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• Compiling ruby1.9.1 hangs and fills swap!

  - by nfm

  I'm compiling Ruby 1.9.1-p376 under Ubuntu 8.04 server LTS (64-bit), by doing the following: $ ./configure $ make $ sudo make install ./configure works without complaints. make hangs indefinitely until all my RAM and swap is gone. It get stuck after the following output: compiling ripper make[1]: Entering directory `/tmp/ruby1.9.1/ruby-1.9.1-p376/ext/ripper' gcc -I. -I../../.ext/include/x86_64-linux -I../.././include -I../.././ext/ripper -I../.. -I../../. -DRUBY_EXTCONF_H=\"extconf.h\" -fPIC -O2 -g -Wall -Wno-parentheses -o ripper.o -c ripper.c If I run the gcc command by hand, with the -v argument to get verbose output, it hangs after the following: Using built-in specs. Target: x86_64-linux-gnu Configured with: ../src/configure -v --enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.2 --program-suffix=-4.2 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu Thread model: posix gcc version 4.2.4 (Ubuntu 4.2.4-1ubuntu4) /usr/lib/gcc/x86_64-linux-gnu/4.2.4/cc1 -quiet -v -I. -I../../.ext/include/x86_64-linux -I../.././include -I../.././ext/ripper -I../.. -I../../. -DRUBY_EXTCONF_H="extconf.h" ripper.c -quiet -dumpbase ripper.c -mtune=generic -auxbase-strip ripper.o -g -O2 -Wall -Wno-parentheses -version -fPIC -fstack-protector -fstack-protector -o /tmp/ccRzHvYH.s ignoring nonexistent directory "/usr/local/include/x86_64-linux-gnu" ignoring nonexistent directory "/usr/lib/gcc/x86_64-linux-gnu/4.2.4/../../../../x86_64-linux-gnu/include" ignoring nonexistent directory "/usr/include/x86_64-linux-gnu" ignoring duplicate directory "../.././ext/ripper" ignoring duplicate directory "../../." #include "..." search starts here: #include <...> search starts here: . ../../.ext/include/x86_64-linux ../.././include ../.. /usr/local/include /usr/lib/gcc/x86_64-linux-gnu/4.2.4/include /usr/include End of search list. GNU C version 4.2.4 (Ubuntu 4.2.4-1ubuntu4) (x86_64-linux-gnu) compiled by GNU C version 4.2.4 (Ubuntu 4.2.4-1ubuntu4). GGC heuristics: --param ggc-min-expand=47 --param ggc-min-heapsize=32795 Compiler executable checksum: 6e11fa7ca85fc28646173a91f2be2ea3 I just compiled ruby on another computer for reference, and it took about 10 seconds to print the following output (after the above Compiler executable checksum line): COLLECT_GCC_OPTIONS='-v' '-I.' '-I../../.ext/include/i686-linux' '-I../.././include' '-I../.././ext/ripper' '-I../..' '-I../../.' '-DRUBY_EXTCONF_H="extconf.h"' '-D_FILE_OFFSET_BITS=64' '-fPIC' '-O2' '-g' '-Wall' '-Wno-parentheses' '-o' 'ripper.o' '-c' '-mtune=generic' '-march=i486' as -V -Qy -o ripper.o /tmp/cca4fa7R.s GNU assembler version 2.20 (i486-linux-gnu) using BFD version (GNU Binutils for Ubuntu) 2.20 COMPILER_PATH=/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/:/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/:/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/ LIBRARY_PATH=/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/4.4.1/:/usr/lib/gcc/i486-linux-gnu/4.4.1/../../../../lib/:/lib/../lib/:/usr/lib/../lib/:/usr/lib/gcc/i486-linux-gnu/4.4.1/../../../:/lib/:/usr/lib/ COLLECT_GCC_OPTIONS='-v' '-I.' '-I../../.ext/include/i686-linux' '-I../.././include' '-I../.././ext/ripper' '-I../..' '-I../../.' '-DRUBY_EXTCONF_H="extconf.h"' '-D_FILE_OFFSET_BITS=64' '-fPIC' '-O2' '-g' '-Wall' '-Wno-parentheses' '-o' 'ripper.o' '-c' '-mtune=generic' '-march=i486' I have absolutely no clue what could be going wrong here - any ideas where I should start?

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• How to use objects as modules/functors in Scala?

  - by Jeff

  Hi. I want to use object instances as modules/functors, more or less as shown below: abstract class Lattice[E] extends Set[E] { val minimum: E val maximum: E def meet(x: E, y: E): E def join(x: E, y: E): E def neg(x: E): E } class Calculus[E](val lat: Lattice[E]) { abstract class Expr case class Var(name: String) extends Expr {...} case class Val(value: E) extends Expr {...} case class Neg(e1: Expr) extends Expr {...} case class Cnj(e1: Expr, e2: Expr) extends Expr {...} case class Dsj(e1: Expr, e2: Expr) extends Expr {...} } So that I can create a different calculus instance for each lattice (the operations I will perform need the information of which are the maximum and minimum values of the lattice). I want to be able to mix expressions of the same calculus but not be allowed to mix expressions of different ones. So far, so good. I can create my calculus instances, but problem is that I can not write functions in other classes that manipulate them. For example, I am trying to create a parser to read expressions from a file and return them; I also was trying to write an random expression generator to use in my tests with ScalaCheck. Turns out that every time a function generates an Expr object I can't use it outside the function. Even if I create the Calculus instance and pass it as an argument to the function that will in turn generate the Expr objects, the return of the function is not recognized as being of the same type of the objects created outside the function. Maybe my english is not clear enough, let me try a toy example of what I would like to do (not the real ScalaCheck generator, but close enough). def genRndExpr[E](c: Calculus[E], level: Int): Calculus[E]#Expr = { if (level > MAX_LEVEL) { val select = util.Random.nextInt(2) select match { case 0 => genRndVar(c) case 1 => genRndVal(c) } } else { val select = util.Random.nextInt(3) select match { case 0 => new c.Neg(genRndExpr(c, level+1)) case 1 => new c.Dsj(genRndExpr(c, level+1), genRndExpr(c, level+1)) case 2 => new c.Cnj(genRndExpr(c, level+1), genRndExpr(c, level+1)) } } } Now, if I try to compile the above code I get lots of error: type mismatch; found : plg.mvfml.Calculus[E]#Expr required: c.Expr case 0 = new c.Neg(genRndExpr(c, level+1)) And the same happens if I try to do something like: val boolCalc = new Calculus(Bool) val e1: boolCalc.Expr = genRndExpr(boolCalc) Please note that the generator itself is not of concern, but I will need to do similar things (i.e. create and manipulate calculus instance expressions) a lot on the rest of the system. Am I doing something wrong? Is it possible to do what I want to do? Help on this matter is highly needed and appreciated. Thanks a lot in advance. After receiving an answer from Apocalisp and trying it. Thanks a lot for the answer, but there are still some issues. The proposed solution was to change the signature of the function to: def genRndExpr[E, C <: Calculus[E]](c: C, level: Int): C#Expr I changed the signature for all the functions involved: getRndExpr, getRndVal and getRndVar. And I got the same error message everywhere I call these functions and got the following error message: error: inferred type arguments [Nothing,C] do not conform to method genRndVar's type parameter bounds [E,C genRndVar(c) Since the compiler seemed to be unable to figure out the right types I changed all function call to be like below: case 0 => new c.Neg(genRndExpr[E,C](c, level+1)) After this, on the first 2 function calls (genRndVal and genRndVar) there were no compiling error, but on the following 3 calls (recursive calls to genRndExpr), where the return of the function is used to build a new Expr object I got the following error: error: type mismatch; found : C#Expr required: c.Expr case 0 = new c.Neg(genRndExpr[E,C](c, level+1)) So, again, I'm stuck. Any help will be appreciated.

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• How to use metaWeblog.newPost (xmlrpc api) properly with PHP ?

