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  • Why does Facebook convert PHP code to C++?

    - by user72245
    I read that Facebook started out in PHP, and then to gain speed, they now compile PHP as C++ code. If that's the case why don't they: Just program in c++? Surely there must be SOME errors/bugs when hitting a magic compiler button that ports PHP to c++ code , right? If this impressive converter works so nicely, why stick to PHP at all? Why not use something like Ruby or Python? Note -- I picked these two at random, but mostly because nearly everyone says coding in those languages is a "joy". So why not develop in a super great language and then hit the magic c++ compile button?

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  • How compilers know about other classes and their properties?

    - by OnResolve
    I'm writing my first programming language that is object orientated and so far so good with create a single 'class'. But, let's say I want to have to classes, say ClassA and ClassB. Provided these two have nothing to do with each other then all is good. However, say ClassA creates a ClassB--this poses 2 related questions: -How would the compiler know when compiling ClassA that ClassB even exists, and, if it does, how does it know it's properties? My thoughts thus far had been: instead of compiling each class at a time (i.e scan, parse and generate code) each "file (not really file, per se, but a "class") do I need to scan + parse each first, then generate code for all?

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  • red-black tree - construction

    - by Chaitanya
    Recently, I have been going through search trees and I encountered red-black trees, the point confusing me is, In r-b tree, the root node should be black thats fine, now how will I decide whether the incoming node assumes red or black color. I have gone through the wiki article but have not found a solution for this. I might be wrong, but I would be happy if someone can guide me through the exact material. Thank you.

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  • [C#] WebClient construction overhead

    - by Barguast
    I have a client which makes a limited number of concurrent web requests. I use WebClient for this purpose. I currently have a pool of WebClient-s which I create once and use whichever one is idle. This approach is becoming a little cumbersome though, and I'm wondering if there is any benefit to having a collection of pre-constructed WebClient instances, or if creating them on the fly wouldn't be too much trouble?

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  • NHibernate criteria construction

    - by brianberns
    I am trying to recreate something like the following SQL using NHibernate criteria: select Range, count(*) from ( select case when ent.ID between 'A' and 'N' then 'A-M' else 'Other' end as Range from Subject ) tbl group by tbl.Range I am able to create the inner select as follows: session.CreateCriteria<Subject>() .SetProjection( Projections.Conditional( Expression.Between("Name", "A", "N"), Projections.Constant("A-N"), Projections.Constant("Other"))) .List(); However, I can't figure out how to pipe those results into a grouping by row count. Any suggestions? Thanks. -- Brian

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  • Setting attributes of a class during construction from **kwargs

    - by Carson Myers
    Python noob here, Currently I'm working with SQLAlchemy, and I have this: from __init__ import Base from sqlalchemy.schema import Column, ForeignKey from sqlalchemy.types import Integer, String from sqlalchemy.orm import relationship class User(Base): __tablename__ = "users" id = Column(Integer, primary_key=True) username = Column(String, unique=True) email = Column(String) password = Column(String) salt = Column(String) openids = relationship("OpenID", backref="users") User.__table__.create(checkfirst=True) #snip definition of OpenID class def create(**kwargs): user = User() if "username" in kwargs.keys(): user.username = kwargs['username'] if "email" in kwargs.keys(): user.username = kwargs['email'] if "password" in kwargs.keys(): user.password = kwargs['password'] return user This is in /db/users.py, so it would be used like: from db import users new_user = users.create(username="Carson", password="1234") new_user.email = "[email protected]" users.add(new_user) #this function obviously not defined yet but the code in create() is a little stupid, and I'm wondering if there's a better way to do it that doesn't require an if ladder, and that will fail if any keys are added that aren't in the User object already. Like: for attribute in kwargs.keys(): if attribute in User: user.__attribute__[attribute] = kwargs[attribute] else: raise Exception("blah") that way I could put this in its own function (unless one hopefully already exists?) So I wouldn't have to do the if ladder again and again, and so I could change the table structure without modifying this code. Any suggestions?

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  • default value support for Entity Framework object construction to avoid having to set this column pa

    - by Greg
    Hi, In entity framework is there a way to have a default value for a column such that Linq to Entity won't require this parameter when constructing a new object? For example I've marked on column in the EF designer with a default value (I typed in "All" as it was a string). But if I try to construct a new record and not specify this parameter I still get a FOREIGN KEY constraint exception. The INSERT statement conflicted with the FOREIGN KEY constraint "FK_FunctionalityTypeInterfaceRelationship"

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  • Linq like or other construction

    - by Yauhen Kavalenka
    I have DB oracle in my solution. I want to have some results in this query. Query example: select * from doctor where doctor.name like '%IVANOV_A%'; But if i do it at LINQ i cannot get any result. from p in repository.Doctor.Where(x => x.Name.ToLower().Containsname)) select p; Where 'name' is variable of string parameter. Web layout request next string: "Ivanov a" or "A Ivanov" But i suggest for user choose you pattetn for query. How i can to get "patient by name" if name consist of "First name" and "Last name" but user doesn't know your doctor's full name?

