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  • Dropping all user tables/sequences in Oracle

    - by Ambience
    As part of our build process and evolving database, I'm trying to create a script which will remove all of the tables and sequences for a user. I don't want to do recreate the user as this will require more permissions than allowed. My script creates a procedure to drop the tables/sequences, executes the procedure, and then drops the procedure. I'm executing the file from sqlplus: drop.sql: create or replace procedure drop_all_cdi_tables is cur integer; begin cur:= dbms_sql.OPEN_CURSOR(); for t in (select table_name from user_tables) loop execute immediate 'drop table ' ||t.table_name|| ' cascade constraints'; end loop; dbms_sql.close_cursor(cur); cur:= dbms_sql.OPEN_CURSOR(); for t in (select sequence_name from user_sequences) loop execute immediate 'drop sequence ' ||t.sequence_name; end loop; dbms_sql.close_cursor(cur); end; / execute drop_all_cdi_tables; / drop procedure drop_all_cdi_tables; / Unfortunately, dropping the procedure causes a problem. There seems to cause a race condition and the procedure is dropped before it executes. E.g.: SQL*Plus: Release 11.1.0.7.0 - Production on Tue Mar 30 18:45:42 2010 Copyright (c) 1982, 2008, Oracle. All rights reserved. Connected to: Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production With the Partitioning, OLAP, Data Mining and Real Application Testing options Procedure created. PL/SQL procedure successfully completed. Procedure created. Procedure dropped. drop procedure drop_all_user_tables * ERROR at line 1: ORA-04043: object DROP_ALL_USER_TABLES does not exist SQL Disconnected from Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64 With the Partitioning, OLAP, Data Mining and Real Application Testing options Any ideas on how to get this working?

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  • Iterator performance contract (and use on non-collections)

    - by polygenelubricants
    If all that you're doing is a simple one-pass iteration (i.e. only hasNext() and next(), no remove()), are you guaranteed linear time performance and/or amortized constant cost per operation? Is this specified in the Iterator contract anywhere? Are there data structures/Java Collection which cannot be iterated in linear time? java.util.Scanner implements Iterator<String>. A Scanner is hardly a data structure (e.g. remove() makes absolutely no sense). Is this considered a design blunder? Is something like PrimeGenerator implements Iterator<Integer> considered bad design, or is this exactly what Iterator is for? (hasNext() always returns true, next() computes the next number on demand, remove() makes no sense). Similarly, would it have made sense for java.util.Random implements Iterator<Double>? Should a type really implement Iterator if it's effectively only using one-third of its API? (i.e. no remove(), always hasNext())

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  • Rails undefined method 'generated_methods' for nil:NilClass

    - by mike
    Okay so I was just starting this rails app and generated my first model ruby script/generate model Grid req:string class:string ctitle:string credits:float grade:string pass:boolean created my table rake db:migrate (in C:/Users/Michael/InstantRails/rails_apps/studentGrid) == CreateGrids: migrating ==================================================== -- create_table(:grids) - 0.0150s == CreateGrids: migrated (0.0150s) =========================================== and went to the console to add some data to my table Grid = Grid(id: integer, req: string, class: string, ctitle: string, credits: float, grade: string, pass: boolean, created_at: datetime, updated_at: datetime) Grid.create(:req="Math Elective", :class="Math 111", :ctitle="Calculus I", :credits=3.0) Pretty standard I thought, but then I get this error and I don't understand why NoMethodError: undefined method 'generated_methods' for nil:NilClass from C:/Users/Michael/InstantRails/ruby/lib/ruby/gems/1.8/gems/activesup port-2.3.5/lib/active_support/whiny_nil.rb:52:inmethod_missing' from C:/Users/Michael/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerec ord-2.3.5/lib/active_record/attribute_methods.rb:352:in respond_to?' from C:/Users/Michael/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerec ord-2.3.5/lib/active_record/base.rb:2746:inattributes=' from C:/Users/Michael/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerec ord-2.3.5/lib/active_record/base.rb:2742:in each' from C:/Users/Michael/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerec ord-2.3.5/lib/active_record/base.rb:2742:inattributes=' from C:/Users/Michael/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerec ord-2.3.5/lib/active_record/base.rb:2438:in initialize' from C:/Users/Michael/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerec ord-2.3.5/lib/active_record/base.rb:721:innew' from C:/Users/Michael/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerec ord-2.3.5/lib/active_record/base.rb:721:in `create' from (irb):2 from :0

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  • SQL 2008: Using separate tables for each datatype to return single row