  - by Sjne

  Update: solved this problem see answer I want to make new posts on my blog remotely with XMLRPC api and i m trying to use metaWeblog.newPost function, because it provides much features. I successfully added new posts into wordpress but i failed to post it in a defined category(categories) i tried lots of various things but failed at end now i m using code from this site http://www.samuelfolkes.com/2009/08/posting-to-wordpress-with-php-and-xml-rpc/ after stripping down the code for my needs here's what i got and its working fine remotepost.class.php <?php class remotePost { private $client; private $wpURL = 'http://localhost/wp/xmlrpc.php '; private $ixrPath = '/wp-includes/class-IXR.php'; private $uname = 'zxc'; private $pass = 'zxc'; public $postID; function __construct($content) { if(!is_array($content)) throw new Exception('Invalid Argument'); include $this->ixrPath; $this->client = new IXR_Client($this->wpURL); $this->postID = $this->postContent($content); } private function postContent($content) { $content['description'] = $content['description']; if(!$this->client->query('metaWeblog.newPost','',$this->uname,$this->pass,$content,true)) throw new Exception($this->client->getErrorMessage()); return $this->client->getResponse(); } } ?> post.php ( you can name it whatever you want ) <?php if(isset($_POST['submit'])) { include "remotepost.class.php"; $content['title'] = $_POST['title']; $content['categories'] = $_POST['category']; $content['description'] = $_POST['description']; try { $posted = new remotePost($content); $pid = $posted->postID; } catch(Exception $e) { echo $e->getMessage(); } } ?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <title>WordPress Poster</title> </head> <body> <?php if(isset($_POST['submit'])) echo "Posted! <a href=\"http://localhost/wp/?p=$pid\">View Post</a><br /><br />"; ?> <form enctype="multipart/form-data" method="post" action="#"> Title <input type="text" name="title" /> <br /> Category <input type="text" name="category" /> <br /> Description <input type="text" name="description" /> <br /> <input type="submit" value="Submit" name="submit" /> </form> </body> </html> dont know whats wrong in this code :( ,failing to post in right directory

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• SSH as root using public key still prompts for password on RHEL 6.1

  - by Dean Schulze

  I've generated rsa keys with cygwin ssh-keygen and copied them to the server with ssh-copy-id -i id_rsa.pub [email protected] I've got the following settings in my /etc/ssh/sshd_config file RSAAuthentication yes PubkeyAuthentication yes AuthorizedKeysFile .ssh/authorized_keys PermitRootLogin yes When I ssh [email protected] it still prompts for a password. The output below from /usr/sbin/sshd -d says that a matching keys was found in the .ssh/authorized_keys file, but it still requires a password from the client. I've read a bunch of web postings about permissions on files and directories, but nothing works. Is it possible to ssh with keys in RHEL 6.1 or is this forbidden? The debug output from ssh and sshd is below. $ ssh -v [email protected] OpenSSH_6.1p1, OpenSSL 1.0.1c 10 May 2012 debug1: Connecting to my.ip.address [my.ip.address] port 22. debug1: Connection established. debug1: identity file /home/dschulze/.ssh/id_rsa type 1 debug1: identity file /home/dschulze/.ssh/id_rsa-cert type -1 debug1: identity file /home/dschulze/.ssh/id_dsa type 2 debug1: identity file /home/dschulze/.ssh/id_dsa-cert type -1 debug1: identity file /home/dschulze/.ssh/id_ecdsa type -1 debug1: identity file /home/dschulze/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3 debug1: match: OpenSSH_5.3 pat OpenSSH_5* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_6.1 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-ctr hmac-md5 none debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Server host key: RSA 9f:00:e0:1e:a2:cd:05:53:c8:21:d5:69:25:80:39:92 debug1: Host 'my.ip.address' is known and matches the RSA host key. debug1: Found key in /home/dschulze/.ssh/known_hosts:3 debug1: ssh_rsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Next authentication method: publickey debug1: Offering RSA public key: /home/dschulze/.ssh/id_rsa debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Offering DSA public key: /home/dschulze/.ssh/id_dsa debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password debug1: Trying private key: /home/dschulze/.ssh/id_ecdsa debug1: Next authentication method: password Here is the server output from /usr/sbin/sshd -d [root@ga2-lab .ssh]# /usr/sbin/sshd -d debug1: sshd version OpenSSH_5.3p1 debug1: read PEM private key done: type RSA debug1: private host key: #0 type 1 RSA debug1: read PEM private key done: type DSA debug1: private host key: #1 type 2 DSA debug1: rexec_argv[0]='/usr/sbin/sshd' debug1: rexec_argv[1]='-d' debug1: Bind to port 22 on 0.0.0.0. Server listening on 0.0.0.0 port 22. debug1: Bind to port 22 on ::. Server listening on :: port 22. debug1: Server will not fork when running in debugging mode. debug1: rexec start in 5 out 5 newsock 5 pipe -1 sock 8 debug1: inetd sockets after dupping: 3, 3 Connection from 172.60.254.24 port 53401 debug1: Client protocol version 2.0; client software version OpenSSH_6.1 debug1: match: OpenSSH_6.1 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.3 debug1: permanently_set_uid: 74/74 debug1: list_hostkey_types: ssh-rsa,ssh-dss debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: client->server aes128-ctr hmac-md5 none debug1: kex: server->client aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST received debug1: SSH2_MSG_KEX_DH_GEX_GROUP sent debug1: expecting SSH2_MSG_KEX_DH_GEX_INIT debug1: SSH2_MSG_KEX_DH_GEX_REPLY sent debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: KEX done debug1: userauth-request for user root service ssh-connection method none debug1: attempt 0 failures 0 debug1: PAM: initializing for "root" debug1: userauth-request for user root service ssh-connection method publickey debug1: attempt 1 failures 0 debug1: test whether pkalg/pkblob are acceptable debug1: PAM: setting PAM_RHOST to "172.60.254.24" debug1: PAM: setting PAM_TTY to "ssh" debug1: temporarily_use_uid: 0/0 (e=0/0) debug1: trying public key file /root/.ssh/authorized_keys debug1: fd 4 clearing O_NONBLOCK debug1: matching key found: file /root/.ssh/authorized_keys, line 1 Found matching RSA key: db:b3:b9:b1:c9:df:6d:e1:03:5b:57:d3:d9:c4:4e:5c debug1: restore_uid: 0/0 Postponed publickey for root from 172.60.254.24 port 53401 ssh2 debug1: userauth-request for user root service ssh-connection method publickey debug1: attempt 2 failures 0 debug1: temporarily_use_uid: 0/0 (e=0/0) debug1: trying public key file /root/.ssh/authorized_keys debug1: fd 4 clearing O_NONBLOCK debug1: matching key found: file /root/.ssh/authorized_keys, line 1 Found matching RSA key: db:b3:b9:b1:c9:df:6d:e1:03:5b:57:d3:d9:c4:4e:5c debug1: restore_uid: 0/0 debug1: ssh_rsa_verify: signature correct debug1: do_pam_account: called Accepted publickey for root from 172.60.254.24 port 53401 ssh2 debug1: monitor_child_preauth: root has been authenticated by privileged process debug1: temporarily_use_uid: 0/0 (e=0/0) debug1: ssh_gssapi_storecreds: Not a GSSAPI mechanism debug1: restore_uid: 0/0 debug1: SELinux support enabled debug1: PAM: establishing credentials PAM: pam_open_session(): Authentication failure debug1: Entering interactive session for SSH2. debug1: server_init_dispatch_20 debug1: server_input_channel_open: ctype session rchan 0 win 1048576 max 16384 debug1: input_session_request debug1: channel 0: new [server-session] debug1: session_new: session 0 debug1: session_open: channel 0 debug1: session_open: session 0: link with channel 0 debug1: server_input_channel_open: confirm session debug1: server_input_global_request: rtype [email protected] want_reply 0 debug1: server_input_channel_req: channel 0 request pty-req reply 1 debug1: session_by_channel: session 0 channel 0 debug1: session_input_channel_req: session 0 req pty-req debug1: Allocating pty. debug1: session_pty_req: session 0 alloc /dev/pts/1 ssh_selinux_setup_pty: security_compute_relabel: Invalid argument debug1: server_input_channel_req: channel 0 request shell reply 1 debug1: session_by_channel: session 0 channel 0 debug1: session_input_channel_req: session 0 req shell debug1: Setting controlling tty using TIOCSCTTY. debug1: Received SIGCHLD. debug1: session_by_pid: pid 17323 debug1: session_exit_message: session 0 channel 0 pid 17323 debug1: session_exit_message: release channel 0 debug1: session_pty_cleanup: session 0 release /dev/pts/1 debug1: session_by_channel: session 0 channel 0 debug1: session_close_by_channel: channel 0 child 0 debug1: session_close: session 0 pid 0 debug1: channel 0: free: server-session, nchannels 1 Received disconnect from 172.60.254.24: 11: disconnected by user debug1: do_cleanup debug1: PAM: cleanup debug1: PAM: deleting credentials

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• I don't understand how work call_once

