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  • Is there a way to make `enum` type to be unsigned?

    - by Kirill V. Lyadvinsky
    Is there a way to make enum type to be unsigned? The following code gives me a warning about signed/unsigned comparison. enum EEE { X1 = 1 }; int main() { size_t x = 2; EEE t = X1; if ( t < x ) std::cout << "ok" << std::endl; return 0; } I've tried to force compiler to use unsigned underlying type for enum with the following: enum EEE { X1 = 1, XN = 18446744073709551615LL }; But that still gives the warning.

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  • Any way to access the type of a Scala Option declaration at runtime using reflection?

    - by Graham Lea
    So, I have a Scala class that looks like this: class TestClass { var value: Option[Int] = None } and I'm tackling a problem where I have a String value and I want to coerce it into that Option[Int] at runtime using reflection. To do so, I need to know that the field is an Option and that the type parameter of the Option is Int. What are my options for figuring out that the type of 'value' is Option[Int] at runtime (i.e. using reflection)? I have seen similar problems solved by annotating the field, e.g. @OptionType(Int.class). I'd prefer a solution that didn't require annotations on the reflection target if possible.

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  • Resource interpreted as other but transferred with MIME type text/html.

    - by Zhami
    I'm transferring fragments of HTML via Ajax. Safari (4.0.5) reports: "Resource interpreted as other but transferred with MIME type text/html." The file name of the file I get has a .html extension. The server does set the header for this: Content-Type:text/html As I said, the content is a fragment of HTML, which is injected into the page (with jQuery). The contents of the file look like: <html> ... some valid html ... </html> What else might Safari need to see to make it interpret the received content as HTML? TIA.

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  • How to coerce type of ActiveRecord attribute returned by :select phrase on joined table?

    - by tribalvibes
    Having trouble with AR 2.3.5, e.g.: users = User.all( :select => "u.id, c.user_id", :from => "users u, connections c", :conditions => ... ) Returns, e.g.: => [#<User id: 1000>] >> users.first.attributes => {"id"=>1000, "user_id"=>"1000"} Note that AR returns the id of the model searched as numeric but the selected user_id of the joined model as a String, although both are int(11) in the database schema. How could I better form this type of query to select columns of tables backing multiple models and retrieving their natural type rather than String ? Seems like AR is punting on this somewhere. How could I coerce the returned types at AR load time and not have to tack .to_i (etc.) onto every post-hoc access?

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  • In C#: How to declare a generic Dictionary whose key and value types have a common constraint type?

    - by Marcel
    Hi all, I want to declare a dictionary that stores typed IEnumerable's of a specific type, with that exact type as key, like so: private IDictionary<T, IEnumerable<T>> _dataOfType where T: BaseClass; //does not compile! The concrete classes I want to store, all derive from BaseClass, therefore the idea to use it as constraint. The compiler complains that it expects a semicolon after the member name. If it would work, I would expect this would make the later retrieval from the dictionary simple like: IEnumerable<ConcreteData> concreteData; _sitesOfType.TryGetValue(typeof(ConcreteType), out concreteData); How to define such a dictionary?

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  • How do I restrict accepting only one type in my generic method?

    - by kunjaan
    I have a generic function foo, which accepts any type and prints them out. public static <T> T foo(T... arg) { List<T> foo = Arrays.asList(arg); for (T t : foo) { System.out.println(t); } return null; } How do I make sure that the arguments received are of only 1 type. For example, {1,'a',3} should be invalid. It should either be all numbers or all characters.

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  • Is it possible in Scala to force the caller to specify a type parameter for a polymorphic method ?

    - by Alex Kravets
    //API class Node class Person extends Node object Finder { def find[T <: Node](name: String): T = doFind(name).asInstanceOf[T] } //Call site (correct) val person = find[Person]("joe") //Call site (dies with a ClassCast inside b/c inferred type is Nothing) val person = find("joe") In the code above the client site "forgot" to specify the type parameter, as the API writer I want that to mean "just return Node". Is there any way to define a generic method (not a class) to achieve this (or equivalent). Note: using a manifest inside the implementation to do the cast if (manifest != scala.reflect.Manifest.Nothing) won't compile ... I have a nagging feeling that some Scala Wizard knows how to use Predef.<:< for this :-) Ideas ?

