for everyone's input...

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fullcalendar : updating option function callbacks after init

- by Paul Maneesilasan

Ok, so I have a problem with setting options whose values are callback functions when I try to set them after plugin initialization. I think this would be a common behavior, to dynamically set event callback after init'ing the calendar. Here is a snipit of code: $(document).ready(function() { $('#calendar').fullCalendar({ editable: false ,events:[{"title":"meeting.title","start":"2010-05-21 15:58:16 UTC"},{"title":"meeting.title","start":"2010-05-24 15:58:16", "url":"http://google.com"}] /* ,eventClick: function(event) { if (event.url) { window.open(event.url); return false; } } */ }); $('#calendar').fullCalendar('options', 'eventClick', function(event) { if (event.url) { window.open(event.url); return false; } }); }); You can see that I have setting the eventClick function as an init option commented out. If I do it that way, it works fine. However if I try to set it after the init, it doesn't work :( Is the some other way to do this? Or am I stuck with having to set the behavior upfront?

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Poor LLVM JIT performance

- by Paul J. Lucas

I have a legacy C++ application that constructs a tree of C++ objects. I want to use LLVM to call class constructors to create said tree. The generated LLVM code is fairly straight-forward and looks repeated sequences of: ; ... %11 = getelementptr [11 x i8*]* %Value_array1, i64 0, i64 1 %12 = call i8* @T_string_M_new_A_2Pv(i8* %heap, i8* getelementptr inbounds ([10 x i8]* @0, i64 0, i64 0)) %13 = call i8* @T_QueryLoc_M_new_A_2Pv4i(i8* %heap, i8* %12, i32 1, i32 1, i32 4, i32 5) %14 = call i8* @T_GlobalEnvironment_M_getItemFactory_A_Pv(i8* %heap) %15 = call i8* @T_xs_integer_M_new_A_Pvl(i8* %heap, i64 2) %16 = call i8* @T_ItemFactory_M_createInteger_A_3Pv(i8* %heap, i8* %14, i8* %15) %17 = call i8* @T_SingletonIterator_M_new_A_4Pv(i8* %heap, i8* %2, i8* %13, i8* %16) store i8* %17, i8** %11, align 8 ; ... Where each T_ function is a C "thunk" that calls some C++ constructor, e.g.: void* T_string_M_new_A_2Pv( void *v_value ) { string *const value = static_cast<string*>( v_value ); return new string( value ); } The thunks are necessary, of course, because LLVM knows nothing about C++. The T_ functions are added to the ExecutionEngine in use via ExecutionEngine::addGlobalMapping(). When this code is JIT'd, the performance of the JIT'ing itself is very poor. I've generated a call-graph using kcachegrind. I don't understand all the numbers (and this PDF seems not to include commas where it should), but if you look at the left fork, the bottom two ovals, Schedule... is called 16K times and setHeightToAtLeas... is called 37K times. On the right fork, RAGreed... is called 35K times. Those are far too many calls to anything for what's mostly a simple sequence of call LLVM instructions. Something seems horribly wrong. Any ideas on how to improve the performance of the JIT'ing?

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Code Golf: Shortest Turing-complete interpreter.

- by ilya n.

I've just tried to create the smallest possible language interpreter. Would you like to join and try? Rules of the game: You should specify a programming language you're interpreting. If it's a language you invented, it should come with a list of commands in the comments. Your code should start with example program and data assigned to your code and data variables. Your code should end with output of your result. It's preferable that there are debug statements at every intermediate step. Your code should be runnable as written. You can assume that data are 0 and 1s (int, string or boolean, your choice) and output is a single bit. The language should be Turing-complete in the sense that for any algorithm written on a standard model, such as Turing machine, Markov chains, or similar of your choice, it's reasonably obvious (or explained) how to write a program that after being executred by your interpreter performs the algorithm. The length of the code is defined as the length of the code after removal of input part, output part, debug statements and non-necessary whitespaces. Please add the resulting code and its length to the post. You can't use functions that make compiler execute code for you, such as eval(), exec() or similar. This is a Community Wiki, meaning neither the question nor answers get the reputation points from votes. But vote anyway!

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Handling incremental Data Modeling Changes in Functional Programming

- by Adam Gent

Most of the problems I have to solve in my job as a developer have to do with data modeling. For example in a OOP Web Application world I often have to change the data properties that are in a object to meet new requirements. If I'm lucky I don't even need to programmatically add new "behavior" code (functions,methods). Instead I can declarative add validation and even UI options by annotating the property (Java). In Functional Programming it seems that adding new data properties requires lots of code changes because of pattern matching and data constructors (Haskell, ML). How do I minimize this problem? This seems to be a recognized problem as Xavier Leroy states nicely on page 24 of "Objects and Classes vs. Modules" - To summarize for those that don't have a PostScript viewer it basically says FP languages are better than OOP languages for adding new behavior over data objects but OOP languages are better for adding new data objects/properties. Are there any design pattern used in FP languages to help mitigate this problem? I have read Phillip Wadler's recommendation of using Monads to help this modularity problem but I'm not sure I understand how?