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  • Source operator doesn't work in if construction in bash

    - by Igor
    Hello, I'd like to include a config file in my bash script with 2 conditions: 1) the config file name is constructed on-the-fly and stored in variable, and 2) in case if config file doesn't exist, the script should fail: config.cfg: CONFIGURED=yes test.sh: #!/bin/sh $CFG=config.cfg echo Source command doesn't work here: [ -f $CFG ] && ( source $CFG ) || (echo $CFG doesnt exist; exit 127) echo $CONFIGURED echo ... but works here: source $CFG echo $CONFIGURED What's wrong in [...] statement?

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  • Call method immediately after object construction in LINQ query

    - by Steffen
    I've got some objects which implement this interface: public interface IRow { void Fill(DataRow dr); } Usually when I select something out of db, I go: public IEnumerable<IRow> SelectSomeRows { DataTable table = GetTableFromDatabase(); foreach (DataRow dr in table.Rows) { IRow row = new MySQLRow(); // Disregard the MySQLRow type, it's not important row.Fill(dr); yield return row; } } Now with .Net 4, I'd like to use AsParallel, and thus LINQ. I've done some testing on it, and it speeds up things alot (IRow.Fill uses Reflection, so it's hard on the CPU) Anyway my problem is, how do I go about creating a LINQ query, which calls Fills as part of the query, so it's properly parallelized? For testing performance I created a constructor which took the DataRow as argument, however I'd really love to avoid this if somehow possible. With the constructor in place, it's obviously simple enough: public IEnumerable<IRow> SelectSomeRowsParallel { DataTable table = GetTableFromDatabase(); return from DataRow dr in table.Rows.AsParallel() select new MySQLRow(dr); } However like I said, I'd really love to be able to just stuff my Fill method into the LINQ query, and thus not need the constructor overload.

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  • Inversion of control domain objects construction problem

    - by Andrey
    Hello! As I understand IoC-container is helpful in creation of application-level objects like services and factories. But domain-level objects should be created manually. Spring's manual tells us: "Typically one does not configure fine-grained domain objects in the container, because it is usually the responsibility of DAOs and business logic to create/load domain objects." Well. But what if my domain "fine-grained" object depends on some application-level object. For example I have an UserViewer(User user, UserConstants constants) class. There user is domain object which cannot be injected, but UserViewer also needs UserConstants which is high-level object injected by IoC-container. I want to inject UserConstants from the IoC-container, but I also need a transient runtime parameter User here. What is wrong with the design? Thanks in advance! UPDATE It seems I was not precise enough with my question. What I really need is an example how to do this: create instance of class UserViewer(User user, UserService service), where user is passed as the parameter and service is injected from IoC. If I inject UserViewer viewer then how do I pass user to it? If I create UserViewer viewer manually then how do I pass service to it?

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  • Javascript table construction bug using JQuery in Firefox on Mac OSX

    - by Poita_
    I'm using some code to build up tables using JQuery, but in Firefox 3.5.3 on Mac OSX, the table cells all appear on separate lines by themselves, instead of in their respective rows. Chrome 5.0.342.7 beta on OSX correctly produces the table, as does Safari 4.0.5. Here is a minimal reproduction case: <html> <body> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script> <script type="text/javascript"> $(document).ready(function() { var b = $('body'); b.append("<table>"); for (var i = 0; i < 3; ++i) { b.append("<tr>"); for (var j = 0; j < 3; ++j) b.append("<td>x</td>"); b.append("</tr>"); } b.append("</table>"); }); </script> </body> </html> In Chrome and Safari, I get this correct output: x x x x x x x x x but Firefox produces: x x x x x x x x x Note that if I manually create that exact table without using Javascript (i.e. direct into the HTML) then the table appears correctly in Firefox. Also, if I change the JS to append then entire table in one call then it also works -- the only time it doesn't work is if you append it part-by-part as I have done before. My question is: is this to be expected, or should I report this as a bug to Firefox? I'm pretty sure this is a Firefox bug, but I'm a bit of a newbie to JS and web development in general, so perhaps there's something I'm missing? P.S. obviously there are easy ways to get around this -- that's not my concern. See above.