  - by SABROG

  Please help me understand how work call_once Here is thread-safe code. I don't understand why this need Thread Local Storage and global_epoch variables. Variable _fast_pthread_once_per_thread_epoch can be changed to constant/enum like {FAST_PTHREAD_ONCE_INIT, BEING_INITIALIZED, FINISH_INITIALIZED}. Why needed count calls in global_epoch? I think this code can be rewriting with logc: if flag FINISH_INITIALIZED do nothing, else go to block with mutexes and this all. #ifndef FAST_PTHREAD_ONCE_H #define FAST_PTHREAD_ONCE_H #include #include typedef sig_atomic_t fast_pthread_once_t; #define FAST_PTHREAD_ONCE_INIT SIG_ATOMIC_MAX extern __thread fast_pthread_once_t _fast_pthread_once_per_thread_epoch; #ifdef __cplusplus extern "C" { #endif extern void fast_pthread_once( pthread_once_t *once, void (*func)(void) ); inline static void fast_pthread_once_inline( fast_pthread_once_t *once, void (*func)(void) ) { fast_pthread_once_t x = *once; /* unprotected access */ if ( x _fast_pthread_once_per_thread_epoch ) { fast_pthread_once( once, func ); } } #ifdef __cplusplus } #endif #endif FAST_PTHREAD_ONCE_H Source fast_pthread_once.c The source is written in C. The lines of the primary function are numbered for reference in the subsequent correctness argument. #include "fast_pthread_once.h" #include static pthread_mutex_t mu = PTHREAD_MUTEX_INITIALIZER; /* protects global_epoch and all fast_pthread_once_t writes */ static pthread_cond_t cv = PTHREAD_COND_INITIALIZER; /* signalled whenever a fast_pthread_once_t is finalized */ #define BEING_INITIALIZED (FAST_PTHREAD_ONCE_INIT - 1) static fast_pthread_once_t global_epoch = 0; /* under mu */ __thread fast_pthread_once_t _fast_pthread_once_per_thread_epoch; static void check( int x ) { if ( x == 0 ) abort(); } void fast_pthread_once( fast_pthread_once_t *once, void (*func)(void) ) { /*01*/ fast_pthread_once_t x = *once; /* unprotected access */ /*02*/ if ( x _fast_pthread_once_per_thread_epoch ) { /*03*/ check( pthread_mutex_lock(µ) == 0 ); /*04*/ if ( *once == FAST_PTHREAD_ONCE_INIT ) { /*05*/ *once = BEING_INITIALIZED; /*06*/ check( pthread_mutex_unlock(µ) == 0 ); /*07*/ (*func)(); /*08*/ check( pthread_mutex_lock(µ) == 0 ); /*09*/ global_epoch++; /*10*/ *once = global_epoch; /*11*/ check( pthread_cond_broadcast(&cv;) == 0 ); /*12*/ } else { /*13*/ while ( *once == BEING_INITIALIZED ) { /*14*/ check( pthread_cond_wait(&cv;, µ) == 0 ); /*15*/ } /*16*/ } /*17*/ _fast_pthread_once_per_thread_epoch = global_epoch; /*18*/ check (pthread_mutex_unlock(µ) == 0); } } This code from BOOST: #ifndef BOOST_THREAD_PTHREAD_ONCE_HPP #define BOOST_THREAD_PTHREAD_ONCE_HPP // once.hpp // // (C) Copyright 2007-8 Anthony Williams // // Distributed under the Boost Software License, Version 1.0. (See // accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) #include #include #include #include "pthread_mutex_scoped_lock.hpp" #include #include #include namespace boost { struct once_flag { boost::uintmax_t epoch; }; namespace detail { BOOST_THREAD_DECL boost::uintmax_t& get_once_per_thread_epoch(); BOOST_THREAD_DECL extern boost::uintmax_t once_global_epoch; BOOST_THREAD_DECL extern pthread_mutex_t once_epoch_mutex; BOOST_THREAD_DECL extern pthread_cond_t once_epoch_cv; } #define BOOST_ONCE_INITIAL_FLAG_VALUE 0 #define BOOST_ONCE_INIT {BOOST_ONCE_INITIAL_FLAG_VALUE} // Based on Mike Burrows fast_pthread_once algorithm as described in // http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2007/n2444.html template void call_once(once_flag& flag,Function f) { static boost::uintmax_t const uninitialized_flag=BOOST_ONCE_INITIAL_FLAG_VALUE; static boost::uintmax_t const being_initialized=uninitialized_flag+1; boost::uintmax_t const epoch=flag.epoch; boost::uintmax_t& this_thread_epoch=detail::get_once_per_thread_epoch(); if(epoch #endif I right understand, boost don't use atomic operation, so code from boost not thread-safe?

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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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• Are their any suggestions for this new assembly language?

  - 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 exit 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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• Are there any suggestions for these new 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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• Listview with objectdatasource Delete not working

  - by Radhi

  Hello, i have one Listview in my Usercontrol & 1 objectdatasource binded with the ListView. now in objectdatasource's Deletemethod i have taken businessobject as argument but at runtime i am not getting value in my businessobject's properties... i also tried to use "Bind" instead of "eval" in ItemTemplate. but not getting any value at runtime in my DeleteMethod provided in objectdatasource's Deletecommand... can anybody help to know weather i am mising anything or what? my Listview's ItemTemplate <ItemTemplate> <asp:HiddenField ID="hidUserAchievementInfoId" runat="server" Value='<%# Bind("UserAchievementInfoId") %>' /> <asp:HiddenField ID="hidUserIdField" runat="server" Value='<%# Bind("UserId") %>' /> <tr> <td class="style1"> <asp:Label ID="AwardLabel" runat="server" Text="Award "></asp:Label> </td> <td> <asp:Label ID="lblAward" runat="server" Text='<%# Bind("Awards") %>'></asp:Label> </td> </tr> <tr> <td class="style1"> <asp:Label ID="FieldofAwardLabel" runat="server" Text="Field of Award "></asp:Label> </td> <td> <asp:Label ID="lblFieldofAward" runat="server" Text='<%# Bind("FieldofAward") %>'></asp:Label> </td> </tr> <tr> <td class="style1"> <asp:Label ID="TournamentLabel" runat="server" Text="Tournament "></asp:Label> </td> <td> <asp:Label ID="lblTournament" runat="server" Text='<%# Bind("Tournament") %>'></asp:Label> </td> </tr> <tr> <td class="style1"> <asp:Label ID="AwardYearLabel" runat="server" Text="Award Year "></asp:Label> </td> <td> <asp:Label ID="AwardYear" runat="server" Text='<%# Bind("AwardYear") %>'></asp:Label> </td> </tr> <tr> <td class="style1"> <asp:Label ID="AwardDescriptionLabel" runat="server" Text="Description "></asp:Label> </td> <td> <asp:Label ID="lblAwardDescription" runat="server" Text='<%# Bind("AwardDescription") %>'></asp:Label> </td> </tr> <tr> <td class="style1"> <asp:LinkButton ID="EditButton" runat="server" CommandName="Edit" Text="Edit"></asp:LinkButton> </td> <td> <asp:LinkButton ID="DeleteButton" runat="server" CommandName="Delete" Text="Delete"></asp:LinkButton> </td> </tr> </ItemTemplate> Delete Method used in objectdata source's Deletecommand public void DeleteUserAchievementInfo(UserAchivementInfoBO BOInstance) { try { Int64 UserAchievementInfoId=BOInstance.UserAchievementInfoId objUserBasicInfoServiceClient.DeleteUserAchievementInfo(UserAchievementInfoId); } catch (Exception ex) { HandleException.LogError(ex); } }

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• Trying to write a std::iterator : Compilation error

  - by Naveen

  I am trying to write an std::iterator for the CArray<Type,ArgType> MFC class. This is what I have done till now: template <class Type, class ArgType> class CArrayIterator : public std::iterator<std::random_access_iterator_tag, ArgType> { public: CArrayIterator(CArray<Type,ArgType>& array_in, int index_in = 0) : m_pArray(&array_in), m_index(index_in) { } void operator++() { ++m_index; } void operator++(int) { ++m_index; } void operator--() { --m_index; } void operator--(int) { --m_index; } void operator+=(int n) { m_index += n; } void operator-=(int n) { m_index -= n; } typename ArgType operator*() const{ return m_pArray->GetAt(m_index); } typename ArgType operator->() const { return m_pArray->GetAt(m_index); } bool operator==(const CArrayIterator& other) const { return m_pArray == other.m_pArray && m_index == other.m_index; } bool operator!=(const CArrayIterator& other) const { return ! (operator==(other)); } private: CArray<Type,ArgType>* m_pArray; int m_index; }; I also provided two helper functions to create the iterators like this: template<class Type, class ArgType> CArrayIterator<Type,ArgType> make_begin(CArray<Type,ArgType>& array_in) { return CArrayIterator<Type,ArgType>(array_in, 0); } template<class Type, class ArgType> CArrayIterator<Type,ArgType> make_end(CArray<Type,ArgType>& array_in) { return CArrayIterator<Type,ArgType>(array_in, array_in.GetSize()); } To test the code, I wrote a simple class A and tried to use it like this: class A { public: A(int n): m_i(n) { } int get() const { return m_i; } private: int m_i; }; struct Test { void operator()(A* p) { std::cout<<p->get()<<"\n"; } }; int main(int argc, char **argv) { CArray<A*, A*> b; b.Add(new A(10)); b.Add(new A(20)); std::for_each(make_begin(b), make_end(b), Test()); return 0; } But when I compile this code, I get the following error: Error 4 error C2784: 'bool std::operator <(const std::_Tree<_Traits &,const std::_Tree<_Traits &)' : could not deduce template argument for 'const std::_Tree<_Traits &' from 'CArrayIterator' C:\Program Files\Microsoft Visual Studio 9.0\VC\include\xutility 1564 Vs8Console Can anybody throw some light on what I am doing wrong and how it can be corrected? I am using VC9 compiler if it matters.