    - by Thomas C
    Hi all I thought I'd be flexible this time around and let the users decide what contact information the wish to store in their database. In theory it would look as a single row containing, for instance; name, adress, zipcode, Category X, Listitems A. Example FieldType table defining the datatypes available to a user: FieldTypeID, FieldTypeName, TableName 1,"Integer","tblContactInt" 2,"String50","tblContactStr50" ... A user the define his fields in the FieldDefinition table: FieldDefinitionID, FieldTypeID, FieldDefinitionName 11,2,"Name" 12,2,"Adress" 13,1,"Age" Finally we store the actual contact data in separate tables depending on its datatype. Master table, only contains the ContactID tblContact: ContactID 21 22 tblContactStr50: ContactStr50ID,ContactID,FieldDefinitionID,ContactStr50Value 31,21,11,"Person A" 32,21,12,"Adress of person A" 33,22,11,"Person B" tblContactInt: ContactIntID,ContactID,FieldDefinitionID,ContactIntValue 41,22,13,27 Question: Is it possible to return the content of these tables in two rows like this: ContactID,Name,Adress,Age 21,"Person A","Adress of person A",NULL 22,"Person B",NULL,27 I have looked into using the COALESCE and Temp tables, wondering if this is at all possible. Even if it is: maybe I'm only adding complexity whilst sacrificing performance for benefit in datastorage and user definition option. What do you think? Best Regards /Thomas C

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  • Running SQLite 3 in MicroApache

    - by Alien426
    I'm running MicroApache (http://microapache.amadis.sytes.net) on Windows XP and would like to use SQLite 3 databases. The PHP version is 5.2.9-2. My MicroApache version has SQLite 2 support through 2 lines in the php.ini: extension=php_pdo.dll extension=php_sqlite.dll I test whether the extension works in 3 ways: 1. phpinfo() 2. extension_loaded() and get_loaded_extensions() 3. using sample code that var_dump()s the constant SQLITE3_NUM (should be the integer 2) and tries to create a database (error: class 'SQLite3' does not exist) Things I have tried (if I can remember them all): 1. copied php_sqlite3.dll from a full installation of PHP and added "extension=php_sqlite3.dll" to php.ini - error "Procedure entry point gc_remove_zval_from_buffer was not found in php5ts.dll" 2. compressed the DLL with UPX (like the other DLLs of MicroApache seem to be) - does not display an error on start, nor in the log file, but does not work 3. tried various things with php.ini - created a section "[sqlite3]" - prefixed "sqlite3." to "extension_dir=." and "extension=php_sqlite3.dll" - ... 4. tried to use PDO, it says it 'could not find driver' Who can help me get SQLite 3 to work?

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  • Thread Message Loop Hangs in Delphi

    - by erikjw
    Hello all. I have a simple Delphi program that I'm working on, in which I am attempting to use threading to separate the functionality of the program from its GUI, and to keep the GUI responsive during more lengthy tasks, etc. Basically, I have a 'controller' TThread, and a 'view' TForm. The view knows the controller's handle, which it uses to send the controller messages via PostThreadMessage. I have had no problem in the past using this sort of model for forms which are not the main form, but for some reason, when I attempt to use this model for the main form, the message loop of the thread just quits. Here is my code for the threads message loop: procedure TController.Execute; var Msg : TMsg; begin while not Terminated do begin if (Integer(GetMessage(Msg, hwnd(0), 0, 0)) = -1) then begin Synchronize(Terminate); end; TranslateMessage(Msg); DispatchMessage(Msg); case Msg.message of // ...call different methods based on message end; end; To set up the controller, I do this: Controller := TController.Create(true); // Create suspended Controller.FreeOnTerminate := True; Controller.Resume; For processing the main form's messages, I have tried using both Application.Run and the following loop (immediately after Controller.Resume) while not Application.Terminated do begin Application.ProcessMessages; end; I've run stuck here - any help would be greatly appreciated.

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  • VB.NET handling data between different forms