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  • XmlSerializer construction with same named extra types

    - by NoizWaves
    Hey, I am hitting trouble constructing an XmlSerializer where the extra types contains types with the same Name (but unique Fullname). Below is an example that illustrated my scenario. Type definitions in external assembly I cannot manipulate: public static class Wheel { public enum Status { Stopped, Spinning } } public static class Engine { public enum Status { Idle, Full } } Class I have written and have control over: public class Car { public Wheel.Status WheelStatus; public Engine.Status EngineStatus; public static string Serialize(Car car) { var xs = new XmlSerializer(typeof(Car), new[] {typeof(Wheel.Status),typeof(Engine.Status)}); var output = new StringBuilder(); using (var sw = new StringWriter(output)) xs.Serialize(sw, car); return output.ToString(); } } The XmlSerializer constructor throws a System.InvalidOperationException with Message "There was an error reflecting type 'Engine.Status'" This exception has an InnerException of type System.InvalidOperationException and with Message "Types 'Wheel.Status' and 'Engine.Status' both use the XML type name, 'Status', from namespace ''. Use XML attributes to specify a unique XML name and/or namespace for the type." Given that I am unable to alter the enum types, how can I construct an XmlSerializer that will serialize Car successfully?

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  • C++ Dynamic object construction

    - by Rajesh Subramanian
    I have a base class, class Msg { ParseMsg() { ParseMsgData(); ParseTrailer(); } virtual void ParseMsgData() = 0; ParseTrailer(); }; and derived classes, class InitiateMsg { void ParseMsgData() { ... } }; class ReadOperationMsg { void ParseMsgData() { ... } }; class WriteOperationMsg { void ParseMsgData() { ... } }; and the scenario is below, void UsageFunction(string data) { Msg* msg = ParseHeader(data); ParseMsg } Msg* ParseHeader(string data) { Msg *msg = NULL; .... switch() { case 1: msg = new InitiateMsg(); break; case 2: msg = new ReadOperationMsg{(); break; case 3: msg = new WriteOperationMsg{(); break; .... } return msg; } based on the data ParseHeader method will decide which object has to be created, So I have implemented ParseHeader function outside the class where I am using. How can I make the ParseHeader function inside the Msg class and then use it? In C# the same is achieved by defining ParseHeader method as static with in class and use it from outside,

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  • Php dynamic class construction

    - by pistacchio
    Hi to all, I'm trying to avoid the use of eval. I can dynamically instantiate a class like this: class myclass {} $my_class_name = 'myclass'; $obj = new $myclass(); If the constructor is like follows: class myclass { public function __construct( $argument1, $argument2 ) {} } and i have the values of the arguments in an array, how can i dynamically instantiate the class and pass it dynamic arguments? Mind that I have no way to modify the class, so I have to work on the way of using it. Thanks

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  • C++ Class Construction and Member Initialization

    - by anachoret
    The first print shows the member value to be false, and the other two prints show it as true. Why does the first output differ from the last two? #include #include using namespace std; class MyClass { public: bool value; bool stuff; }; class Container { public: vector my_classes; Container() { MyClass c; cout

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  • SQL query construction - separate data in a column into two columns

    - by Tommy
    I have a column that contains links. The problem is that the titles of the links are in the same column, so it looks like this: linktitle|-|linkurl I want link title and linkurl in separate columns. I've created a new column for the urls, so I'm looking for a way to extract them and update the linkurl column with them. Is there any clever way to construct a query that does this?

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  • C++ dynamic type construction and detection

    - by KneLL
    There was an interesting problem in C++, but it concerns more likely architecture. There are many (10, 20, 40, etc) classes that describe some characteristics (mix-in classes), for exmaple: struct Base { virtual ~Base() {} }; struct A : virtual public Base { int size; }; struct B : virtual public Base { float x, y; }; struct C : virtual public Base { bool some_bool_state; }; struct D : virtual public Base { string str; } // .... Primary module declares and exports a function (for simplicity just function declarations without classes): // .h file void operate(Base *pBase); // .cpp file void operate(Base *pBase) { // .... } Any other module can has a code like this: #include "mixins.h" #include "primary.h" class obj1_t : public A, public C, public D {}; class obj2_t : public B, public D {}; // ... void Pass() { obj1_t obj1; obj2_t obj2; operate(&obj1); operate(&obj2); } The question is how to know what the real type of given object in operate() without dynamic_cast and any type information in classes (constants, etc)? Function operate() is used with big array of objects in small time periods and dynamic_cast is too slow for it. And I don't want to include constants (enum obj_type { ... }) because this is not OOP-way. // module operate.cpp void some_operate(Base *pBase) { processA(pBase); processB(pBase); } void processA(A *pA) { } void processB(B *pB) { } I cannot directly pass a pBase to these functions. And it's impossible to have all possible combinations of classes, because I can add new classes just by including new .h files. As one of solutions that comed to mind, in editor application I can use a composite container: struct CompositeObject { vector<Base *pBase> parts; }; But editor does not need a time optimization and can use dynamic_cast for parts to determine the exact type. In operate() I cannot use this solution. So, is it possible to not use a dynamic_cast and type information to solve this problem? Or maybe I should use another architecture?

