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  • Placeholders in strings

    - by dotancohen
    I find that I sometimes use placeholders in strings, like this: $ cat example-apache <VirtualHost *:80> ServerName ##DOMAIN_NAME## ServerAlias www.##DOMAIN_NAME## DocumentRoot /var/www/##DOMAIN_NAME##/public_html </VirtualHost> Now I am sure that it is a minor issue if the placeholder is ##DOMAIN_NAME##, !!DOMAIN_NAME!!, {{DOMAIN_NAME}}, or some other variant. However, I now need to standardize with other developers on a project, and we all have a vested interest in having our own placeholder format made standard in the organization. Are there any good reasons for choosing any of these, or others? I am trying to quantify these considerations: Aesthetics and usability. For example, __dict__ may be hard to read as we don't know how many underscores are in there. Compatibility. Will some language try to do something funny with {} syntax in a string (such as PHP does with "Welcome to {$siteName} today!")? Actually, I know that PHP and Python won't, but others? Will a C++ preprocessor choke on ## format? If I need to store the value in some SQL engine, will it not consider something a comment? Any other pitfalls to be wary of? Maintainability. Will the new guy mistake ##SOME_PLACEHOLDER## as a language construct? The unknown. Surely the wise folk here will think of other aspects of this decision that I have not thought of. I might be bikeshedding this, but if there are real issues that might be lurking then I would certainly like to know about them before mandating that our developers adhere to a potentially-problematic convention.

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  • Don't speak to the DBA while he/she is doing the job?!

    - by Uri Dimant
    Our DBA was very busy today, he helped out our developers to write efficient code,explained to the programmer how to launch the old DTS package on SQL Server 2005 and etc. You know how it is, someone comes in and asking the question and you answer the question at the same time you are busy to do something. So  today answering one of such questions he deleted by mistake very ctitical database. Fortunately, we had zero data loss,thanks to our backup/recovery strategy. I think that is acceptable to say that you are busy right now ,please ask the question later on, what do you think? How do you respond if someone asks you a queston while you are doing something on the server/database and etc.?   Share this post: email it! | bookmark it! | digg it! | reddit! | kick it! | live it!

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  • Redesigning my website has destroyed my SEO

    - by user20721
    Unfortunately i read an article on how to avoid destroying your websites SEO from a redesign article AFTER its was too late! Here is the article (http://www.searchenginejournal.com/how-to-avoid-seo-disaster-during-a-website-redesign/42824/) On 20 November 12 completely redesigned our www.retromodern.com.au . We get ALL our customers from our website as we do not have a shop. Since that dreaded day a month ago the phone pretty much stopped, basically no emails, Google rankings down and Google analytics have halved by 50%. Yesterday i did some research into as as i had no idea that a re-design of a website could have such a damaging effect - yes i am a novice and use a WYSIWYG type web builder. There are lots of info on how to AVOID this from happening BUT what do i do as i have already made the mistake? Yesterday i reloaded my OLD site with my new pages in the background hoping this would be a start. I really have no idea of how to get out of this mess. Please please help. Thanks in Advance. Monique

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  • Ubuntu 12.10 and nVidia drivers don't like each other?

    - by mingos
    I decided to upgrade both my computers from Precise to Quantal. What a mistake that was. My laptop has a nVidia GT 330M card, while the desktop has an nVidia 9600 GT. In both cases everything goes great as long as I use the Nouveau driver (ugh!). Can't really play games (Amnesia... and hoping for Steam Beta participation...), even though it's OK for work. Now, ever since 9.04 or so, I just installed nvidia-current and all just worked. Since 12.10, after installing nVidia drivers, Unity won't start at all (hangs with only the wallpaper displayed, no cursor or widgets), Gnome Shell is permanently in fallback mode. Now, I have tried on both computers, with multiple clean installs on Ubuntu (two separate downloads, just in case), one from Ubuntu Gnome Remix. And additionally, Fedora 17, which seems to suffer from the same issue. Tried all nVidia driver suggestions available in Software Sources, and even compiled the drivers myself. I tried several versions of the driver to exclude an issue with the newest one. In my frustration, I have switched to Windows (which, ironically, "just works" with my hardware), but still hold a twin OS configuration on the desktop and would like to use Ubuntu again. So, can anyone point me to where the issue might lie?