    - by niuchu
    Hi, I'm writing a simple application - address book. User enters new addresses and they are added as an entry to a list visible on the main form (frmStart). I use one form to add and edit (AddContForm). Add button on the frmStart works fine, however I experience some problems with the edit button as when I press it and enter new data they are added as new entry however the previous entry is still there. Logic is handled by Contact.vb class. Please let me know how to fix this problem. Here is the code: Contact.vb Public Class Contact Public Contact As String Public Title As String Public Fname As String Public Surname As String Public Address As String Private myCont As String Public Property Cont() Get Return myCont End Get Set(ByVal value) myCont = Value End Set End Property Public Overrides Function ToString() As String Return Me.Cont End Function Public Sub Display() Dim C As New Contact C.Cont = frmAddCont.txtTitle.Text C.Fname = frmAddCont.txtFName.Text C.Surname = frmAddCont.txtSName.Text C.Address = frmAddCont.txtAddress.Text frmStart.lstContact.Items.Add(C) End Sub End Class Here is frmStart.vb Public Class frmStart Public Button As String Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click Button = "" Button = "Add" frmAddCont.ShowDialog() End Sub Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDel.Click Button = "" Button = "Del" Dim DelCont As Contact DelCont = Me.lstContact.SelectedItem() lstContact.Items.Remove(DelCont) End Sub Private Sub lstContact_SelectedIndexChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles lstContact.SelectedIndexChanged End Sub Private Sub btnEdit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEdit.Click Button = "" Button = "Edit" Dim C As Contact If lstContact.SelectedItem IsNot Nothing Then C = DirectCast(lstContact.SelectedItem, Contact) frmAddCont.ShowDialog() End If End Sub End Class Here is AddContFrm.vb Public Class frmAddCont Public Class ControlObject Dim Title As String Dim FName As String Dim SName As String Dim Address As String Dim TelephoneNumber As Integer Dim emailAddress As String Dim Website As String Dim Photograph As String End Class Private Sub btnConfirmAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnConfirmAdd.Click Dim B As String B = frmStart.Button Dim C As New Contact C.Display() Me.Hide() If B = "Edit" Then C = DirectCast(frmStart.lstContact.SelectedItem, Contact) frmStart.lstContact.SelectedItems.Remove(C) End If End Sub Private Sub frmAddCont_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load End Sub End Class

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  • How to implement IEquatable<T> when mutable fields are part of the equality - Problem with GetHashCo

    - by Shimmy
    Hello! I am using Entity Framework in my application. I implemented with the partial class of an entity the IEquatable<T> interface: Partial Class Address : Implements IEquatable(Of Address) 'Other part generated Public Overloads Function Equals(ByVal other As Address) As Boolean _ Implements System.IEquatable(Of Address).Equals If ReferenceEquals(Me, other) Then Return True Return AddressId = other.AddressId End Function Public Overrides Function Equals(ByVal obj As Object) As Boolean If obj Is Nothing Then Return MyBase.Equals(obj) If TypeOf obj Is Address Then Return Equals(DirectCast(obj, Address)) Else Return False End Function Public Overrides Function GetHashCode() As Integer Return AddressId.GetHashCode End Function End Class Now in my code I use it this way: Sub Main() Using e As New CompleteKitchenEntities Dim job = e.Job.FirstOrDefault Dim address As New Address() job.Addresses.Add(address) Dim contains1 = job.Addresses.Contains(address) 'True e.SaveChanges() Dim contains2 = job.Addresses.Contains(address) 'False 'The problem is that I can't remove it: Dim removed = job.Addresses.Remoeve(address) 'False End Using End Sub Note (I checked in the debugger visualizer) that the EntityCollection class stores its entities in HashSet so it has to do with the GetHashCode function, I want it to depend on the ID so entities are compared by their IDs. The problem is that when I hit save, the ID changes from 0 to its db value. So the question is how can I have an equatable object, being properly hashed. Please help me find what's wrong in the GetHashCode function (by ID) and what can I change to make it work. Thanks a lot.

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  • SQL query using information from 4 tables (not all directly linked)

    - by Yvonne
    I'm developing a simple classroom system, where teachers manage classes and their subjects. I have 2 levels of access in my teachers table, assigned by an integer (1 = admin, 2 = user)... Meaning that the headteacher is the admin :) A teacher (of level 1) can have have many classes and a class can have many teachers (so I have 'TeachersClasses' table). A class can have many subjects, and a teacher can have many subjects. Basically, I'm attempting a query to display the admin teacher's (level 1) subjects. However, only teachers with a level of 2, are directly related to a subject, which is set by the admin user. The headteacher can view all of their subjects via the classroom, but I cannot get all of the subjects to be displayed on one page, instead I can only get the subjects to appear under a specific classroom right now... This is what I have so far, which is returning nothing. (I'm guessing this may require an SQL clause more advanced that 'INNER JOIN' which is the only join type I am familiar with, and thought it would be enough! $query = "SELECT subjects.subjectid, subjects.subjectname, subjects.subjectdetails, classroom.classid, classroom.classname FROM subjects INNER JOIN classroom ON subjects.subjectid = classroom.classid INNER JOIN teacherclasses ON classroom.classid = teacherclasses.classid INNER JOIN teachers ON teacherclasses.teacherid = teachers.teacherid WHERE teachers.teacherid = '".intval( $_SESSION['SESS_TEACHERID'] )."'"; In order for all subjects related to the headteachers class to be displayed, I'm gathering that all of my tables will need to be called up here? Thanks for any help! Example output: subject name: maths // teacher: mr smith // classroom: DG99 x10 for all the subjects associated with the headteachers classrooms :)