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• Why isn't my algorithm for find the biggest and smallest inputs working?

  - by Matt Ellen

  I have started a new job, and with it comes a new language: Ironpython. Thankfully a good language :D Before starting I got to grips with Python on the whole, but that was only a week's worth of learning. Now I'm writing actual code. I've been charged with writing an algorithm that finds the best input parameter to collect data with. The basic algorithm is (as I've been instructed): Set the input parameter to a good guess Start collecting data When data is available stop collecting find the highest point If the point before this (i.e. for the previous parameter value) was higher and the point before that was lower then we've found the max otherwise the input parameter is increased by the initial guess. goto 2 If the max is found then the min needs to be found. To do this the algorithm carries on increasing the input, but by 1/10 of the max, until the current point is greater than the previous point and the point before that is also greater. Once the min is found then the algorithm stops. Currently I have a simplified data generator outputting the sin of the input, so that I know that the min value should be PI and the max value should be PI/2 The main Python code looks like this (don't worry, this is just for my edification, I don't write real code like this): import sys sys.path.append(r"F:\Programming Source\C#\PythonHelp\PythonHelp\bin\Debug") import clr clr.AddReferenceToFile("PythonHelpClasses.dll") import PythonHelpClasses from PHCStruct import Helper from System import Math helper = Helper() def run(): b = PythonHelpClasses.Executor() a = PythonHelpClasses.HasAnEvent() b.Input = 0.0 helper.__init__() def AnEventHandler(e): b.Stop() h = helper h.lastLastVal, h.lastVal, h.currentVal = h.lastVal, h.currentVal, e.Number if h.lastLastVal < h.lastVal and h.currentVal < h.lastVal and h.NotPast90: h.NotPast90 = False h.bestInput = h.lastInput inputInc = 0.0 if h.NotPast90: inputInc = Math.PI/10.0 else: inputInc = h.bestInput/10.0 if h.lastLastVal > h.lastVal and h.currentVal > h.lastVal and h.NotPast180: h.NotPast180 = False if h.NotPast180: h.lastInput, b.Input = b.Input, b.Input + inputInc b.Start(a) else: print "Best input:", h.bestInput print "Last input:", h.lastInput b.Stop() a.AnEvent += AnEventHandler b.Start(a) PHCStruct.py: class Helper(): def __init__(self): self.currentVal = 0 self.lastVal = 0 self.lastLastVal = 0 self.NotPast90 = True self.NotPast180 = True self.bestInput = 0 self.lastInput = 0 PythonHelpClasses has two small classes I wrote in C# before I realised how to do it in Ironpython. Executor runs a delegate asynchronously while it's running member is true. The important code: public void Start(HasAnEvent hae) { running = true; RunDelegate r = new RunDelegate(hae.UpdateNumber); AsyncCallback ac = new AsyncCallback(UpdateDone); IAsyncResult ar = r.BeginInvoke(Input, ac, null); } public void Stop() { running = false; } public void UpdateDone(IAsyncResult ar) { RunDelegate r = (RunDelegate)((AsyncResult)ar).AsyncDelegate; r.EndInvoke(ar); if (running) { AsyncCallback ac = new AsyncCallback(UpdateDone); IAsyncResult ar2 = r.BeginInvoke(Input, ac, null); } } HasAnEvent has a function that generates the sin of its input and fires an event with that result as its argument. i.e.: public void UpdateNumber(double val) { AnEventArgs e = new AnEventArgs(Math.Sin(val)); System.Threading.Thread.Sleep(1000); if (null != AnEvent) { AnEvent(e); } } The sleep is in there just to slow things down a bit. The problem I am getting is that the algorithm is not coming up with the best input being PI/2 and the final input being PI, but I can't see why. Also the best and final inputs are different each time I run the programme. Can anyone see why? Also when the algorithm terminates the best and final inputs are printed to the screen multiple times, not just once. Can someone explain why?

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• Function signature-like expressions as C++ template arguments

  - by Jeff Lee

  I was looking at Don Clugston's FastDelegate mini-library and noticed a weird syntactical trick with the following structure: TemplateClass< void( int, int ) > Object; It almost appears as if a function signature is being used as an argument to a template instance declaration. This technique (whose presence in FastDelegate is apparently due to one Jody Hagins) was used to simplify the declaration of template instances with a semi-arbitrary number of template parameters. To wit, it allowed this something like the following: // A template with one parameter template<typename _T1> struct Object1 { _T1 m_member1; }; // A template with two parameters template<typename _T1, typename _T2> struct Object2 { _T1 m_member1; _T2 m_member2; }; // A forward declaration template<typename _Signature> struct Object; // Some derived types using "function signature"-style template parameters template<typename _Dummy, typename _T1> struct Object<_Dummy(_T1)> : public Object1<_T1> {}; template<typename _Dummy, typename _T1, typename _T2> struct Object<_Dummy(_T1, _T2)> : public Object2<_T1, _T2> {}; // A. "Vanilla" object declarations Object1<int> IntObjectA; Object2<int, char> IntCharObjectA; // B. Nifty, but equivalent, object declarations typedef void UnusedType; Object< UnusedType(int) > IntObjectB; Object< UnusedType(int, char) > IntCharObjectB; // C. Even niftier, and still equivalent, object declarations #define DeclareObject( ... ) Object< UnusedType( __VA_ARGS__ ) > DeclareObject( int ) IntObjectC; DeclareObject( int, char ) IntCharObjectC; Despite the real whiff of hackiness, I find this kind of spoofy emulation of variadic template arguments to be pretty mind-blowing. The real meat of this trick seems to be the fact that I can pass textual constructs like "Type1(Type2, Type3)" as arguments to templates. So here are my questions: How exactly does the compiler interpret this construct? Is it a function signature? Or, is it just a text pattern with parentheses in it? If the former, then does this imply that any arbitrary function signature is a valid type as far as the template processor is concerned? A follow-up question would be that since the above code sample is valid code, why doesn't the C++ standard just allow you to do something like the following, which is does not compile? template<typename _T1> struct Object { _T1 m_member1; }; // Note the class identifier is also "Object" template<typename _T1, typename _T2> struct Object { _T1 m_member1; _T2 m_member2; }; Object<int> IntObject; Object<int, char> IntCharObject;

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• Calling system commands from Perl

  - by Dan J

  In an older version of our code, we called out from Perl to do an LDAP search as follows: # Pass the base DN in via the ldapsearch-specific environment variable # (rather than as the "-b" paramater) to avoid problems of shell # interpretation of special characters in the DN. $ENV{LDAP_BASEDN} = $ldn; $lcmd = "ldapsearch -x -T -1 -h $gLdapServer" . <snip> " > $lworkfile 2>&1"; system($lcmd); if (($? != 0) || (! -e "$lworkfile")) { # Handle the error } The code above would result in a successful LDAP search, and the output of that search would be in the file $lworkfile. Unfortunately, we recently reconfigured openldap on this server so that a "BASE DC=" is specified in /etc/openldap/ldap.conf and /etc/ldap.conf. That change seems to mean ldapsearch ignores the LDAP_BASEDN environment variable, and so my ldapsearch fails. I've tried a couple of different fixes but without success so far: (1) I tried going back to using the "-b" argument to ldapsearch, but escaping the shell metacharacters. I started writing the escaping code: my $ldn_escaped = $ldn; $ldn_escaped =~ s/\/\\/g; $ldn_escaped =~ s/`/\`/g; $ldn_escaped =~ s/$/\$/g; $ldn_escaped =~ s/"/\"/g; That threw up some Perl errors because I haven't escaped those regexes properly in Perl (the line number matches the regex with the backticks in). Backticks found where operator expected at /tmp/mycommand line 404, at end of line At the same time I started to doubt this approach and looked for a better one. (2) I then saw some Stackoverflow questions (here and here) that suggested a better solution. Here's the code: print("Processing..."); # Pass the arguments to ldapsearch by invoking open() with an array. # This ensures the shell does NOT interpret shell metacharacters. my(@cmd_args) = ("-x", "-T", "-1", "-h", "$gLdapPool", "-b", "$ldn", <snip> ); $lcmd = "ldapsearch"; open my $lldap_output, "-|", $lcmd, @cmd_args; while (my $lline = <$lldap_output>) { # I can parse the contents of my file fine } $lldap_output->close; The two problems I am having with approach (2) are: a) Calling open or system with an array of arguments does not let me pass > $lworkfile 2>&1 to the command, so I can't stop the ldapsearch output being sent to screen, which makes my output look ugly: Processing...ldap_bind: Success (0) additional info: Success b) I can't figure out how to choose which location (i.e. path and file name) to the file handle passed to open, i.e. I don't know where $lldap_output is. Can I move/rename it, or inspect it to find out where it is (or is it not actually saved to disk)? Based on the problems with (2), this makes me think I should return back to approach (1), but I'm not quite sure how to

