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  • Integer Surrogate Key?

    - by CitadelCSAlum
    I need something real simple, that for some reason I am unable to accomplish to this point. I have also been unable to Google the answer surprisingly. I need to number the entries in different tables uniquely. I am aware of AUTO INCREMENT in MySQL and that it will be involved. My situation would be as follows If I had a table like Table EXAMPLE ID - INTEGER FIRST_NAME - VARCHAR(45) LAST_NAME - VARCHAR(45) PHONE - VARCHAR(45) CITY - VARCHAR(45) STATE - VARCHAR(45) ZIP - VARCHAR(45) This would be the setup for the table where ID is an integer that is auto-incremented every time an entry is inserted into the table. The thing I need is that I do not want to have to account for this field when inserting data into the database. From my understanding this would be a surrogate key, that I can tell the database to automatically increment and I do not have to include it in the INSERT STATEMENT so instead of INSERT INTO EXAMPLE VALUES (2,'JOHN','SMITH',333-333-3333,'NORTH POLE'.... I can leave out the first ID column and just write something like INSERT INTO EXAMPLE VALUES ('JOHN','SMITH'.....etc) Notice I Wouldnt have to define the ID column... I know this is a very common task to do, but for some reason I cant get to the bottom of it. I am using MySQL, just to clarify. Thanks alot

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  • Perceptron Classification and Model Training

    - by jake pinedo
    I'm having an issue with understanding how the Perceptron algorithm works and implementing it. cLabel = 0 #class label: corresponds directly with featureVectors and tweets for m in range(miters): for point in featureVectors: margin = answers[cLabel] * self.dot_product(point, w) if margin <= 0: modifier = float(lrate) * float(answers[cLabel]) modifiedPoint = point for x in modifiedPoint: if x != 0: x *= modifier newWeight = [modifiedPoint[i] + w[i] for i in range(len(w))] w = newWeight self._learnedWeight = w This is what I've implemented so far, where I have a list of class labels in answers and a learning rate (lrate) and a list of feature vectors. I run it for the numbers of iterations in miter and then get the final weight at the end. However, I'm not sure what to do with this weight. I've trained the perceptron and now I have to classify a set of tweets, but I don't know how to do that. EDIT: Specifically, what I do in my classify method is I go through and create a feature vector for the data I'm given, which isn't a problem at all, and then I take the self._learnedWeight that I get from the earlier training code and compute the dot-product of the vector and the weight. My weight and feature vectors include a bias in the 0th term of the list so I'm including that. I then check to see if the dotproduct is less than or equal to 0: if so, then I classify it as -1. Otherwise, it's 1. However, this doesn't seem to be working correctly.

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  • How to handle Lightbox with Capybara , Selenium and Cucumber framework?

    - by Sushil
    Im trying to run test suite that will handle the jquery light-box. Light box contains a text-area and a submit button. Before Light box appears both of these fields are hidden. But selenium framework not understanding the visibility of these element in Light box. It just shows following error. And I fill comment box with "Text !!" # features/step_definitions/web_steps.rb:333 Element is not currently visible and so may not be interacted with (Selenium::WebDriver::Error::ElementNotVisibleError) [remote server] file:///tmp/webdriver-profile20120403-6182-1rd9z23/extensions/[email protected]/components/command_processor.js:9509:in `unknown' [remote server] file:///tmp/webdriver-profile20120403-6182-1rd9z23/extensions/[email protected]/components/command_processor.js:10510:in `unknown' [remote server] file:///tmp/webdriver-profile20120403-6182-1rd9z23/extensions/[email protected]/components/command_processor.js:10529:in `unknown' [remote server] file:///tmp/webdriver-profile20120403-6182-1rd9z23/extensions/[email protected]/components/command_processor.js:10534:in `unknown' [remote server] file:///tmp/webdriver-profile20120403-6182-1rd9z23/extensions/[email protected]/components/command_processor.js:10482:in `unknown' (eval):2:in `send' (eval):2:in `fill_in' ./features/step_definitions/web_steps.rb:335:in `/^I fill comment box with "([^"]*)"$/' features/courses_flow.feature:21:in `And I fill comment box with "Text !!"'

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  • Using pipes in Linux with C

    - by Dave
    Hi, I'm doing a course in Operating Systems and we're supposed to learn how to use pipes to transfer data between processes. We were given this simple piece of code which demonstrates how to use pipes,but I'm having difficulty understanding it. #include <stdio.h> #include <stdlib.h> #include <unistd.h> main() { int pipefd [2], n; char buff[100] ; if( pipe( pipefd) < 0) { printf("can not create pipe \n"); } printf("read fd = %d, write fd = %d \n", pipefd[0], pipefd[1]); if ( write (pipefd[1],"hello world\n", 12)!= 12) { printf("pipe write error \n"); } if( ( n = read ( pipefd[0] , buff, sizeof ( buff) ) ) <= 0 ) { printf("pipe read error \n"); } write ( 1, buff, n ) ; exit (0); } What does the write function do? It seems to send data to the pipe and also print it to the screen (at least it seems like the second time the write function is called it does this). Does anyone have any suggestions of good websites for learning about topics such as this, FIFO, signals, other basic linux commands used in C?