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  • Compiling and using NTL c++ library for Windows

    - by Martin Lauridsen
    Hi there, I have compiled the NTL inifite precision integer arithmetic library for c++, using Microsoft Visual Studio 2008. I did as explained, on this site, using the Visual Studio interface, rather than from the command prompt. Actually I would rather do it from the command prompt, but I was not sure how to. Anyhow, I got the library compiled, and I now want to compile a program using the library, from the command prompt. The program I am trying to compile, has been tested on a linux system, where I compile it with the following c++ -I/appl/htopopt/Linux_x86_64/NTL-5.4.2/include mpqs.cpp main.cpp -o main -L/appl/htopopt/Linux_x86_64/NTL-5.4.2/lib -lntl -L/appl/htopopt/Linux_x86_64/gmp-4.2.1/lib -lgmp -lm Nevermind the gmp stuff, I dont have that installed on Windows. It is purely an optional thing that will make the NTL run faster. Anyhow, this works fine on linux. Now on Windows I write the following cl /EHsc /I D:\Downloads\WinNTL-5_5_2\include mpqs.cpp main.cpp /link /LIBPATH:"D:\Documents\Visual Studio 2008\Projects\ntl\Debug" But this results in the following errors: mpqs.cpp mpqs.cpp(38) : error C2039: 'find_smooth_vals' : is not a member of 'QS' d:\desktop\qs\mpqs.h(12) : see declaration of 'QS' mpqs.cpp(41) : error C2065: 'M' : undeclared identifier mpqs.cpp(41) : error C2065: 'n' : undeclared identifier mpqs.cpp(42) : error C2065: 'sieve_table' : undeclared identifier mpqs.cpp(42) : error C2228: left of '.size' must have class/struct/union type is ''unknown-type'' mpqs.cpp(43) : error C2065: 'sieve_table' : undeclared identifier mpqs.cpp(44) : error C2065: 'qx_table' : undeclared identifier mpqs.cpp(44) : error C3861: 'test_smoothness': identifier not found mpqs.cpp(45) : error C2065: 'smooth_indices' : undeclared identifier mpqs.cpp(45) : error C2228: left of '.push_back' must have class/struct/union type is ''unknown-type'' main.cpp Generating Code... It is as if, my mpqs.h file is not included into the compilation process? Also I dont understand why it complains about .push_back() for a vector type? Help is much appreciated!

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  • possible xml elements in Android resources xmls ?

    - by Vijay C
    I recently came across a forum post in thelink text android developers group. (link below) It has one post which contains following xml. It is xml file which can be used in drawable folder. <selector xmlns:android="http://schemas.android.com/apk/res/android"> <!-- Non focused states --> <item android:state_focused="false" android:state_selected="false" android:state_pressed="false" android:drawable="@drawable/tab_unselected" /> <item android:state_focused="false" android:state_selected="true" android:state_pressed="false" android:drawable="@drawable/tab_selected" /> <!-- Focused states --> <item android:state_focused="true" android:state_selected="false" android:state_pressed="false" android:drawable="@drawable/tab_focus" /> <item android:state_focused="true" android:state_selected="true" android:state_pressed="false" android:drawable="@drawable/tab_focus"/> <!-- Pressed --> <item android:state_pressed="true" android:drawable="@drawable/tab_press" /> </selector> Now my question is, where is the documentation which tells me that i can use the following xml tags <selector> , <item>, <color>, <integer-array>, <string-array> and many others tag to create xml resources...? I hope, i have explained what i want to know ?

