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• Getting float values out of PostgreSQL

  - by skymander

  I am having trouble retrieving float/real values out of PostgreSQL. For example, I would like to store: 123456789123456, the retrieve that exact same number with a select statement. table tbl (num real) insert into tbl(num) values('123456789123456'); As it is now, if I "select num from tbl" the result is "1.23457e+14" If I run "select CAST(num AS numeric) as num from tbl" the result is 123457000000000 If I run "select CAST(num AS float) as num from tbl" the result is 123456788103168 (where did this number come from) How on earth can I select the value and get "123456789123456" as the result? Thanks so much in advance

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• Mono mkbundle issue

  - by Sean

  Hello, I am trying to bundle mono runtime with a C# a simple (console) program that does nothing, but 'hello world'. Got Cygwin, configured it all, though it fails: $ mkbundle -o x2 x.exe --deps -z OS is: Windows Sources: 1 Auto-dependencies: True embedding: C:\cygwin\home\Sean\x.exe compression ratio: 31.71% embedding: C:\PROGRA~2\MONO-2~1.1\lib\mono\4.0\mscorlib.dll compression ratio: 34.68% Compiling: as -o temp.o temp.s gcc -mno-cygwin -g -o x2 -Wall temp.c `pkg-config --cflags --libs mono-2|dos2unix` -lz temp.o temp.c: In function `main': temp.c:173: warning: implicit declaration of function `g_utf16_to_utf8' temp.c:173: warning: assignment makes pointer from integer without a cast temp.c:188: warning: assignment makes pointer from integer without a cast /tmp/ccu8fTcQ.o: In function `main': /home/Sean/temp.c:173: undefined reference to `_g_utf16_to_utf8' /home/Sean/temp.c:188: undefined reference to `_g_utf16_to_utf8' collect2: ld returned 1 exit status [Fail] Tried post with similar problem to mine here, but it didn't work either. My configuration: Windows 7 64bit Mono 2.8.1 Latest Cygwin Not sure what's the story here. Help appreciated.

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• Semi-complex aggregate select statement confusion

  - by Ian Henry

  Alright, this problem is a little complicated, so bear with me. I have a table full of data. One of the table columns is an EntryDate. There can be multiple entries per day. However, I want to select all rows that are the latest entry on their respective days, and I want to select all the columns of said table. One of the columns is a unique identifier column, but it is not the primary key (I have no idea why it's there; this is a pretty old system). For purposes of demonstration, say the table looks like this: create table ExampleTable ( ID int identity(1,1) not null, PersonID int not null, StoreID int not null, Data1 int not null, Data2 int not null, EntryDate datetime not null ) The primary key is on PersonID and StoreID, which logically defines uniqueness. Now, like I said, I want to select all the rows that are the latest entries on that particular day (for each Person-Store combination). This is pretty easy: --Figure 1 select PersonID, StoreID, max(EntryDate) from ExampleTable group by PersonID, StoreID, dbo.dayof(EntryDate) Where dbo.dayof() is a simple function that strips the time component from a datetime. However, doing this loses the rest of the columns! I can't simply include the other columns, because then I'd have to group by them, which would produce the wrong results (especially since ID is unique). I have found a dirty hack that will do what I want, but there must be a better way -- here's my current solution: select cast(null as int) as ID, PersonID, StoreID, cast(null as int) as Data1, cast(null as int) as Data2, max(EntryDate) as EntryDate into #StagingTable from ExampleTable group by PersonID, StoreID, dbo.dayof(EntryDate) update Target set ID = Source.ID, Data1 = Source.Data1, Data2 = Source.Data2, from #StagingTable as Target inner join ExampleTable as Source on Source.PersonID = Target.PersonID and Source.StoreID = Target.StoreID and Source.EntryDate = Target.EntryDate This gets me the correct data in #StagingTable but, well, look at it! Creating a table with null values, then doing an update to get the values back -- surely there's a better way to do this? A single statement that will get me all the values the first time? It is my belief that the correct join on that original select (Figure 1) would do the trick, like a self-join or something... but how do you do that with the group by clause? I cannot find the right syntax to make the query execute. I am pretty new with SQL, so it's likely that I'm missing something obvious. Any suggestions? (Working in T-SQL, if it makes any difference)

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• Why does GetSqlDecimal throw when GetDecimal doesn't?