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• Monorail - Form submission using GET instead of POST

  - by Septih

  Hello, I'm writing some additions to a Castle MonoRail based site involving an Add and an Edit form. The add form works fine and uses POST but the edit form uses GET. The only major difference I can see is that the edit method is called with the Id of the object being edited in the query string. When the submit button is pressed on the edit form, the only argument passed is this object Id again. Here is the code for the edit form: <form action="edit.ashx" method="post"> <h3>Coupon Description</h3> <textarea name="comments" width="200">$comments</textarea> <br/><br/> <h3>Coupon Actions</h3> <br/> <div>Give Stories</div> <ul class="checklist" style="overflow:auto;height:144px;width:100%"> #foreach ($story in $stories.Values) <li> <label> #set ($associated = "") #foreach($storyId in $storyIds) #if($story.Id == $storyId) #set($associated = " checked='true'") #end #end <input type="checkbox" name="chk_${story.Id}" id="chk_${story.Id}" value="true" class="checkbox" $associated/> $story.Name </label> </li> #end </ul> <br/><br/> <div>Give Credit Amount</div> <input type="text" name="credit" value="$credit" /> <br/><br/> <h3>Coupon Uses</h3> <input type="checkbox" name="multi" #if($multi) checked="true" #end /> Multi-Use Coupon?<br/><br/> <b>OR</b> <br/> <br/> Number of Uses per Coupon: <input type="text" name="uses" value="$uses" /> <br/> <input type="submit" name="Save" /> </form> The differences between this and the add form is the velocity stuff to do with association and the values of the inputs being from the PropertyBag. The Method dealing with this on the controller starts like this: public void Edit(int id) { Coupon coupon = Coupon.GetRepository(User.Site.Id).FindById(id).Value; if(coupon == null) { RedirectToReferrer(); return; } IFutureQueryOfList<Story> stories = Story.GetRepository(User.Site.Id).OnlyReturnEnabled().FindAll("Name", true); if (Params["Save"] == null) { ... } } It reliably gets called but a breakpoint on the Params["Save"] lets me see that the HttpMethod is "GET" and the only arguments passed (In the Form and the Request) are the object Id and additional HTTP headers. At the end of the day I'm not that familiar with MonoRail and this may be a stupid mistake on my behalf, but I would very much appreciate being made a fool out of if it fixes the problem! :) Thanks

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• How do I use constructor dependency injection to supply Models from a collection to their ViewModels

  - by GraemeF

  I'm using constructor dependency injection in my WPF application and I keep running into the following pattern, so would like to get other people's opinion on it and hear about alternative solutions. The goal is to wire up a hierarchy of ViewModels to a similar hierarchy of Models, so that the responsibility for presenting the information in each model lies with its own ViewModel implementation. (The pattern also crops up under other circumstances but MVVM should make for a good example.) Here's a simplified example. Given that I have a model that has a collection of further models: public interface IPerson { IEnumerable<IAddress> Addresses { get; } } public interface IAddress { } I would like to mirror this hierarchy in the ViewModels so that I can bind a ListBox (or whatever) to a collection in the Person ViewModel: public interface IPersonViewModel { ObservableCollection<IAddressViewModel> Addresses { get; } void Initialize(); } public interface IAddressViewModel { } The child ViewModel needs to present the information from the child Model, so it's injected via the constructor: public class AddressViewModel : IAddressViewModel { private readonly IAddress _address; public AddressViewModel(IAddress address) { _address = address; } } The question is, what is the best way to supply the child Model to the corresponding child ViewModel? The example is trivial, but in a typical real case the ViewModels have more dependencies - each of which has its own dependencies (and so on). I'm using Unity 1.2 (although I think the question is relevant across the other IoC containers), and I am using Caliburn's view strategies to automatically find and wire up the appropriate View to a ViewModel. Here is my current solution: The parent ViewModel needs to create a child ViewModel for each child Model, so it has a factory method added to its constructor which it uses during initialization: public class PersonViewModel : IPersonViewModel { private readonly Func<IAddress, IAddressViewModel> _addressViewModelFactory; private readonly IPerson _person; public PersonViewModel(IPerson person, Func<IAddress, IAddressViewModel> addressViewModelFactory) { _addressViewModelFactory = addressViewModelFactory; _person = person; Addresses = new ObservableCollection<IAddressViewModel>(); } public ObservableCollection<IAddressViewModel> Addresses { get; private set; } public void Initialize() { foreach (IAddress address in _person.Addresses) Addresses.Add(_addressViewModelFactory(address)); } } A factory method that satisfies the Func<IAddress, IAddressViewModel> interface is registered with the main UnityContainer. The factory method uses a child container to register the IAddress dependency that is required by the ViewModel and then resolves the child ViewModel: public class Factory { private readonly IUnityContainer _container; public Factory(IUnityContainer container) { _container = container; } public void RegisterStuff() { _container.RegisterInstance<Func<IAddress, IAddressViewModel>>(CreateAddressViewModel); } private IAddressViewModel CreateAddressViewModel(IAddress model) { IUnityContainer childContainer = _container.CreateChildContainer(); childContainer.RegisterInstance(model); return childContainer.Resolve<IAddressViewModel>(); } } Now, when the PersonViewModel is initialized, it loops through each Address in the Model and calls CreateAddressViewModel() (which was injected via the Func<IAddress, IAddressViewModel> argument). CreateAddressViewModel() creates a temporary child container and registers the IAddress model so that when it resolves the IAddressViewModel from the child container the AddressViewModel gets the correct instance injected via its constructor. This seems to be a good solution to me as the dependencies of the ViewModels are very clear and they are easily testable and unaware of the IoC container. On the other hand, performance is OK but not great as a lot of temporary child containers can be created. Also I end up with a lot of very similar factory methods. Is this the best way to inject the child Models into the child ViewModels with Unity? Is there a better (or faster) way to do it in other IoC containers, e.g. Autofac? How would this problem be tackled with MEF, given that it is not a traditional IoC container but is still used to compose objects?

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• Ladder-like word game in Java

  - by sasquatch90

  I've found this question http://stackoverflow.com/questions/2844190/choosing-design-method-for-ladder-like-word-game and I would also like to do this kind of program. I've written some code but already have two issues. Here's what I already have : GRID : public class Grid { public Grid(){} public Grid( Element e ){} } ELEMENT : public class Element { final int INVISIBLE = 0; final int EMPTY = 1; final int FIRST_LETTER = 2; final int OTHER_LETTER = 3; private int state; private String letter; public Element(){} //empty block public Element(int state){ this("", 0); } //filled block public Element(String s, int state){ this.state = state; this.letter = s; } public static void changeState(int s){ } public int getState(){ return state; } public boolean equalLength(){ return true; } public boolean equalValue(){ return true; } @Override public String toString(){ return "["+letter+"]"; } } MAIN: import java.util.Scanner; public class Main { public static void main(String[] args){ Scanner sc = new Scanner(System.in); System.out.println("Height: "); while (!sc.hasNextInt()) { System.out.println("int, please!"); sc.next(); } final int height = sc.nextInt(); Grid[] game = new Grid[height]; for(int i = 1; i <= height; i++) { String s; do { System.out.println("Length " + i + ", please!"); s = sc.next(); } while (s.length() != i); Element[] line = new Element[s.length()+1]; Element single = null; String[] temp = null; //issue here temp = s.split(""); System.out.println("s.length: "+s.length()); System.out.println("temp.length: "+temp.length); // for(String str : temp){ System.out.println("str:"+str); } for (int k = 0 ; k < temp.length ; k++) { if( k == 0 ){ single = new Element(temp[k], 2); System.out.println("single1: "+single); } else{ single = new Element(temp[k], 3); System.out.println("single2: "+single); } line[k] = single; } for (Element l : line) { System.out.println("line:"+l); } //issue here game[i] = line; } // for (Grid g : game) { System.out.println(g); } } } And sample output for debug : Height: 3 Length 1, please! A s.length: 1 temp.length: 2 str: str:A single1: [] single2: [A] line:[] line:[A] Here's what I think it should work like. I grab a word from user. Next create Grid element for whole game. Then for each line I create Element[] array called line. I split the given text and here's the first problem. Why string.split() adds a whitespace ? You can see clearly in output that it is added for no reason. How can I get rid of it (now I had to add +1 to the length of line just to run the code). Continuing I'm throwing the splitted text into temporary String array and next from each letter I create Element object and throw it to line array. Apart of this empty space output looks fine. But next problem is with Grid. I've created constructor taking Element as an argument, but still I can't throw line as Grid[] elements because of 'incompatible types'. How can I fix that ? Am I even doing it right ? Maybe I should get rid of line as Element[] and just create Grid[][] ?