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  • Configuring network to set wlan0 as primary

    - by Sheed
    I recently had to rebuild my pc and decided to go for ubuntu 14.04. I think the mistake I made was I started from a 12.04 install disk instead of the 12.10 disk I'd used previously and when given the option set my primary connection as ethernet (because the wireless option didn't work). After upgrading to 14.04 etc, I managed to get the wireless working, or more using steps like ifconfig -a and the likes I managed to prove that the wireless card etc. is all installed and working. However every time I boot without a hard wired connection plugged in I get the message "waiting for network configuration". I can then once it's booted without a network get my wirless working using sudo ifconfig wlan0 up iwlist wlan0 scan This seems to kick the wireless module into life and it appears in the GUI and I can then select a network, however all the options like edit network and disconnect etc are all greyed out. What I would like of course is if the WLAN0 was just set as my primary default network so I've been looking for a solution to this and it would seem that I need to adjust the old /etc/network/interfaces file but when I try to do so using the sudo vi /etc/network/interfaces command I, well I simply have no idea what I'm doing. Other than that typing :q! gets me out of there before I do to much damage! As far as I can tell (by navigating to the file in the GUI) the output of my /etc/network/interfaces is as follows: (obviously not including the " in each line that's just to break the heading rule of the #) "# This file describes the network interfaces available on your system "# and how to activate them. For more information, see interfaces(5). "# The loopback network interface auto lo iface lo inet loopback "# The primary network interface auto eth0 iface eth0 inet dhcp If this is the case then this clearly doesn't contain what it should do but I don't how to fix it. Nor do I even know if I'm on the right track. Any help would be appreciated thanks :)

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  • The very beggining research for web developing

    - by stckxchng
    It is a general question to ask what would be the easiest way to start a website, however every one need a little boost up at the begging. There are content management systems, or admin panels, or some people have developed their own systems and many more diffirent things people use at the very beggining. Among others my way was looking for a very lightweight cms and develop a system on to it, unfortunately I couldn't find a good system to develop on, for example I decided to develop on snewscms (the lightest weight cms) but it is really hard to manage since it is not developed with object oriented programming standarts and I thought it would be a mistake to continue developing on to such a system. On the other hand starting to code from the core would be weak about security, and using a massive cms like joomla or drupal will not be good since there will be many things that are unused and moreover I will not feel well when I don't know what I am controlling since it is not easy to know every part of them. What I am asking is what would you do if you had lost all the files you are currently using today, where would you start from? What tool would you use? Or is there a lightweight and well coded tool to get start with?

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  • When to open source a project under development? [closed]

    - by QuasarDonkey
    Possible Duplicate: Is it OK to push my code to GitHub while it is still in early development? I've been working on a hobby project for a few months now; it's clocking in at over 15000 source lines of code. A number of people have expressed interest in joining development, and I have full intentions of going open source, since it would not be feasible for me to complete the project alone. I'm just not sure when to open-source it. For context, I've notice many successful open source projects, such as the Linux kernel, had considerable work done before they were open-sourced. In my case, I'd been planning on open-sourcing it after I complete all the underlying libraries and overall architecture. Is this a mistake; should I just release it right now? I'm worried that since certain critical underlying components haven't been finalized, if people build a large codebase around them, it will be very difficult to change or fix things later. On the other hand, it's a very large project that will require multiple developers to complete in a reasonable time. So when is the right time during development to go open source? Preferably, I'd like to hear from some folks who have started their own projects.

