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  • Parsing C# code to evaluate expressions (basically, implementing Intellisense)

    - by halivingston
    I'm trying to evaluate C# code as it gets typed, think of it as if I'm trying to write an IDE. So a person types code, I want to find out what code did he just write: String x = ""; I want to now register that x is a type of String. And now everytime the user types x again, and I want to show him all the things he can do with x, basically like Visual Studio Intellisense. Will I need some lexers or parsers for this? Will that make it easier? I've heard VS 2010 has some features around this that Microsoft has released. Any ideas?

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  • How to check if TypeIdenitifier(T) is an Object?

    - by John
    I'm creating a generic list class that has a member of type Array(Array of ). The problem is the class descruction,because the class is supposed to be used for types from byte to types inheriting TObject. Specifically: destructor Destroy; var elem:T; begin /*if(T is Tobject) then //Check if T inherits TObject {Compiler error!} for elem in FData do TObject(elem).Free;*/ // do not know how to do it SetLength(FItems,0); //FItems : Array of T inherited Destroy; end; How do I check if T is TObject so I can free every member if the typeidenitifier is a class,for example?

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  • iOS sdk question: how do I cast a UIView to a UIImage View (alternativly how do I get a UIImageView from a GestureRecognzer?)

    - by user439299
    Desired end result: user taps a UIImageView and the image changes to another image (a subsequent tap returns the image to the original state) Problem: I add a (unique) selector to a bunch of UIImageViews (in an array) and point the action at the same function - let's call this function imageTapped: for now. Here is my code so far: -(void)imageTapped:(UITapGestureRecognizer *)tapGesture { UIImageView *view = tapGesture.view; // rest of code... } This code actually works fine but gets a warning when I run it: "Incompatible objective c types initilizing 'struct UIView *', expected 'struct UIImageView *' Any way to get rid of this? Not sure how casting works in objective c... primitive types seem to work fine such as (int)someFloat works fine but (UIImageView)someUiView doesn't work. Like I said, code works alright when I run it but would like to get ride of the compiler warning. Any help would be awesome.... I am very new to objective c (or any non java language for that matter) so be gentle. Thanks in advance.

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  • How to normalize SVG path data (cross browser)?

    - by Timo
    I have tried to find a way to implement cross browser path normalizer. There IS a native way which is described here and functional example is here, but it works only in newest Opera (but not in IE, FF, Safari, Chrome). The native way uses pathElm.normalizedPathSegList and it converts all relative coordinates to absolute ones and represents all path segment types as a following subset of types: M,L,C,z. I have found only one javascript code and jsfiddled functional example of it, but it works only in IE and FF. Chrome gives "Uncaught Error: INDEX_SIZE_ERR: DOM Exception 1". How this could be fixed to work also in Opera, Safari and Chrome or is there any other way for normalizing SVG paths?

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  • What's the best way to store custom objects in relational database?

    - by user342610
    I have my objects with their properties. Objects could change their structure: properties may be added/removed/changed. Objects could be absolutely dropped. So object's metadata (description, classes, call them like you want :) )could be changed. The database should store objects schemas and instances of these objects. What's the best way to organise a relational database structure to store data mentioned above? Currently I see only two ways: 1) Store objects schemas in a few tables: schema general data,schema properties, possible properties types. Store instances in their tables: instance general data, a few tables - per each type from possible properties types table to store instance properties data. And so on. 2) store objects schemas like in p1 but store instances like XML files in one table: one table for general instance info and one table with instance XML. please, don't ask why/for what I need this. Just need to store custom objects and DB should work fast :)

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  • What should layers in dotnet application ?

    - by haansi
    I am using layered architecture in dotnet (mostly I work on web projects). I am confuse what layers should I use ? I have small idea that there should be the following layers. user interface customer types (custom entities) business logic layer data access layer My purpose is sure quality of work and maximum re-usability of code. some one suggested to add common types layer in it. Please guide me what should be layers ? and in each layer what part should go ?

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  • Another problem with decltype

    - by There is nothing we can do
    template<class IntT, IntT low = IntT(), IntT high = IntT()> struct X { static_assert(std::is_same<decltype(low),decltype(high)>::value,"Different types not allowed");//this should give error if types are different decltype(low) a; decltype(high) b; X():a(decltype(a)()),b(decltype(b)())//WHY THIS DOES NOT COMPILE? { cout << typeid(a).name() << '\n'; cout << typeid(b).name() << '\n'; } }; int _tmain(int argc, _TCHAR* argv[]) { X<char,1,'a'> x;//this according to static_assert shouldn't compile but it does return 0; } Using VS2010. Please see 3 comments in code above.

