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  • Ruby Socket Inheritance

    - by Jarsen
    I'm writing a Ruby class that extends TCPSocket. Assume it looks something like this: class FooSocket < TCPSocket def hello puts 'hello' end end I have a TCPServer listening for incoming connections server = TCPServer.new 1234 socket = server.accept When my server finally accepts a connection, it will return a TCPSocket. However, I want a FooSocket so that I can call socket.hello. How can I change TCPSocket into a FooSocket? I could duck-punch the methods and attributes I want directly onto the TCPSocket class, but I'm using it elsewhere and so I don't want to do that. Probably the easiest solution is to write a class that encapsulates a TCPSocket, and just pass the socket returned by accept as a param. However, I'm interested to know how to do it through inheritance—I've been trying to bend my mind around it but can't figure it out. Thanks in advance.

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  • linux thread synchronization

    - by johnnycrash
    I am new to linux and linux threads. I have spent some time googling to try to understand the differences between all the functions available for thread synchronization. I still have some questions. I have found all of these different types of synchronizations, each with a number of functions for locking, unlocking, testing the lock, etc. gcc atomic operations futexes mutexes spinlocks seqlocks rculocks conditions semaphores My current (but probably flawed) understanding is this: semaphores are process wide, involve the filesystem (virtually I assume), and are probably the slowest. Futexes might be the base locking mechanism used by mutexes, spinlocks, seqlocks, and rculocks. Futexes might be faster than the locking mechanisms that are based on them. Spinlocks dont block and thus avoid context swtiches. However they avoid the context switch at the expense of consuming all the cycles on a CPU until the lock is released (spinning). They should only should be used on multi processor systems for obvious reasons. Never sleep in a spinlock. The seq lock just tells you when you finished your work if a writer changed the data the work was based on. You have to go back and repeat the work in this case. Atomic operations are the fastest synch call, and probably are used in all the above locking mechanisms. You do not want to use atomic operations on all the fields in your shared data. You want to use a lock (mutex, futex, spin, seq, rcu) or a single atomic opertation on a lock flag when you are accessing multiple data fields. My questions go like this: Am I right so far with my assumptions? Does anyone know the cpu cycle cost of the various options? I am adding parallelism to the app so we can get better wall time response at the expense of running fewer app instances per box. Performances is the utmost consideration. I don't want to consume cpu with context switching, spinning, or lots of extra cpu cycles to read and write shared memory. I am absolutely concerned with number of cpu cycles consumed. Which (if any) of the locks prevent interruption of a thread by the scheduler or interrupt...or am I just an idiot and all synchonization mechanisms do this. What kinds of interruption are prevented? Can I block all threads or threads just on the locking thread's CPU? This question stems from my fear of interrupting a thread holding a lock for a very commonly used function. I expect that the scheduler might schedule any number of other workers who will likely run into this function and then block because it was locked. A lot of context switching would be wasted until the thread with the lock gets rescheduled and finishes. I can re-write this function to minimize lock time, but still it is so commonly called I would like to use a lock that prevents interruption...across all processors. I am writing user code...so I get software interrupts, not hardware ones...right? I should stay away from any functions (spin/seq locks) that have the word "irq" in them. Which locks are for writing kernel or driver code and which are meant for user mode? Does anyone think using an atomic operation to have multiple threads move through a linked list is nuts? I am thinking to atomicly change the current item pointer to the next item in the list. If the attempt works, then the thread can safely use the data the current item pointed to before it was moved. Other threads would now be moved along the list. futexes? Any reason to use them instead of mutexes? Is there a better way than using a condition to sleep a thread when there is no work? When using gcc atomic ops, specifically the test_and_set, can I get a performance increase by doing a non atomic test first and then using test_and_set to confirm? *I know this will be case specific, so here is the case. There is a large collection of work items, say thousands. Each work item has a flag that is initialized to 0. When a thread has exclusive access to the work item, the flag will be one. There will be lots of worker threads. Any time a thread is looking for work, they can non atomicly test for 1. If they read a 1, we know for certain that the work is unavailable. If they read a zero, they need to perform the atomic test_and_set to confirm. So if the atomic test_and_set is 500 cpu cycles because it is disabling pipelining, causes cpu's to communicate and L2 caches to flush/fill .... and a simple test is 1 cycle .... then as long as I had a better ratio of 500 to 1 when it came to stumbling upon already completed work items....this would be a win.* I hope to use mutexes or spinlocks to sparilngly protect sections of code that I want only one thread on the SYSTEM (not jsut the CPU) to access at a time. I hope to sparingly use gcc atomic ops to select work and minimize use of mutexes and spinlocks. For instance: a flag in a work item can be checked to see if a thread has worked it (0=no, 1=yes or in progress). A simple test_and_set tells the thread if it has work or needs to move on. I hope to use conditions to wake up threads when there is work. Thanks!