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  • Why this Either-monad code does not type check?

    - by pf_miles
    instance Monad (Either a) where return = Left fail = Right Left x >>= f = f x Right x >>= _ = Right x this code frag in 'baby.hs' caused the horrible compilation error: Prelude> :l baby [1 of 1] Compiling Main ( baby.hs, interpreted ) baby.hs:2:18: Couldn't match expected type `a1' against inferred type `a' `a1' is a rigid type variable bound by the type signature for `return' at <no location info> `a' is a rigid type variable bound by the instance declaration at baby.hs:1:23 In the expression: Left In the definition of `return': return = Left In the instance declaration for `Monad (Either a)' baby.hs:3:16: Couldn't match expected type `[Char]' against inferred type `a1' `a1' is a rigid type variable bound by the type signature for `fail' at <no location info> Expected type: String Inferred type: a1 In the expression: Right In the definition of `fail': fail = Right baby.hs:4:26: Couldn't match expected type `a1' against inferred type `a' `a1' is a rigid type variable bound by the type signature for `>>=' at <no location info> `a' is a rigid type variable bound by the instance declaration at baby.hs:1:23 In the first argument of `f', namely `x' In the expression: f x In the definition of `>>=': Left x >>= f = f x baby.hs:5:31: Couldn't match expected type `b' against inferred type `a' `b' is a rigid type variable bound by the type signature for `>>=' at <no location info> `a' is a rigid type variable bound by the instance declaration at baby.hs:1:23 In the first argument of `Right', namely `x' In the expression: Right x In the definition of `>>=': Right x >>= _ = Right x Failed, modules loaded: none. why this happen? and how could I make this code compile ? thanks for any help~

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  • Generic property- specify the type at runtime

    - by Lirik
    I was reading a question on making a generic property, but I'm a little confused at by the last example from the first answer (I've included the relevant code below): You have to know the type at compile time. If you don't know the type at compile time then you must be storing it in an object, in which case you can add the following property to the Foo class: public object ConvertedValue { get { return Convert.ChangeType(Value, Type); } } That's seems strange: it's converting the value to the specified type, but it's returning it as an object when the value was stored as an object. Doesn't the returned object still require un-boxing? If it does, then why bother with the conversion of the type? I'm also trying to make a generic property whose type will be determined at run time: public class Foo { object Value {get;set;} Type ValType{get;set;} Foo(object value, Type type) { Value = value; ValType = type; } // I need a property that is actually // returned as the specified value type... public object ConvertedValue { get { return Convert.ChangeType(Value, ValType); } } } Is it possible to make a generic property? Does the return property still require unboxing after it's accessed?

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  • Event type property lost in IE-8

    - by Channel72
    I've noticed a strange Javascript error which only seems to happen on Internet Explorer 8. Basically, on IE-8 if you have an event handler function which captures the event object in a closure, the event "type" property seems to become invalidated from within the closure. Here's a simple code snippet which reproduces the error: <html> <head> <script type = "text/javascript"> function handleClickEvent(ev) { ev = (ev || window.event); alert(ev.type); window.setTimeout(function() { alert(ev.type); // Causes error on IE-8 }, 20); } function foo() { var query = document.getElementById("query"); query.onclick = handleClickEvent; } </script> </head> <body> <input id = "query" type = "submit"> <script type = "text/javascript"> foo(); </script> </body> </html> So basically, what happens here is that within the handleClickEvent function, we have the event object ev. We call alert(ev.type) and we see the event type is "click". So far, so good. But then when we capture the event object in a closure, and then call alert(ev.type) again from within the closure, now all of a sudden Internet Explorer 8 errors, saying "Member not found" because of the expression ev.type. It seems as though the type property of the event object is mysteriously gone after we capture the event object in a closure. I tested this code snippet on Firefox, Safari and Chrome, and none of them report an error condition. But in IE-8, the event object seems to become somehow invalidated after it's captured in the closure. Question: Why is this happening in IE-8, and is there any workaround?