  - by I. J. Kennedy

  I have a database table that has a column of type money, allowing nulls. Using a SqlDataReader named reader, I can do decimal d = reader.GetDecimal(1); which works, unless of course we're reading a null. If I try using SqlDecimal instead--and I thought the whole point of the SqlTypes was to deal with nulls--then I get an invalid cast, whether or not the value is null. SqlDecimal s = reader.GetSqlDecimal(1); // throws an invalid cast exception What am I doing wrong? Do I really have to write a conditional statement to shepherd the value from the database to a SqlDecimal variable?

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• How to read verbose VC++ linker output

  - by Assaf Lavie

  Trying to debug some linker errors, I turned on /VERBOSE and I'm trying to make sense of the output. It occurs to me that I really don't know how to read it. For example: 1>Compiling version info 1>Linking... 1>Starting pass 1 1>Processed /DEFAULTLIB:mfc80.lib 1>Processed /DEFAULTLIB:mfcs80.lib 1>Processed /DEFAULTLIB:msvcrt.lib 1>Processed /DEFAULTLIB:kernel32.lib 1>Processed /DEFAULTLIB:user32.lib .... 1>Processed /DEFAULTLIB:libgslcblasMD.lib 1>Searching libraries 1> Searching V:\Src\Solutions\\..\..\\Common\Win32\Lib\PlxApi.lib: 1> Searching ..\..\..\..\out\win32\release\lib\camerageometry.lib: 1> Searching ..\..\..\..\out\win32\release\lib\geometry.lib: 1> Found "public: __thiscall VisionMap::Geometry::Box2d::operator class VisionMap::Geometry::Box2DInt(void)const " (??BBox2d@Geometry@VisionMap@@QBE?AVBox2DInt@12@XZ) 1> Referenced in FocusDlg.obj 1> Loaded geometry.lib(Box2d.obj) 1>Processed /DEFAULTLIB:CGAL-vc80-mt.lib 1>Processed /DEFAULTLIB:boost_thread-vc80-mt-1_33_1.lib What's going on here? I think I understand this bit: 1>Processed /DEFAULTLIB:libgslcblasMD.lib 1>Searching libraries 1> Searching V:\Src\Solutions\\..\..\\Common\Win32\Lib\PlxApi.lib: 1> Searching ..\..\..\..\out\win32\release\lib\camerageometry.lib: 1> Searching ..\..\..\..\out\win32\release\lib\geometry.lib: 1> Found "public: __thiscall VisionMap::Geometry::Box2d::operator class VisionMap::Geometry::Box2DInt(void)const " (??BBox2d@Geometry@VisionMap@@QBE?AVBox2DInt@12@XZ) 1> Referenced in FocusDlg.obj 1> Loaded geometry.lib(Box2d.obj) It's trying to find the implementation of the above operator, which is used somewhere in FocusDlg.cpp, and it finds it in geometry.lib. But what does 1>Processed /DEFAULTLIB:libgslcblasMD.lib mean? What determines the order of symbol resolution? Why is it loading this particular symbol while processing libgslcblasMD.lib which is a 3rd party library? Or am I reading it wrong? It seems that the linker is going through the symbols referenced in the project's various object files, but I have no idea in what order. It then searches the static libraries the project uses - by project reference, explicit import and automatic default library imports; but it does so in an order that, again, seems arbitrary to me. When it finds a symbol, for example in geometry.lib, it then continues to find a bunch of other symbols from the same lib: 1> Searching V:\Src\Solutions\\..\..\\Common\Win32\Lib\PlxApi.lib: 1> Searching ..\..\..\..\out\win32\release\lib\camerageometry.lib: 1> Searching ..\..\..\..\out\win32\release\lib\geometry.lib: 1> Found "public: __thiscall VisionMap::Geometry::Box2d::operator class VisionMap::Geometry::Box2DInt(void)const " (??BBox2d@Geometry@VisionMap@@QBE?AVBox2DInt@12@XZ) 1> Referenced in FocusDlg.obj 1> Loaded geometry.lib(Box2d.obj) 1>Processed /DEFAULTLIB:CGAL-vc80-mt.lib 1>Processed /DEFAULTLIB:boost_thread-vc80-mt-1_33_1.lib 1> Found "public: __thiscall VisionMap::Geometry::Box2DInt::Box2DInt(int,int,int,int)" (??0Box2DInt@Geometry@VisionMap@@QAE@HHHH@Z) 1> Referenced in FocusDlg.obj 1> Referenced in ImageView.obj 1> Referenced in geometry.lib(Box2d.obj) 1> Loaded geometry.lib(Box2DInt.obj) 1> Found "public: virtual __thiscall VisionMap::Geometry::Point3d::~Point3d(void)" (??1Point3d@Geometry@VisionMap@@UAE@XZ) 1> Referenced in GPSFrm.obj 1> Referenced in MainFrm.obj 1> Loaded geometry.lib(Point3d.obj) 1> Found "void __cdecl VisionMap::Geometry::serialize<class boost::archive::binary_oarchive>(class boost::archive::binary_oarchive &,class VisionMap::Geometry::Point3d &,unsigned int)" (??$serialize@Vbinary_oarchive@archive@boost@@@Geometry@VisionMap@@YAXAAVbinary_oarchive@archive@boost@@AAVPoint3d@01@I@Z) 1> Referenced in GPSFrm.obj 1> Referenced in MainFrm.obj 1> Loaded geometry.lib(GeometrySerializationImpl.obj) But then, for some reason, it goes on to find symbols that are defined in other libs, and returns to geometry later on (a bunch of times). So clearly it's not doing "look in geometry and load every symbol that's references in the project, and then continue to other libraries". But it's not clear to me what is the order of symbol lookup. And what's the deal with all those libraries being processed at the beginning of the linker's work, but not finding any symbols to load from them? Does this project really not use anything from msvcrt.lib, kernel32.lib? Seems unlikely. So basically I'm looking to decipher the underlying order in the linker's operation.