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• Optimizing Python code with many attribute and dictionary lookups

  - by gotgenes

  I have written a program in Python which spends a large amount of time looking up attributes of objects and values from dictionary keys. I would like to know if there's any way I can optimize these lookup times, potentially with a C extension, to reduce the time of execution, or if I need to simply re-implement the program in a compiled language. The program implements some algorithms using a graph. It runs prohibitively slowly on our data sets, so I profiled the code with cProfile using a reduced data set that could actually complete. The vast majority of the time is being burned in one function, and specifically in two statements, generator expressions, within the function: The generator expression at line 202 is neighbors_in_selected_nodes = (neighbor for neighbor in node_neighbors if neighbor in selected_nodes) and the generator expression at line 204 is neighbor_z_scores = (interaction_graph.node[neighbor]['weight'] for neighbor in neighbors_in_selected_nodes) The source code for this function of context provided below. selected_nodes is a set of nodes in the interaction_graph, which is a NetworkX Graph instance. node_neighbors is an iterator from Graph.neighbors_iter(). Graph itself uses dictionaries for storing nodes and edges. Its Graph.node attribute is a dictionary which stores nodes and their attributes (e.g., 'weight') in dictionaries belonging to each node. Each of these lookups should be amortized constant time (i.e., O(1)), however, I am still paying a large penalty for the lookups. Is there some way which I can speed up these lookups (e.g., by writing parts of this as a C extension), or do I need to move the program to a compiled language? Below is the full source code for the function that provides the context; the vast majority of execution time is spent within this function. def calculate_node_z_prime( node, interaction_graph, selected_nodes ): """Calculates a z'-score for a given node. The z'-score is based on the z-scores (weights) of the neighbors of the given node, and proportional to the z-score (weight) of the given node. Specifically, we find the maximum z-score of all neighbors of the given node that are also members of the given set of selected nodes, multiply this z-score by the z-score of the given node, and return this value as the z'-score for the given node. If the given node has no neighbors in the interaction graph, the z'-score is defined as zero. Returns the z'-score as zero or a positive floating point value. :Parameters: - `node`: the node for which to compute the z-prime score - `interaction_graph`: graph containing the gene-gene or gene product-gene product interactions - `selected_nodes`: a `set` of nodes fitting some criterion of interest (e.g., annotated with a term of interest) """ node_neighbors = interaction_graph.neighbors_iter(node) neighbors_in_selected_nodes = (neighbor for neighbor in node_neighbors if neighbor in selected_nodes) neighbor_z_scores = (interaction_graph.node[neighbor]['weight'] for neighbor in neighbors_in_selected_nodes) try: max_z_score = max(neighbor_z_scores) # max() throws a ValueError if its argument has no elements; in this # case, we need to set the max_z_score to zero except ValueError, e: # Check to make certain max() raised this error if 'max()' in e.args[0]: max_z_score = 0 else: raise e z_prime = interaction_graph.node[node]['weight'] * max_z_score return z_prime Here are the top couple of calls according to cProfiler, sorted by time. ncalls tottime percall cumtime percall filename:lineno(function) 156067701 352.313 0.000 642.072 0.000 bpln_contextual.py:204(<genexpr>) 156067701 289.759 0.000 289.759 0.000 bpln_contextual.py:202(<genexpr>) 13963893 174.047 0.000 816.119 0.000 {max} 13963885 69.804 0.000 936.754 0.000 bpln_contextual.py:171(calculate_node_z_prime) 7116883 61.982 0.000 61.982 0.000 {method 'update' of 'set' objects}

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• Php template caching design

  - by Thomas

  Hello to all, I want to include caching in my app design. Caching templates for starters. The design I have used so far is very modular. I have created an ORM implementation for all my tables and each table is represented by the corresponding class. All the requests are handled by one controller which routes them to the appropriate webmethod functions. I am using a template class for handling UI parts. What I have in mind for caching includes the implementation of a separate Cache class for handling caching with the flexibility to either store in files, apc or memcache. Right now I am testing with file caching. Some thoughts Should I include the logic of checking for cached versions in the Template class or in the webmethods which handle the incoming requests and which eventually call the Template class. In the first case, things are pretty simple as I will not have to change anything more than pass the template class an extra argument (whether to load from cache or not). In the second case however, I am thinking of checking for a cached version immediately in the webmethod and if found return it. This will save all the processing done until the logic reaches the template (first case senario). Both senarios however, rely on an accurate mechanism of invalidating caches, which brings as to Invalidating caches As I see it (and you can add your input freely) a template cached file, becomes invalidate if: a. the expiration set, is reached. b. the template file itself is updated (ie by the developer when adding a new line) c. the webmethod that handles the request changes (ie the developer adds/deletes something in the code) d. content coming from the db and ending in the template file is modified I am thinking of storing a json encoded array inside the cached file. The first value will be the expiration timestamp of the cache. The second value will be the modification time of the php file with the code handling the request (to cope with option c above) The third will be the content itself The validation process I am considering, according to the above senarios, is: a. If the expiration of the cached file (stored in the array) is reached, delete the cache file b. if the cached file's mod time is smaller than the template's skeleton file mod time, delete the cached file c. if the mod time of the php file is greated than the one stored in the cache, delete the cached file. d. This is tricky. In the ORM implementation I ahve added event handlers (which fire when adding, updating, deleting objects). I could delete the cache file every time an object thatprovides content to the template, is modified. The problem is how to keep track which cached files correpond to each schema object. Take this example, a user has his shortprofile page and a full profile page (2 templates) These templates can be cached. Now, every time the user modifies his profile, the event handler would need to know which templates or cached files correspond to the User, so that these files can be deleted. I could store them in the db but I am looking for a beter approach

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• Modern alternatives to Java

  - by Ralph

  I have been a Java developer for 14 years and have written an enterprise-level (~500 kloc) Swing application that uses most of the standard library APIs. Recently, I have become disappointed with the progress that the language has made to "modernize" itself, and am looking for an alternative for ongoing development. I have considered moving to the .NET platform, but I have issues with using something the only runs well in Windows (I know about Mono, but that is still far behind Microsoft). I also plan on buying a new Macbook Pro as soon as Apple releases their new rumored Arrandale-based machines and want to develop in an environment that will feel "at home" in Unix/Linux. I have considered using Python or Ruby, but the standard Java library is arguably the largest of any modern language. In JVM-based languages, I looked at Groovy, but am disappointed with its performance. Rumor has it that with the soon-to-be released JDK7, with its InvokeDynamic instruction, this will improve, but I don't know how much. Groovy is also not truly a functional language, although it provides closures and some of the "functional" features on collections. It does not embrace immutability. I have narrowed my search down to two JVM-based alternatives: Scala and Clojure. Each has its strengths and weaknesses. I am looking for opinions. I am not an expert at either of these languages; I have read 2 1/2 books on Scala and am currently reading Stu Halloway's book on Clojure. Scala is strongly statically typed. I know the dynamic language folks claim that static typing is a crutch for not doing unit testing, but it does provide a mechanism for compile-time location of a whole class of errors. Scala is more concise than Java, but not as much as Clojure. Scala's inter-operation with Java seems to be better than Clojure's, in that most Java operations are easier to do in Scala than in Clojure. For example, I can find no way in Clojure to create a non-static initialization block in a class derived from a Java superclass. For example, I like the Apache commons CLI library for command line argument parsing. In Java and Scala, I can create a new Options object and add Option items to it in an initialization block as follows (Java code): final Options options = new Options() { { addOption(new Option("?", "help", false, "Show this usage information"); // other options } }; I can't figure out how to the same thing in Clojure (except by using (doit...)), although that may reflect my lack of knowledge of the language. Clojure's collections are optimized for immutability. They rarely require copy-on-write semantics. I don't know if Scala's immutable collections are implemented using similar algorithms, but Rich Hickey (Clojure's inventor) goes out of his way to explain how that language's data structures are efficient. Clojure was designed from the beginning for concurrency (as was Scala) and with modern multi-core processors, concurrency takes on more importance, but I occasionally need to write simple non-concurrent utilities, and Scala code probably runs a little faster for these applications since it discourages, but does not prohibit, "simple" mutability. One could argue that one-off utilities do not have to be super-fast, but sometimes they do tasks that take hours or days to complete. I know that there is no right answer to this "question", but I thought I would open it up for discussion. Are there other JVM-based languages that can be used for enterprise level development?