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  • Why Apple’s New SDK Limitation is So Offensive

    - by TStewartDev
    I am not an Apple fanboy, nor have I ever been. However, I have owned a Mac, an iPod, and an iPhone in my lifetime, and for more than a decade, I have defended Apple against the untruths that the haters so enjoy spewing. I encouraged my wife to buy a MacBook when she needed a new laptop two years ago, and I often recommend them to my friends and relatives. I have proudly and happily used my first generation iPhone for nearly three years. Now, for the first time in well over ten years, I find myself ready to swear off Apple and encourage everyone I know to do the same. I was disappointed when Apple wouldn't allow native apps, but I still bought the iPhone. I've stomached their ambiguous app approval process even though it's apparent that Steve may just reject your app because he doesn't like you or feels threatened by you (I'm still lamenting the rejection of the Google Voice app). But, as a developer, I can no longer tolerate Apple's terms and the kind of totalitarian control they indicate Apple wants. In case you are not already familiar, Apple has dictated in their OS 4.0 SDK license agreement (the now infamous Section 3.3.1) that all apps developed for the iPhone must be coded in C, C++, or Objective C, and moreover, that using any cross-compiling platforms is a violation of the agreement. For those of you who aren't developers, let me try to illustrate why this angers those of us who are. Imagine you're a professional writer. You've had articles published in some journals and magazines, and you've got a couple popular books out there, too. You've got an idea for a new book, and so you take it to your publisher. Your publisher agrees that it's a good idea. "But," says the publisher, "we want to hold our books to a tighter standard so that our readers get the experience we want them to have. Therefore, from now on, all our writers may only use words from this list of the 10,000 most common English words. Furthermore, if you cite any other works or quote anyone, they must comply with that same list, or you'll have to rewrite the entire work as well in case our readers want to look up your citation." What do you do? If your work is a children's book, this probably isn't a big deal to you. If it's an autobiography, textbook, or even a novel, though, you're going to have a lot of trouble describing your content with only common words. It's going to take you longer to complete your book, too, since you'll be looking up less common words frequently to see if you can use them. You could always go to another publisher, but this one has the best ability to distribute your book. The next largest distributor can only do a quarter as much. You could abandon the project altogether, but then everyone loses. Isn't this a silly scenario? Who would put such a limitation on writers? Yet this is very much what Apple is doing. They are using their dominant position in the market to coerce developers to write their apps exclusively for the iPhone OS by making it too expensive to write for multiple platforms. It is at least a threefold attack, striking at Adobe who is set to release a compiler that lets Flash source be compiled to iPhone binaries; striking at Google whose Android platform stands the best chance at the moment of providing serious competition to the iPhone; and reinforcing their own strong position by keeping popular apps exclusively to iPhone. And while developers are already very upset about this, the sad fact is that most of us will cave and give in to Apple because consumers don't know any better. They will continue to buy Apple's toy forcing developers to play Apple's maniacal game in order to make any money, at least until Steve Jobs decides he doesn't like them or he intends to release a competing application (bye-bye OpenFeint). Apple has been kept in check on the desktop front by a very dominant Microsoft, but I'm afraid that their success with iPods, iTunes, and iPhones has created a monster that we may have to bear until it is slain by an anti-trust suit or dies with the retirement of Steve Jobs.

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  • linebreak in url with Bibtex and hyperref package

    - by Tim
    Why is this item not shown properly in my bibliography? @misc{ann, abstract = {ANN is an implbmentation of nearest neighbor search.}, author = {David M. Mount and Sunil Arya}, howpublished = {\url{http://www.cs.umd.edu/~mount/ANN/}}, keywords = {knn}, posted-at = {2010-04-08 00:05:04}, priority = {2}, title = {ANN.}, url = "http://www.cs.umd.edu/~mount/ANN/", year = {2008} } @misc{Nilsson96introductionto, author = {Nilsson, Nils J.}, citeulike-article-id = {6995464}, howpublished = {\url{http://robotics.stanford.edu/people/nilsson/mlbook.html}}, keywords = {*file-import-10-04-11}, posted-at = {2010-04-11 06:52:28}, priority = {2}, title = {Introduction to Machine Learning: An Early Draft of a Proposed Textbook.}, year = {1996} } EDIT: I am using \usepackage{hyperref}, not \usepackage{url}. I don't know what changes I just made made the first item appear properly now @misc{ann, abstract = {ANN is an implbmentation of nearest neighbor search.}, author = {David M. Mount and Sunil Arya}, howpublished = {\url{http://www.cs.umd.edu/~mount/ANN/}}, keywords = {ann}, posted-at = {2010-04-08 00:05:04}, priority = {2}, title = {The \textsc{A}pproximate \textsc{N}earest \textsc{N}eighbor \textsc{S}earching \textsc{L}ibrary.}, url = "http://www.cs.umd.edu/~mount/ANN/", year = {2008} } EDIT: Since I am using hyperref package, it produces error when using url package together with it. So the two cannot work together? I would like to use hyper links inside pdf file, so I would like to use hyperref package instead of url package. I googled a bit, and try \usepackage[hyperindex,breaklinks]{hyperref}, but there is still no line break just as before. How can I do it? Is there conflict in the packages that I am now using?: \usepackage{amsmath} \usepackage{amsfonts} \usepackage[dvips]{graphicx} \usepackage{wrapfig} \graphicspath{{./figs/}} \DeclareGraphicsExtensions{.eps} \usepackage{fixltx2e} \usepackage{array} \usepackage{times} \usepackage{fancyhdr} \usepackage{multirow} \usepackage{algorithmic} \usepackage{algorithm} \usepackage{slashbox} \usepackage{multirow} \usepackage{rotating} \usepackage{longtable} \usepackage[hyperindex,breaklinks]{hyperref} \usepackage{forloop} \usepackage{lscape} \usepackage{supertabular} \usepackage{amssymb} \usepackage{amsthm}

