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  • Scope of the c++ using directive

    - by ThomasMcLeod
    From section 7.3.4.2 of the c++11 standard: A using-directive specifies that the names in the nominated namespace can be used in the scope in which the using-directive appears after the using-directive. During unqualified name lookup (3.4.1), the names appear as if they were declared in the nearest enclosing namespace which contains both the using-directive and the nominated namespace. [ Note: In this context, “contains” means “contains directly or indirectly”. —end note ] What do the second and third sentences mean exactly? Please give example. Here is the code I am attempting to understand: namespace A { int i = 7; } namespace B { using namespace A; int i = i + 11; } int main(int argc, char * argv[]) { std::cout << A::i << " " << B::i << std::endl; return 0; } It print "7 7" and not "7 18" as I would expect. Sorry for the typo, the program actually prints "7 11".

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  • What does using mean in c++?

    - by user198729
    Like : using ::size_t; using ::fpos_t; using ::FILE; In fact it's a question inspired by the comment under this question: http://stackoverflow.com/questions/2532412/when-is-h-not-needed-to-include-a-header-file

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  • Uploading to TwitVid using x_verify_credentials_authorization

    - by deepa
    Hi, I am developing an iPhone application that uploads videos to TwitVid using the library TwitVid-iPhone-OAuth3. I have selected this library since Twitter is shifting to OAuth mechanism of authentication. 1) Does this new library allows to upload without user-name and password parameters? 2) I am using the following steps for uploading videos (assumed that new library allows to upload without user-name and password parameters). But, I am getting the error 'Incorrect Signature'. I am not able to identify the mistake that I am doing here. Could you please help me out to solve this problem. Authenticate the app using OAuth (MGTwitterEngine etc) which redirects the user to the web-page asking for log-in and app authentication. If the user authenticates the app, access token will obtained as final step. Upload the video to TwitVid using the following code snippet: OAuth *authorizer = [[OAuth alloc] initWithConsumerKey: @"my_consumer_key" andConsumerSecret: @"my_consumer_secret"]; authorizer.oauth_token = //The key-part of the access token obtained in step 2 authorizer.oauth_token_secret = //The secret-part of the access token obtained in step 2 authorizer.oauth_token_authorized = YES; //Since authenticated in steps 1 and 2 NSString *authHeader = [authorizer oAuthHeaderForMethod: @"POST" andUrl: @"https://api.twitter.com/1/account/verify_credentials.xml" andParams: nil]; twitVid = [[TwitVid alloc] init]; [mTwitVid setDelegate: self]; [mTwitVid authenticateWithXVerifyCredentialsAuthorization: authHeader xAuthServiceProvider: nil]; Thanks and Regards, Deepa

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  • Using Reflection.Emit to emit a "using (x) { ... }" block?

    - by Lasse V. Karlsen
    I'm trying to use Reflection.Emit in C# to emit a using (x) { ... } block. At the point I am in code, I need to take the current top of the stack, which is an object that implements IDisposable, store this away in a local variable, implement a using block on that variable, and then inside it add some more code (I can deal with that last part.) Here's a sample C# piece of code I tried to compile and look at in Reflector: public void Test() { TestDisposable disposable = new TestDisposable(); using (disposable) { throw new Exception("Test"); } } This looks like this in Reflector: .method public hidebysig instance void Test() cil managed { .maxstack 2 .locals init ( [0] class LVK.Reflection.Tests.UsingConstructTests/TestDisposable disposable, [1] class LVK.Reflection.Tests.UsingConstructTests/TestDisposable CS$3$0000, [2] bool CS$4$0001) L_0000: nop L_0001: newobj instance void LVK.Reflection.Tests.UsingConstructTests/TestDisposable::.ctor() L_0006: stloc.0 L_0007: ldloc.0 L_0008: stloc.1 L_0009: nop L_000a: ldstr "Test" L_000f: newobj instance void [mscorlib]System.Exception::.ctor(string) L_0014: throw L_0015: ldloc.1 L_0016: ldnull L_0017: ceq L_0019: stloc.2 L_001a: ldloc.2 L_001b: brtrue.s L_0024 L_001d: ldloc.1 L_001e: callvirt instance void [mscorlib]System.IDisposable::Dispose() L_0023: nop L_0024: endfinally .try L_0009 to L_0015 finally handler L_0015 to L_0025 } I have no idea how to deal with that ".try ..." part at the end there when using Reflection.Emit. Can someone point me in the right direction?