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  • JPA @ManyToMany on only one side?

    - by Ethan Leroy
    I am trying to refresh the @ManyToMany relation but it gets cleared instead... My Project class looks like this: @Entity public class Project { ... @ManyToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER) @JoinTable(name = "PROJECT_USER", joinColumns = @JoinColumn(name = "PROJECT_ID", referencedColumnName = "ID"), inverseJoinColumns = @JoinColumn(name = "USER_ID", referencedColumnName = "ID")) private Collection<User> users; ... } But I don't have - and I don't want - the collection of Projects in the User entity. When I look at the generated database tables, they look good. They contain all columns and constraints (primary/foreign keys). But when I persist a Project that has a list of Users (and the users are still in the database), the mapping table doesn't get updated gets updated but when I refresh the project afterwards, the list of Users is cleared. For better understanding: Project project = ...; // new project with users that are available in the db System.out.println(project getUsers().size()); // prints 5 em.persist(project); System.out.println(project getUsers().size()); // prints 5 em.refresh(project); System.out.println(project getUsers().size()); // prints 0 So, how can I refresh the relation between User and Project?

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  • randomized quicksort: probability of two elements comparison?

    - by bantu
    I am reading "Probability and Computing" by M.Mitzenmacher, E.Upfal and I have problems understanding how the probability of comparison of two elements is calculated. Input: the list (y1,y2,...,YN) of numbers. We are looking for pivot element. Question: what is probability that two elements yi and yj (ji) will be compared? Answer (from book): yi and yj will be compared if either yi or yj will be selected as pivot in first draw from sequence (yi,yi+1,...,yj-1,yj). So the probablity is: 2/(y-i+1). The problem for me is initial claim: for example, picking up yi in the first draw from the whole list will cause the comparison with yj (and vice-versa) and the probability is 2/n. So, rather the "reverse" claim is true -- none of the (yi+1,...,yj-1) elements can be selected beforeyi or yj, but the "pool" size is not fixed (in first draw it is n for sure, but on the second it is smaller). Could someone please explain this, how the authors come up with such simplified conclusion? Thank you in advance

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  • How to write a custom solution using a python package, modules etc

    - by morpheous
    I am writing a packacge foobar which consists of the modules alice, bob, charles and david. From my understanding of Python packages and modules, this means I will create a folder foobar, with the following subdirectories and files (please correct if I am wrong) foobar/ __init__.py alice/alice.py bob/bob.py charles/charles.py david/david.py The package should be executable, so that in addition to making the modules alice, bob etc available as 'libraries', I should also be able to use foobar in a script like this: python foobar --args=someargs Question1: Can a package be made executable and used in a script like I described above? Question 2 The various modules will use code that I want to refactor into a common library. Does that mean creating a new sub directory 'foobar/common' and placing common.py in that folder? Question 3 How will the modules foo import the common module ? Is it 'from foobar import common' or can I not use this since these modules are part of the package? Question 4 I want to add logic for when the foobar package is being used in a script (assuming this can be done - I have only seen it done for modules) The code used is something like: if __name__ == "__main__": dosomething() where (in which file) would I put this logic ?

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  • Linux C++: Linker is outputting strange errors

