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• Are there any free Xml Diff/Merge tools available?

  - by Russell

  I have several config files in my .net applications which I would like to merge application settings elements etc. I was about to begin doing it manually as I usually do, however thought there must be an XML diff GUI tool available somewhere. The tool would be able to go to the element level to compare and display the differences etc. However Google gave no substantive free tool results and no hints for anything of value. Is such a tool available? That is very useful? For free? Thanks in advance. :) Edit: Here is a bit of clarification of the functionality that would turn my error-prone, tedious manual job into a 1-minute simpler task (and potential to automate): In KDiff3, you can do a diff/merge of entire directories. There is a hierarchical diff which is very accurate, user-friendly and clear. I was interested in finding a similar solution, however instead of directory hierarchy, an XML element hierarchy. If there is no such open source software, I am considering creating one on CodePlex to provide this functionality.

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• Where to start with the development of first database driven Web App (long question)?

  - by Ryan

  Hi all, I've decided to develop a database driven web app, but I'm not sure where to start. The end goal of the project is three-fold: 1) to learn new technologies and practices, 2) deliver an unsolicited demo to management that would show how information that the company stores as office documents spread across a cumbersome network folder structure can be consolidated and made easier to access and maintain and 3) show my co-workers how Test Drive Development and prototyping via class diagrams can be very useful and reduces future maintenance headaches. I think this ends up being a basic CMS to which I have generated a set of features, see below. 1) Create a database to store the site structure (organized as a tree with a 'project group'-project structure). 2) Pull the site structure from the database and display as a tree using basic front end technologies. 3) Add administrator privileges/tools for modifying the site structure. 4) Auto create required sub pages* when an admin adds a new project. 4.1) There will be several sub pages under each project and the content for each sub page is different. 5) add user privileges for assigning read and write privileges to sub pages. What I would like to do is use Test Driven Development and class diagramming as part of my process for developing this project. My problem; I'm not sure where to start. I have read on Unit Testing and UML, but never used them in practice. Also, having never worked with databases before, how to I incorporate these items into the models and test units? Thank you all in advance for your expertise.

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• PHP - How do you secure a unique variable name?

  - by 102319141763223461745

  This function cropit, which I shamelessly stole off the internet, crops a 90x60 area from an existing image. In this code, when I use the function for more than one item (image) the one will display on top of the other (they come to occupy the same output space). I think this is because the function has the same (static) name ($dest) for the destination of the image when it's created (imagecopy). I tried, as you can see to include a second argument to the cropit function which would serve as the "name" of the $dest variable, but it didn't work. In the interest of full disclosure I have 22 hours of PHP experience (incidentally the same number of hours since the last I slept) and I am not that smart to begin with. Even if there's something else at work here entirely, seems to me that generally it must be useful to have a way to secure that a variable is always given a unique name. function cropit($srcimg, $dest) { $im = imagecreatefromjpeg($srcimg); $img_width = imagesx($im); $img_height = imagesy($im); $width = 90; $height = 60; $tlx = floor($img_width / 2) - floor ($width / 2); $tly = floor($img_height / 2) - floor ($height / 2); if ($tlx < 0) { $tlx = 0; } if ($tly < 0) { $tly = 0; } if (($img_width - $tlx) < $width) { $width = $img_width - $tlx; } if (($img_height - $tly) < $height) { $height = $img_height - $tly; } $dest = imagecreatetruecolor ($width, $height); imagecopy($dest, $im, 0, 0, $tlx, $tly, $width, $height); imagejpeg($dest); imagedestroy($dest); } $img = "imagefolder\imageone.jpg"; $img2 = "imagefolder\imagetwo.jpg"; cropit($img, $i1); cropit($img2, $i2); ?

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• How costly performance-wise are these actions in iPhone objective-C?