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• Boost bind function

  - by Gokul

  Hi, I have a abstract base class A and a set of 10 derived classes. The infix operator is overloaded in all of the derived classes class A{ void printNode( std::ostream& os ) { this->printNode_p(); } void printNode_p( std::ostream& os ) { os << (*this); } }; There is a container which stores the base class pointers. I want to use boost::bind function to call the overloaded infix operator in each of its derived class. I have written like this std::vector<A*> m_args .... std::ostream os; for_each( m_args.begin(), m_args.end(), bind(&A::printNode, _1, os) ); What is the problem with this code? Thanks, Gokul.

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• Reflection Permission problems when using the GSON library in a applet.

  - by mridang

  I'm writing an Applet that makes some JSON-RPC calls. I'm using the Google JSON library (GSON) to cast the response JSON into a class. Thsi seems to work fine as is but when I use this code in my Applet, I'm hit with a java.lang.reflect.reflectpermission. From what I read on this thread on SO, it seems that since GSON uses Reflection, I cannot use it in Applets unless I explicitly modify the security policy. How can I get around this? I've created a bunch of classes in my application and was using the Gson.fromJson method to cast it into the class. Is there any way to achieve the same functionality without having to re-write half my code. (The complexity of dealing with JSON in Java seems to be in a league of its own!) Thanks in advance guys.

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• Overriding LINQ extension methods

  - by Ruben Vermeersch

  Is there a way to override extension methods (provide a better implementation), without explicitly having to cast to them? I'm implementing a data type that is able to handle certain operations more efficiently than the default extension methods, but I'd like to keep the generality of IEnumerable. That way any IEnumerable can be passed, but when my class is passed in, it should be more efficient. As a toy example, consider the following: // Compile: dmcs -out:test.exe test.cs using System; namespace Test { public interface IBoat { void Float (); } public class NiceBoat : IBoat { public void Float () { Console.WriteLine ("NiceBoat floating!"); } } public class NicerBoat : IBoat { public void Float () { Console.WriteLine ("NicerBoat floating!"); } public void BlowHorn () { Console.WriteLine ("NicerBoat: TOOOOOT!"); } } public static class BoatExtensions { public static void BlowHorn (this IBoat boat) { Console.WriteLine ("Patched on horn for {0}: TWEET", boat.GetType().Name); } } public class TestApp { static void Main (string [] args) { IBoat niceboat = new NiceBoat (); IBoat nicerboat = new NicerBoat (); Console.WriteLine ("## Both should float:"); niceboat.Float (); nicerboat.Float (); // Output: // NiceBoat floating! // NicerBoat floating! Console.WriteLine (); Console.WriteLine ("## One has an awesome horn:"); niceboat.BlowHorn (); nicerboat.BlowHorn (); // Output: // Patched on horn for NiceBoat: TWEET // Patched on horn for NicerBoat: TWEET Console.WriteLine (); Console.WriteLine ("## That didn't work, but it does when we cast:"); (niceboat as NiceBoat).BlowHorn (); (nicerboat as NicerBoat).BlowHorn (); // Output: // Patched on horn for NiceBoat: TWEET // NicerBoat: TOOOOOT! Console.WriteLine (); Console.WriteLine ("## Problem is: I don't always know the type of the objects."); Console.WriteLine ("## How can I make it use the class objects when the are"); Console.WriteLine ("## implemented and extension methods when they are not,"); Console.WriteLine ("## without having to explicitely cast?"); } } } Is there a way to get the behavior from the second case, without explict casting? Can this problem be avoided?