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  • Is there a PHP benchmark that meets these specific criteria? [closed]

    - by Alex R
    I'm working on a tool which converts PHP code to Scala. As one of the finishing touches, I'm in need of a really good (er, somewhat biased) benchmark. By dumb luck my first benchmark attempt was with some code which uses bcmath extensively, which unfortunately is 1000x slower in Java, making the Scala code 22x slower overall than the original PHP. So I'm looking for some meaningful PHP benchmark with the following characteristics: The PHP source needs to be in a single file. It should solve a real-world problem. No silly looping over empty methods etc. I need it to be simple to setup - no databases, hard-to-find input files, etc. Simple text input and output preferred. It should not use features that are slow in Java (BigInteger, trigonometric functions, etc). It should not use exoteric or dynamic PHP functions (e.g. no "eval" or "variable vars"). It should not over-rely on built-in libraries, e.g. MD5, crypt, etc. It should not be I/O bound. A CPU-bound memory-hungry algorithm is preferred. Basically, intensive OO operations, integer and string manipulation, recursion, etc would be great. Thanks

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  • PHP OOP: Providing Domain Entities with "Identity"

    - by sunwukung
    Bit of an abstract problem here. I'm experimenting with the Domain Model pattern, and barring my other tussles with dependencies - I need some advice on generating Identity for use in an Identity Map. In most examples for the Data Mapper pattern I've seen (including the one outlined in this book: http://apress.com/book/view/9781590599099) - the user appears to manually set the identity for a given Domain Object using a setter: $UserMapper = new UserMapper; //returns a fully formed user object from record sets $User = $UserMapper->find(1); //returns an empty object with appropriate properties for completion $UserBlank = $UserMapper->get(); $UserBlank->setId(); $UserBlank->setOtherProperties(); Now, I don't know if I'm reading the examples wrong - but in the first $User object, the $id property is retrieved from the data store (I'm assuming $id represents a row id). In the latter case, however, how can you set the $id for an object if it has not yet acquired one from the data store? The problem is generating a valid "identity" for the object so that it can be maintained via an Identity Map - so generating an arbitrary integer doesn't solve it. My current thinking is to nominate different fields for identity (i.e. email) and demanding their presence in generating blank Domain Objects. Alternatively, demanding all objects be fully formed, and using all properties as their identity...hardly efficient. (Or alternatively, dump the Domain Model concept and return to DBAL/DAO/Transaction Scripts...which is seeming increasingly elegant compared to the ORM implementations I've seen...)

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  • How to make this OO?

    - by John
    Hello, Sorry for the poor title,I'm new to OOP so I don't know what is the term for what I need to do. I have, say, 10 different Objects that inherit one Object.They have different amount and type of class members,but all of them have one property in common - Visible. type TObj1=class(TObject) private a:integer; ...(More members) Visible:Boolean; end; TObj2=class(TObject) private b:String; ...(More members) Visible:Boolean; end; ...(Other 8 objects) For each of them I have a variable. var Obj1:TObj1; Obj2:TObj2; Obj3:TObj3; ....(Other 7 objects) Rule 1: Only one object can be initialized at a time(others have to be freed) to be visible. For this rule I have a global variable var CurrentVisibleObj:TObject; //Because they all inherit TObject Finally there is a procedure that changes visibility. procedure ChangeObjVisibility(newObj:TObject); begin CurrentVisibleObj.Free; //Free the old object CurrentVisibleObj:=newObj; //assign the new object CurrentVisibleObj:= ??? //Create new object CurrentVisibleObj.Visible:=true; //Set visibility to new object end; There is my problem,I don't know how to initialize it,because the derived class is unknown. How do I do this? I simplified the explanation,in the project there are TFrames each having different controls and I have to set visible/not visible the same way(By leaving only one frame initialized). Sorry again for the title,I'm very new to OOP.

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  • What is the name of this geometrical function?

    - by Spike
    In a two dimentional integer space, you have two points, A and B. This function returns an enumeration of the points in the quadrilateral subset bounded by A and B. A = {1,1} B = {2,3} Fn(A,B) = {{1,1},{1,2},{1,3},{2,1},{2,2},{2,3}} I can implement it in a few lines of LINQ. private void UnknownFunction(Point to, Point from, List<Point> list) { var vectorX = Enumerable.Range(Math.Min(to.X, from.X), Math.Abs(to.X - from.Y) + 1); var vectorY = Enumerable.Range(Math.Min(to.Y, from.Y), Math.Abs(to.Y - from.Y) + 1); foreach (var x in vectorX) foreach (var y in vectorY) list.Add(new Point(x, y)); } I'm fairly sure that this is a standard mathematical operation, but I can't think what it is. Feel free to tell me that it's one line of code in your language of choice. Or to give me a cunning implementation with lambdas or some such. But mostly I just want to know what it's called. It's driving me nuts. It feels a little like a convolution, but it's been too long since I was at school for me to be sure.