  - by Alex Gosselin

  This is really a few questions in one, I'm wondering what the performance cost is for these things, as I haven't really been following a best practice of any sort for these. The answers may also be useful to other readers, if somebody knows these. (1) If I need the core data managed object context, is it bad to use #import "myAppDelegate.h" //farther down in the code: NSManagedObjectContext *context = [(myAppDelegate.h*)[[UIApplication sharedApplication] delegate] managedObjectContext]; as opposed to leaving the warning you get if you don't cast the delegate? (2) What is the cheapest way to hard-code a string? I have been using return @"myString"; on occasion in some functions where I need to pass it to a variety of places, is it better to do it this way: static NSString *str = @"myString"; return str; (3) How costly is it to subclass an object i wrote vs. making a new one, in general? (4) When I am using core data and navigating through a hierarchy of some sort, is it necessary to turn things back into faults somehow after I read some info from them? or is this done automatically? Thanks for any help.

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• Operator Overloading << in c++

  - by thlgood

  I'm a fresh man in C++. I write this simple program to practice Overlaoding. This is my code: #include <iostream> #include <string> using namespace std; class sex_t { private: char __sex__; public: sex_t(char sex_v = 'M'):__sex__(sex_v) { if (sex_v != 'M' && sex_v != 'F') { cerr << "Sex type error!" << sex_v << endl; __sex__ = 'M'; } } const ostream& operator << (const ostream& stream) { if (__sex__ == 'M') cout << "Male"; else cout << "Female"; return stream; } }; int main(int argc, char *argv[]) { sex_t me('M'); cout << me << endl; return 0; } When I compiler it, It print a lots of error message: The error message was in a mess. It's too hard for me to found useful message sex.cpp: ???‘int main(int, char**)’?: sex.cpp:32:10: ??: ‘operator<<’?‘std::cout << me’????? sex.cpp:32:10: ??: ???: /usr/include/c++/4.6/ostream:110:7: ??: std::basic_ostream<_CharT, _Traits>::__ostream_type& std::basic_ostream<_CharT, _Traits>::operator<<(std::basic_ostre

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• Looking for a book which teaches how to write applications (as opposed to writng code)

  - by rumtscho

  I am not a developer. I have coded for fun and for university projects in several languages, and during an internship, I have written code which is still in use by a department of Fortune Global 500 company. I also have extensive theoretical knowledge of software engineering - process models, architecture, project management, UI construction using Lauesen's virtual windows... you get the picture. But I am not involved with software development in my job. I recently decided to start coding for fun again, and now I have some free days to do it. But this time, I want to do it right. I want to write a real, useful application, install it on my devices and use it myself. Also I want to publish it for others to use, should they want to do so. I am vaguely aware that there is more to writing an application than to writing code. There is stuff like version control software, decision for the right IDE, having a suite of unit tests, producing an installation package - and probably lots of other things I never thought of but which must be taken care of in a proper application, as opposed to a bunch of classes I am running from my IDE. All this is stuff I should know before I start, but I have not learned it. Coding books touch on some of the subjects like IDE choice, but don't go into detail, and are not exhaustive. Theoretical software engineering textbooks are even less helpful. So is there a book which teaches exactly that? I know that I can find information on each of these topics on the Internet, but I'd rather have a systematic book exhaustively listing all the things I should take care of if I want to create a good application, and offering the currently accepted solutions for them. In the best case, it will be language- and platform independent, but if you know of a good book focusing on a specific platform, I would like to know about it too. I know I want a lot, but given how important such knowledge is and how many people need it, surely somebody must have written such a book?