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• c struct pointer issues

  - by clear2k

  I'm trying to cast a struct into another struct but I'm having incompatible pointer issues within the cast and the malloc under some_func (structs layout are the same) struct stu1 **some_func(struct stu1 *my_struct) { my_struct = (struct stu1 **)malloc(sizeof(struct stu1 *)*total_size); for(i=0;i<20;i++){ my_struct[i] = (struct stu1 *)malloc(sizeof(struct stu1)); printf("%s",my_struct[i++]->a); } } int main() { struct stu1 **my_struct; struct stu2 **my_struct2; struct stu3 **my_struct3; my_struct = some_func(my_struct); my_struct2 = (struct stu2**)some_func((struct stu1*)my_struct2); my_struct3 = (struct stu3**)some_func((struct stu1*)my_struct3); }

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• Creating a castable entity class wrapper

  - by Tony

  Hi I need to have a wrapper class that exposes some properties of my entity class called ProfileEntity. I tried doing it by deriving from this entity and then creating properties that return specific entity properties, but it says I cannot cast from ProfileEntity to ProfileEntityWrapper. When I try to put the return values of a method that returns a 'ProfileEntity' into the wrapper I get the above error. How do I create such a wrapper class that is castable? Example class ProfileEntityWrapper : ProfileEntity { public string Name { get { return this.ProfileEntityName; } } public class Someclass { public ProfileEntity SomeMethod() { return ProfileEntity; // example of method returning this object } } public class SomeOtherlClass { SomeClass sc = new SomeClass(); public void DoSomething() { ProfileEntityWrapper ew = (ProfileEntityWrapper)sc.SomeMethod(); // Cannot do this cast!!! } }

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• Enumerate shared folders on Windows with low privileges

  - by Phil Nash

  Using C++ (VS2008) I need to be able to enumerate all shared folders on the current machine and get or construct the local and remote names. We've been using NetShareEnum for this fairly successfully, but have hit a problem where we need to run with a user account with low privileges. To get the local path using NetShareEnum we need to retrieve at least SHARE_INFO_2 structures - but that requires "Administrator, Power User, Print Operator, or Server Operator group membership". I've been trying to use WNetOpenEnum and WNetEnumResource instead but I don't seem to be getting the local name back for that for shares either - and I can't seem to get it to enumerate just local resources - it goes off and finds all shared resources on the local network - which is not an acceptable overhead. So I'd either like help on where I'm going wrong with WNetEnumResource, or a suggestion as to another way of doing this. Any suggestions are much appreciated.

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• Load a Settings.settings into ListView?

  - by clefranc

  Hi, I've managed to save ListView items to a System.Collections.Specialized.StringCollection property settings using this LINQ one liner: My.Settings.Property1.AddRange(ListView1.Items.Cast(Of ListViewItem)().[Select](Function(a) String.Join(Convert.ToChar(Keys.Tab), a.SubItems.Cast(Of System.Windows.Forms.ListViewItem.ListViewSubItem)().[Select](Function(s) s.Text).ToArray())).ToArray()) Now, I want to do the opposite, ie load the ListView1 from the My.Settings.Property1. It's fairly easy to do using a For Each loop, but I wonder if someone can show me a similar LINQ query. The lines in My.Settings.Property1 looks like this (Tab separated): Word1 Word2 Word3 Word4 Word5 Word6 Original code is from this answer: http://stackoverflow.com/questions/2295068/show-listview-items-in-a-combobox

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• Java generic return type

  - by Colby77

  Hi, I'd like to write a method that can accept a type param (or whatever the method can figure out the type from) and return a value of this type so I don't have to cast the return type. Here is a method: public Object doIt(Object param){ if(param instanceof String){ return "string"; }else if(param instanceof Integer){ return 1; }else{ return null; } } When I call this method, and pass in it a String, even if I know the return type will be a String I have to cast the return Object. This is similar to the int param. How shall I write this method to accept a type param, and return this type?

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• Is this an F# quotations bug?