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  • Accurate least-squares fit algorithm needed

    - by ggkmath
    I've experimented with the two ways of implementing a least-squares fit (LSF) algorithm shown here. The first code is simply the textbook approach, as described by Wolfram's page on LSF. The second code re-arranges the equation to minimize machine errors. Both codes produce similar results for my data. I compared these results with Matlab's p=polyfit(x,y,1) function, using correlation coefficients to measure the "goodness" of fit and compare each of the 3 routines. I observed that while all 3 methods produced good results, at least for my data, Matlab's routine had the best fit (the other 2 routines had similar results to each other). Matlab's p=polyfit(x,y,1) function uses a Vandermonde matrix, V (n x 2 matrix) and QR factorization to solve the least-squares problem. In Matlab code, it looks like: V = [x1,1; x2,1; x3,1; ... xn,1] % this line is pseudo-code [Q,R] = qr(V,0); p = R\(Q'*y); % performs same as p = V\y I'm not a mathematician, so I don't understand why it would be more accurate. Although the difference is slight, in my case I need to obtain the slope from the LSF and multiply it by a large number, so any improvement in accuracy shows up in my results. For reasons I can't get into, I cannot use Matlab's routine in my work. So, I'm wondering if anyone has a more accurate equation-based approach recommendation I could use that is an improvement over the above two approaches, in terms of rounding errors/machine accuracy/etc. Any comments appreciated! thanks in advance.

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  • Computer science textbooks

    - by Barrett Conrad
    I would like to try the book question a little bit differently. My goal is to know what the community thinks are the quintessential computer science textbooks. <beginsadstory>I lost all of my computer science and math books from college in Hurricane Katrina in 2005. I greatly miss having my familiar tomes to refer to when topics and problems come up, so I am looking to rebuild my library.<endsadstory> What are your recommendations for the best examples of academic caliber books for the field of computer science and its associated mathematics? I am looking for books on subjects like computational theory, programming languages, compilers, operating systems, algorithms and so on. Don't limit your suggestions to your textbooks only. If there is a book you have read that covers computer science or a related math in a formal way, but is not strictly a textbook, I would be love to hear about them as well. Finally, for the sake of creating a good reference for all of us, may I suggest posting one book per answer so they can be rated individually.

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  • Place the business logic in Java Beans?

    - by Lirik
    I was reading this page and I found the following statement: MVC in Java Server Pages Now that we have a convenient architucture to separate the view, how can we leverage that? Java Server Pages (JSP) becomes more interesting because the HTML content can be separated from the Java business objects. JSP can also make use of Java Beans. The business logic could be placed inside Java Beans. If the design is architected correctly, a Web Designer could work with HTML on the JSP site without interfering with the Java developer. Interestingly in my textbook I pulled the following quote: In the MVC architecture... the original request is always handled by a servlet. The servlet invokes the business logic and data access code and creates beans to represent the results (that’s the model). Then, the servlet decides which Java Server Page is appropriate to present those particular results and forwards the request there (the JSP is the view). The servlet decides what business logic code applies and which JSP should present the results (the servlet is the controller). The two statements seem slightly contradicting. What is the best way to use beans: should we place business logic in them or should we only place results in them? Are there ways in which beans are inadequate for representing a model?