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  • why this httaccess code results into a redirect loop?

    - by user3606997
    Here I am stuck with my htaccess code. I have been trying to figure it out for the last 11 hours why am I getting a redirect loop for the below code. Options -Indexes +FollowSymLinks RewriteEngine on #Check for no www or www RewriteCond %{HTTP_HOST} ^dummysite.com$ [or] RewriteCond %{HTTP_HOST} ^www.dummysite.com$ [NC] RewriteRule . - [E=FIRSTPART:true] # IE 6 RewriteCond %{HTTP_USER_AGENT} !MSIE\s6 RewriteCond %{ENV:FIRSTPART} true RewriteRule ^(.*)$ https://www.dummysite.com/$1 [R=302,L] Why the above code results into a redirect loop? EDIT: What I actually want is that if the user is from IE6 then he should be redirected to http version with www as prefix no matter if he types www or not in the url. And on the other hand if the user is from any other browsers then he should be redirected to a https version with www as prefix no matter if he types www in the url or not.

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  • Can't INSERT INTO SELECT into a table with identity column

    - by Eran Goldin
    In SQL server, I'm using a table variable and when done manipulating it I want to insert its values into a real table that has an identity column which is also the PK. The table variable I'm making has two columns; the physical table has four, the first of which is the identity column, an integer IK. The data types for the columns I want to insert are the same as the target columns' data types. INSERT INTO [dbo].[Message] ([Name], [Type]) SELECT DISTINCT [Code],[MessageType] FROM @TempTableVariable END This fails with Cannot insert duplicate key row in object 'dbo.Message' with unique index 'IX_Message_Id'. The duplicate key value is (ApplicationSelection). But when trying to insert just Values (...) it works ok. How do I get it right?

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  • is this possible: c# collection of Type with constrains, or collection of generic type?

    - by Jon
    I'm trying to store types in a collection, so that i can later instantiate objects of the types in the collection. But I'm not sure how to do this the best way. What i have so far: List<Type> list = new List<Type>(); list.Add(typeof(MyClass)); var obj = (MyClass)Activator.CreateInstance(list[0]); I would like to have some constrains on the Type, or better yet, just a generic type in the collection instead of an instantiated Type object. Is this possible?

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  • Theme the node-create and node-edit template

    - by Toxid
    I'm using drupal 6. I've managed to make a .tpl file for one content type, that is for images in my image gallery. I did that by adding this code in template.php: function artbasic_theme($existing, $type, $theme, $path) { return array( 'galleryimage_node_form' => array( 'arguments' => array('form' => NULL), 'template' => 'galleryimage_node_form' ) ); } And then I created galleryimage_node_form.tpl.php, and was good to go. Now it happens so that I want to have other template files for the forms of other content types, for example link_contrib_node_form.tpl.php. I've tried a couple of ways to change this function to include more content types, but I can't figure it out. Can anyone help?

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  • How to cast/convert form Object in an byte[] array

    - by maddash
    I've got a maybe simple problem, but at the moment I am not able to solve it. I have an Object and I need to convert it into a byte[]. public byte[] GetMapiPropertyBytes(string propIdentifier) { return (byte[])this.GetMapiProperty(propIdentifier); //InvalidCastException } Exception: Unable to cast COM object of type 'System.__ComObject' to class type 'System.Byte[]'. Instances of types that represent COM components cannot be cast to types that do not represent COM components; however they can be cast to interfaces as long as the underlying COM component supports QueryInterface calls for the IID of the interface. So far so good - I've tried to serialize it, but I got another exception - NOT serializable Could someone help me? I need a method to convert it...

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  • Force type of C++ template

    - by gregseth
    Hi, I've a basic template class, but I'd like to restrain the type of the specialisation to a set of classes or types. e.g.: template <typename T> class MyClass { .../... private: T* _p; }; MyClass<std::string> a; // OK MYCLass<short> b; // OK MyClass<double> c; // not OK Those are just examples, the allowed types may vary. Is that even possible? If it is, how to do so? Thanks.