    - by knight666
    Alright, here is the output I get: arm-none-linux-gnueabi-ld --entry=main -dynamic-linker=/system/bin/linker -rpath-link=/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib -L/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib -nostdlib -lstdc++ -lm -lGLESv1_CM -rpath=/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib -rpath=../../YoghurtGum/lib/Android -L./lib/Android intermediate/Alien.o intermediate/Bullet.o intermediate/Game.o intermediate/Player.o ../../YoghurtGum/bin/YoghurtGum.a -o bin/Galaxians.android intermediate/Game.o: In function `Galaxians::Init()': /media/YoghurtGum/Tests/Galaxians/src/Game.cpp:45: undefined reference to `__cxa_end_cleanup' /media/YoghurtGum/Tests/Galaxians/src/Game.cpp:44: undefined reference to `__cxa_end_cleanup' intermediate/Game.o:(.ARM.extab+0x18): undefined reference to `__gxx_personality_v0' intermediate/Game.o: In function `Player::Update()': /media/YoghurtGum/Tests/Galaxians/src/Player.h:41: undefined reference to `__cxa_end_cleanup' intermediate/Game.o:(.ARM.extab.text._ZN6Player6UpdateEv[_ZN6Player6UpdateEv]+0x0): undefined reference to `__gxx_personality_v0' intermediate/Game.o:(.rodata._ZTIN10YoghurtGum4GameE[_ZTIN10YoghurtGum4GameE]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info' intermediate/Game.o:(.rodata._ZTI6Player[_ZTI6Player]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Game.o:(.rodata._ZTIN10YoghurtGum6EntityE[_ZTIN10YoghurtGum6EntityE]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Game.o:(.rodata._ZTIN10YoghurtGum6ObjectE[_ZTIN10YoghurtGum6ObjectE]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info' intermediate/Game.o:(.rodata._ZTI6Bullet[_ZTI6Bullet]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Game.o:(.rodata._ZTI5Alien[_ZTI5Alien]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Game.o:(.rodata+0x20): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' ../../YoghurtGum/bin/YoghurtGum.a(Sprite.o):(.rodata._ZTIN10YoghurtGum16SpriteDataOpenGLE[_ZTIN10YoghurtGum16SpriteDataOpenGLE]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' ../../YoghurtGum/bin/YoghurtGum.a(Sprite.o):(.rodata._ZTIN10YoghurtGum10SpriteDataE[_ZTIN10YoghurtGum10SpriteDataE]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info' make: *** [bin/Galaxians.android] Fout 1 Here's an error I managed to decipher: intermediate/Game.o: In function `Galaxians::Init()': /media/YoghurtGum/Tests/Galaxians/src/Game.cpp:45: undefined reference to `__cxa_end_cleanup' /media/YoghurtGum/Tests/Galaxians/src/Game.cpp:44: undefined reference to `__cxa_end_cleanup' This is line 43 through 45: Assets::AddSprite(new Sprite("media\\ViperMarkII.bmp"), "ship"); Assets::AddSprite(new Sprite("media\\alien.bmp"), "alien"); Assets::AddSprite(new Sprite("media\\bat_ball.bmp"), "bullet"); So, what seems funny to me is that the first new is fine (line 43), but the second one isn't. What could cause this? intermediate/Game.o: In function `Player::Update()': /media/YoghurtGum/Tests/Galaxians/src/Player.h:41: undefined reference to `__cxa_end_cleanup' Another issue with new: Engine::game->scene_current->AddObject(new Bullet(m_X + 10, m_Y)); I have no idea where to begin with the other issues. These are my makefiles, They're a giant mess because I'm just trying to get it to work. Static library: # ====================================== # # # # YoghurtGum static library # # # # ====================================== # include ../YoghurtGum.mk PROGS = bin/YoghurtGum.a SOURCES = $(wildcard src/*.cpp) #$(YG_PATH_LIB)/libGLESv1_CM.so \ #$(YG_PATH_LIB)/libEGL.so \ YG_LINK_OPTIONS = -shared YG_LIBRARIES = \ $(YG_PATH_LIB)/libc.a \ $(YG_PATH_LIB)/libc.so \ $(YG_PATH_LIB)/libstdc++.a \ $(YG_PATH_LIB)/libstdc++.so \ $(YG_PATH_LIB)/libm.a \ $(YG_PATH_LIB)/libm.so \ $(YG_PATH_LIB)/libui.so \ $(YG_PATH_LIB)/liblog.so \ $(YG_PATH_LIB)/libGLESv2.so \ $(YG_PATH_LIB)/libcutils.so \ YG_OBJECTS = $(patsubst src/%.cpp, $(YG_INT)/%.o, $(SOURCES)) YG_NDK_PATH_LIB = /home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib all: $(PROGS) rebuild: clean $(PROGS) # remove all .o objects from intermediate and all .android objects from bin clean: rm -f $(YG_INT)/*.o $(YG_BIN)/*.a copy: acpy ../$(PROGS) $(PROGS): $(YG_OBJECTS) $(YG_ARCHIVER) -vq $(PROGS) $(YG_NDK_PATH_LIB)/crtbegin_static.o $(YG_NDK_PATH_LIB)/crtend_android.o $^ && \ $(YG_ARCHIVER) -vr $(PROGS) $(YG_LIBRARIES) $(YG_OBJECTS): $(YG_INT)/%.o : $(YG_SRC)/%.cpp $(YG_COMPILER) $(YG_FLAGS) -I $(GLES_INCLUDES) -c $< -o $@ Test game project: # ====================================== # # # # Galaxians # # # # ====================================== # include ../../YoghurtGum.mk PROGS = bin/Galaxians.android YG_COMPILER = arm-none-linux-gnueabi-g++ YG_LINKER = arm-none-linux-gnueabi-ld YG_PATH_LIB = ./lib/Android YG_LIBRARIES = ../../YoghurtGum/bin/YoghurtGum.a YG_PROGS = bin/Galaxians.android GLES_INCLUDES = ../../YoghurtGum/src ANDROID_NDK_ROOT = /home/oem/android-ndk-r3 NDK_PLATFORM_VER = 5 YG_NDK_PATH_LIB = $(ANDROID_NDK_ROOT)/build/platforms/android-$(NDK_PLATFORM_VER)/arch-arm/usr/lib YG_LIBS = -nostdlib -lstdc++ -lm -lGLESv1_CM #YG_COMPILE_OPTIONS = -g -rdynamic -Wall -Werror -O2 -w YG_COMPILE_OPTIONS = -g -Wall -Werror -O2 -w YG_LINK_OPTIONS = --entry=main -dynamic-linker=/system/bin/linker -rpath-link=$(YG_NDK_PATH_LIB) -L$(YG_NDK_PATH_LIB) $(YG_LIBS) SOURCES = $(wildcard src/*.cpp) YG_OBJECTS = $(patsubst src/%.cpp, intermediate/%.o, $(SOURCES)) all: $(PROGS) rebuild: clean $(PROGS) clean: rm -f intermediate/*.o bin/*.android $(PROGS): $(YG_OBJECTS) $(YG_LINKER) $(YG_LINK_OPTIONS) -rpath=$(YG_NDK_PATH_LIB) -rpath=../../YoghurtGum/lib/Android -L$(YG_PATH_LIB) $^ $(YG_LIBRARIES) -o $@ $(YG_OBJECTS): intermediate/%.o : src/%.cpp $(YG_COMPILER) $(YG_COMPILE_OPTIONS) -I ../../YoghurtGum/src/GLES -I ../../YoghurtGum/src -c $< -o $@ Any help would be appreciated.