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• filtering search results with php

  - by fl3x7

  Hello, Cant really find any useful information on this through Google so hope someone here with some knowledge can help. I have a set of results which are pulled from a multi dimensional array. Currently the array key is the price of a product whilst the item contains another array which contains all the product details. key=>Item(name=>test, foo=>bar) So currently when I list the items I just order by the key, smallest first and it lists the products smallest price first. However I want to build on this so that when a user sees the results they can choose other ordering options like list all products by a name, certain manufacturer, colour, x ,y ,z etc etc from a drop down box(or something similar) This is where I need some guidance. Im just not sure how to go about it or best practise or anything. The only way I can think of is to order all the items by the nested array eg by the name, manufacturer etc. but how do I do that in PHP? Hope you understand what im trying to achieve(if not just ask). Any help on this with ideas, approaches or examples would be great. Thanks for reading p.s Im using PHP5

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• Joomla get plugin id

  - by Christian Sciberras

  I wrote a Joomla plugin which will eventually load a library. The path to library is a plugin parameter, as such when the path is incorrect, a message pops up in the backend, together with a link to edit the plugin parameters: /administrator/index.php?option=com_plugins&view=plugin&client=site&task=edit&cid[]=36 See the 36 at the end? That's my plugin's id in the database (table jos_plugins). My issue is that this id changes on installation, ie, on different installs, it would be something else. So I need to find this id programmatically. The problem is that I couldn't find this id from the plugin object itself (as to why not, that would be joomla's arguably short-sighted design decision). So unless you know about some neat trick, (I've checked and double checked JPlugin and JPluginHelper classes), I'll be using the DB. Edit; Some useful links: http://docs.joomla.org/Plugin_Developer_Overview http://api.joomla.org/Joomla-Framework/Plugin/JPlugin.html http://api.joomla.org/Joomla-Framework/Plugin/JPluginHelper.html http://forum.joomla.org/viewtopic.php?p=2227737 Guess I'll be using the wisdom from that last link...

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• Querying for a unique value based on the aggregate of another value while grouping on a third value

  - by Justin Swartsel

  So I know this problem isn't a new one, but I'm trying to wrap my head around it and understand the best way to deal with scenarios like this. Say I have a hypothetical table 'X' that looks like this: GroupID ID (identity) SomeDateTime -------------------------------------------- 1 1000 1/1/01 1 1001 2/2/02 1 1002 3/3/03 2 1003 4/4/04 2 1004 5/5/05 I want to query it so the result set looks like this: ---------------------------------------- 1 1002 3/3/03 2 1004 5/5/05 Basically what I want is the MAX SomeDateTime value grouped by my GroupID column. The kicker is that I DON'T want to group by the ID column, I just want to know the 'ID' that corresponds to the MAX SomeDateTime. I know one pseudo-solution would be: ;WITH X1 as ( SELECT MAX(SomeDateTime) as SomeDateTime, GroupID FROM X GROUP BY GroupID ) SELECT X1.SomeDateTime, X1.GroupID, X2.ID FROM X1 INNER JOIN X as X2 ON X.DateTime = X2.DateTime But this doesn't solve the fact that a DateTime might not be unique. And it seems sloppy to join on a DateTime like that. Another pseudo-solution could be: SELECT X.GroupID, MAX(X.ID) as ID, MAX(X.SomeDateTime) as SomeDateTime FROM X GROUP BY X.GroupID But there are no guarantees that ID will actually match the row that SomeDateTime comes from. A third less useful option might be: SELECT TOP 1 X.GroupID, X.ID, X.SomeDateTime FROM X WHERE X.GroupID = 1 ORDER BY X.SomeDateTime DESC But obviously that only works with a single, known, GroupID. I want to be able to join this result set on GroupID and/or ID. Does anyone know of any clever solutions? Any good uses of windowing functions? Thanks!

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• Smarter println that shows the depth in the stack

  - by Hectoret

  I am using System.out.println in my code to track the execution of a program and get some useful output. This creates results like this in the console: Main function. Program starts. Method getArea. Getting values Method getSide. Side is 6 Method getArea. First value is 6 Method getSide. Side is 8 Method getArea. Second value is 8 Method getArea. Area is 48 Main function. The final area is 48 I would like to create tha method, which adds a space in front of the output every time the code goes deeper in the method call stack. For example, the same code but instead of using System.out.println, now with Misc.smartPrintln: Main function. Program starts. Method getArea. Getting values Method getSide. Side is 6 Method getArea. First value is 6 Method getSide. Side is 8 Method getArea. Second value is 8 Method getArea. Area is 48 Main function. The final area is 48 The method would have this definition: public static void smartPrintln(String string); I don't know how to implement this functionality. Any ideas how to solve this? And, could the use of a logger offer this functionality?