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  • class T in c++ (your definition)

    - by JohnWong
    The one advantage of using class T in c++ is to reduce the time to redefine data types in a function, if those data types are defined in other function, for example, in int main. template <class T> void showabs(T number) { if (number < 0 ) number = -number; cout << number << endl; return 0; } int main() { int num1 = -4; float num2 = -4.23f; showabs(num1); showabs(num2); return 0; } So in this case, without class T, for each data type, we have to add its corresponding data-type condition, that is, another set of if statement for int, and another one for float. Am I correct?

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  • JavaScript: filter() for Objects

    - by AgileMeansDoAsLittleAsPossible
    ECMAScript 5 has the filter() prototype for Array types, but not Object types, if I understand correctly. How would I implement a filter() for Objects in JavaScript? Let's say I have this object: var foo = { bar: "Yes" }; And I want to write a filter() that works on Objects: Object.prototype.filter = function(predicate) { var result = {}; for (key in this) { if (this.hasOwnProperty(key) && !predicate(this[key])) { result[key] = this[key]; } } return result; }; This works when I use it in jsfiddle (http://jsfiddle.net/MPUnL/4/), but when I add it to my site that uses jQuery 1.5 and jQuery UI 1.8.9, I get JavaScript errors in FireBug.

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  • jquery problem where the returned data from an XML file seems inaccessible

    - by squeaker
    Hi all, I'm using an xml file to generate some links which i would like to then be able to click on to populate an input box: $(xmlResponse).find('types').each(function(){ var id = $(this).attr('id'); var type = $(this).find('type').text(); $('<span title=\"'+type+'\" class=\"type\">'+type+'</span>').appendTo('#types'); }); $('span.type').click(function() { var title = $(this).attr('title'); $("input[name='type']").val(title); }); But for some reason clicking on the liks does not populate the input box. It does work if the span is hard coded into the page for example: <span title="text to populate" class="type">test</span> I'm guessing that the XML is not getting loaded into the DOM in the right way (or something like that) Any Ideas?

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  • function declaration

    - by robUK
    Hello, gcc 4.1.2 c89 I am reviewing some code and I have come across the following function. I have never seen a function declared like this before. There are no data types for the paraemeters. My best guess is that the function is using a list of data types separated by semi-colons. The return type seems to be returning a function with those parameters. However, the read function is not defined anywhere. What is the advantage and purpose of declaring a function like this? Many thanks for any advice, int my_read(fd, ptr, cnt) int fd; char *ptr; unsigned cnt; { printf("Read\n"); return(read(fd, ptr, cnt)); }

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  • Load a dll library on Java

    - by crimson_king
    I need to load a library written in C on java. I have only dlls and header files. Since I didn't understand how to translate pointers or other derivated types from JNI documentation I tried to use an automating tool for this, gluegen and SWIG, but I couldn't manage on how to use them. I tried to create an interface file for SWIG but it only gives errors. Is there an example on how to load a dll to a java program using ANY tool that works and can generate translated C function and types from .h files ?

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  • In a JDBC ResultSet, what should happen when getLong() or getShort() is called on an int result colu

    - by Uri
    Say that I have a JDBC ResultSet, and I call the getLong() or getshort() method. For which of the following SQL types {SMALLINT, INT, BIGINT} should I get long, and for which types should I get an error? In other words, if I have an INT and I want a SMALLINT (A short), would I get it, or would I get an error? Similarly, if I have an INT and want a BIGINT (a long), would I get it, or would I get an error? The Javadocs (listed below) say nothing. public long getLong(int columnIndex) throws SQLException Retrieves the value of the designated column in the current row of this ResultSet object as a long in the Java programming language. Parameters: columnIndex - the first column is 1, the second is 2, ... Returns: the column value; if the value is SQL NULL, the value returned is 0 Throws: SQLException - if a database access error occurs

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  • Unicorn installation error on Debian 5