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  • How Can I: Generate 40/64 Bit WEP Key In Python?

    - by Aktariel
    So, I've been beating my head against the wall of this issue for several months now, partly because it's a side interest and partly because I suck at programming. I've searched and researched all across the web, but have not had any luck (except one small bit of success; see below), so I thought I might try asking the experts. What I am trying to do is, as the title suggests, generate a 40/64 bit WEP key from a passphrase, according to the "de facto" standard. (A site such as [http://www.powerdog.com/wepkey.cgi] produces the expected outputs.) I have already written portions of the script that take inputs and write them to a file; one of the inputs would be the passphrase, sanitized to lower case. For the longest time I had no idea what the defacto standard was, much less how to even go about implementing it. I finally stumbled across a paper (http://www.lava.net/~newsham/wlan/WEP_password_cracker.pdf) that sheds as much light as I've had yet on the issue (page 18 has the relevant bits). Apparently, the passphrase is "mapped to a 32-bit value with XOR," the result of which is then used as the seed for a "linear congruential PRNG (which one of the several PRNGs Python has would fit this description, I don't know), and then from that result several bits of the result are taken. I have no idea how to go about implementing this, since the description is rather vague. What I need is help in writing the generator in Python, and also in understanding how exactly the key is generated. I'm not much of a programmer, so explanations are appreciated as well. (Yes, I know that WEP isn't secure.)

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  • Nginx rewrite for link shortener and Wordpress

    - by detusueno
    I'm a complete newbie to Nginx, so much so that I followed a online guide to do most of my server setup. I'm trying to learn but I'm still a ways away from understanding it all. So what I'm trying to create is a link shortener that redirects (example.com/x) to (example.com/short.php?id=x). Keep in mind that I'm also running a Wordpress blog on the same domain and plan on using the redirects/shortening for external links. The guide has so far had me add the following rewrites to enable Wordpress pretty URLs: # WordPress pretty URLs: (as per dominiek.com) if (-f $request_filename) { break; } if (-d $request_filename) { break; } rewrite ^(.+)$ /index.php?q=$1 last; # Enable nice permalinks for WordPress: (as per Yawn.it) error_page 404 = //index.php?q=$uri; And if it matters any, it was saved at (/usr/local/nginx/conf/wordpress_params.regular). Additionally, my Wordpress link structure adds "news" to all internal links (example.com/news/post-blah, example.com/news/category, ect.). What's the best way to tackle this setup?

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  • c# web extracting programming, which libraries, examples samples please

    - by user287745
    I have just started programming and have made a few small applications in C and C#. My understanding is that programming for web and thing related to web is nowadays a very easy task. Please note this is for personnel learning, not for rent a coder or any money making. An application which can run on any Windows platform even Windows 98. The application should start automatically at a scheduled time and do the following. Connect to a site which displays stock prices summary (high low current open). Capture the data (excluding the other things in the site.) And save it to disk (an SQL database) Please note:- Internet connection is assumed to be there always. Do not want to know how to make database schema or database. The stock exchange has no law prohibiting the use of the data provided on its site, but I do not want to mention the name in case I am wrong, but it's for personal private use only. The data of summary of pricing is arranged in a table such that when copied pasted to MS Excel it automatically forms a table. need steps guidance please, examples, lbraries

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  • Linear feedback shift register?

    - by Mattia Gobbi
    Lately I bumped repeatedly into the concept of LFSR, that I find quite interesting because of its links with different fields and also fascinating in itself. It took me some effort to understand, the final help was this really good page, much better than the (at first) cryptic wikipedia entry. So I wanted to write some small code for a program that worked like a LFSR. To be more precise, that somehow showed how a LFSR works. Here's the cleanest thing I could come up with after some lenghtier attempts (Python): def lfsr(seed, taps): sr, xor = seed, 0 while 1: for t in taps: xor += int(sr[t-1]) if xor%2 == 0.0: xor = 0 else: xor = 1 print xor sr, xor = str(xor) + sr[:-1], 0 print sr if sr == seed: break lfsr('11001001', (8,7,6,1)) #example I named "xor" the output of the XOR function, not very correct. However, this is just meant to show how it circles through its possible states, in fact you noticed the register is represented by a string. Not much logical coherence. This can be easily turned into a nice toy you can watch for hours (at least I could :-) def lfsr(seed, taps): import time sr, xor = seed, 0 while 1: for t in taps: xor += int(sr[t-1]) if xor%2 == 0.0: xor = 0 else: xor = 1 print xor print time.sleep(0.75) sr, xor = str(xor) + sr[:-1], 0 print sr print time.sleep(0.75) Then it struck me, what use is this in writing software? I heard it can generate random numbers; is it true? how? So, it would be nice if someone could: explain how to use such a device in software development come up with some code, to support the point above or just like mine to show different ways to do it, in any language Also, as theres not much didactic stuff around about this piece of logic and digital circuitry, it would be nice if this could be a place for noobies (like me) to get a better understanding of this thing, or better, to understand what it is and how it can be useful when writing software. Should have made it a community wiki? That said, if someone feels like golfing... you're welcome.