  - by ControlFlow

  [<ReflectedDefinition>] let rec x = (fun() -> x + "abc") () The sample code with the recursive value above produces the following F# compiler error: error FS0432: [<ReflectedDefinition>] terms cannot contain uses of the prefix splice operator '%' I can't see any slicing operator usage in the code above, looks like a bug... :) Looks like this is the problem with the quotation via ReflectedDefinitionAttribute only, normal quotation works well: let quotation = <@ let rec x = (fun() -> x + "abc") () in x @> produces expected result with the hidden Lazy.create and Lazy.force usages: val quotation : Quotations.Expr<string> = LetRecursive ([(x, Lambda (unitVar, Application (Lambda (unitVar0, Call (None, String op_Addition[String,String,String](String, String), [Call (None, String Force[String](Lazy`1[System.String]), [x]), Value ("abc")])), Value (<null>)))), (x, Call (None, Lazy`1[String] Create[String](FSharpFunc`2[Unit,String]), [x])), (x, Call (None, String Force[String](Lazy`1[String]), [x]))], x) So the question is: is this an F# compiler bug or not?

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• postgres - ERROR: syntax error at or near "COST"

  - by cino21122

  EDIT Taking COST 100 out made the command go through, however, I'm still unable to run my query because it yields this error: ERROR: function group_concat(character) does not exist HINT: No function matches the given name and argument types. You may need to add explicit type casts. The query I'm running is this: select tpid, group_concat(z) as z, group_concat(cast(r as char(2))) as r, group_concat(to_char(datecreated,'DD-Mon-YYYY HH12:MI am')) as datecreated, group_concat(to_char(datemodified,'DD-Mon-YYYY HH12:MI am')) as datemodified from tpids group by tpid order by tpid, zip This function seems to work fine locally, but moving it online yields this error... Is there something I'm missing? CREATE OR REPLACE FUNCTION group_concat(text, text) RETURNS text AS $BODY$ SELECT CASE WHEN $2 IS NULL THEN $1 WHEN $1 IS NULL THEN $2 ELSE $1 operator(pg_catalog.||) ',' operator(pg_catalog.||) $2 END $BODY$ LANGUAGE 'sql' IMMUTABLE COST 100; ALTER FUNCTION group_concat(text, text) OWNER TO j76dd3;

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• What Causes Boost Asio to Crash Like This?