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• Can Visual Studio (should it be able to) compute a diff between any two changesets associated with a

  - by Hamish Grubijan

  Here is my use case: I start on a project XYZ, for which I create a work item, and I make frequent check-ins, easily 10-20 in total. ALL of the code changes will be code-read and code-reviewed. The change sets are not consecutive - other people check-in in-between my changes, although they are very unlikely to touch the exact same files. So ... at the en of the project I am interested in a "total diff" - as if there was a single check-in by me to complete the entire project. In theory this is computable. From the list of change sets associated with the work item, you get the list of all files that were affected. Then, the algorithm can aggregate individual diffs over each file and combine them into one. It is possible that a pure total diff is uncomputable due to the fact that someone else renamed files, or changed stuff around very closely, or in the same functions as me. I that case ... I suppose a total diff can include those changes by non-me as well, and warn me about the fact. I would find this very useful, but I do not know how to do t in practice. Can Visual Studio 2008/2010 (and/or TFS server) do it? Are there other source control systems capable of doing this? Thanks.

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

  - by BrianH

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

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• Is there any good reason for private methods existence in C# (and OOP in general)?

  - by Piotr Lopusiewicz

  I don't mean to troll but I really don't get it. Why would language designers allow private methods instead of some naming convention (see __ in Python) ? I searched for the answer and usual arguments are: a) To make the implementation cleaner/avoid long vertical list of methods in IDE autocompletion b) To announce to the world which methods are public interface and which may change and are just for implementation purpose c) Readability Ok so now, all of those could be achieved by naming all private methods with __ prefix or by "private" keyword which doesn't have any implications other than be information for IDE (don't put those in autocompletion) and other programers (don't use it unless you really must). Hell, one could even require unsafe-like keyword to access private methods to really discourage this. I am asking this because I work with some c# code and I keep changing private methods to public for test purposes as many in-between private methods (like string generators for xml serialization) are very useful for debugging purposes (like writing some part of string to log file etc.). So my question is: Is there anything which is achieved by access restriction but couldn't be achieved by naming conventions without restricting the access ?

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• Anything like Heroku for PHP or .NET?

  - by Wayne M

  In my area PHP is very widespread, so is .NET. Ruby not so much; most places have never heard of it. For some personal things I am "forced" to choose Rails because I want to take advantage of Heroku - the ability to deploy and scale on the cloud very easily is the main reason. Also, they offer a small FREE plan that I can use for demo sites or, in this case, for my business' static page; as a totally bootstrapped startup I have maybe $50 or so in initial capital and cannot afford to pay monthly fees while I'm getting started. Are there any similar offerings for other languages? Specifically, I really like the small, 5MB site for free that Heroku offers - is there anything like that for PHP and/or .NET? I'm not even that concerned about the "cloud" part, but that would be a nice bonus. If there is, I might be able to kill two birds with one stone and pick up a useful skill as I'm doing my own thing instead of using something that nobody else knows or cares about. I should add I'm specifically interested in something that offers a free plan. As I said, Heroku has a 5mb plan that you can have as many as you want for free; I have yet to find anything similar for any other platform, and to be honest I'm not too thrilled about using Ruby on Rails for everything simply to take advantage of this.

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• Sending a message to nil?