    - by Luc
    I am running ruby1.9 on Debian 5, and did not manage to install 'unicorn' with rubygems. I got this error and do not really know how to solve it. Do you have any idea of the possible root cause ? > gem install unicorn Building native extensions. This could take a while... ERROR: Error installing unicorn: ERROR: Failed to build gem native extension. /usr/bin/ruby1.9 extconf.rb checking for CLOCK_MONOTONIC in time.h... yes checking for clockid_t in time.h... yes checking for clock_gettime() in -lrt... yes checking for t_open() in -lnsl... no checking for socket() in -lsocket... no checking for poll() in poll.h... yes checking for getaddrinfo() in sys/types.h,sys/socket.h,netdb.h... yes checking for getnameinfo() in sys/types.h,sys/socket.h,netdb.h... yes checking for struct sockaddr_storage in sys/types.h,sys/socket.h... yes checking for accept4() in sys/socket.h... no checking for sys/select.h... yes checking for ruby/io.h... yes checking for rb_io_t.fd in ruby.h,ruby/io.h... yes checking for rb_io_t.mode in ruby.h,ruby/io.h... yes checking for rb_io_t.pathv in ruby.h,ruby/io.h... no checking for struct RFile in ruby.h,ruby/io.h... yes checking size of struct RFile in ruby.h,ruby/io.h... 24 checking for struct RObject... no checking size of int... 4 checking for rb_io_ascii8bit_binmode()... no checking for rb_thread_blocking_region()... yes checking for rb_thread_io_blocking_region()... no checking for rb_str_set_len()... yes checking for rb_time_interval()... yes checking for rb_wait_for_single_fd()... no creating Makefile make cc -I. -I/usr/include/ruby-1.9.0/x86_64-linux -I/usr/include/ruby-1.9.0 -I. -DHAVE_TYPE_CLOCKID_T -DHAVE_POLL -DHAVE_GETADDRINFO -DHAVE_GETNAMEINFO -DHAVE_TYPE_STRUCT_SOCKADDR_STORAGE -DHAVE_SYS_SELECT_H -DHAVE_RUBY_IO_H -DHAVE_RB_IO_T_FD -DHAVE_ST_FD -DHAVE_RB_IO_T_MODE -DHAVE_ST_MODE -DHAVE_TYPE_STRUCT_RFILE -DSIZEOF_STRUCT_RFILE=24 -DSIZEOF_INT=4 -DHAVE_RB_THREAD_BLOCKING_REGION -DHAVE_RB_STR_SET_LEN -DHAVE_RB_TIME_INTERVAL -D_GNU_SOURCE -DPOSIX_C_SOURCE=1-D_POSIX_C_SOURCE=200112L -fPIC -fno-strict-aliasing -g -g -O2 -O2 -g -Wall -Wno-parentheses -fPIC -o kgio_ext.o -c kgio_ext.c cc -I. -I/usr/include/ruby-1.9.0/x86_64-linux -I/usr/include/ruby-1.9.0 -I. -DHAVE_TYPE_CLOCKID_T -DHAVE_POLL -DHAVE_GETADDRINFO -DHAVE_GETNAMEINFO -DHAVE_TYPE_STRUCT_SOCKADDR_STORAGE -DHAVE_SYS_SELECT_H -DHAVE_RUBY_IO_H -DHAVE_RB_IO_T_FD -DHAVE_ST_FD -DHAVE_RB_IO_T_MODE -DHAVE_ST_MODE -DHAVE_TYPE_STRUCT_RFILE -DSIZEOF_STRUCT_RFILE=24 -DSIZEOF_INT=4 -DHAVE_RB_THREAD_BLOCKING_REGION -DHAVE_RB_STR_SET_LEN -DHAVE_RB_TIME_INTERVAL -D_GNU_SOURCE -DPOSIX_C_SOURCE=1-D_POSIX_C_SOURCE=200112L -fPIC -fno-strict-aliasing -g -g -O2 -O2 -g -Wall -Wno-parentheses -fPIC -o autopush.o -c autopush.c cc -I. -I/usr/include/ruby-1.9.0/x86_64-linux -I/usr/include/ruby-1.9.0 -I. -DHAVE_TYPE_CLOCKID_T -DHAVE_POLL -DHAVE_GETADDRINFO -DHAVE_GETNAMEINFO -DHAVE_TYPE_STRUCT_SOCKADDR_STORAGE -DHAVE_SYS_SELECT_H -DHAVE_RUBY_IO_H -DHAVE_RB_IO_T_FD -DHAVE_ST_FD -DHAVE_RB_IO_T_MODE -DHAVE_ST_MODE -DHAVE_TYPE_STRUCT_RFILE -DSIZEOF_STRUCT_RFILE=24 -DSIZEOF_INT=4 -DHAVE_RB_THREAD_BLOCKING_REGION -DHAVE_RB_STR_SET_LEN -DHAVE_RB_TIME_INTERVAL -D_GNU_SOURCE -DPOSIX_C_SOURCE=1-D_POSIX_C_SOURCE=200112L -fPIC -fno-strict-aliasing -g -g -O2 -O2 -g -Wall -Wno-parentheses -fPIC -o wait.o -c wait.c cc -I. -I/usr/include/ruby-1.9.0/x86_64-linux -I/usr/include/ruby-1.9.0 -I. -DHAVE_TYPE_CLOCKID_T -DHAVE_POLL -DHAVE_GETADDRINFO -DHAVE_GETNAMEINFO -DHAVE_TYPE_STRUCT_SOCKADDR_STORAGE -DHAVE_SYS_SELECT_H -DHAVE_RUBY_IO_H -DHAVE_RB_IO_T_FD -DHAVE_ST_FD -DHAVE_RB_IO_T_MODE -DHAVE_ST_MODE -DHAVE_TYPE_STRUCT_RFILE -DSIZEOF_STRUCT_RFILE=24 -DSIZEOF_INT=4 -DHAVE_RB_THREAD_BLOCKING_REGION -DHAVE_RB_STR_SET_LEN -DHAVE_RB_TIME_INTERVAL -D_GNU_SOURCE -DPOSIX_C_SOURCE=1-D_POSIX_C_SOURCE=200112L -fPIC -fno-strict-aliasing -g -g -O2 -O2 -g -Wall -Wno-parentheses -fPIC -o connect.o -c connect.c cc -I. -I/usr/include/ruby-1.9.0/x86_64-linux -I/usr/include/ruby-1.9.0 -I. -DHAVE_TYPE_CLOCKID_T -DHAVE_POLL -DHAVE_GETADDRINFO -DHAVE_GETNAMEINFO -DHAVE_TYPE_STRUCT_SOCKADDR_STORAGE -DHAVE_SYS_SELECT_H -DHAVE_RUBY_IO_H -DHAVE_RB_IO_T_FD -DHAVE_ST_FD -DHAVE_RB_IO_T_MODE -DHAVE_ST_MODE -DHAVE_TYPE_STRUCT_RFILE -DSIZEOF_STRUCT_RFILE=24 -DSIZEOF_INT=4 -DHAVE_RB_THREAD_BLOCKING_REGION -DHAVE_RB_STR_SET_LEN -DHAVE_RB_TIME_INTERVAL -D_GNU_SOURCE -DPOSIX_C_SOURCE=1-D_POSIX_C_SOURCE=200112L -fPIC -fno-strict-aliasing -g -g -O2 -O2 -g -Wall -Wno-parentheses -fPIC -o poll.o -c poll.c poll.c:11:18: error: st.h: No such file or directory poll.c: In function 'do_poll': poll.c:148: error: 'RUBY_UBF_IO' undeclared (first use in this function) poll.c:148: error: (Each undeclared identifier is reported only once poll.c:148: error: for each function it appears in.) make: *** [poll.o] Error 1 Gem files will remain installed in /usr/lib/ruby/gems/1.9.0/gems/kgio-2.5.0 for inspection. Results logged to /usr/lib/ruby/gems/1.9.0/gems/kgio-2.5.0/ext/kgio/gem_make.out