  - by Scott Lawson

  My program appears to run just fine most of the time, but occasionally I get a segmentation fault. boost version = 1.41.0 running on RHEL 4 compiled with GCC 3.4.6 Backtrace: #0 0x08138546 in boost::asio::detail::posix_fd_set_adapter::is_set (this=0xb74ed020, descriptor=-1) at /home/scottl/boost_1_41_0/boost/asio/detail/posix_fd_set_adapter.hpp:57 __result = -1 'ÿ' #1 0x0813e1b0 in boost::asio::detail::reactor_op_queue::perform_operations_for_descriptors (this=0x97f3b6c, descriptors=@0xb74ed020, result=@0xb74ecec8) at /home/scottl/boost_1_41_0/boost/asio/detail/reactor_op_queue.hpp:204 op_iter = {_M_node = 0xb4169aa0} i = {_M_node = 0x97f3b74} #2 0x081382ca in boost::asio::detail::select_reactor::run (this=0x97f3b08, block=true) at /home/scottl/boost_1_41_0/boost/asio/detail/select_reactor.hpp:388 read_fds = {fd_set_ = {fds_bits = {16, 0 }}, max_descriptor_ = 65} write_fds = {fd_set_ = {fds_bits = {0 }}, max_descriptor_ = -1} retval = 1 lock = { = {}, mutex_ = @0x97f3b1c, locked_ = true} except_fds = {fd_set_ = {fds_bits = {0 }}, max_descriptor_ = -1} max_fd = 65 tv_buf = {tv_sec = 0, tv_usec = 710000} tv = (timeval *) 0xb74ecf88 ec = {m_val = 0, m_cat = 0x81f2c24} sb = { = {}, blocked_ = true, old_mask_ = {__val = {0, 0, 134590223, 3075395548, 3075395548, 3075395464, 134729792, 3075395360, 135890240, 3075395368, 134593920, 3075395544, 135890240, 3075395384, 134599542, 3020998404, 135890240, 3075395400, 134614095, 3075395544, 4, 3075395416, 134548135, 3021172996, 4294967295, 3075395432, 134692921, 3075395504, 0, 3075395448, 134548107, 3021172992}}} #3 0x0812eb45 in boost::asio::detail::task_io_service ::do_one (this=0x97f3a70, lock=@0xb74ed230, this_idle_thread=0xb74ed240, ec=@0xb74ed2c0) at /home/scottl/boost_1_41_0/boost/asio/detail/task_io_service.hpp:260 more_handlers = false c = {lock_ = @0xb74ed230, task_io_service_ = @0x97f3a70} h = (boost::asio::detail::handler_queue::handler *) 0x97f3aa0 polling = false task_has_run = true #4 0x0812765f in boost::asio::detail::task_io_service ::run (this=0x97f3a70, ec=@0xb74ed2c0) at /home/scottl/boost_1_41_0/boost/asio/detail/task_io_service.hpp:103 ctx = { = {}, owner_ = 0x97f3a70, next_ = 0x0} this_idle_thread = {wakeup_event = { = {}, cond_ = {__c_lock = { __status = 0, __spinlock = 22446}, __c_waiting = 0x2bd7, __padding = "\000\000\000\000×+\000\000\000\000\000\000×+\000\000\000\000\000\000\204:\177\t\000\000\000", __align = 0}, signalled_ = true}, next = 0x0} lock = { = {}, mutex_ = @0x97f3a84, locked_ = false} n = 11420 #5 0x08125e99 in boost::asio::io_service::run (this=0x97ebbcc) at /home/scottl/boost_1_41_0/boost/asio/impl/io_service.ipp:58 ec = {m_val = 0, m_cat = 0x81f2c24} s = 8 #6 0x08154424 in boost::_mfi::mf0::operator() (this=0x9800870, p=0x97ebbcc) at /home/scottl/boost_1_41_0/boost/bind/mem_fn_template.hpp:49 No locals. #7 0x08154331 in boost::_bi::list1 ::operator(), boost::_bi::list0 (this=0x9800878, f=@0x9800870, a=@0xb74ed337) at /home/scottl/boost_1_41_0/boost/bind/bind.hpp:236 No locals. #8 0x081541e5 in boost::_bi::bind_t, boost::_bi::list1 ::operator() (this=0x9800870) at /home/scottl/boost_1_41_0/boost/bind/bind_template.hpp:20 a = {} #9 0x08154075 in boost::detail::thread_data, boost::_bi::list1 ::run (this=0x98007a0) at /home/scottl/boost_1_41_0/boost/thread/detail/thread.hpp:56 No locals. #10 0x0816fefd in thread_proxy () at /usr/lib/gcc/i386-redhat-linux/3.4.6/../../../../include/c++/3.4.6/bits/locale_facets.tcc:2443 __ioinit = {static _S_refcount = , static _S_synced_with_stdio = } ---Type to continue, or q to quit--- typeinfo for common::RuntimeException = {} typeinfo name for common::RuntimeException = "N6common16RuntimeExceptionE" #11 0x00af23cc in start_thread () from /lib/tls/libpthread.so.0 No symbol table info available. #12 0x00a5c96e in __init_misc () from /lib/tls/libc.so.6 No symbol table info available.

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• Using string constants in implicit conversion

  - by kornelijepetak

  Consider the following code: public class TextType { public TextType(String text) { underlyingString = text; } public static implicit operator String(TextType text) { return text.underlyingString; } private String underlyingString; } TextType text = new TextType("Something"); String str = text; // This is OK. But I want to be able do the following, if possible. TextType textFromStringConstant = "SomeOtherText"; I can't extend the String class with the TextType implicit operator overload, but is there any way to assign a literal string to another class (which is handled by a method or something)? String is a reference type so when they developed C# they obviously had to use some way to get a string literal to the class. I just hope it's not hardcoded into the language.

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• Brainstorming: Weird JPA problem, possibly classpath or jar versioning problem???