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  • Weird mapping error in linq-to-sql dbml file in VS2010

    - by rwwilden
    Since I switched to VS2010, several times a day I get a compilation error in my dbml file: DBML1005: Mapping between DbType 'bigint' and Type 'MyNamespace.SecurityToken' in Column 'SecurityToken' of Type 'Employee' is not supported When I restart VS2010 the error disappears. I have no problems running my application using this dbml file (specifically, there are no problems getting correct values inside the SecurityToken property of Employee objects). The SecurityToken property is of an enum type defined as follows: [Flags] public enum SecurityToken : long { None = 1, Admin = 2, ...... } The SecurityToken column in the database is of type bigint. Am I missing something? It's especially weird that the error only happens sometimes, when I'm writing code that isn't related at all to the LINQ model.

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  • windows I/O manager - IRP's classification in read-like and write-like

    - by clyfe
    I am writing a windows filesystem minifilter driver that must fail IRP's in a preoperation callback. How can I find out from the callback parameters if the operation is read-like ( only reads data ) or it's write-like ( modifies data on the disk - write, delete etc ) ? I'm thinking on: Data->Iopb->TargetFileObject->ReadAccess Data->Iopb->TargetFileObject->WriteAccess But I'm not sure, I think thees are available only in postoperation callback. The documentation is really cumbersome. Code sample: FLT_PREOP_CALLBACK_STATUS Fail ( __inout PFLT_CALLBACK_DATA Data, __in PCFLT_RELATED_OBJECTS FltObjects, __deref_out_opt PVOID *CompletionContext ) { FLT_PREOP_CALLBACK_STATUS status = FLT_PREOP_SUCCESS_NO_CALLBACK; if ( IS WRITE_LIKE(Data, FltObjects) ) { // ??? HOW DO I FIND OUT???? if( FLT_IS_FASTIO_OPERATION(Data) ){ status = FLT_PREOP_DISALLOW_FASTIO; } else { status = FLT_PREOP_COMPLETE; } Data->IoStatus.Status = STATUS_ACCESS_DENIED; Data->IoStatus.Information = 0; return status; } return status; }

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  • Python code formatting

    - by Curious2learn
    In response to another question of mine, someone suggested that I avoid long lines in the code and to use PEP-8 rules when writing Python code. One of the PEP-8 rules suggested avoiding lines which are longer than 80 characters. I changed a lot of my code to comply with this requirement without any problems. However, changing the following line in the manner shown below breaks the code. Any ideas why? Does it have to do with the fact that what follows return command has to be in a single line? The line longer that 80 characters: def __str__(self): return "Car Type \n"+"mpg: %.1f \n" % self.mpg + "hp: %.2f \n" %(self.hp) + "pc: %i \n" %self.pc + "unit cost: $%.2f \n" %(self.cost) + "price: $%.2f "%(self.price) The line changed by using Enter key and Spaces as necessary: def __str__(self): return "Car Type \n"+"mpg: %.1f \n" % self.mpg + "hp: %.2f \n" %(self.hp) + "pc: %i \n" %self.pc + "unit cost: $%.2f \n" %(self.cost) + "price: $%.2f "%(self.price)

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  • /SUBSYSTEM:Windows program will not write to command line

    - by user144182
    I have a mixed mode C++-CLI program in Visual Studio 2005 that is set to use the /SUBSYSTEM:Windows. Generally speaking it is a graphical application that is launched from its shortcut or through the filetype registered to it. However, there is a rare occasion where a user will want to run it from the command line with arguments. I can access the arguments just fine, its when it comes to writing to the console, in response to the program being launched from the command line with arguments, where I don't see Console::WriteLine having any effect. What am I doing wrong?