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  • Windows 7, file properties - Is "date accessed" ALWAYS 100% accurate?

    - by Robert
    Hello, Here's the situation: I went on vacation for a couple of weeks, but before I left, I took the harddrive out of my computer and hid it in a different location. Upon coming back on Monday and putting the harddrive back in my computer, I right-clicked on different files to see their properties. Interestingly enough, several files had been accessed during the time I was gone! I right-clicked different files in various locations on the harddrive, and all of these suspect files had been accessed within a certain time range (Sunday, ?January ?09, ?2011, approximately ??between 6:52:16 PM - 7:16:25 PM). Some of them had been accessed at the exact same time--down to the very second. This makes me think that someone must have done a search on my harddrive for certain types of files and then copied all those files to some other medium. The Windows 7 installation on this harddrive is password protected, but NOT encrypted, so they could have easily put the harddrive into an enclosure/toaster to access it from a different computer. Of course I did not right-click every single file on my computer, but did so in different folders. For instance, one of the folders I went through has different types of files: .mp3, ,prproj, .3gp, .mpg, .wmv, .xmp, .txt with file-sizes ranging from 2 KB to 29.7 MB (there is also a sub-folder in this folder which contains only .jpg files); however, of all these different types of files in this folder and its subfolder, all of them had been accessed (including the .jpg files from the sub-folder) EXCEPT the .mp3 files (if it makes any difference, the .mp3 files in this folder range in size from 187 KB to 4881 KB). Additionally, this sub-folder which contained only .jpg files (48 .jpg files to be exact) was not accessed during this time--only the .jpg files within it were accessed-- (between 6:57:03 PM - 6:57:08 PM). I thought that perhaps this was some kind of Windows glitch that was displaying the wrong access date, but then I looked at the "date created" and "date modified" for all of these files in question, and their created/modified dates and times were spot on correct. My first thought was that someone put the harddrive into an enclosure/toaster and viewed the files; but then I realized that this was impossible because several of the files had been accessed at the same exact time down to the second. So this made me think that the only other way the "date accessed" could have changed would have been if someone copied the files. Is there any chance at all whatsoever that this is some kind of Windows glitch or something, or is it a fact that someone was indeed accessing my files (and if someone was accessing my files, am I right about the files in question having been copied)? Is there any other possibility for what could have happened? Do I need to use any kinds of forensics tools to further investigate this matter (and if so, which tools), or is there any other way in which I can be certain of what took place in that timeframe the day before I got back? Or is what I see with Windows 7 good enough (i.e. accurate and truthful)? Thanks in advance, and please let me know if any other details are required on my part.

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  • ASP.NET MVC 3 Hosting :: New Features in ASP.NET MVC 3