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Questions about the MVC architecture

- by ah123

I started coding a considerably complicated web application, and it became quite a mess. So I figured I'd try to organize it in a better way. MVC seemed appropriate. I've never used MVC before, and researching about it I'm trying to consolidate a better perception of it (and my questions obviously reflect what I think I've learned so far). My questions are slightly JavaScript oriented: What object should make "AJAX" requests? The Controller or the Model? (seperation -- should the Model just store/manipulate the data, should it not care/know where the data came from, or should it be the one fetching it?) Should the Model call View functions providing them with data as arguments or should the View query (reference) the Model within itself? (seperation principles in mind, "the View shouldn't care/know where it gets the data from" -- is that correct?) In general, should the View "know" of the Model's existance, and vice-versa? Is the Controller the only thing gluing them together or is that simply incorrect? (I really doubt that statement is generally correct) There's a good chance I'd want to port this into a desktop/mobile application, so I would like to seperate components in a way that will allow me to achieve that task, replacing the current source of the data, HTTP requests, with DB access, and replacing the View. Maybe every approach that I've asked about is still "valid" MVC and it's just up to me to choose. I understand that nothing is set in stone, I'm just trying to have a (better) general idea in my head.

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How to build Graceful Degradation AJAX web page?

- by Morgan Cheng

I want to build web page with "Graceful Degradation". That is, the web page functions even javascript is disabled. Now I have to make design decision on the format of AJAX response. If javascript is disabled, each HTTP request to server will generate HTML as response. The browser refreshes with the returned HTML. That's fine. If javascript is enabled, each AJAX HTTP request to server will generate ... well, JSON or HTML. If it is HTML, it is easy to implement. Just have javascript to replace part of page with the returned HTML. And, in server side, not much code change is needed. If it is JSON, then I have to implement JSON-to-html logic in javascript again which is almost duplicate of server side logic. Duplication is evil. I really don't like it. The benefit is that the bandwidth usage is better than HTML, which brings better performance. So, what's the best solution to Graceful Degradation? AJAX request better to return JSON or HTML?

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How to wrap a thirdparty library COM class for notifications in a C++ project

- by geocoin

A thirdparty vendor has provided a COM interface as an external API to their product, and for sending instructions to it, it's fine with the mechanism of generating class wrappers with visual studio by importing from the dll, then creating instances of the created classes, calling their CreateDispatch(), using the access functions and releasing when done. For return notifications, I'd normally create an EventsListener class derived from IDispatch using the Invoke function to handle events returning from the interface. This vendor has created an Events lass which I have to wrap and expose, then explicitly tell the installation where to look. all the example are given is C# where it's really easy, but I'm struggling on how to do it in C++ in the C# example, the interop dll provided is simply added as a reference and derived into a class like so: using System; using System.Runtime.InteropServices; using System.Windows.Forms; using System.Text; using <THIER INTEROP LIB> namespace some.example.namespace { [ComVisible(true)] public class EventViewer : IEvents //where IEvents is their events class { public void OnEvent(EventID EventID, object pData) //overridden function { //event handled here } } } In broad terms I assume that I must create a COM interface, since they require a ProgID from me to instantiate, but how do I derive that's been wrapped by the import and then expose the created class to COM I'm just not sure where to even start, as all the tutorials I've seen so far talk in terms of creating brand new classes not wrapping a third party one

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Convert float to decimal in Informix

- by prabhu

I have a table with a column of type decimal. There is a ESQL/C structure that represents the table. It has a member of type decimal. I also have a normal C structure for equivalent for the same table. The type of the above mentioned field is a float. Since we use memcpy to copy data to and from ESQL/C structure to C structure, there is an issue with decimal to float conversion. When I searched the Informix ESQL/C Programmer's manual, I couldn't find any function that can do this. Google search led me to the deccvflt() function. This function converts from a float to a decimal type. Though I couldn't find this function listed in the manual, I see the declarations in decimal.h. Are these functions still recommended to be used? Alternatively, I was also thinking about using the decimal type in the C structure also, as it happens to be a C structure. This way, I can still use the memcpy right? Please share your thoughts. IBM Informix Dynamic Server Version 11.50.FC3 Thanks, prabhu

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What is Ruby's analog to Python Metaclasses?

- by Sean Copenhaver

Python has the idea of metaclasses that, if I understand correctly, allow you to modify an object of a class at the moment of construction. You are not modifying the class, but instead the object that is to be created then initialized. Python (at least as of 3.0 I believe) also has the idea of class decorators. Again if I understand correctly, class decorators allow the modifying of the class definition at the moment it is being declared. Now I believe there is an equivalent feature or features to the class decorator in Ruby, but I'm currently unaware of something equivalent to metaclasses. I'm sure you can easily pump any Ruby object through some functions and do what you will to it, but is there a feature in the language that sets that up like metaclasses do? So again, Does Ruby have something similar to Python's metaclasses? Edit I was off on the metaclasses for Python. A metaclass and a class decorator do very similar things it appears. They both modify the class when it is defined but in different manners. Hopefully a Python guru will come in and explain better on these features in Python. But a class or the parent of a class can implement a __new__(cls[,..]) function that does customize the construction of the object before it is initialized with __init__(self[,..]).

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How can I round money values to the nearest $5.00 interval?

- by Frank Developer

I have an Informix-SQL based Pawnshop app which calculates an estimate of how much money should be loaned to a customer, based on the weight and purity of gold. The minimum the pawnshop lends is $5.00. The pawnshop employee will typically lend amounts which either ends with a 5 or 0. examples: 10, 15, 20, 100, 110, 125, etc. They do this so as to not run into shortage problems with $1.00 bills. So, if for example my system calculates the loan should be: $12.49, then round it to $10, $12.50 to $15.00, $13.00 to $15.00, $17.50 to $20.00, and so on!..The employee can always override the rounded amount if necessary. Is it possible to accomplish this within the instructions section of a perform screen or would I have to write a cfunc and call it from within perform?.. Are there any C library functions which perform interval rounding of money values?.. On another note, I think the U.S. Government should discontinue the use of pennies so that businesses can round amounts to the nearest nickel, it would save so much time and weight in our pockets!

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