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  • xml schema construction

    - by amanrahahla
    in xml can any concept inhert the attribute of the main concept as an example: book( -author -title -isbn -price) and textbook as a subconcept from book can textbook take the same attribute of book and how?

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  • C++ Template Classes and Copy Construction

    - by themoondothshine
    Is there any way I can construct an new object from the given object if the template parameters of both objects are identical at run-time? For example: I have a template class with the declaration: template<typename _Type1, typename _Type2> class Object; Next, I have two instantiations of the template: template class Object<char, int>; template class Object<wchar_t, wint_t>; Now, I want to write a member function such as: template<typename _Type1, typename _Type2> Object<char, int> Object<_Type1, _Type2>::toCharObject() { if(__gnu_cxx::__are_same<_Type1, char>::__value) return *this; else { //Perform some kind of conversion and return an Object<char, int> } } I have tried a couple of techniques, such as using __gnu_cxx::__enable_if<__gnu_cxx::__are_same<_Type1, char>::__value, _Type1>::__type in a copy constructor for the Oject class, but I keep running into the error: error: conversion from ‘Object<wchar_t, wint_t>’ to non-scalar type ‘Object<char, int>’ requested Is there no way I can do this? Any help will be greatly appreciated!

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  • Eclipse Dynamic Web Project fails to load under WTP

    - by Cue
    When trying to run an Eclipse Dynamic Web Project under a Tomcat setup using WTP, it fails with the attached stacktrace. Checklist At the project properties, under "Java EE Module Dependencies" I have checked the "Maven Dependencies" At the wtp deploy directory, under lib indeed all dependencies are present (esp. struts-taglib-1.3.10.jar) On the other hand, if I package with maven and copy the war file under the webapps directory everything is working as normal. Specification Eclipse JEE Galileo SR2 (with WTP 3.1.1) Tomcat 6.0.26 Java(TM) SE Runtime Environment (build 1.6.0_17-b04-248-10M3025) Java HotSpot(TM) 64-Bit Server VM (build 14.3-b01-101, mixed mode) stacktrace org.apache.jasper.JasperException: Unable to read TLD "META-INF/tld/struts-html-el.tld" from JAR file "file:/Users/cue/Development/workspace/eclipse/.metadata/.plugins/org.eclipse.wst.server.core/tmp2/wtpwebapps/ticketing/WEB-INF/lib/struts-el-1.3.10.jar": org.apache.jasper.JasperException: Failed to load or instantiate TagExtraInfo class: org.apache.struts.taglib.html.MessagesTei at org.apache.jasper.compiler.DefaultErrorHandler.jspError(DefaultErrorHandler.java:51) at org.apache.jasper.compiler.ErrorDispatcher.dispatch(ErrorDispatcher.java:409) at org.apache.jasper.compiler.ErrorDispatcher.jspError(ErrorDispatcher.java:181) at org.apache.jasper.compiler.TagLibraryInfoImpl.<init>(TagLibraryInfoImpl.java:182) at org.apache.jasper.compiler.Parser.parseTaglibDirective(Parser.java:383) at org.apache.jasper.compiler.Parser.parseDirective(Parser.java:446) at org.apache.jasper.compiler.Parser.parseElements(Parser.java:1393) at org.apache.jasper.compiler.Parser.parse(Parser.java:130) at org.apache.jasper.compiler.ParserController.doParse(ParserController.java:255) at org.apache.jasper.compiler.ParserController.parse(ParserController.java:103) at org.apache.jasper.compiler.Compiler.generateJava(Compiler.java:185) at org.apache.jasper.compiler.Compiler.compile(Compiler.java:347) at org.apache.jasper.compiler.Compiler.compile(Compiler.java:327) at org.apache.jasper.compiler.Compiler.compile(Compiler.java:314) at org.apache.jasper.JspCompilationContext.compile(JspCompilationContext.java:589) at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:317) at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:313) at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:260) at javax.servlet.http.HttpServlet.service(HttpServlet.java:717) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298) at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:852) at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588) at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489) at java.lang.Thread.run(Thread.java:637)

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  • C headers: compiler specific vs library specific?