  - by Vinnie

  I'm seeing a weird error message and am looking for some ideas as to what the problem could be. I'm sort of new to using the JPA. I have an application where I'm using Spring's Entity Manager Factory (LocalContainerEntityManagerFactoryBean), EclipseLink as my ORM provider, connected to a MySQL DB and built with Maven. I'm not sure if any of this matters..... When I deploy this application to Glassfish, the application works as expected. The problem is, I've created a set of stand alone unit tests to run outside of Glassfish that aren't working correctly. I get the following error (I've edited the class names a little) com.xyz.abc.services.persistence.entity.MyEntity cannot be cast to com.xyz.abc.services.persistence.entity.MyEntity The object cannot be cast to a class of the same type? How can that be? Here's a snippet of the code that is in error Query q = entityManager.createNamedQuery("MyEntity.findAll"); List entityObjects = q.getResultList(); for (Object entityObject: entityObjects) { com.xyz.abc.services.persistence.entity.MyEntity entity = (com.xyz.abc.services.persistence.entity.MyEntity) entityObject; Previously, I had this code that produced the same error: CriteriaQuery cq = entityManager.getCriteriaBuilder().createQuery(); cq.select(cq.from(com.xyz.abc.services.persistence.entity.MyEntity.class)); List entityObjects = entityManager.createQuery(cq).getResultList(); for (Object entityObject: entityObjects) { com.xyz.abc.services.persistence.entity.MyEntity entity = (com.xyz.abc.services.persistence.entity.MyEntity) entityObject; This code is question is the same that I have deployed to the server. Here's the innermost exception if it helps Caused by: java.lang.ClassCastException: com.xyz.abc.services.persistence.entity.MyEntity cannot be cast to com.xyz.abc.services.persistence.entity.MyEntity at com.xyz.abc.services.persistence.entity.factory.MyEntityFactory.createBeans(MyEntityFactory.java:47) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:115) ... 37 more I'm guessing that there's some jar I'm using in Glassfish that is different than the ones I'm using in test. I've looked at all the jars I have listed as "provided" and am pretty sure they are all the same ones from Glassfish. Let me know if you've seen this weird issue before, or any ideas for correcting it.

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• how to store BigInteger values in oracle database.

  - by Bipul

  I have connected Java program to Oracle database using JDBC. I want to store BigInteger values(512 bits) in the database. What should be the type of the column? I m trying like this: I have taken a column of number type in the database. I converted BigInteger to BigDecimal like this: BigInteger b=new BigInteger("5779857570957802579079"); Number n =b; BigDecimal d=(BigDecimal)n; PreparedStatement pstmt=con.prepareStatemant("insert into database values(?,?)"); pstmt.setString(1,"john"); pstmt.setBigDecimal(2,d); I am getting the following exception: javax.servlet.ServletException: java.lang.ClassCastException: java.math.BigInteger cannot be cast to java.math.BigDecimal root cause java.lang.ClassCastException: java.math.BigInteger cannot be cast to java.math.BigDecimal Is there anything wrong in this code snippet? If there is, please suggest other methods.

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• Nonstandard SSIS lookup

  - by Stefan

  I have a situation where I am trying to lookup a value in one table based on values in another table, using a BETWEEN operator and not an = operator. In one table, I have a value "EffectiveDate". I want to get a Weight number from another table, but the other table has two fields: "Inception" and "Termination". What I want to do is extract the Weight from that table for use where the EffectiveDate is between Inception and Termination. SSIS doesn't seem to provide a way to do this. It's good at matching one column to another column, but doesn't seem to allow one to many-column comparison/operations. Am I missing anything? Is this possible to do somehow?

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• Corner Cases, Unexpected and Unusual Matlab

  - by Mikhail

  Over the years, reading others code, I encountered and collected some examples of Matlab syntax which can be at first unusual and counterintuitive. Please, feel free to comment or complement this list. I verified it r2006a. set([], 'Background:Color','red') Matlab is very forgiving sometimes. In this case, setting properties to an array of objects works also with nonsense properties, at least when the array is empty. myArray([1,round(end/2)]) This use of end keyword may seem unclean but is sometimes very handy instead of using length(myArray). any([]) ~= all([]) Surprisigly any([]) returns false and all([]) returns true. And I always thought that all is stronger then any. EDIT: with not empty argument all() returns true for a subset of values for which any() returns true (e.g. truth table). This means that any() false implies all() false. This simple rule is being violated by Matlab with [] as argument. Loren also blogged about it. Select(Range(ExcelComObj)) Procedural style COM object method dispatch. Do not wonder that exist('Select') returns zero! [myString, myCell] Matlab makes in this case an implicit cast of string variable myString to cell type {myString}. It works, also if I would not expect it to do so. [double(1.8), uint8(123)] => 2 123 Another cast example. Everybody would probably expect uint8 value being cast to double but Mathworks have another opinion. a = 5; b = a(); It looks silly but you can call a variable with round brackets. Actually it makes sense because this way you can execute a function given its handle. a = {'aa', 'bb' 'cc', 'dd'}; Surprsisingly this code neither returns a vector nor rises an error but defins matrix, using just code layout. It is probably a relict from ancient times. set(hobj, {'BackgroundColor','ForegroundColor'},{'red','blue'}) This code does what you probably expect it to do. That function set accepts a struct as its second argument is a known fact and makes sense, and this sintax is just a cell2struct away. Equvalence rules are sometimes unexpected at first. For example 'A'==65 returns true (although for C-experts it is self-evident). About which further unexpected/unusual Matlab features are you aware?