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  • how to solve eclipse's Type The project was not built due to "Could not delete

    - by user50680
    when I change a properties file's content, Eclipse always show error,say "Description Resource Path Location Type The project was not built due to "Could not delete '/lichong-test-tester/target/test-classes/config'.". Fix the problem, then try refreshing this project and building it since it may be inconsistent lichong-test-tester Unknown Java Problem ". I have to clean and rebuild whole project to solve this problem ,can anybody tell me how to avoid this. https://skydrive.live.com/redir.aspx?cid=02a1e6543b4cc73e&resid=2A1E6543B4CC73E!458&parid=root that's my Screenshot

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  • SQL SERVER – FT_IFTS_SCHEDULER_IDLE_WAIT – Full Text – Wait Type – Day 13 of 28

    - by pinaldave
    In the last few days during this series, I got many question about this Wait type. It would be great if you read my original related wait stats query in the first post because I have filtered it out in WHERE clause. However, I still get questions about this being one of the most wait types they encounter. The truth is, this is a background task processing and it really does not matter and it should be filtered out. There are many new Wait types related to Full Text Search that are introduced in SQL Server 2008. If you run the following query, you will be able to find them in the list. Currently there is not enough information for all of them available on BOL or any other place. But don’t worry; I will write an in-depth article when I learn more about them. SELECT * FROM sys.dm_os_wait_stats WHERE wait_type LIKE 'FT_%' The result set will contain following rows. FT_RESTART_CRAWL FT_METADATA_MUTEX FT_IFTSHC_MUTEX FT_IFTSISM_MUTEX FT_IFTS_RWLOCK FT_COMPROWSET_RWLOCK FT_MASTER_MERGE FT_IFTS_SCHEDULER_IDLE_WAIT We have understood so far that there is not much information available. But the problem is when you have this Wait type, what should you do?  The answer is to filter them out for the moment (i.e, do not pay attention on them) and focus on other pressing issues in wait stats or performance tuning. Here are two of my informal suggestions, which are totally independent from wait stats: Turn off the Full Text Search service in your system if you are  not necessarily using it on your server. Learn proper Full Text Search methodology. You can get Michael Coles’ book: Pro Full-Text Search in SQL Server 2008. Now I invite you to speak out your suggestions or any input regarding Full Text-related best practices and wait stats issue. Please leave a comment. Note: The information presented here is from my experience and there is no way that I claim it to be accurate. I suggest reading Book OnLine for further clarification. All the discussions of Wait Stats in this blog are generic and vary from system to system. It is recommended that you test this on a development server before implementing it to a production server. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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  • C# tip: do not use “is” type, if you will need cast “as” later

    - by Michael Freidgeim
    We have a debate with one of my collegues, is it agood style to check, if the object of particular style, and then cast  as this  type. The perfect answer of Jon Skeet   and answers in Cast then check or check then cast? confirmed my point.//good    var coke = cola as CocaCola;    if (coke != null)    {        // some unique coca-cola only code    }    //worse    if (cola is CocaCola)    {        var coke =  cola as CocaCola;        // some unique coca-cola only code here.    }

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  • IIS MIME type for XML content

    - by Rodolfo
    recently a third party plugin I'm using to display online magazines stopped working on mobile devices. According to their help page, this happens for people serving with IIS. Their solution is to set the MIME type .xml to "application/xml". It's by default set to "text/xml". Changing it does work, but would that have unintended side effects or is it actually the correct way and IIS just set it wrong?

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  • SQL Server Geography Data Type

    We are working on the migration to SQL Server 2008 and have geospatial data that we would like to move over as well. As part of our application we house information on locations across the globe. Which data type should we use?