  - by Ryan Delucchi

  As a Java developer who is reading Apple's Objective-C 2.0 documentation: I wonder as to what sending a message to nil means - let alone how it is actually useful. Taking an excerpt from the documentation: There are several patterns in Cocoa that take advantage of this fact. The value returned from a message to nil may also be valid: If the method returns an object, any pointer type, any integer scalar of size less than or equal to sizeof(void*), a float, a double, a long double, or a long long, then a message sent to nil returns 0. If the method returns a struct, as defined by the Mac OS X ABI Function Call Guide to be returned in registers, then a message sent to nil returns 0.0 for every field in the data structure. Other struct data types will not be filled with zeros. If the method returns anything other than the aforementioned value types the return value of a message sent to nil is undefined. Has Java rendered my brain incapable of grokking the explanation above? Or is there something that I am missing that would make this as clear as glass? Note: Yes, I do get the idea of messages/receivers in Objective-C, I am simply confused about a receiver that happens to be nil.

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• Looking for PyQt4 embeddable terminal widget

  - by redShadow

  I wrote an application that, among other things, launches some "backend" processes to do some stuff. These subprocesses are very likely to fail or have unexpected behavior since they have to operate in quite hard conditions, so I prefer to give full control over them to the operator. NOTE: I am running these processes using a subprocess module based class instead of QProcess to have some more control functionality over the running process. At the moment, I'm using a QPlainTextEdit widget to which I append standard output/error from the subprocess, plus some buttons to quickly send some common signals (INT, STOP, CONT, KILL, ..), but: In some cases it would be useful to send some input too. Although it could be done with a text input box, I would prefer using something more "professional" Of course, there is no direct way to interpret special control characters, such as color codes, cursor movement, etc.. I had to implement an auto-scroll management of the console, but it is not guaranteed 100% to work nicely (sometimes the scroll locking doesn't work as expected, etc.) So: does anyone know something I could use to accomplish these needs? I found qtermwidget but it seems more oriented on handling a shell process (and the Python bindings seems to let you run /bin/bash only) by itself than communicating with an already existing process I/O.

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• Looking for an email/report templating engine with database backend - for end-users ...

  - by RizwanK

  We have a number of customers that we have to send monthly invoices too. Right now, I'm managing a codebase that does SQL queries against our customer database and billing database and places that data into emails - and sends it. I grow weary of maintaining this every time we want to include a new promotion or change our customer service phone numbers. So, I'm looking for a replacement to move more of this into the hands of those requesting the changes. In my ideal world, I need : A WYSIWYG (man, does anyone even say that anymore?) email editor that generates templates based upon the output from a Database Query. The ability to drag and drop various fields from the database query into the email template. Display of sample email results with the database query. Web application, preferably not requiring IIS. Involve as little code as possible for the end-user, but allow basic functionality (i.e. arrays/for loops) Either comes with it's own email delivery engine, or writes output in a way that I can easily write a Python script to deliver the email. Support for generic Database Connectors. (I need MSSQL and MySQL) F/OSS So ... can anyone suggest a project like this, or some tools that'd be useful for rolling my own? (My current alternative idea is using something like ERB or Tenjin, having them write the code, but not having live-preview for the editor would suck...)

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• Testing Hibernate DAO, without building the universe around it.

  - by Varun Mehta

  We have an application built using spring/Hibernate/MySQL, now we want to test the DAO layer, but here are a few shortcomings we face. Consider the use case of multiple objects connected to one another, eg: Book has Pages. The Page object cannot exist without the Book as book_id is mandatory FK in Page. For testing a Page I have to create a Book. This simple usecase is easy to manage, but if you start building a Library, till you don't create the whole universe surrounding the Book and Page, you cannot test it! So to test Page; Create Library Create Section Create Genre Create Author Create Book Create Page Now test Page. Is there an easy way to by pass this "universe creation" and just test he page object in isolation. I also want to be able to test HQLs related to Page. eg: SELECT new com.test.BookPage (book.id, page.name) FROM Book book, Page page. JUnit is supposed to run in isolation, so I have to write the whole test case to create the Page. Any tips will be useful.

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• What is the best practice when using UIStoryboards?