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• how to add a function to that program, and call that function from the command line in the function

  - by user336291

  a#include "smallsh.h" /*include file for example*/ /*program buffers and work pointers*/ static char inpbuf[MAXBUF], tokbuf[2*MAXBUF], *ptr = inpbuf, *tok = tokbuf; userin(p) /*print prompt and read a line*/ char *p; { int c, count; /*initialization for later routines*/ ptr = inpbuf; tok = tokbuf; /*display prompt*/ printf("%s ",p); for(count = 0;;) { if((c = getchar()) == EOF) return(EOF); if(count<MAXBUF) inpbuf[count++] = c; if(c == '\n' && count <MAXBUF) { inpbuf[count] = '\0'; return(count); } /*if line too long restart*/ if(c == '\n') { printf("smallsh:input line too long\n"); count = 0; printf("%s",p); } } } gettok(outptr) /*get token and place into tokbuf*/ char **outptr; { int type; *outptr = tok; /*strip white space*/ for(;*ptr == ' ' || *ptr == '\t'; ptr++) ; *tok++ = *ptr; switch(*ptr++) { case '\n': type = EOL; break; case '&': type = AMPERSAND; break; case ';': type = SEMICOLON; break; case '#': type = POUND; break; default: type = ARG; while(inarg(*ptr)) *tok++ = *ptr++; } *tok++ = '\0'; return(type); } static char special[]= {' ', '\t', '&', ':', '\n', '\0'}; inarg(c) /*are we in an ordinary argument*/ char c; { char *wrk; for(wrk = special;*wrk != '\0';wrk++) if(c == *wrk) return(0); return(1); } #include "smallsh.h" procline() /*process input line*/ { char *arg[MAXARG+1]; /*pointer array for runcommand*/ int toktype; /*type of token in command*/ int narg; /*number of arguments so far*/ int type; /*FOREGROUND or BACKGROUND*/ for(narg = 0;;) { /*loop FOREVER*/ /*take action according to token type*/ switch(toktype = gettok(&arg[narg])) { case ARG: if(narg<MAXARG) narg++; break; case EOL: case SEMICOLON: case AMPERSAND: case POUND: type = (toktype == AMPERSAND) ? BACKGROUND : FOREGROUND; if(narg!=0) { arg[narg] = NULL; runcommand(arg, type); } if((toktype == EOL)||(toktype=POUND)) return; narg = 0; break; } } } #include "smallsh.h" /*execute a command with optional wait*/ runcommand(cline,where) char **cline; int where; { int pid, exitstat, ret; if((pid = fork()) <0) { perror("smallsh"); return(-1); } if(pid == 0) { /*child*/ execvp(*cline, cline); perror(*cline); exit(127); } /*code for parent*/ /*if background process print pid and exit*/ if(where == BACKGROUND) { printf("[Process id %d]\n", pid); return(0); } /*wait until process pid exists*/ while( (ret=wait(&exitstat)) != pid && ret != -1) ; return(ret == -1 ? -1 : exitstat); } #include "smallsh.h" char *prompt = "Command>"; /*prompt*/ main() { while(userin(prompt) != EOF) procline(); }

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• Do you 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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• Insane SmartGWT + GWT situation... Error on instantiating ListGridRecord?

  - by Xandel

  Hi all, I am asking this here in the hope that someone has maybe come across this situation too... I have posted this on the SmartGWT forum: I am having an issue when trying to instantiate a ListGridRecord object on my server side. I am using the ListGrid on the client side, I want to use GWT's RPC to pass back an array of ListGridRecord objects to populate the grid with. I know that SmartGWT is designed to link to a datasource but I want full control over when I populate the grid and this shouldn't be as much of a nightmare as it is to do. I have searched high and low and cannot find anyone complaining about the same thing. The exception however (listed below) has come up (in my search findings) as a possible memory error - where increasing the memory (-Xmx512m argument) has apparently solved the problem. It did not, however, sort out mine. If anyone can shed any light on this I would greatly appreciate it! Here are my details: Developing using Eclipse Galileo on Ubuntu 9.04 (Jaunty) and GWT 2.0.3, I built the initial GWT project using the webAppCreator bundled with the GWT 2.0.3 release and imported the project into Eclipse as described on the GWT Getting Started Page (as using the GWT Eclipse plugin caused even more nightmares when trying to connect to a database - this is apparently due to using the Google App Engine and turning it off as all the posts suggested only causes ClassNotFound exceptions). The line that causes the error is literally: ListGridRecord a = new ListGridRecord(); The error I get is the following: 00:00:25.916 [WARN] Exception while dispatching incoming RPC call com.google.gwt.user.server.rpc.UnexpectedException : Service method 'public abstract java.lang.String za.co.company.product.client.service.EmployeeServi ce.getAllEmployeeAsListGridRecord()' threw an unexpected exception: java.lang.UnsatisfiedLinkError: com.smartgwt.client.util.LogUtil.setJSNIErrorHandl er()V at com.google.gwt.user.server.rpc.RPC.encodeResponseF orFailure(RPC.java:378) at com.google.gwt.user.server.rpc.RPC.invokeAndEncode Response(RPC.java:581) at com.google.gwt.user.server.rpc.RemoteServiceServle t.processCall(RemoteServiceServlet.java:188) at com.google.gwt.user.server.rpc.RemoteServiceServle t.processPost(RemoteServiceServlet.java:224) at com.google.gwt.user.server.rpc.AbstractRemoteServi ceServlet.doPost(AbstractRemoteServiceServlet.java :62) at javax.servlet.http.HttpServlet.service(HttpServlet .java:637) at javax.servlet.http.HttpServlet.service(HttpServlet .java:717) at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:487) at org.mortbay.jetty.servlet.ServletHandler.handle(Se rvletHandler.java:362) at org.mortbay.jetty.security.SecurityHandler.handle( SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(Se ssionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(Co ntextHandler.java:729) at org.mortbay.jetty.webapp.WebAppContext.handle(WebA ppContext.java:405) at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152) at org.mortbay.jetty.handler.RequestLogHandler.handle (RequestLogHandler.java:49) at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:324) at org.mortbay.jetty.HttpConnection.handleRequest(Htt pConnection.java:505) at org.mortbay.jetty.HttpConnection$RequestHandler.co ntent(HttpConnection.java:843) at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:647) at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa rser.java:211) at org.mortbay.jetty.HttpConnection.handle(HttpConnec tion.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(Selec tChannelEndPoint.java:395) at org.mortbay.thread.QueuedThreadPool$PoolThread.run (QueuedThreadPool.java:488) Caused by: java.lang.UnsatisfiedLinkError: com.smartgwt.client.util.LogUtil.setJSNIErrorHandl er()V at com.smartgwt.client.util.LogUtil.setJSNIErrorHandl er(Native Method) at com.smartgwt.client.core.JsObject.(JsObjec t.java:30) at za.co.company.product.server.service.EmployeeServi ceImpl.getAllEmployeeAsListGridRecord(EmployeeServ iceImpl.java:83) at sun.reflect.NativeMethodAccessorImpl.invoke0(Nativ e Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Native MethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(De legatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at com.google.gwt.user.server.rpc.RPC.invokeAndEncode Response(RPC.java:562) at com.google.gwt.user.server.rpc.RemoteServiceServle t.processCall(RemoteServiceServlet.java:188) at com.google.gwt.user.server.rpc.RemoteServiceServle t.processPost(RemoteServiceServlet.java:224) at com.google.gwt.user.server.rpc.AbstractRemoteServi ceServlet.doPost(AbstractRemoteServiceServlet.java :62) at javax.servlet.http.HttpServlet.service(HttpServlet .java:637) at javax.servlet.http.HttpServlet.service(HttpServlet .java:717) at org.mortbay.jetty.servlet.ServletHolder.handle(Ser vletHolder.java:487) at org.mortbay.jetty.servlet.ServletHandler.handle(Se rvletHandler.java:362) at org.mortbay.jetty.security.SecurityHandler.handle( SecurityHandler.java:216) at org.mortbay.jetty.servlet.SessionHandler.handle(Se ssionHandler.java:181) at org.mortbay.jetty.handler.ContextHandler.handle(Co ntextHandler.java:729) at org.mortbay.jetty.webapp.WebAppContext.handle(WebA ppContext.java:405) at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152) at org.mortbay.jetty.handler.RequestLogHandler.handle (RequestLogHandler.java:49) at org.mortbay.jetty.handler.HandlerWrapper.handle(Ha ndlerWrapper.java:152) at org.mortbay.jetty.Server.handle(Server.java:324) at org.mortbay.jetty.HttpConnection.handleRequest(Htt pConnection.java:505) at org.mortbay.jetty.HttpConnection$RequestHandler.co ntent(HttpConnection.java:843) at org.mortbay.jetty.HttpParser.parseNext(HttpParser. java:647) at org.mortbay.jetty.HttpParser.parseAvailable(HttpPa rser.java:211) at org.mortbay.jetty.HttpConnection.handle(HttpConnec tion.java:380) at org.mortbay.io.nio.SelectChannelEndPoint.run(Selec tChannelEndPoint.java:395) at org.mortbay.thread.QueuedThreadPool$PoolThread.run (QueuedThreadPool.java:488) Thanks in advance! Xandel