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  • JQuery UI Tabs: Apply opacity toggle to only specific inner element?

    - by Kerri
    I am using Jquery UI tabs, and have it set to toggle the opacity with each slide change. I'm wondering if there's a way to apply the opacity toggle to only a single element within each tab, instead of the entire tab. My understanding of jQuery is pretty basic, so bear with me. So, If I have something like this: <div id="tabs"> <ul id="tabs-nav><li></li></ul> <div id="tab-1"> <img /> <p /> </div> <div id="tab-2"> <img /> <p /> </div> ...etc </div> How could I set it so that only the <img> has an effect applied, and the rest just switches normally? Here are the basics of the call I have for UI tabs: var $tabs = $('#slides').tabs({fx: { opacity: 'toggle' } }); $(".ui-tabs-panel").each(function(i){ //stuff to create previous/next links }); $('.next-tab, .prev-tab').click(function() { $tabs.tabs('select', $(this).attr("rel")); return false; });

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  • Qt, MSVC, and /Zc:wchar_t- == I want to blow up the world

    - by Noah Roberts
    So Qt is compiled with /Zc:wchar_t- on windows. What this means is that instead of wchar_t being a typedef for some internal type (__wchar_t I think) it becomes a typedef for unsigned short. The really cool thing about this is that the default for MSVC is the opposite, which of course means that the libraries you're using are likely compiled with wchar_t being a different type than Qt's wchar_t. This doesn't become an issue of course until you try to use something like std::wstring in your code; especially when one or more libraries have functions that accept it as parameters. What effectively happens is that your code happily compiles but then fails to link because it's looking for definitions using std::wstring<unsigned short...> but they only contain definitions expecting std::wstring<__wchar_t...> (or whatever). So I did some web searching and ran into this link: http://bugreports.qt.nokia.com/browse/QTBUG-6345 Based on the statement by Thiago Macieira, "Sorry, we will not support building Qt like this," I've been worried that fixing Qt to work like everything else might cause some problem and have been trying to avoid it. We recompiled all of our support libraries with the /Zc:wchar_t- flag and have been fairly content with that until a couple days ago when we started trying to port over (we're in the process of switching from Wx to Qt) some serialization code. Because of how win32 works, and because Wx just wraps win32, we've been using std::wstring to represent string data with the intent of making our product as i18n ready as possible. We did some testing and Wx did not work with multibyte characters when trying to print special stuff (even not so special stuff like the degree symbol was an issue). I'm not so sure that Qt has this problem since QString isn't just a wrapper to the underlying _TCHAR type but is a Unicode monster of some sort. At any rate, the serialization library in boost has compiled parts. We've attempted to recompile boost with /Zc:wchar_t- but so far our attempts to tell bjam to do this have gone unheeded. We're at an impasse. From where I'm sitting I have three options: Recompile Qt and hope it works with /Zc:wchar_t. There's some evidence around the web that others have done this but I have no way of predicting what will happen. All attempts to ask Qt people on forums and such have gone unanswered. Hell, even in that very bug report someone asks why and it just sat there for a year. Keep fighting with bjam until it listens. Right now I've got someone under me doing that and I have more experience fighting with things to get what I want but I do have to admit to getting rather tired of it. I'm also concerned that I'll KEEP running into this issue just because Qt wants to be a c**t. Stop using wchar_t for anything. Unfortunately my i18n experience is pretty much 0 but it seems to me that I just need to find the right to/from function in QString (it has a BUNCH) to encode the Unicode into 8-bytes and visa-versa. UTF8 functions look promising but I really want to be sure that no data will be lost if someone from Zimbabfuckegypt starts writing in their own language and the documentation in QString frightens me a little into thinking that could happen. Of course, I could always run into some library that insists I use wchar_t and then I'm back to 1 or 2 but I rather doubt that would happen. So, what's my question... Which of these options is my best bet? Is Qt going to eventually cause me to gouge out my own eyes because I decided to compile it with /Zc:wchar_t anyway? What's the magic incantation to get boost to build with /Zc:wchar_t- and will THAT cause permanent mental damage? Can I get away with just using the standard 8-bit (well, 'common' anyway) character classes and be i18n compliant/ready? How do other Qt developers deal with this mess?