    - by mbridge
    Razor View Engine The Razor view engine is a new view engine option for ASP.NET MVC that supports the Razor templating syntax. The Razor syntax is a streamlined approach to HTML templating designed with the goal of being a code driven minimalist templating approach that builds on existing C#, VB.NET and HTML knowledge. The result of this approach is that Razor views are very lean and do not contain unnecessary constructs that get in the way of you and your code. ASP.NET MVC 3 Preview 1 only supports C# Razor views which use the .cshtml file extension. VB.NET support will be enabled in later releases of ASP.NET MVC 3. For more information and examples, see Introducing “Razor” – a new view engine for ASP.NET on Scott Guthrie’s blog. Dynamic View and ViewModel Properties A new dynamic View property is available in views, which provides access to the ViewData object using a simpler syntax. For example, imagine two items are added to the ViewData dictionary in the Index controller action using code like the following: public ActionResult Index() {          ViewData["Title"] = "The Title";          ViewData["Message"] = "Hello World!"; } Those properties can be accessed in the Index view using code like this: <h2>View.Title</h2> <p>View.Message</p> There is also a new dynamic ViewModel property in the Controller class that lets you add items to the ViewData dictionary using a simpler syntax. Using the previous controller example, the two values added to the ViewData dictionary can be rewritten using the following code: public ActionResult Index() {     ViewModel.Title = "The Title";     ViewModel.Message = "Hello World!"; } “Add View” Dialog Box Supports Multiple View Engines The Add View dialog box in Visual Studio includes extensibility hooks that allow it to support multiple view engines, as shown in the following figure: Service Location and Dependency Injection Support ASP.NET MVC 3 introduces improved support for applying Dependency Injection (DI) via Inversion of Control (IoC) containers. ASP.NET MVC 3 Preview 1 provides the following hooks for locating services and injecting dependencies: - Creating controller factories. - Creating controllers and setting dependencies. - Setting dependencies on view pages for both the Web Form view engine and the Razor view engine (for types that derive from ViewPage, ViewUserControl, ViewMasterPage, WebViewPage). - Setting dependencies on action filters. Using a Dependency Injection container is not required in order for ASP.NET MVC 3 to function properly. Global Filters ASP.NET MVC 3 allows you to register filters that apply globally to all controller action methods. Adding a filter to the global filters collection ensures that the filter runs for all controller requests. To register an action filter globally, you can make the following call in the Application_Start method in the Global.asax file: GlobalFilters.Filters.Add(new MyActionFilter()); The source of global action filters is abstracted by the new IFilterProvider interface, which can be registered manually or by using Dependency Injection. This allows you to provide your own source of action filters and choose at run time whether to apply a filter to an action in a particular request. New JsonValueProviderFactory Class The new JsonValueProviderFactory class allows action methods to receive JSON-encoded data and model-bind it to an action-method parameter. This is useful in scenarios such as client templating. Client templates enable you to format and display a single data item or set of data items by using a fragment of HTML. ASP.NET MVC 3 lets you connect client templates easily with an action method that both returns and receives JSON data. Support for .NET Framework 4 Validation Attributes and IvalidatableObject The ValidationAttribute class was improved in the .NET Framework 4 to enable richer support for validation. When you write a custom validation attribute, you can use a new IsValid overload that provides a ValidationContext instance. This instance provides information about the current validation context, such as what object is being validated. This change enables scenarios such as validating the current value based on another property of the model. The following example shows a sample custom attribute that ensures that the value of PropertyOne is always larger than the value of PropertyTwo: public class CompareValidationAttribute : ValidationAttribute {     protected override ValidationResult IsValid(object value,              ValidationContext validationContext) {         var model = validationContext.ObjectInstance as SomeModel;         if (model.PropertyOne > model.PropertyTwo) {            return ValidationResult.Success;         }         return new ValidationResult("PropertyOne must be larger than PropertyTwo");     } } Validation in ASP.NET MVC also supports the .NET Framework 4 IValidatableObject interface. This interface allows your model to perform model-level validation, as in the following example: public class SomeModel : IValidatableObject {     public int PropertyOne { get; set; }     public int PropertyTwo { get; set; }     public IEnumerable<ValidationResult> Validate(ValidationContext validationContext) {         if (PropertyOne <= PropertyTwo) {            yield return new ValidationResult(                "PropertyOne must be larger than PropertyTwo");         }     } } New IClientValidatable Interface The new IClientValidatable interface allows the validation framework to discover at run time whether a validator has support for client validation. This interface is designed to be independent of the underlying implementation; therefore, where you implement the interface depends on the validation framework in use. For example, for the default data annotations-based validator, the interface would be applied on the validation attribute. Support for .NET Framework 4 Metadata Attributes ASP.NET MVC 3 now supports .NET Framework 4 metadata attributes such as DisplayAttribute. New IMetadataAware Interface The new IMetadataAware interface allows you to write attributes that simplify how you can contribute to the ModelMetadata creation process. Before this interface was available, you needed to write a custom metadata provider in order to have an attribute provide extra metadata. This interface is consumed by the AssociatedMetadataProvider class, so support for the IMetadataAware interface is automatically inherited by all classes that derive from that class (notably, the DataAnnotationsModelMetadataProvider class). New Action Result Types In ASP.NET MVC 3, the Controller class includes two new action result types and corresponding helper methods. HttpNotFoundResult Action The new HttpNotFoundResult action result is used to indicate that a resource requested by the current URL was not found. The status code is 404. This class derives from HttpStatusCodeResult. The Controller class includes an HttpNotFound method that returns an instance of this action result type, as shown in the following example: public ActionResult List(int id) {     if (id < 0) {                 return HttpNotFound();     }     return View(); } HttpStatusCodeResult Action The new HttpStatusCodeResult action result is used to set the response status code and description. Permanent Redirect The HttpRedirectResult class has a new Boolean Permanent property that is used to indicate whether a permanent redirect should occur. A permanent redirect uses the HTTP 301 status code. Corresponding to this change, the Controller class now has several methods for performing permanent redirects: - RedirectPermanent - RedirectToRoutePermanent - RedirectToActionPermanent These methods return an instance of HttpRedirectResult with the Permanent property set to true. Breaking Changes The order of execution for exception filters has changed for exception filters that have the same Order value. In ASP.NET MVC 2 and earlier, exception filters on the controller with the same Order as those on an action method were executed before the exception filters on the action method. This would typically be the case when exception filters were applied without a specified order Order value. In MVC 3, this order has been reversed in order to allow the most specific exception handler to execute first. As in earlier versions, if the Order property is explicitly specified, the filters are run in the specified order. Known Issues When you are editing a Razor view (CSHTML file), the Go To Controller menu item in Visual Studio will not be available, and there are no code snippets.

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