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  • Office Automation Libraries

    - by Ian
    Some time ago I posted about a question about reading Excel files as a server process, to get around the tighter restrictions Microsoft have been applying on Office Automation. I now need to extend this, by finding methods/libraries to read other sorts of Office files in an automated way on a server. The applications I'm interested in are Word, Powerpoint, Project and to a lesser extent Word and Visio. I need to be able to support 97-2003 office files, and the newer open xml formats (e.g. xlsx, docx) at a very least. With regards to Word integration, I also need to be able to handle writing/reading RTF text. If anyone has any suggestions I'd be pleased to hear them. Thanks

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  • PDF writeHTML for rendering tables

    - by sami
    I'm using TCPDF and following this example which uses writeHTML and heredoc syntax to write a table. http://www.tcpdf.org/examples/example_048.phps I'm trying to do though is switch the font using setFont before writing each column. This means I have to break the html and write it on different pieces (see pseudo code). But once I break the HTML like that, it doesn't work, I think because it becomes invalid. writeHTML <tr> writeHTML first column setFont() writeHTML second column writeHTML </tr> I want to use writeHTML because it helps me write the table without having to manually construct. But how can I make modifications before I output each cell?

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  • Functionality in a Data Access Layer formed by a dbml

    - by Younes
    I got a Data Access Layer that's being formed by one DBML in which i just include all object I need. Is it necessary to write more functionality in this dbml or can I just use the dbml as my DAL? I ask this because I am currently writing functionality to, for example, get all Articles from a Table in the Business Logic Layer. So I'm kind of lost now. What kind of examples can be given so that it's clear to me what to put in the Business Layer.

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  • What language is to binary, as Perl is to text?

    - by ehdr
    I am looking for a scripting (or higher level programming) language (or e.g. modules for Python or similar languages) for effortlessly analyzing and manipulating binary data in files (e.g. core dumps), much like Perl allows manipulating text files very smoothly. Things I want to do include presenting arbitrary chunks of the data in various forms (binary, decimal, hex), convert data from one endianess to another, etc. That is, things you normally would use C or assembly for, but I'm looking for a language which allows for writing tiny pieces of code for highly specific, one-time purposes very quickly. Any suggestions?

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  • Entity Framework v4 examples and tutorials of conceptual model mapping

    - by Rody van Sambeek
    In an application I'm writing I have a fairly complicated Database model. I'd like to use EF4 to map this to a whole lot nicer conceptual model. However all the tutorials I've read are with samples of 2 or 3 tables which all map 1 on 1 to the conceptual model. I'd like to learn how to correctly map the database model to a different conceptual model using VS 2010. However I can't find any good tutorials or (preferabally) instruction video's. Somebody got any tips, links or even books?

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  • LockWorkStation - Compilation error - identifier not found

    - by Microkernel
    Hi All, I am writing an application in which I got to lock the computer screen (OS is Windows). My Application is in C++. For this purpose I used the LockWorkStation() API defined on msdn, http://msdn.microsoft.com/en-us/library/aa376875%28VS.85%29.aspx I have included windows.h as told but still I am getting compilation error: .\source.cpp(5) : error C3861: 'LockWorkStation': identifier not found here is a sample code thats giving error. #include <Windows.h> int main() { LockWorkStation(); return 0; } Please tell me what I am missing here :( I am using MS-Visual studio 2005. Regards.

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  • Is there a way in Sphinx/Pygments to emphasize one or more lines of code in literal includes?

    - by Casey
    In some sphinx docs I am writing, I am including code samples from an ancillary file like so: .. literalinclude:: mymodule.py :pyobject: MyClass :linenos: This particular doc is a tutorial, where the classes are build up step by step. What I would like to do is include the entire class or a single method, and emphasize only the lines of interest to that section. That way the context is preserved but the interesting parts are obvious at a glance. Right now I have resorted to just referring to line numbers in the text, which is ok, but far from ideal. Looking at the docs and code for sphinx and pygments I don't find an obvious way to do this. I'm not opposed to patching them or doing something tricky in conf.py, but I wondered if anyone had solved this.

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  • When does printf("%s", char*) stop printing?