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  • Why is 'using' improving C# performances

    - by Wernight
    It seems that in most cases the C# compiler could call Dispose() automatically. Like most cases of the using pattern look like: public void SomeMethod() { ... using (var foo = new Foo()) { ... } // Foo isn't use after here (obviously). ... } Since foo isn't used (that's a very simple detection) and since its not provided as argument to another method (that's a supposition that applies to many use cases and can be extended), the compiler could automatically call Dispose() without the developper requiring to do it. This means that in most cases the using is pretty useless if the compiler does some smart job. IDisposable seem low level enough to me to be taken in account by a compiler. Now why isn't this done? Wouldn't that improve the performances (if the developpers are... dirty).

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  • Try a sample: Using the counter predicate for event sampling

    - by extended_events
    Extended Events offers a rich filtering mechanism, called predicates, that allows you to reduce the number of events you collect by specifying criteria that will be applied during event collection. (You can find more information about predicates in Using SQL Server 2008 Extended Events (by Jonathan Kehayias)) By evaluating predicates early in the event firing sequence we can reduce the performance impact of collecting events by stopping event collection when the criteria are not met. You can specify predicates on both event fields and on a special object called a predicate source. Predicate sources are similar to action in that they typically are related to some type of global information available from the server. You will find that many of the actions available in Extended Events have equivalent predicate sources, but actions and predicates sources are not the same thing. Applying predicates, whether on a field or predicate source, is very similar to what you are used to in T-SQL in terms of how they work; you pick some field/source and compare it to a value, for example, session_id = 52. There is one predicate source that merits special attention though, not just for its special use, but for how the order of predicate evaluation impacts the behavior you see. I’m referring to the counter predicate source. The counter predicate source gives you a way to sample a subset of events that otherwise meet the criteria of the predicate; for example you could collect every other event, or only every tenth event. Simple CountingThe counter predicate source works by creating an in memory counter that increments every time the predicate statement is evaluated. Here is a simple example with my favorite event, sql_statement_completed, that only collects the second statement that is run. (OK, that’s not much of a sample, but this is for demonstration purposes. Here is the session definition: CREATE EVENT SESSION counter_test ON SERVERADD EVENT sqlserver.sql_statement_completed    (ACTION (sqlserver.sql_text)    WHERE package0.counter = 2)ADD TARGET package0.ring_bufferWITH (MAX_DISPATCH_LATENCY = 1 SECONDS) You can find general information about the session DDL syntax in BOL and from Pedro’s post Introduction to Extended Events. The important part here is the WHERE statement that defines that I only what the event where package0.count = 2; in other words, only the second instance of the event. Notice that I need to provide the package name along with the predicate source. You don’t need to provide the package name if you’re using event fields, only for predicate sources. Let’s say I run the following test queries: -- Run three statements to test the sessionSELECT 'This is the first statement'GOSELECT 'This is the second statement'GOSELECT 'This is the third statement';GO Once you return the event data from the ring buffer and parse the XML (see my earlier post on reading event data) you should see something like this: event_name sql_text sql_statement_completed SELECT ‘This is the second statement’ You can see that only the second statement from the test was actually collected. (Feel free to try this yourself. Check out what happens if you remove the WHERE statement from your session. Go ahead, I’ll wait.) Percentage Sampling OK, so that wasn’t particularly interesting, but you can probably see that this could be interesting, for example, lets say I need a 25% sample of the statements executed on my server for some type of QA analysis, that might be more interesting than just the second statement. All comparisons of predicates are handled using an object called a predicate comparator; the simple comparisons such as equals, greater than, etc. are mapped to the common mathematical symbols you know and love (eg. = and >), but to do the less common comparisons you will need to use the predicate comparators directly. You would probably look to the MOD operation to do this type sampling; we would too, but we don’t call it MOD, we call it divides_by_uint64. This comparator evaluates whether one number is divisible by another with no remainder. The general syntax for using a predicate comparator is pred_comp(field, value), field is always first and value is always second. So lets take a look at how the session changes to answer our new question of 25% sampling: CREATE EVENT SESSION counter_test_25 ON SERVERADD EVENT sqlserver.sql_statement_completed    (ACTION (sqlserver.sql_text)    WHERE package0.divides_by_uint64(package0.counter,4))ADD TARGET package0.ring_bufferWITH (MAX_DISPATCH_LATENCY = 1 SECONDS)GO Here I’ve replaced the simple equivalency check with the divides_by_uint64 comparator to check if the counter is evenly divisible by 4, which gives us back every fourth record. I’ll leave it as an exercise for the reader to test this session. Why order matters I indicated at the start of this post that order matters when it comes to the counter predicate – it does. Like most other predicate systems, Extended Events evaluates the predicate statement from left to right; as soon as the predicate statement is proven false we abandon evaluation of the remainder of the statement. The counter predicate source is only incremented when it is evaluated so whether or not the counter is incremented will depend on where it is in the predicate statement and whether a previous criteria made the predicate false or not. Here is a generic example: Pred1: (WHERE statement_1 AND package0.counter = 2)Pred2: (WHERE package0.counter = 2 AND statement_1) Let’s say I cause a number of events as follows and examine what happens to the counter predicate source. Iteration Statement Pred1 Counter Pred2 Counter A Not statement_1 0 1 B statement_1 1 2 C Not statement_1 1 3 D statement_1 2 4 As you can see, in the case of Pred1, statement_1 is evaluated first, when it fails (A & C) predicate evaluation is stopped and the counter is not incremented. With Pred2 the counter is evaluated first, so it is incremented on every iteration of the event and the remaining parts of the predicate are then evaluated. In this example, Pred1 would return an event for D while Pred2 would return an event for B. But wait, there is an interesting side-effect here; consider Pred2 if I had run my statements in the following order: Not statement_1 Not statement_1 statement_1 statement_1 In this case I would never get an event back from the system because the point at which counter=2, the rest of the predicate evaluates as false so the event is not returned. If you’re using the counter target for sampling and you’re not getting the expected events, or any events, check the order of the predicate criteria. As a general rule I’d suggest that the counter criteria should be the last element of your predicate statement since that will assure that your sampling rate will apply to the set of event records defined by the rest of your predicate. Aside: I’m interested in hearing about uses for putting the counter predicate criteria earlier in the predicate statement. If you have one, post it in a comment to share with the class. - Mike Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Bind Variable and SQL error during statement preparation