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  • What is a good standard exercise to learn the OO features of a language?

    - by FarmBoy
    When I'm learning a new language, I often program some mathematical functions to get used to the control flow syntax. After that, I like to implement some sorting algorithms to get used to the array/list constructs. But I don't have a standard exercise for exploring the languages OO features. Does anyone have a stock exercise for this? A good answer would naturally lend to inheritance, polymorphism, etc., for a programmer already comfortable with these concepts. An ideal answer would be one that could be communicated in a few words, without ambiguity, in the way that "implement mergesort" is completely unambiguous. (As an example, answering "design a game" is so vague as to be useless.) Any ideas? EDIT: I have to remark that the results here are somewhat ironic. 10 upvotes and (originally) 5 favorites suggest that this is a question others are interested in. Yet the most upvoted answer is one that says there is no good answer. Oh well. I think I'll look at the textbook below, I've found games useful in the past for OO.

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  • Manually listing objects in Django (problem with field ordering)

    - by Chris
    I'm having some trouble figuring out the best/Djangoic way to do this. I'm creating something like an interactive textbook. It has modules, which are more or less like chapters. Each module page needs to list the topics in that module, grouped into sections. My question is how I can ensure that they list in the correct order in the template? Specifically: 1) How to ensure the sections appear in the correct order? 2) How to ensure the topics appear in the correct order in the section? I imagine I could add a field to each model purely for the sake of ordering, but the problem with that is that a topic might appear in different modules, and in whatever section they are in there they would again have to be ordered somehow. I would probably give up and do it all manually were it not for the fact that I need to have the Topic as object in the template (or view) so I can mark it up according to how the user has labeled it. So I suppose my question is really to do with whether I should create the contents pages manually, or whether there is a way of ordering the query results in a way I haven't thought of. Thanks for your help!

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  • What is the fastest, most efficient way to get up to speed on a new technology?

    - by SLC
    My current job involves working with a huge number of technologies, most of which are very niche and unheard of. In some cases I have to write something about the technology, or with the technology, such as some lessons, examples, or tutorials, on behalf of the developer of that technology or someone that is backing it. When I get told to learn about a new technology, my first port of call is to check our internal library, and then look on amazon for a book on the subject. Failing that, or if the project is too small to warrant a purchase, I hit up google and youtube. However the results of randomly googling what I want to learn are hit and miss. Some days, I can find everything I want to know in a series of lessons or videos, and it's no problem. Other times, I can find almost nothing, and I really have to piece together things from sites. The result is that there are various resources out there, videos, interactive lessons, tutorials, books etc. but when I need to learn something fast, I often don't know the best way to go about it. It's not about fun, because I don't always have the luxury of working my way through a 600 page textbook named "A Complete Guide To Technology X", I have to deliver results quickly. One of the examples I'd like to use is ASP.NET MVC 2 which is something I have been told to learn. I grabbed a book on MVC 1 to refresh my knowledge, but googling it does't produce much useful information. I've seen a ton of ScottGu's tutorials on it, but they are mostly feature presentations, and some date back almost a year. The same applies to channel 9 and there are no books out yet on amazon. My question therefore has two parts, the first asks, "Where are the best places to look to get the information needed to learn a new technology?" and the second asks "What is the most efficient way to use such resources to learn a new technology?"

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  • Having an issue with org.hibernate.SessionException: Session is closed! in Hibernate