    - by remagen
    In my class we are writing our own copy of C's malloc() function. To test my code (which can currently allocate space fine) I was using: char* ptr = my_malloc(6*sizeof(char)); memcpy(ptr, "Hello\n", 6*sizeof(char)); printf("%s", ptr); The output would typically be this: Hello Unprintable character Some debugging figured that my code wasn't causing this per say, as ptr's memory is as follows: [24 bytes of meta info][Number of requested bytes][Padding] So I figured that printf was reaching into the padding, which is just garbage. So I ran a test of: printf("%s", "test\nd"); and got: test d Which makes me wonder, when DOES printf("%s", char*) stop printing chars?

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  • Form Design ScriptControlClass

    - by raghumithra
    I am working on a form designer. We have two parts: first is designing form by placing controls, and second is writing VB code in rich text editor. How do i integrate design and code (events of the controls) in runtime? I am using ScriptControlClass Form4 f4 = new Form4(); f4.Name = "dgfdfg"; f4.Text = "Raghudfgmithra"; Button btn = new Button(); btn.Text = "HI"; btn.Left = 25; btn.Top = 50; btn.Name = "btnSubmit"; f4.Controls.Add(btn); script.AddObject("form", f4, true); script.AddCode("???????????); script.ExecuteStatement(????????????);

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  • How to determine if code is running in Foundation or GUI?

    - by Mitch Cohen
    I'm writing a Mac app with two targets - a regular Cocoa GUI and a Foundation command-line tool. They do very similar things other than the GUI, so I'm sharing most of the code between the two. I'd like to do a few things slightly differently depending on which target is running. I can think of many ways to do this (#define something in the pch, check for existence of GUI definitions...). I'm curious if there's a standard or recommended way to do this. Thanks!

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  • default maven compiler setting

    - by Jeeyoung Kim
    Hello Maven gurus, Right now, I'm writing a small java application by my own, with few maven pom.xml files. I want to make all my maven packages to compile with jdk 1.6, and I can't find a good way to do it without manually setting it on every single POMs - I'm sick of copy-and-pasting <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <configuration> <source>1.6</source> <target>1.6</target> </configuration> in every single pom.xml file I generate. Is there a simpler way to resolve this issue?

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  • DataGridView's SelectionChange event firing more than once on DataBinding

    - by Shantanu Gupta
    This Code triggers selection change event twice. how can I prevent it ? Currently i m using a flag or focused property to prevent this. But what is the actual way ? I am using it on winfoms EDIT Mistake in writing Question, here is the correct code that i wanted to ask private void frmGuestInfo_Load(object sender, EventArgs e) { this.dgvGuestInfo.SelectionChanged -= new System.EventHandler(this.dgvGuestInfo_SelectionChanged); dgvGuestInfo.DataSource=dsFillControls.Tables["tblName"]; this.dgvGuestInfo.SelectionChanged += new System.EventHandler(this.dgvGuestInfo_SelectionChanged); } private void dgvGuestInfo_SelectionChanged(object sender, EventArgs e) { }

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  • How to post Arabic characters in PHP

    - by Peter Stuart
    Okay, So I am writing an OpenCart extension that must allow Arabic characters when posting data. Whenever I post ????? the print_r($_POST) returns with this: u0645u0631u062du0628u0627 I check the HTML header and it has this: <meta charset="UTF-8" /> I checked the PHP file that triggers all SQL queries and it has this code: mysql_query("SET NAMES 'utf8'", $this->link); mysql_query("SET CHARACTER SET utf8", $this->link); mysql_query("SET CHARACTER_SET_CONNECTION=utf8", $this->link); This is in my form tag: <form action="<?php echo $action; ?>" method="post" enctype="multipart/form-data" id="form" accept-charset="utf-8"> I can't think of what else I am doing wrong. The rest of the OpenCart framework supports UTF8 and arabic characters. It is just in this instance where I can't post anything arabic? Could someone please help me? Many Thanks Peter

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  • Allow single-line accessor (getter/setter) syntax with Checkstyle

    - by Sam3
    We'd like to have trivial Java property accessors using a single line syntax, so they take up much much less space, and are more readable (in terms of 'seeing' the set of accessors quickly). But we do want to enforce multi-line method syntax for everything else in our checkstyle configuration. But I'm not sure how to make this exception for accessors in Checkstyle config and suspect it may not be possible. So we'd like our accessors to look something like this: public String getFoo() { return foo; } public void setFoo(String foo) { this.foo = foo; } [In fact we'd rather not have trivial accessors at all and instead just annotate the private member variables with @Property or something and have the accessors generated for us, since writing endless get and set code delivers no real benefit, but that's a general Java frustration and an aside as far as this question goes.]