    - by Abhishek Dwivedi
    Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;}  I was getting the following exception at run-time. JBO-27122: SQL error during statement preparation. Statement: SELECT AxEO.A_ID, AxEO.B_ID, AxEO.C_ID, ByEO.A_ID, ByEO.B_ID, ByEO.C_ID, Cz.A_ID, Cz.B_ID, Cz.C_ID FROM ABC_x AxEO, ABC_y ByEO, ABC_z CzEO WHERE AxEO.A_ID = ByEO.A_ID AND  CzEO.A_ID = :Bind_PId I copied and pasted the query on SQL worksheet, replaced :Bind_PId with a valid id, and executed the query. The query worked alright, implying the query was alright. I tried to connect to different DBs but the issue persisted, meaning it was not a DB issue either. Finally, the root cause was found to be in the concerned VO; one of the bind variables (say Bind_TId) was marked "Required". De-selecting the Required check-box resolved the issue. In retrospect, the issue looks to be rather straight-forward. However, the error message is not very helpful, if not misleading. Besides, it's counter-intuitive to think that a bind variable which is not being used in a query can cause error while statement preparation. The other bind variable - Bind_TId - was being used in other view criteria, not the view criteria involved in the given query. Still, it was required.

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  • Execute TSQL statement with ExecuteStoreQuery in entity framework 4.0