  - by Scott Sherwood

  Having used storyboards for a while now I have found them extremely useful however, they do have some limitations or at least unnatural ways of doing things. While it seems like a single storyboard should be used for your app, when you get to even a moderately sized application this presents several problems. Working within teams is made more difficult as conflicts in Storyboards can be problematic to resolve (any tips with this would also be welcome) The storyboard itself can become quite cluttered and unmanageable. So my question is what are the best practices of use? I have considered using a hybrid approach having logical tasks being split into separate storyboards, however this results in the UX flow being split between the code and the storyboard. To me this feels like the best way to create reusable actions such as login actions etc. Also should I still consider a place for Xibs? This article has quite a good overview of many of the issues and it proposes that for scenes that only have one screen, xibs should be used in this case. Again this feels unusual to me with Apples support for instantiating unconnected scenes from a storyboard it would suggest that xibs won't have a place in the future but I could be wrong.

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• jQuery date calculator - show/hide IMG

  - by utopicam

  I have a problem with the following code. I tried changing many things (symbols, classes, imgs in the code) but this is killing me and I have no idea how to fix it. Sorry it's so specific, when solved I'll change the title to something more useful. I have two images. My jquery has to calculate the day and show one image or the other depending on that (using a class with display:none). My month has 24 days (it's a xmas thing). This is what I have so far: <script type="text/javascript"> $(document).ready(function(){ var currentTime = new Date() var day = currentTime.getDate(); if (day > 24){ day = 1; } $(".calDate").each(function(){ var curDate = $(this).attr("date"); if (curDate < day){ $(this).addClass("xMasPast"); } else if(curDate==day){ $(this).addClass("xMasActive"); } else { $(this).addClass("xMasInactive"); } }); $(".calDate2").each(function(){ var curDate = $(this).attr("date"); if (curDate > day){ $(this).addClass("xMasInactive"); } else if(curDate==day){ $(this).addClass("xMasActive"); } else { $(this).addClass("xMasActive"); } }); }); </script> But it's showing all the images. What am I missing? (any ideas on making the code simpler are more than welcomed). Thanks for your help! Update: simplified HTML <div><img src="day21.png" which="21"/></a></div> <img id="bola21" class="calDate2" src="day21.png"/>

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• Is there a way in VS2008 (c#) to see all the possible exception types that can originate from a meth

  - by Matt

  Is there a way in VS2008 IDE for c# to see all the possible exception types that can possibly originate from a method call or even for an entire try-catch block? I know that intellisense or the object browser tells me this method can throw these types of exceptions but is there another way than using the object browser everytime? Something more accessible when coding? Furthermore, I don't think intellisense or the object browser do anything more than read the XML code comments. Shouldn't it be possible to scan a class's source and find all the exception types that can be thrown. (Forget path-ing based on method input, just scan the code for exception types) Am I wrong? Extending this idea, you should be able to hover over the 'try' or 'catch' keywords and present a tooltip with all the types of exceptions that can be thrown. My question boils down to, does a VS2008 add on like this exist? Does VS2010 do this perhaps? If not, could you implement it the way I've described, by scanning the class code for thrown exception types and would people find it useful. Exceptions bubble up so you have to scan every bit of code every method call, which I guess could be impractical, though I suppose you could build an index the first time and increase your speed that way. (It might be a cool little project....)

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• The cross-thread usage of "HttpContext.Current" property and related things