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  • Question about the Cloneable interface and the exception that should be thrown

    - by Nazgulled
    Hi, The Java documentation says: A class implements the Cloneable interface to indicate to the Object.clone() method that it is legal for that method to make a field-for-field copy of instances of that class. Invoking Object's clone method on an instance that does not implement the Cloneable interface results in the exception CloneNotSupportedException being thrown. By convention, classes that implement this interface should override Object.clone (which is protected) with a public method. See Object.clone() for details on overriding this method. Note that this interface does not contain the clone method. Therefore, it is not possible to clone an object merely by virtue of the fact that it implements this interface. Even if the clone method is invoked reflectively, there is no guarantee that it will succeed. And I have this UserProfile class: public class UserProfile implements Cloneable { private String name; private int ssn; private String address; public UserProfile(String name, int ssn, String address) { this.name = name; this.ssn = ssn; this.address = address; } public UserProfile(UserProfile user) { this.name = user.getName(); this.ssn = user.getSSN(); this.address = user.getAddress(); } // get methods here... @Override public UserProfile clone() { return new UserProfile(this); } } And for testing porpuses, I do this in main(): UserProfile up1 = new UserProfile("User", 123, "Street"); UserProfile up2 = up1.clone(); So far, no problems compiling/running. Now, per my understanding of the documentation, removing implements Cloneable from the UserProfile class should throw an exception in up1.clone() call, but it doesn't. I've read around here that the Cloneable interface is broken but I don't really know what that means. Am I missing something?

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  • Delphi 6 OleServer.pas Invoke memory leak

    - by Mike Davis
    There's a bug in delphi 6 which you can find some reference online for when you import a tlb the order of the parameters in an event invocation is reversed. It is reversed once in the imported header and once in TServerEventDIspatch.Invoke. you can find more information about it here: http://cc.embarcadero.com/Item/16496 somewhat related to this issue there appears to be a memory leak in TServerEventDispatch.Invoke with a parameter of a Variant of type Var_Array (maybe others, but this is the more obvious one i could see). The invoke code copies the args into a VarArray to be passed to the event handler and then copies the VarArray back to the args after the call, relevant code pasted below: // Set our array to appropriate length SetLength(VarArray, ParamCount); // Copy over data for I := Low(VarArray) to High(VarArray) do VarArray[I] := OleVariant(TDispParams(Params).rgvarg^[I]); // Invoke Server proxy class if FServer <> nil then FServer.InvokeEvent(DispID, VarArray); // Copy data back for I := Low(VarArray) to High(VarArray) do OleVariant(TDispParams(Params).rgvarg^[I]) := VarArray[I]; // Clean array SetLength(VarArray, 0); There are some obvious work-arounds in my case: if i skip the copying back in case of a VarArray parameter it fixes the leak. to not change the functionality i thought i should copy the data in the array instead of the variant back to the params but that can get complicated since it can hold other variants and seems to me that would need to be done recursively. Since a change in OleServer will have a ripple effect i want to make sure my change here is strictly correct. can anyone shed some light on exactly why memory is being leaked here? I can't seem to look up the callstack any lower than TServerEventDIspatch.Invoke (why is that?) I imagine that in the process of copying the Variant holding the VarArray back to the param list it added a reference to the array thus not allowing it to be release as normal but that's just a rough guess and i can't track down the code to back it up. Maybe someone with a better understanding of all this could shed some light?

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  • HttpURLConnection: What's the deal with having to read the whole response?

    - by stormin986
    My current problem is very similar to this one. I have a downloadFile(URL) function that creates a new HttpURLConnection, opens it, reads it, returns the results. When I call this function on the same URL multiple times, the second time around it almost always returns a response code of -1 (But throws no exception!!!). The top answer in that question is very helpful, but there are a few things I'm trying to understand. So, if setting http.keepAlive to false solves the problem, it indicates what exactly? That the server is responding in a way that violates the http protocol? Or more likely, my code is violating the protocol in some way? What will the trace tell me? What should I look for? And what's the deal with this: You need to read everything from error stream. Otherwise, it's going to confuse next connection and that's the cause of -1. Does this mean if the response is some type of error (which would be what response code(s)?), the stream HAS to be fully read? Also, every time I am attempting an http request I am basically creating a new connection, and then disconnect()ing it at the end. However, in my case I'm not getting a 401 or whatever. It's always a 200. But my second connection almost always fails. Does this mean there's some other data I should be reading that I'm not (in a similar manner that the error stream must be fully read)? Please help shed some light on this? I feel like there's some fundamental http protocol understanding I'm missing.

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  • How to pass parameters to manage_shared_memory.construct() in Boost.Interprocess

    - by recipriversexclusion
    I've stared at the Boost.Interprocess documentation for hours but still haven't been able to figure this out. In the doc, they have an example of creating a vector in shared memory like so: //Define an STL compatible allocator of ints that allocates from the managed_shared_memory. //This allocator will allow placing containers in the segment typedef allocator<int, managed_shared_memory::segment_manager> ShmemAllocator; //Alias a vector that uses the previous STL-like allocator so that allocates //its values from the segment typedef vector<int, ShmemAllocator> MyVector; int main(int argc, char *argv[]) { //Create a new segment with given name and size managed_shared_memory segment(create_only, "MySharedMemory", 65536); //Initialize shared memory STL-compatible allocator const ShmemAllocator alloc_inst (segment.get_segment_manager()); //Construct a vector named "MyVector" in shared memory with argument alloc_inst MyVector *myvector = segment.construct<MyVector>("MyVector")(alloc_inst); Now, I understand this. What I'm stuck is how to pass a second parameter to segment.construct() to specify the number of elements. The interprocess document gives the prototype for construct() as MyType *ptr = managed_memory_segment.construct<MyType>("Name") (par1, par2...); but when I try MyVector *myvector = segment.construct<MyVector>("MyVector")(100, alloc_inst); I get compilation errors. My questions are: Who actually gets passed the parameters par1, par2 from segment.construct, the constructor of the object, e.g. vector? My understanding is that the template allocator parameter is being passed. Is that correct? How can I add another parameter, in addition to alloc_inst that is required by the constructor of the object being created in shared memory? There's very little information other than the terse Boost docs on this.