    - by Jalpesh P. Vadgama
    I was playing with entity framework in recent days and I was searching something that how we can execute TSQL statement in entity framework. And I have found one great way to do that with entity framework ‘ExecuteStoreQuery’ method. It’s executes a TSQL statement against data source given enity framework context and returns strongly typed result. You can find more information about ExcuteStoreQuery from following link. http://msdn.microsoft.com/en-us/library/dd487208.aspx So let’s examine how it works. So Let’s first create a table against which we are going to execute TSQL statement. So I have added a SQL Express database as following. Now once we are done with adding a database let’s add a table called Client like following. Here you can see above Client table is very simple. There are only two fields ClientId and ClientName where ClientId is primary key and ClientName is field where we are going to store client name. Now it’s time to add some data to the table. So I have added some test data like following. Now it’s time to add entity framework model class. So right click project->Add new item and select ADO.NET entity model as following. After clicking on add button a wizard will start it will ask whether we need to create model classes from database or not but we already have our client table ready so I have selected generate from database as following. Once you process further in wizard it will be presented a screen where we can select the our table like following. Now once you click finish it will create model classes with for us. Now we need a gridview control where we need to display those data. So in Default.aspx page I have added a grid control like following. <%@ Page Title="Home Page" Language="C#" MasterPageFile="~/Site.master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="EntityFramework._Default" %> <asp:Content ID="HeaderContent" runat="server" ContentPlaceHolderID="HeadContent"> </asp:Content> <asp:Content ID="BodyContent" runat="server" ContentPlaceHolderID="MainContent"> <h2> Welcome to ASP.NET! </h2> <p> To learn more about ASP.NET visit <a href="http://www.asp.net" title="ASP.NET Website">www.asp.net</a>. </p> <p> You can also find <a href="http://go.microsoft.com/fwlink/?LinkID=152368&amp;clcid=0x409" title="MSDN ASP.NET Docs">documentation on ASP.NET at MSDN</a>. <asp:GridView ID="grdClient" runat="server"> </asp:GridView> </p> </asp:Content> Now once we are done with adding Gridview its time to write code for server side. So I have written following code in Page_load event of default.aspx page. protected void Page_Load(object sender, EventArgs e) { if (!Page.IsPostBack) { using (var context = new EntityFramework.TestEntities()) { ObjectResult<Client> result = context.ExecuteStoreQuery<Client>("Select * from Client"); grdClient.DataSource = result; grdClient.DataBind(); } } } Here in the above code you can see that I have written create a object of our entity model and then with the help of the ExecuteStoreQuery method I have execute a simple select TSQL statement which will return a object result. I have bind that object result with gridview to display data. So now we are done with coding.So let’s run application in browser. Following is output as expected. That’s it. Hope you like it. Stay tuned for more..Till then happy programming.

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  • Add "not" to if statement in shell script

    - by John Crawford
    I have the following script that should exist if the user does not exist. #check if user currently exists on system if id $User > /dev/null 2>&1 then #user exists no need to exit program echo "blah blah, what a waste of space" else echo "This user does NOT exists. Please create that user before using this script.\n" exit fi My problem is that I would ideally like to place a "not" if that first if statement so that I can trim down my if, else statement. Ideally I would like something like this: if !(id $User > /dev/null 2>&1) then echo "This user does NOT exists. Please create that user before using this script.\n" exit fi

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  • EPM 11.1.2 - Issues during configuration when using Oracle DB if not using UTF8

    - by Ahmed A
    If you see issues during configuration when using Oracle DB if not using UTF8: Workaround: a. During configuration of EPM products, a warning message is displayed if the Oracle DB is not UTF8 enabled. If you continue with the configuration, certain products will not work as they will not be able to read the contents in the tables as the format is wrong.b. The Oracle DB must be setup to use AL32UTF8 or a superset that contains AL32UTF8. c. The only difference between AL32UTF8 and UTF8 character sets is that AL32UTF8 stores characters beyond U+FFFF as four bytes (exactly as Unicode defines UTF-8). Oracle’s “UTF8” stores these characters as a sequence of two UTF-16 surrogate characters encoded using UTF-8 (or six bytes per character). Besides this storage difference, another difference is better support for supplementary characters in AL32UTF8 character set.

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  • Neues Statement Of Direction veröffentlicht

    - by carstenczarski
    Das APEX Entwicklerteam hat ein neues Statement Of Direction (SOD) für die Version 5.0 veröffentlicht. Wie immer wird es die Verbesserung und Erweiterung vorhandener und die Einführung neuer Funktionen geben. Wie immer, ist das Statement Of Direction dazu gedacht, die Pläne und Ziele des APEX-Entwicklerteams mit der Community zu teilen. Insofern ist für APEX 5.0 unter anderem geplant ... ... modale Dialoge deklarativ bereitzustellen ... den Drag and Drop Layout Editor zurückzubringen ... HTML5 noch besser zu unterstützen ... mehr Varianten und Möglichkeiten für PDF-Ausgabe bereitzustellen ... spezielle User Interfaces für Tablets einzuführen ... Master / Detail / Detail Formulare zu ermöglichen ... mehrerer Interaktive Berichte auf einer Seite zu erlauben ... und vieles weitere mehr. Die APEX-Erfolgsgeschichte geht also weiter.