  - by smwikipedia

  I read from < Essential ASP.NET with Examples in C# the following statement: Another useful property to know about is the static Current property of the HttpContext class. This property always points to the current instance of the HttpContext class for the request being serviced. This can be convenient if you are writing helper classes that will be used from pages or other pipeline classes and may need to access the context for whatever reason. By using the static Current property to retrieve the context, you can avoid passing a reference to it to helper classes. For example, the class shown in Listing 4-1 uses the Current property of the context to access the QueryString and print something to the current response buffer. Note that for this static property to be correctly initialized, the caller must be executing on the original request thread, so if you have spawned additional threads to perform work during a request, you must take care to provide access to the context class yourself. I am wondering about the root cause of the bold part, and one thing leads to another, here is my thoughts: We know that a process can have multiple threads. Each of these threads have their own stacks, respectively. These threads also have access to a shared memory area, the heap. The stack then, as I understand it, is kind of where all the context for that thread is stored. For a thread to access something in the heap it must use a pointer, and the pointer is stored on its stack. So when we make some cross-thread calls, we must make sure that all the necessary context info is passed from the caller thread's stack to the callee thread's stack. But I am not quite sure if I made any mistake. Any comments will be deeply appreciated. Thanks. ADD Here the stack is limited to user stack.

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• Java: GatheringByteChannel advantages?

  - by Jason S

  I'm wondering when the GatheringByteChannel's write methods (taking in an array of ByteBuffers) have advantages over the "regular" WritableByteChannel write methods. I tried a test where I could use the regular vs. the gathering write method on a FileChannel, with approx 400KB/sec total in ByteBuffers of between 23-27 bytes in length in both cases. Gathering writes used an array of 64. The regular method used up approx 12% of my CPU, and the gathering method used up approx 16% of my CPU (worse than the regular method!) This tells me it's NOT useful to use gathering writes on a FileChannel around this range of operating parameters. Why would this be the case, and when would you ever use GatheringByteChannel? (on network I/O?) Relevant differences here: public void log(Queue<Packet> packets) throws IOException { if (this.gather) { int Nbuf = 64; ByteBuffer[] bbufs = new ByteBuffer[Nbuf]; int i = 0; Packet p; while ((p = packets.poll()) != null) { bbufs[i++] = p.getBuffer(); if (i == Nbuf) { this.fc.write(bbufs); i = 0; } } if (i > 0) { this.fc.write(bbufs, 0, i); } } else { Packet p; while ((p = packets.poll()) != null) { this.fc.write(p.getBuffer()); } } }

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• geb StaleElementReferenceException

  - by Brian Mortenson

  I have just started using geb with webdriver for automating testing. As I understand it, when I define content on a page, the page element should be looked up each time I invoke a content definition. //In the content block of SomeModule, which is part of a moduleList on the page: itemLoaded { waitFor{ !loading.displayed } } loading { $('.loading') } //in the page definition moduleItems {index -> moduleList SomeModule, $("#module-list > .item"), index} //in a test on this page def item = moduleItems(someIndex) assert item.itemLoaded So in this code, I think $('.loading') should be called repeatedly, to find the element on the page by its selector, within the context of the module's base element. Yet I sometimes get a StaleElementReference exception at this point. As far as I can tell, the element does not get removed from the page, but even if it does, that should not produce this exception unless $ is doing some caching behind the scenes, but if that were the case it would cause all sorts of other problems. Can someone help me understand what's happening here? Why is it possible to get a StaleElementReferenceException while looking up an element? A pointer to relevant documentation or geb source code would be useful as well.

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• C++: getting the address of the start of an std::vector ?

  - by shoosh

  Sometimes it is useful to use the starting address of an std::vector and temporarily treat that address as the address of a regularly allocated buffer. For instance replace this: char* buf = new char[size]; fillTheBuffer(buf, size); useTheBuffer(buf, size); delete[] buf; With This: vector<char> buf(size); fillTheBuffer(&buf[0], size); useTheBuffer(&buf[0], size); The advantage of this is of course that the buffer is deallocated automatically and I don't have to worry about the delete[]. The problem I'm having with this is when size == 0. In that case the first version works ok. An empty buffer is "allocated" and the subsequent functions do nothing size they get size == 0. The second version however fails if size == 0 since calling buf[0] may rightly contain an assertion that 0 < size. So is there an alternative to the idiom &buf[0] that returns the address of the start of the vector even if the vector is empty? I've also considered using buf.begin() but according to the standard it isn't even guaranteed to return a pointer.

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