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  • Serializing Exceptions WCF + Silverlight

    - by Bram
    I have a WCF service I use to submit bugs for my project. Snippet of the data class: Private _exception As Exception <DataMember()> _ Public Property Exception As Exception Get Return _exception End Get Set(ByVal value As Exception) _exception = value End Set End Property I have a Silverlight app that uses the WCF service to send any bugs home if and when they occur. This is the error I'm testing with: Dim i As Integer = 5 i = i / 0 The problem is SL is banging on with this message: System.ServiceModel.CommunicationException was unhandled by user code Message=There was an error while trying to serialize parameter :bug. The InnerException message was 'Type 'System.OverflowException' with data contract name 'OverflowException:http://schemas.datacontract.org/2004/07/System' is not expected. Add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.'. Please see InnerException for more details. Is there some trick to get a generic .NET Exception (any InnerException) to serialize properly? I'm not doing anything funky with the exception - it's just a plain 'ol exception Thanks for any help.

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  • What Scheme Does Ghuloum Use?

    - by Don Wakefield
    I'm trying to work my way through Compilers: Backend to Frontend (and Back to Front Again) by Abdulaziz Ghuloum. It seems abbreviated from what one would expect in a full course/seminar, so I'm trying to fill in the pieces myself. For instance, I have tried to use his testing framework in the R5RS flavor of DrScheme, but it doesn't seem to like the macro stuff: src/ghuloum/tests/tests-driver.scm:6:4: read: illegal use of open square bracket I've read his intro paper on the course, An Incremental Approach to Compiler Construction, which gives a great overview of the techniques used, and mentions a couple of Schemes with features one might want to implement for 'extra credit', but he doesn't mention the Scheme he uses in the course. Update I'm still digging into the original question (investigating options such as Petit Scheme suggested by Eli below), but found an interesting link relating to Gholoum's work, so I am including it here. [Ikarus Scheme](http://en.wikipedia.org/wiki/Ikarus_(Scheme_implementation)) is the actual implementation of Ghuloum's ideas, and appears to have been part of his Ph.D. work. It's supposed to be one of the first implementations of R6RS. I'm trying to install Ikarus now, but the configure script doesn't want to recognize my system's install of libgmp.so, so my problems are still unresolved. Example The following example seems to work in PLT 2.4.2 running in DrEd using the Pretty Big (require lang/plt-pretty-big) (load "/Users/donaldwakefield/ghuloum/tests/tests-driver.scm") (load "/Users/donaldwakefield/ghuloum/tests/tests-1.1-req.scm") (define (emit-program x) (unless (integer? x) (error "---")) (emit " .text") (emit " .globl scheme_entry") (emit " .type scheme_entry, @function") (emit "scheme_entry:") (emit " movl $~s, %eax" x) (emit " ret") ) Attempting to replace the require directive with #lang scheme results in the error message foo.scm:7:3: expand: unbound identifier in module in: emit which appears to be due to a failure to load tests-driver.scm. Attempting to use #lang r6rs disables the REPL, which I'd really like to use, so I'm going to try to continue with Pretty Big. My thanks to Eli Barzilay for his patient help.

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  • Python byte per byte XOR decryption

    - by neurino
    I have an XOR encypted file by a VB.net program using this function to scramble: Public Class Crypter ... 'This Will convert String to bytes, then call the other function. Public Function Crypt(ByVal Data As String) As String Return Encoding.Default.GetString(Crypt(Encoding.Default.GetBytes(Data))) End Function 'This calls XorCrypt giving Key converted to bytes Public Function Crypt(ByVal Data() As Byte) As Byte() Return XorCrypt(Data, Encoding.Default.GetBytes(Me.Key)) End Function 'Xor Encryption. Private Function XorCrypt(ByVal Data() As Byte, ByVal Key() As Byte) As Byte() Dim i As Integer If Key.Length <> 0 Then For i = 0 To Data.Length - 1 Data(i) = Data(i) Xor Key(i Mod Key.Length) Next End If Return Data End Function End Class and saved this way: Dim Crypter As New Cryptic(Key) 'open destination file Dim objWriter As New StreamWriter(fileName) 'write crypted content objWriter.Write(Crypter.Crypt(data)) Now I have to reopen the file with Python but I have troubles getting single bytes, this is the XOR function in python: def crypto(self, data): 'crypto(self, data) -> str' return ''.join(chr((ord(x) ^ ord(y)) % 256) \ for (x, y) in izip(data.decode('utf-8'), cycle(self.key)) I had to add the % 256 since sometimes x is 256 i.e. not a single byte. This thing of two bytes being passed does not break the decryption because the key keeps "paired" with the following data. The problem is some decrypted character in the conversion is wrong. These chars are all accented letters like à, è, ì but just a few of the overall accented letters. The others are all correctly restored. I guess it could be due to the 256 mod but without it I of course get a chr exception... Thanks for your support

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  • Have suggestions for these assembly mnemonics?