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  • Using block around a static/singleton resource reference

    - by byte
    This is interesting (to me anyway), and I'd like to see if anyone has a good answer and explanation for this behavior. Say you have a singleton database object (or static database object), and you have it stored in a class Foo. public class Foo { public static SqlConnection DBConn = new SqlConnection(ConfigurationManager.ConnectionStrings["BAR"].ConnectionString); } Then, lets say that you are cognizant of the usefulness of calling and disposing your connection (pretend for this example that its a one-time use for purposes of illustration). So you decide to use a 'using' block to take care of the Dispose() call. using (SqlConnection conn = Foo.DBConn) { conn.Open(); using (SqlCommand cmd = new SqlCommand()) { cmd.Connection = conn; cmd.CommandType = System.Data.CommandType.StoredProcedure; cmd.CommandText = "SP_YOUR_PROC"; cmd.ExecuteNonQuery(); } conn.Close(); } This fails, with an error stating that the "ConnectionString property is not initialized". It's not an issue with pulling the connection string from the app.config/web.config. When you investigate in a debug session you see that Foo.DBConn is not null, but contains empty properties. Why is this?

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  • How to enter text in AJAX HTML Editor using watin

    - by Shaki
    Hi, I could not figure out how to enter text into HTML Editor using Watin. I tried //ie.TextField(Find.ById("htmlDetail_ctl06_ctl04")).TypeText("ABCD"); But got error: Can't move focus to the control because it is invisible, not enabled, or of a type that does not accept the focus. Can you give some example how to enter text into AJAX HTML Editor using watin please? I am not sure what to plug in frameSrc and java script from this solution - http://stackoverflow.com/questions/939448/unit-testing-the-ms-ajax-toolkit-html-editor Here is html from Develper tool when click the text box: Thanks in advance

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  • Dynamics of the using keyword

    - by AngryHacker
    Consider the following code: // module level declaration Socket _client; void ProcessSocket() { _client = GetSocketFromSomewhere(); using (_client) { DoStuff(); // receive and send data Close(); } } void Close() { _client.Close(); _client = null; } Given that that the code calls the Close() method, which closes the _client socket and sets it to null, while still inside the `using' block, what exactly happens behind the scenes? Does the socket really get closed? Are there side effects? P.S. This is using C# 3.0 on the .NET MicroFramework, but I suppose the c#, the language, should function identically. The reason i am asking is that occasionally, very rarely, I run out of sockets (which is a very precious resource on a .NET MF devices).

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  • organize using directives, re-run tests?

    - by Sarah Vessels
    Before making a commit, I prefer to run all hundred-something unit tests in my C# Solution, since they only take a couple minutes to run. However, if I've already run them all, all is well, and then I decide to organize the using directives in my Solution, is it really necessary to re-run the unit tests? I have a macro that goes through all files in the Solution and runs Visual Studio's 'Remove and Sort' command on each. In my understanding, so long as all projects still build after using directives are changed around, things should be fine at runtime, too. Is this correct thinking?

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  • How can I make an SQL statement that finds unassociated records?

    - by William Calleja
    I have two tables as follows: tblCountry (countryID, countryCode) tblProjectCountry(ProjectID, countryID) The tblCountry table is a list of all countries with their codes and the tblProjectCountry table associates certain countries with certain projects. I need an SQL statement that gives me a list of the countries with their country code that do NOT have an associated record in the tblProjectCountry table. so far I got to here: SELECT tblCountry.countryID, tblCountry.countryCode FROM tblProjectCountry INNER JOIN tblCountry ON tblProjectCountry.countryID = tblCountry.countryID WHERE (SELECT COUNT(ProjectID) FROM tblProjectCountry WHERE (ProjectID = 1) AND (countryID = tblCountry.countryID)) = 0 The above statement parses as correct but doesn't give the exact result I'm looking for. Can anyone help?

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  • Wrap MemoryStream in a using block REST WCF

    - by Mark
    I'm learning REST to implement some Services with WCF. I implemented an example with a MemoryStream. Because MemoryStream is Disposable I wrapped it in a using. When I do this I sometimes can see the xml response in the browser (IE8) and sometimes it will just show me the following Errormessage: The download of the specified resource has failed. Error processing resource 'http://localhost:8889/SimpleGetService/'. Why does this occur? When I don't wrap it in a using, I never seem to get the error.