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• Confusion on C++ Python extensions. Things like getting C++ values for python values.

  - by Matthew Mitchell

  I'm wanted to convert some of my python code to C++ for speed but it's not as easy as simply making a C++ function and making a few function calls. I have no idea how to get a C++ integer from a python integer object. I have an integer which is an attribute of an object that I want to use. I also have integers which are inside a list in the object which I need to use. I wanted to test making a C++ extension with this function: def setup_framebuffer(surface,flip=False): #Create texture if not done already if surface.texture is None: create_texture(surface) #Render child to parent if surface.frame_buffer is None: surface.frame_buffer = glGenFramebuffersEXT(1) glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, c_uint(int(surface.frame_buffer))) glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, surface.texture, 0) glPushAttrib(GL_VIEWPORT_BIT) glViewport(0,0,surface._scale[0],surface._scale[1]) glMatrixMode(GL_PROJECTION) glLoadIdentity() #Load the projection matrix if flip: gluOrtho2D(0,surface._scale[0],surface._scale[1],0) else: gluOrtho2D(0,surface._scale[0],0,surface._scale[1]) That function calls create_texture, so I will have to pass that function to the C++ function which I will do with the third argument. This is what I have so far, while trying to follow information on the python documentation: #include <Python.h> #include <GL/gl.h> static PyMethodDef SpamMethods[] = { ... {"setup_framebuffer", setup_framebuffer, METH_VARARGS,"Loads a texture from a Surface object to the OpenGL framebuffer."}, ... {NULL, NULL, 0, NULL} /* Sentinel */ }; static PyObject * setup_framebuffer(PyObject *self, PyObject *args){ bool flip; PyObject *create_texture, *arg_list,*pyflip,*frame_buffer_id; if (!PyArg_ParseTuple(args, "OOO", &surface,&pyflip,&create_texture)){ return NULL; } if (PyObject_IsTrue(pyflip) == 1){ flip = true; }else{ flip = false; } Py_XINCREF(create_texture); //Create texture if not done already if(texture == NULL){ arglist = Py_BuildValue("(O)", surface) result = PyEval_CallObject(create_texture, arglist); Py_DECREF(arglist); if (result == NULL){ return NULL; } Py_DECREF(result); } Py_XDECREF(create_texture); //Render child to parent frame_buffer_id = PyObject_GetAttr(surface, Py_BuildValue("s","frame_buffer")) if(surface.frame_buffer == NULL){ glGenFramebuffersEXT(1,frame_buffer_id); } glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, surface.frame_buffer)); glFramebufferTexture2DEXT(GL_FRAMEBUFFER_EXT, GL_COLOR_ATTACHMENT0_EXT, GL_TEXTURE_2D, surface.texture, 0); glPushAttrib(GL_VIEWPORT_BIT); glViewport(0,0,surface._scale[0],surface._scale[1]); glMatrixMode(GL_PROJECTION); glLoadIdentity(); //Load the projection matrix if (flip){ gluOrtho2D(0,surface._scale[0],surface._scale[1],0); }else{ gluOrtho2D(0,surface._scale[0],0,surface._scale[1]); } Py_INCREF(Py_None); return Py_None; } PyMODINIT_FUNC initcscalelib(void){ PyObject *module; module = Py_InitModule("cscalelib", Methods); if (m == NULL){ return; } } int main(int argc, char *argv[]){ /* Pass argv[0] to the Python interpreter */ Py_SetProgramName(argv[0]); /* Initialize the Python interpreter. Required. */ Py_Initialize(); /* Add a static module */ initscalelib(); }

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• Where are the function address literals in c++?

  - by academicRobot

  First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). <UPDATE> After some reading with help from answer by Chris Dodd, what I'm looking for is literal function addresses as template parameters. Chris' answer indicates how to do this for standard functions, but how can the addresses of member functions be used as template parameters? Since the standard prohibits non-static member function addresses as template parameters (c++03 14.3.2.3), I suspect the work around is quite complicated. Any ideas for a workaround? Below the original form of the question is left as is for context. </UPDATE> The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one. Edit The intent of this question is not to implement delegates, rather to identify a pattern that will embed a conventional function call, (in immediate mode) directly into third party code, possibly a template.

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• Help in building an 16 bit os

  - by Barshan Das

  I am trying to build an old 16 bit dos like os. My bootloader code: ; This is not my code. May be of Fritzos. I forgot the source. ORG 7c00h jmp Start drive db 0 msg db " Loader Initialization",0 msg2 db "ACos Loaded",0 print: lodsb cmp al, 0 je end mov ah, 0Eh int 10h jmp print end: ret Start: mov [ drive ], dl ; Get the floppy OS booted from ; Update the segment registers xor ax, ax ; XOR ax mov ds, ax ; Mov AX into DS mov si,msg call print ; Load Kernel. ResetFloppy: mov ax, 0x00 ; Select Floppy Reset BIOS Function mov dl, [ drive ] ; Select the floppy ADos booted from int 13h ; Reset the floppy drive jc ResetFloppy ; If there was a error, try again. ReadFloppy: mov bx, 0x9000 ; Load kernel at 9000h. mov ah, 0x02 ; Load disk data to ES:BX mov al, 17 ; Load two floppy head full's worth of data. mov ch, 0 ; First Cylinder mov cl, 2 ; Start at the 2nd Sector to load the Kernel mov dh, 0 ; Use first floppy head mov dl, [ drive ] ; Load from the drive kernel booted from. int 13h ; Read the floppy disk. jc ReadFloppy ; Error, try again. ; Clear text mode screen mov ax, 3 int 10h ;print starting message mov si,msg2 call print mov ax, 0x0 mov ss, ax mov sp, 0xFFFF jmp 9000h ; This part makes sure the bootsector is 512 bytes. times 510-($-$$) db 0 ;bootable sector signature dw 0xAA55 My example kernel code: asm(".code16\n"); void putchar(char); int main() { putchar('A'); return 0; } void putchar(char val) { asm("movb %0, %%al\n" "movb $0x0E, %%ah\n" "int $0x10\n" : :"r"(val) ) ; } This is how I compile it : nasm -f bin -o ./bin/boot.bin ./source/boot.asm gcc -nostdinc -fno-builtin -I./include -c -o ./bin/kernel.o ./source/kernel.c ld -Ttext=0x9000 -o ./bin/kernel.bin ./bin/kernel.o -e 0x0 dd if=/dev/zero of=./bin/empty.bin bs=1440K count=1 cat ./bin/boot.bin ./bin/kernel.bin ./bin/empty.bin|head -c 1440K > ./bin/os rm ./bin/empty.bin and I run it in virtual machine. When I make the putchar function ( in kernel code ) for constant value ....i.e like this: void putchar() { char val = 'A'; asm("movb %0, %%al\n" "movb $0x0E, %%ah\n" "int $0x10\n" : :"r"(val) ) ; } then it works fine. But when I pass argument to it ( That is in the previous code ) , then it prints a space for any character. What should I do?

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