    - by Noctis Skytower
    Greetings! Last semester in college, my teacher in the Computer Languages class taught us the esoteric language named Whitespace. In the interest of learning the language better with a very busy schedule (midterms), I wrote an interpreter and assembler in Python. An assembly language was designed to facilitate writing programs easily, and a sample program was written with the given assembly mnemonics. Now that it is summer, a new project has begun with the objective being to rewrite the interpreter and assembler for Whitespace 0.3, with further developments coming afterwards. Since there is so much extra time than before to work on its design, you are presented here with an outline that provides a revised set of mnemonics for the assembly language. This post is marked as a wiki for their discussion. Have you ever had any experience with assembly languages in the past? Were there some instructions that you thought should have been renamed to something different? Did you find yourself thinking outside the box and with a different paradigm than in which the mnemonics were named? If you can answer yes to any of those questions, you are most welcome here. Subjective answers are appreciated! Stack Manipulation (IMP: [Space]) Stack manipulation is one of the more common operations, hence the shortness of the IMP [Space]. There are four stack instructions. hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item Arithmetic (IMP: [Tab][Space]) Arithmetic commands operate on the top two items on the stack, and replace them with the result of the operation. The first item pushed is considered to be left of the operator. add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo Heap Access (IMP: [Tab][Tab]) Heap access commands look at the stack to find the address of items to be stored or retrieved. To store an item, push the address then the value and run the store command. To retrieve an item, push the address and run the retrieve command, which will place the value stored in the location at the top of the stack. save Store load Retrieve Flow Control (IMP: [LF]) Flow control operations are also common. Subroutines are marked by labels, as well as the targets of conditional and unconditional jumps, by which loops can be implemented. Programs must be ended by means of [LF][LF][LF] so that the interpreter can exit cleanly. L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller halt End the program I/O (IMP: [Tab][LF]) Finally, we need to be able to interact with the user. There are IO instructions for reading and writing numbers and individual characters. With these, string manipulation routines can be written. The read instructions take the heap address in which to store the result from the top of the stack. print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack Question: How would you redesign, rewrite, or rename the previous mnemonics and for what reasons?

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  • JPA/Hibernate query with class name?

    - by Petteri Hietavirta
    In this example com.test.Cat extends com.test.Animal and there is no field DB in CAT table of com.test.Cat explicitly defining its type (it wasn't me). When I query my animals from DB I get a collection of Animals. It is possible to sort them by class name: order by r.class but is there a way to use class name as a criteria? For example I would like to get all animals expect dogs. But no luck - even this does not work: where r.class = ? (String "ccc.test.Cat") as I get an exception: Caused by: java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Integer at org.hibernate.type.IntegerType.set(IntegerType.java:64) at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:154) at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:136) at org.hibernate.param.PositionalParameterSpecification.bind(PositionalParameterSpecification.java:62) at org.hibernate.loader.hql.QueryLoader.bindParameterValues(QueryLoader.java:514) at org.hibernate.loader.Loader.prepareQueryStatement(Loader.java:1589) at org.hibernate.loader.Loader.doQuery(Loader.java:696) at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259) at org.hibernate.loader.Loader.doList(Loader.java:2228) at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2125) at org.hibernate.loader.Loader.list(Loader.java:2120) at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:401) at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:361) at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196) at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1148) at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102) at org.hibernate.ejb.QueryImpl.getResultList(QueryImpl.java:67)

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  • Triangle numbers problem....show within 4 seconds

    - by Daredevil
    The sequence of triangle numbers is generated by adding the natural numbers. So the 7th triangle number would be 1 + 2 + 3 + 4 + 5 + 6 + 7 = 28. The first ten terms would be: 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, ... Let us list the factors of the first seven triangle numbers: 1: 1 3: 1,3 6: 1,2,3,6 10: 1,2,5,10 15: 1,3,5,15 21: 1,3,7,21 28: 1,2,4,7,14,28 We can see that 28 is the first triangle number to have over five divisors. Given an integer n, display the first triangle number having at least n divisors. Sample Input: 5 Output 28 Input Constraints: 1<=n<=320 I was obviously able to do this question, but I used a naive algorithm: Get n. Find triangle numbers and check their number of factors using the mod operator. But the challenge was to show the output within 4 seconds of input. On high inputs like 190 and above it took almost 15-16 seconds. Then I tried to put the triangle numbers and their number of factors in a 2d array first and then get the input from the user and search the array. But somehow I couldn't do it: I got a lot of processor faults. Please try doing it with this method and paste the code. Or if there are any better ways, please tell me.