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  • In an If-Else Statement for a method return, should an Else be explicitly stated if it can instead b

    - by ccomet
    I have a method that checks certain things and returns a Boolean based on those checks. It involves a single branching If section that checks about 5 conditions in sequence. If any of those conditions return true, then the method will return true;. If none of the conditions return true, then the method will return false;. Since the code after the If section will only run if none of the conditions are true, then that code is logically identical to including an actual Else statement. So is it a better idea to actually write in the Else statement for this kind of situation?

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  • Checking if the email had been already taken in the following if statement (Rails)?

    - by alexchenco
    I have the following action: users.rb: def omniauth_create auth = request.env["omniauth.auth"] user = User.from_omniauth(env["omniauth.auth"]) unless user.email.blank? if user.id.nil? # Save the user since he hasn't been created yet user.save! end sign_in user redirect_back_or user else # Send user to a form to fill his email #session[:omniauth] = request.env['omniauth.auth'].except('extra') redirect_to(enter_email_path(oprovider: user.provider, ouid: user.uid, oname: user.name, opassword: user.password, opassword_confirmation: user.password)) end end It does the following: If the user's email is not blank, sign him in, and redirect him to his profile (and save him if his id is nil. In other words, if he hasn't been created yet). If the user's email is blank, send him to enter_email_path (where the user can enter his email). Now I want to add another if statement that flashes an error if the email had been already taken, and redirects the user to the root_path I'm not very sure how to do this, Any suggestions? (and where to put that if statement?)

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  • Detecting a Dispose() from an exception inside using block

    - by Augusto Radtke
    I have the following code in my application: using (var database = new Database()) { var poll = // Some database query code. foreach (Question question in poll.Questions) { foreach (Answer answer in question.Answers) { database.Remove(answer); } // This is a sample line that simulate an error. throw new Exception("deu pau"); database.Remove(question); } database.Remove(poll); } This code triggers the Database class Dispose() method as usual, and this method automatically commits the transaction to the database, but this leaves my database in an inconsistent state as the answers are erased but the question and the poll are not. There is any way that I can detect in the Dispose() method that it being called because of an exception instead of regular end of the closing block, so I can automate the rollback? I don´t want to manually add a try ... catch block, my objective is to use the using block as a logical safe transaction manager, so it commits to the database if the execution was clean or rollbacks if any exception occured. Do you have some thoughts on that?

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  • Getting rid of nested using(...) statements

    - by Ghostrider
    Sometimes I need to use several disposable objects within a function. Most common case is having StreamReader and StreamWriter but sometimes it's even more than this. Nested using statements quickly add up and look ugly. To remedy this I've created a small class that collects IDisposable objects and disposes of them when it itself is disposed. public class MultiDispose : HashSet<IDisposable>, IDisposable { public MultiDispose(params IDisposable[] objectsToDispose) { foreach (IDisposable d in objectsToDispose) { this.Add(d); } } public T Add<T>(T obj) where T : IDisposable { base.Add(obj); return obj; } public void DisposeObject(IDisposable obj) { obj.Dispose(); base.Remove(obj); } #region IDisposable Members public void Dispose() { foreach (IDisposable d in this) { d.Dispose(); } } #endregion } So my code now looks like this: using (MultiDispose md = new MultiDispose()) { StreamReader rdr = md.Add(new StreamReader(args[0])); StreamWriter wrt = md.Add(new StreamWriter(args[1])); WhateverElseNeedsDisposing w = md.Add(new WhateverElseNeedsDisposing()); // code } Is there anything wrong with this approach that can cause problems down the road? I left the Remove function inherited from the HashSet on purpose so that the class would be more flexible. Surely misusing this function can lead to objects not being disposed of properly, but then there many other ways to shoot yourself in the foot without this class.

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  • Declare 2 types inside using statement gives compile error?

    - by citronas
    I want to use this line of code: using (ADataContext _dc = new ADataContext(ConnectionString), BDataContext _dc2 = new BrDataContext(ConnectionString)){ // ...} This gives a compile error: Cannot use more than one type in a for, using, fixed or declartion statement. I thought this was possible? MSDN says it is: http://msdn.microsoft.com/en-us/library/yh598w02%28VS.80%29.aspx In the MSDN sample code Font is used, which is class and thereby a reference type as well as my two DataContext classes. What went wrong here? How does my attempt differ from the MSDN sample?

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