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  • Update Package Manager failed, E:type "ain"

    - by Robert
    The Update Manager failed and gave me this error: E:Type 'ain' is not known on line 3 in source list /etc/apt/sources.list.d/scopes-packagers-ppa-precise.list What should I do? This message came up when I followed the editor's instructions: $cat /etc/apt/sources.list.d/scopes-packagers-ppa-precise.list deb http://ppa.launchpad.net/scopes-packagers/ppa/ubuntu precise main deb-src http://ppa.launchpad.net/scopes-packagers/ppa/ubuntu precise main ain$

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  • C++11 Tidbits: Decltype (Part 2, trailing return type)

    - by Paolo Carlini
    Following on from last tidbit showing how the decltype operator essentially queries the type of an expression, the second part of this overview discusses how decltype can be syntactically combined with auto (itself the subject of the March 2010 tidbit). This combination can be used to specify trailing return types, also known informally as "late specified return types". Leaving aside the technical jargon, a simple example from section 8.3.5 of the C++11 standard usefully introduces this month's topic. Let's consider a template function like: template <class T, class U> ??? foo(T t, U u) { return t + u; } The question is: what should replace the question marks? The problem is that we are dealing with a template, thus we don't know at the outset the types of T and U. Even if they were restricted to be arithmetic builtin types, non-trivial rules in C++ relate the type of the sum to the types of T and U. In the past - in the GNU C++ runtime library too - programmers used to address these situations by way of rather ugly tricks involving __typeof__ which now, with decltype, could be rewritten as: template <class T, class U> decltype((*(T*)0) + (*(U*)0)) foo(T t, U u) { return t + u; } Of course the latter is guaranteed to work only for builtin arithmetic types, eg, '0' must make sense. In short: it's a hack. On the other hand, in C++11 you can use auto: template <class T, class U> auto foo(T t, U u) -> decltype(t + u) { return t + u; } This is much better. It's generic and a construct fully supported by the language. Finally, let's see a real-life example directly taken from the C++11 runtime library as implemented in GCC: template<typename _IteratorL, typename _IteratorR> inline auto operator-(const reverse_iterator<_IteratorL>& __x, const reverse_iterator<_IteratorR>& __y) -> decltype(__y.base() - __x.base()) { return __y.base() - __x.base(); } By now it should appear be completely straightforward. The availability of trailing return types in C++11 allowed fixing a real bug in the C++98 implementation of this operator (and many similar ones). In GCC, C++98 mode, this operator is: template<typename _IteratorL, typename _IteratorR> inline typename reverse_iterator<_IteratorL>::difference_type operator-(const reverse_iterator<_IteratorL>& __x, const reverse_iterator<_IteratorR>& __y) { return __y.base() - __x.base(); } This was guaranteed to work well with heterogeneous reverse_iterator types only if difference_type was the same for both types.

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  • System won't boot unless I type "exit" at initramfs prompt

    - by Ozzah
    I installed MDADM for my RAID, and ever since that when I boot up the system just sits at the purple screen forever. After pulling my hair out for a week, I finally discovered - purely by accident - that it's sitting at an initramfs prompt in the background and I have to blindly type "exit" and then Ubuntu resumes normal boot. How do I fix this? I am unable to reboot my machine if I'm not sitting in front of it because it will never boot!

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  • Lot of "file not found" when using sudo find / -type s

    - by Andrea Moro
    In the attempt to understand why I keep getting the following error error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)' while using the command sudo find / -type s the terminal prompted something like this find: ‘/proc/31348/task/31348/fd/5’: No such file or directory find: ‘/proc/31348/task/31348/fdinfo/5’: No such file or directory find: ‘/proc/31348/fd/5’: No such file or directory find: ‘/proc/31348/fdinfo/5’: No such file or directory What does this mean?

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  • What is this type of sound effect called?

    - by Fibericon
    There is a sound typically associated with a bright flash of light, which starts with a lower whirring noise, then breaks into a higher pitched sound. What is that type of sound called? I'm not sure how to begin searching for that, so a typical name for it would be very helpful. It's something similar to what occurs at 0:41 in this youtube video (here's a link to a few seconds beforehand), where Naruto 6 tails transforms into Kyuubei in Naruto Generations.

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  • An Overview of the SQL Server xml Data Type

    XML is, it seems, everywhere. SQL Server has ever-improving functionality that helps us peek into, shred, store, manipulate and otherwise utilize XML. This article covers XML variables, XML columns, typed vs. untyped XML, and the xml data type methods.