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• python: iif or (x ? a : b)

  - by Albert

  If Python would support the (x ? a : b) syntax from C/C++, I would write: print paid ? ("paid: " + str(paid) + " €") : "not paid" I really don't want to have an if-check and two independent prints here (because that is only an example above, in my code, it looks much more complicated and would really be stupid to have almost the same code twice). However, Python does not support this operator or any similar operator (afaik). What is the easiest/cleanest/most common way to do this? I have searched a bit and seen someone defining an iif(cond,iftrue,iffalse) function, inspired from Visual Basic. I wondered if I really have to add that code and if/why there is no such basic function in the standard library.

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• Creating an AST node in Erlang

  - by dagda1

  Hi, I am playing about with Erlang and I am trying to write a simple arithmetic parser. I want to try and parse the following expression: ((12+3)-4) I want to parse the expression into a stack of AST nodes. When parsing this expression, I would first of all create a binary expression for the (12+3) expression which would look something like this in C#: var binaryStructure = new BinaryStructure(); binaryStructure.Left = IntegerLiteralExpression(12); binaryStructure.Right = IntegerLiteralExpression(4); binaryStructure.Operator = binaryExpression.Operator != BinaryOperatorType.Addition; I am quite new to Erlang and I am wondering how I would go about creating a structure like this in Erlang that I can place on a List that I would use as the stack of expressions. Can anyone suggest how to create such a tree like structure? Would a function be a good fit? Thanks Paul

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• May volatile be in user defined types to help writing thread-safe code

  - by David Rodríguez - dribeas

  I know, it has been made quite clear in a couple of questions/answers before, that volatile is related to the visible state of the c++ memory model and not to multithreading. On the other hand, this article by Alexandrescu uses the volatile keyword not as a runtime feature but rather as a compile time check to force the compiler into failing to accept code that could be not thread safe. In the article the keyword is used more like a required_thread_safety tag than the actual intended use of volatile. Is this (ab)use of volatile appropriate? What possible gotchas may be hidden in the approach? The first thing that comes to mind is added confusion: volatile is not related to thread safety, but by lack of a better tool I could accept it. Basic simplification of the article: If you declare a variable volatile, only volatile member methods can be called on it, so the compiler will block calling code to other methods. Declaring an std::vector instance as volatile will block all uses of the class. Adding a wrapper in the shape of a locking pointer that performs a const_cast to release the volatile requirement, any access through the locking pointer will be allowed. Stealing from the article: template <typename T> class LockingPtr { public: // Constructors/destructors LockingPtr(volatile T& obj, Mutex& mtx) : pObj_(const_cast<T*>(&obj)), pMtx_(&mtx) { mtx.Lock(); } ~LockingPtr() { pMtx_->Unlock(); } // Pointer behavior T& operator*() { return *pObj_; } T* operator->() { return pObj_; } private: T* pObj_; Mutex* pMtx_; LockingPtr(const LockingPtr&); LockingPtr& operator=(const LockingPtr&); }; class SyncBuf { public: void Thread1() { LockingPtr<BufT> lpBuf(buffer_, mtx_); BufT::iterator i = lpBuf->begin(); for (; i != lpBuf->end(); ++i) { // ... use *i ... } } void Thread2(); private: typedef vector<char> BufT; volatile BufT buffer_; Mutex mtx_; // controls access to buffer_ };

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• How Do I Loop Through a Date Range in Reverse?

  - by Russ Bradberry

  I have a date range that I would like to be able to loop through in reverse. Give the following, how would I accomplish this, the standard Range operator doesn't seem t be working properly. >> sd = Date.parse('2010-03-01') => Mon, 01 Mar 2010 >> ed = Date.parse('2010-03-05') => Fri, 05 Mar 2010 >> (sd..ed).to_a => [Mon, 01 Mar 2010, Tue, 02 Mar 2010, Wed, 03 Mar 2010, Thu, 04 Mar 2010, Fri, 05 Mar 2010] >> (ed..sd).to_a => [] as you can see, the range operator works properly form start to end, but not from end to start.

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