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  • RESTful design, how to name pages outside CRUD et al?

    - by sscirrus
    Hi all, I'm working on a site that has quite a few pages that fall outside my limited understanding of RESTful design, which is essentially: Create, Read, Update, Delete, Show, List Here's the question: what is a good system for labeling actions/routes when a page doesn't neatly fall into CRUD/show/list? Some of my pages have info about multiple tables at once. I am building a site that gives some customers a 'home base' after they log on. It does NOT give them any information about themselves so it shouldn't be, for example, /customers/show/1. It does have information about companies, but there are other pages on the site that do that differently. What do you do when you have these situations? This 'home-base' is shown to customers and it mainly has info about companies (but not uniquely so). Second case: I have a table called 'Matchings' in between customers and companies. These matchings are accessed in completely different ways on different parts of the site (different layouts, different CSS sheets, different types of users accessing them, etc. They can't ALL be matchings/show. What's the best way to label the others? Thanks very much. =)

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  • rpy2: Converting a data.frame to a numpy array

    - by Mike Dewar
    I have a data.frame in R. It contains a lot of data : gene expression levels from many (125) arrays. I'd like the data in Python, due mostly to my incompetence in R and the fact that this was supposed to be a 30 minute job. I would like the following code to work. To understand this code, know that the variable path contains the full path to my data set which, when loaded, gives me a variable called immgen. Know that immgen is an object (a Bioconductor ExpressionSet object) and that exprs(immgen) returns a data frame with 125 columns (experiments) and tens of thousands of rows (named genes). robjects.r("load('%s')"%path) # loads immgen e = robjects.r['data.frame']("exprs(immgen)") expression_data = np.array(e) This code runs, but expression_data is simply array([[1]]). I'm pretty sure that e doesn't represent the data frame generated by exprs() due to things like: In [40]: e._get_ncol() Out[40]: 1 In [41]: e._get_nrow() Out[41]: 1 But then again who knows? Even if e did represent my data.frame, that it doesn't convert straight to an array would be fair enough - a data frame has more in it than an array (rownames and colnames) and so maybe life shouldn't be this easy. However I still can't work out how to perform the conversion. The documentation is a bit too terse for me, though my limited understanding of the headings in the docs implies that this should be possible. Anyone any thoughts?

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  • Hazelcast Distributed Executor Service KeyOwner

    - by János Veres
    I have problem understanding the concept of Hazelcast Distributed Execution. It is said to be able to perform the execution on the owner instance of a specific key. From Documentation: <T> Future<T> submitToKeyOwner(Callable<T> task, Object key) Submits task to owner of the specified key and returns a Future representing that task. Parameters: task - task key - key Returns: a Future representing pending completion of the task I believe that I'm not alone to have a cluster built with multiple maps which might actually use the same key for different purposes, holding different objects (e.g. something along the following setup): IMap<String, ObjectTypeA> firstMap = HazelcastInstance.getMap("firstMap"); IMap<String, ObjectTypeA_AppendixClass> secondMap = HazelcastInstance.getMap("secondMap"); To me it seems quite confusing what documentation says about the owner of a key. My real frustration is that I don't know WHICH - in which map - key does it refer to? The documentation also gives a "demo" of this approach: import com.hazelcast.core.Member; import com.hazelcast.core.Hazelcast; import com.hazelcast.core.IExecutorService; import java.util.concurrent.Callable; import java.util.concurrent.Future; import java.util.Set; import com.hazelcast.config.Config; public void echoOnTheMemberOwningTheKey(String input, Object key) throws Exception { Callable<String> task = new Echo(input); HazelcastInstance hz = Hazelcast.newHazelcastInstance(); IExecutorService executorService = hz.getExecutorService("default"); Future<String> future = executorService.submitToKeyOwner(task, key); String echoResult = future.get(); } Here's a link to the documentation site: Hazelcast MultiHTML Documentation 3.0 - Distributed Execution Did any of you guys figure out in the past what key does it want?