    - by leonbloy
    Is there some clear-cut distinction between standard C *.h header files that are provided by the C compiler, as oppossed to those which are provided by a standard C library? Is there some list, or some standard locations? Motivation: int this answer I got a while ago, regarding a missing unistd.h in the latest TinyC compiler, the author argued that unistd.h (contrarily to sys/unistd.h) should not be provided by the compiler but by your C library. I could not make much sense of that response (for one thing shouldn't that also apply to, say, stdio.h?) but I'm still wondering about it. Is that correct? Where is some authoritative reference for this? Looking in other compilers, I see that other "self contained" POSIX C compilers that are hosted in Windows (like the GCC toolchain that comes with MinGW, in several incarnations; or Digital Mars compiler), include all header files. And in a standard Linux distribution (say, Centos 5.10) I see that the gcc package provides a few header files (eg, stdbool.h, syslimits.h) in /usr/lib/gcc/i386-redhat-linux/4.1.1/include/, and the glibc-headers package provides the majority of the headers in /usr/include/ (including stdio.h, /usr/include/unistd.h and /usr/include/sys/unistd.h). So, in neither case I see support for the above claim.

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  • C# and Metadata File Errors

    - by j-t-s
    Hi All I've created my own little c# compiler using the tutorial on MSDN, and it's not working properly. I get a few errors, then I fix them, then I get new, different errors, then I fix them, etc etc. The latest error is really confusing me. --------------------------- --------------------------- Line number: 0, Error number: CS0006, 'Metadata file 'System.Linq.dll' could not be found; --------------------------- OK --------------------------- I do not know what this means. Can somebody please explain what's going on here? Here is my code. MY SAMPLE C# COMPILER CODE: using System; namespace JTM { public class CSCompiler { protected string ot, rt, ss, es; protected bool rg, cg; public string Compile(String se, String fe, String[] rdas, String[] fs, Boolean rn) { System.CodeDom.Compiler.CodeDomProvider CODEPROV = System.CodeDom.Compiler.CodeDomProvider.CreateProvider("CSharp"); ot = fe; System.CodeDom.Compiler.CompilerParameters PARAMS = new System.CodeDom.Compiler.CompilerParameters(); // Ensure the compiler generates an EXE file, not a DLL. PARAMS.GenerateExecutable = true; PARAMS.OutputAssembly = ot; foreach (String ay in rdas) { if (ay.Contains(".dll")) PARAMS.ReferencedAssemblies.Add(ay); else { string refd = ay; refd = refd + ".dll"; PARAMS.ReferencedAssemblies.Add(refd); } } System.CodeDom.Compiler.CompilerResults rs = CODEPROV.CompileAssemblyFromFile(PARAMS, fs); if (rs.Errors.Count > 0) { foreach (System.CodeDom.Compiler.CompilerError COMERR in rs.Errors) { es = es + "Line number: " + COMERR.Line + ", Error number: " + COMERR.ErrorNumber + ", '" + COMERR.ErrorText + ";" + Environment.NewLine + Environment.NewLine; } } else { // Compilation succeeded. es = "Compilation Succeeded."; if (rn) System.Diagnostics.Process.Start(ot); } return es; } } } ... And here is the app that passes the code to the above class: using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Windows.Forms; namespace WindowsFormsApplication1 { public partial class Form1 : Form { public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { string[] f = { "Form1.cs", "Form1.Designer.cs", "Program.cs" }; string[] ra = { "System.dll", "System.Windows.Forms.dll", "System.Data.dll", "System.Drawing.dll", "System.Deployment.dll", "System.Xml.dll", "System.Linq.dll" }; JTS.CSCompiler CSC = new JTS.CSCompiler(); MessageBox.Show(CSC.Compile( textBox1.Text, @"Test Application.exe", ra, f, false)); } } } So, as you can see, all the using directives are there. I don't know what this error means. Any help at all is much appreciated. Thank you

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  • Java compiler error: Can't open input server /Library/InputManagers/Inquisitor

    - by unknown (yahoo)
    I am trying to compile HelloWorld in Java under Mac OS X 10.6 (Snow Leopard) and I get this compiler error: java[51692:903] Can't open input server /Library/InputManagers/Inquisitor It happens when I am using terminal command javac and when I am trying to do this in NetBeans. I was trying to open folder "Inquisitor", but I have no access to folder, even if I login as root user. What is going on?

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