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  • Why did this work? ( php dot notation )

    - by Daniel
    Hi, I was writing some php code after a long sint doing ruby and I accidently wrote this: [root@ip-10-160-47-98 test]# cat run.php <?php class MyTest { public function run() { var_dump(this.test); } } $object = new MyTest(); $object->run(); [root@ip-10-160-47-98 test]# php run.php string(8) "thistest" [root@ip-10-160-47-98 test]# Now, this.test should have been $this-test, but the compiler was actually happy to let this run. Does anyone know how (this.test) got converted into a string "thistest"? Compiled and run on php 5.3.2 amazon instance ami-e32273a6 (CentOS 5.4) -daniel

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  • Naming convention for utility classes in Java

    - by Zarjay
    When writing utility classes in Java, what are some good guidelines to follow? Should packges be "util" or "utils"? Is it ClassUtil or ClassUtils? When is a class a "Helper" or a "Utility"? Utility or Utilities? Or do you use a mixture of them? The standard Java library uses both Utils and Utilities: javax.swing.Utilities javax.print.attribute.AttributeSetUtilities javax.swing.plaf.basic.BasicGraphicsUtils Apache uses a variety of Util and Utils, although mostly Utils: org.apache.commons.modeler.util.DomUtil org.apache.commons.modeler.util.IntrospectionUtils org.apache.commons.io.FileSystemUtils org.apache.lucene.wordnet.AnalyzerUtil org.apache.lucene.util.ArrayUtil org.apache.lucene.xmlparser.DOMUtils Spring uses a lot of Helper and Utils classes: org.springframework.web.util.UrlPathHelper org.springframework.core.ReflectiveVisitorHelper org.springframework.core.NestedExceptionUtils org.springframework.util.NumberUtils So, how do you name your utility classes?

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  • Adding JTextField to a JPanel and showing them

    - by Davide Gualano
    I'm building a little app using Java and Swing in NetBeans. Using NetBeans design window, I created a JFrame with a JPanel inside. Now I want to dynamically add some jTextFields to the JPanel. I wrote something like that: Vector textFieldsVector = new Vector(); JTextField tf; int i = 0; while (i < 3) { tf = new JTextField(); textFieldVector.add(tf); myPanel.add(tf); //myPanel is the JPanel where I want to put the JTextFields i++; } myPanel.validate(); myPanel.repaint(); But nothing happens: when I run the app, the JFrame shows with the JPanel inside, but the JTextFields don't. I'm a total newbie in writing graphical Java apps, so I'm surely missing something very simple, but I can't see what.

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  • Adding line with text between pattern and next occurence of the same pattern in bash

    - by kasper
    I am writing a bash script that modifies a file that looks like this: --- usr1 --- data data data data data data data data data data data data --- usr2 --- data data data data data data data data --- usr3 --- data data data data --- endline --- One question is: How to add next user line --- usrn --- after last user data lines? Second one is: How to delete specific user data lines (data lines and --- userx ---) i.e. I would like to delete usr2 with all his data set. It must work on bash 2.05 :) and I think it will use awk or sed, but I'm not sure.

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  • php send mail code not working

    - by anand
    php $to = "[email protected]"; $subject = "Hi!"; $body = "Hi,\n\nHow are you?"; if (mail($to, $subject, $body)) { echo("pMessage successfully sent!/p"); } else { echo("pMessage delivery failed.../p"); } wrote a basic php sendmail code that but it gives me the following error Warning: mail() [function.mail]: "sendmail_from" not set in php.ini or custom "From:" header missing in C:\xampp\htdocs\mail.php on line 5 Message delivery failed... i changed the php.ini file and put [email protected] but still the problem persists... writing the mail script for the first time Am i doing something wrong? is there a better code or way to go thru this? Any help will be appreciated Thank you

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