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  • How to create database records for a financial year

    - by David A Gibson
    Hello, I need to create entities (specifically contracts) in a database table that are associated with a financial year. These contracts will be applied to projects. Any contract variation will be recorded by creating a new contract record for the same financial year but the original will remain associated with the project as a history. The projects can last several years and so at any one time a project will have a live contract record for each year as well as any number of historic contracts for that year. All of which is incidental but I'm trying to provide some context. If the contracts where for the year - it would be easy and I'd just store the Year either as a date field with the 1st of January or just an Integer. However the contracts run for financial years and I don't know how to approach this. I don't want a separate table containing the financial years as I don't want the users to have to maintain this. I don't want to store the financial year as a string "2009/2010" as this is not ideal for sorting/extracting the data. Any ideas will be helpful, my best so far is to have starting and ending year in 2 columns and just "KNOW" that starting is April of the year etc Thanks

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  • Which is better Java programming practice for looping up to an int value: a converted for-each loop

    - by Arvanem
    Hi folks, Given the need to loop up to an arbitrary int value, is it better programming practice to convert the value into an array and for-each the array, or just use a traditional for loop? FYI, I am calculating the number of 5 and 6 results ("hits") in multiple throws of 6-sided dice. My arbitrary int value is the dicePool which represents the number of multiple throws. As I understand it, there are two options: Convert the dicePool into an array and for-each the array: public int calcHits(int dicePool) { int[] dp = new int[dicePool]; for (Integer a : dp) { // call throwDice method } } Use a traditional for loop. public int calcHits(int dicePool) { for (int i = 0; i < dicePool; i++) { // call throwDice method } } I apologise for the poor presentation of the code above (for some reason the code button on the Ask Question page is not doing what it should). My view is that option 1 is clumsy code and involves unnecessary creation of an array, even though the for-each loop is more efficient than the traditional for loop in Option 2. Thanks in advance for any suggestions you might have.

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  • Opengl Iphone SDK: How to tell if you're touching an object on screen?

    - by TheGambler
    First is my touchesBegan function and then the struct that stores the values for my object. I have an array of these objects and I'm trying to figure out when I touch the screen if I'm touching an object on the screen. I don't know if I need to do this by iterating through all my objects and figure out if I'm touching an object that way or maybe there is an easier more efficient way. How is this usually handled? -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{ [super touchesEnded:touches withEvent:event]; UITouch* touch = ([touches count] == 1 ? [touches anyObject] : nil); CGRect bounds = [self bounds]; CGPoint location = [touch locationInView:self]; location.y = bounds.size.height - location.y; float xTouched = location.x/20 - 8 + ((int)location.x % 20)/20; float yTouched = location.y/20 - 12 + ((int)location.y % 20)/20; } typedef struct object_tag // Create A Structure Called Object { int tex; // Integer Used To Select Our Texture float x; // X Position float y; // Y Position float z; // Z Position float yi; // Y Increase Speed (Fall Speed) float spinz; // Z Axis Spin float spinzi; // Z Axis Spin Speed float flap; // Flapping Triangles :) float fi; // Flap Direction (Increase Value) } object;

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  • Keyboard input: how to separate keycodes received from user

    - by Iulian Serbanoiu
    Hello, I am writing an application involving user input from the keyboard. For doing it I use this way of reading the input: #include <stdio.h> #include <termios.h> #include <unistd.h> int mygetch( ) { struct termios oldt, newt; int ch; tcgetattr( STDIN_FILENO, &oldt ); newt = oldt; newt.c_lflag &= ~( ICANON | ECHO ); tcsetattr( STDIN_FILENO, TCSANOW, &newt ); ch = getchar(); tcsetattr( STDIN_FILENO, TCSANOW, &oldt ); return ch; } int main(void) { int c; do{ c = mygetch(); printf("%d\n",c); }while(c!='q'); return 0; } Everyting works fine for letters digits,tabs but when hiting DEL, LEFT, CTRL+LEFT, F8 (and others) I receive not one but 3,4,5 or even 6 characters. The question is: Is is possible to make a separation of these characters (to actually know that I only hit one key or key combination). What I would like is to have a function to return a single integer value for any type of input (letter, digit, F1-F12, DEl, PGUP, PGDOWN, CTRL+A, CTRL+ALT+A, ALT+LEFT, etc). Is this possible? I'm interested in an idea to to this, the language doesn't matter much, though I'd prefer perl or c. Thanks, Iulian

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