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  • compiling and running java on windows

    - by artur grzesiak
    I thought the task should be fairly easy, but my understanding of javac and java in general is rather poor. I am using Windows8 and would like to compile a single file.java that makes use of other classes. I successfully (at least without any warnings) compiled my file by calling: javac -cp relative_path_to_needed_classes relative_path_to_file_java\file.java Now if I want to run the result of compilation (file.class) by calling: java -cp relative_path_to_needed_classes relative_path_to_file_java\file I get: Error: Could not find or load main class relative_path_to_file_java\file I was trying a lot of combination to modify the -cp (eg. by adding .\;relative_path_to_file;) but still the closest where I get is: Exception in thread "main" java.lang.NoClassDefFoundError : relative_path_to_file\file (wrong name: file) The file from (wrong name: file) is the name of the file and the name of the public class within the file. I was reading a lot on SO and other sources but could not figure out what is wrong. Btw. as a result of compilation some other classes were created: file$1.class file$name1.class file$name2.class (where name1 and name2 are names of private classes within file.java) My questions are: What is (the most) probably source of my error / what am I doing wrong? What is the purpose of file$1.class? What is the minimum I should specify in -cp? May encoding play any role? Do every java class have to reside in a package? (rather not directly related to my issue) Do order of paths specified in -cp play any role in runtime?

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  • PubSubHubBub Hubs

    - by PartlyCloudy
    Hi, I'm currently building a live web application based upon the PubSubHubBub protocol. However, I encountered several issues. First, I'm in search of a hub application that I can run on my server. There are several applications, but most of them are not mature yet, or they don't support the 0.3 spec. The official google hub runs on the Google App Engine and can even be executed locally. Unfortunately, "Tasks will not run automatically. Push the 'Run' button to execute each task." This behaviour is useful for debugging and understanding the workflow, but in some live tests, it would be nice not to invoke all tasks manually. Is there a way to tweak the local app engine due automatically run tasks? Next, I have a question concerning the spec itself. The Google reference implementation provides the initial publish method bound to the outpoint uri + /publish. But this is not reflected in the specs. So are there any mature hubs that can be run locally for debugging? Or are there ways to configure the offical google app engine hub to run locally and to execute tasks directly? Thanks in advance

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  • forks in C - exercise

    - by Zka
    I try to repeat and learn more advanced uses and options when cutting trees with forks in the jungle of C. But foolishly I find an example which should be very easy as I have worked with forks before and even written some code, but i can't understand it fully. Here comes : main() { if (fork() == 0) { if (fork() == 0) { printf("3"); } else if ((wait(NULL)) > 0) { printf("2"); } } else { if (fork() == 0) { printf("1"); exit(0); } if (fork() == 0) { printf("4"); } } printf("0"); return 0; } Possible solutions are : 3201040 3104200 1040302 4321000 4030201 1403020 where 2, 5 and 6 are correct answers. First of all, shouldn't there be four zeroes in the output? Second... How does one come to the solution at all? Been doing this on paper for almost an hour and I'm not even close to understanding why the given solution are more correct than the false ones (except for nr3 as it can't end with 2 since a 0 must follow). Anyone with his forks in check who can offer some good explanation?

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  • Opinions on Dual-Salt authentication for low sensitivity user accounts?

    - by Heleon
    EDIT - Might be useful for someone in the future... Looking around the bcrypt class in php a little more, I think I understand what's going on, and why bcrypt is secure. In essence, I create a random blowfish salt, which contains the number of crypt rounds to perform during the encryption step, which is then hashed using the crypt() function in php. There is no need for me to store the salt I used in the database, because it's not directly needed to decrypt, and the only way to gain a password match to an email address (without knowing the salt values or number of rounds) would be to brute force plain text passwords against the hash stored in the database using the crypt() function to verify, which, if you've got a strong password, would just be more effort than it's worth for the user information i'm storing... I am currently working on a web project requiring user accounts. The application is CodeIgniter on the server side, so I am using Ion Auth as the authentication library. I have written an authentication system before, where I used 2 salts to secure the passwords. One was a server-wide salt which sat as an environment variable in the .htaccess file, and the other was a randomly generated salt which was created at user signup. This was the method I used in that authentication system for hashing the password: $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"; //create a random string to be used as the random salt for the password hash $size = strlen($chars); for($i = 0; $i < 22; $i++) { $str .= $chars[rand(0, $size - 1)]; } //create the random salt to be used for the crypt $r_blowfish_salt = "$2a$12$" . $str . "$"; //grab the website salt $salt = getenv('WEBSITE_SALT'); //combine the website salt, and the password $password_to_hash = $pwd . $salt; //crypt the password string using blowfish $password = crypt($password_to_hash, $r_blowfish_salt); I have no idea whether this has holes in it or not, but regardless, I moved over to Ion Auth for a more complete set of functions to use with CI. I noticed that Ion only uses a single salt as part of its hashing mechanism (although does recommend that encryption_key is set in order to secure the database session.) The information that will be stored in my database is things like name, email address, location by country, some notes (which will be recommended that they do not contain sensitive information), and a link to a Facebook, Twitter or Flickr account. Based on this, i'm not convinced it's necessary for me to have an SSL connection on the secure pages of my site. My question is, is there a particular reason why only 1 salt is being used as part as the Ion Auth library? Is it implied that I write my own additional salting in front of the functionality it provides, or am I missing something? Furthermore, is it even worth using 2 salts, or once an attacker has the random salt and the hashed password, are all bets off anyway? (I assume not, but worth checking if i'm worrying about nothing...)

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