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  • SQL SERVER – Introduction to Wait Stats and Wait Types – Wait Type – Day 1 of 28

    - by pinaldave
    I have been working a lot on Wait Stats and Wait Types recently. Last Year, I requested blog readers to send me their respective server’s wait stats. I appreciate their kind response as I have received  Wait stats from my readers. I took each of the results and carefully analyzed them. I provided necessary feedback to the person who sent me his wait stats and wait types. Based on the feedbacks I got, many of the readers have tuned their server. After a while I got further feedbacks on my recommendations and again, I collected wait stats. I recorded the wait stats and my recommendations and did further research. At some point at time, there were more than 10 different round trips of the recommendations and suggestions. Finally, after six month of working my hands on performance tuning, I have collected some real world wisdom because of this. Now I plan to share my findings with all of you over here. Before anything else, please note that all of these are based on my personal observations and opinions. They may or may not match the theory available at other places. Some of the suggestions may not match your situation. Remember, every server is different and consequently, there is more than one solution to a particular problem. However, this series is written with kept wait stats in mind. While I was working on various performance tuning consultations, I did many more things than just tuning wait stats. Today we will discuss how to capture the wait stats. I use the script diagnostic script created by my friend and SQL Server Expert Glenn Berry to collect wait stats. Here is the script to collect the wait stats: -- Isolate top waits for server instance since last restart or statistics clear WITH Waits AS (SELECT wait_type, wait_time_ms / 1000. AS wait_time_s, 100. * wait_time_ms / SUM(wait_time_ms) OVER() AS pct, ROW_NUMBER() OVER(ORDER BY wait_time_ms DESC) AS rn FROM sys.dm_os_wait_stats WHERE wait_type NOT IN ('CLR_SEMAPHORE','LAZYWRITER_SLEEP','RESOURCE_QUEUE','SLEEP_TASK' ,'SLEEP_SYSTEMTASK','SQLTRACE_BUFFER_FLUSH','WAITFOR', 'LOGMGR_QUEUE','CHECKPOINT_QUEUE' ,'REQUEST_FOR_DEADLOCK_SEARCH','XE_TIMER_EVENT','BROKER_TO_FLUSH','BROKER_TASK_STOP','CLR_MANUAL_EVENT' ,'CLR_AUTO_EVENT','DISPATCHER_QUEUE_SEMAPHORE', 'FT_IFTS_SCHEDULER_IDLE_WAIT' ,'XE_DISPATCHER_WAIT', 'XE_DISPATCHER_JOIN', 'SQLTRACE_INCREMENTAL_FLUSH_SLEEP')) SELECT W1.wait_type, CAST(W1.wait_time_s AS DECIMAL(12, 2)) AS wait_time_s, CAST(W1.pct AS DECIMAL(12, 2)) AS pct, CAST(SUM(W2.pct) AS DECIMAL(12, 2)) AS running_pct FROM Waits AS W1 INNER JOIN Waits AS W2 ON W2.rn <= W1.rn GROUP BY W1.rn, W1.wait_type, W1.wait_time_s, W1.pct HAVING SUM(W2.pct) - W1.pct < 99 OPTION (RECOMPILE); -- percentage threshold GO This script uses Dynamic Management View sys.dm_os_wait_stats to collect the wait stats. It omits the system-related wait stats which are not useful to diagnose performance-related bottleneck. Additionally, not OPTION (RECOMPILE) at the end of the DMV will ensure that every time the query runs, it retrieves new data and not the cached data. This dynamic management view collects all the information since the time when the SQL Server services have been restarted. You can also manually clear the wait stats using the following command: DBCC SQLPERF('sys.dm_os_wait_stats', CLEAR); Once the wait stats are collected, we can start analysis them and try to see what is causing any particular wait stats to achieve higher percentages than the others. Many waits stats are related to one another. When the CPU pressure is high, all the CPU-related wait stats show up on top. But when that is fixed, all the wait stats related to the CPU start showing reasonable percentages. It is difficult to have a sure solution, but there are good indications and good suggestions on how to solve this. I will keep this blog post updated as I will post more details about wait stats and how I reduce them. The reference to Book On Line is over here. Of course, I have selected February to run this Wait Stats series. I am already cheating by having the smallest month to run this series. :) Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: DMV, Pinal Dave, PostADay, SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQL Wait Stats, SQL Wait Types, T SQL, Technology

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