    - by hal10001
    I've done quite a bit a research on this with no luck, but all the answers have a tendency to point toward the session context settings in the config file. What is odd is that I get a session connection the very first time I hit the page (and therefore, a successful result set), but then when I reload I get the following exception: org.hibernate.SessionException: Session is closed! Here are my config settings that are not DB connection string related: <property name="hibernate.show_sql">false</property> <property name="hibernate.dialect">org.hibernate.dialect.SQLServerDialect</property> <property name="hibernate.current_session_context_class">thread</property> <property name="hibernate.cache.provider_class">org.hibernate.cache.NoCacheProvider</property> <property name="hibernate.cache.use_query_cache">false</property> <property name="hibernate.cache.use_minimal_puts">false</property> Here is an example of a call I make that produces the situation I described above. public T get(int id) { session.beginTransaction(); T type; try { type = getTypeClass().cast(session.get(getTypeClass(), id)); } catch (ClassCastException classCastException) { throw new ClassCastException(classCastException.getMessage()); } session.getTransaction().commit(); return type; } The session variable reference is to a static field that contains the current session. All of the session connection details are textbook reference manual. For example, here is my Hibernate session utility: import org.hibernate.SessionFactory; import org.hibernate.cfg.Configuration; public class HibernateSessionFactoryUtil { private static final SessionFactory sessionFactory = buildSessionFactory(); private static SessionFactory buildSessionFactory() { try { return new Configuration().configure().buildSessionFactory(); } catch (Throwable ex) { System.err.println("Initial SessionFactory creation failed." + ex); throw new ExceptionInInitializerError(ex); } } public static SessionFactory getSessionFactory() { return sessionFactory; } }

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  • Basic compile issue with QT4

    - by Cobus Kruger
    I've been trying to get a dead simple listing from a university textbook to compile with the newest QT SDK for Windows I downloaded last night. After struggling through the regular nonsense (no make.bat, need to manually add environment variables and so on) I am finally at the point where I can build. But only one of the two libraries seem to work. The .pro file I use is dead simple: SUBDIRS += utils \ dataobjects TEMPLATE = subdirs In each of these two subfolders I have the source for a library. Running QMAKE generates a makefile and running Make runs through all the preliminaries and then fails on the g++ call: g++ -enable-stdcall-fixup -Wl,-enable-auto-import -Wl,-enable-runtime-pseudo-reloc --out-implib,libdataobjects.a -shared -mthreads -Wl -Wl,--out-implib,c:\Users\Cobus\workspace\lib\libdataobjects.a -o ..\..\lib\dataobjects.dll object_script.dataobjects.Debug -L"c:\Users\Cobus\Portab~1\Qt\2010.02.1\qt\lib" -LC:\Users\Cobus\workspace\lib -lutils -lQtXmld4 -lQtGuid4 -lQtCored4 c:/users/cobus/portab~1/qt/2010.02.1/mingw/bin/../lib/gcc/mingw32/4.4.0/../../../../mingw32/bin/ld.exe: cannot find -lutils The problem seems to be right near the end of the command line, where -lutils is added, indicating that there is a library by the name of utils. While I would have expected to see that, you'll notice the library names after --out include lib in the name, so they become libutils and libdataobjects. I have tried to figure out why this is happening, to no avail. Anyone have an idea what's going on?

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  • Multiple Unpacking Assignment in Python when you don't know the sequence length

    - by doug
    The textbook examples of multiple unpacking assignment are something like: import numpy as NP M = NP.arange(5) a, b, c, d, e = M # so of course, a = 0, b = 1, etc. M = NP.arange(20).reshape(5, 4) # numpy 5x4 array a, b, c, d, e = M # here, a = M[0,:], b = M[1,:], etc. (ie, a single row of M is assigned each to a through e) (My Q is not numpy specfic; indeed, i would prefer a pure python solution.) W/r/t the piece of code i'm looking at now, i see two complications on that straightforward scenario: i usually won't know the shape of M; and i want to unpack a certain number of items (definitely less than all items) and i want to put the remainder into a single container so back to the 5x4 array above, what i would very much like to be able to do is, for instance, assign the first three rows of M to a, b, and c respectively (exactly as above) and the rest of the rows (i have no idea how many there will be, just some positive integer) to a single container, all_the_rest = []. I'm not sure if i have explained this clearly; in any event, if i get feedback i'll promptly edit my Question.

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  • Which Stroustrup book should I use?

    - by Chris Simmons
    I'm a C# programmer that is looking to branch out. I'm bored of writing business software and want to start getting into graphics programming and games/simulators. So I figured, although writing that stuff isn't impossible in managed code, the "right" way to do that would be to look to C++, of course focussing on the language first, then getting into OpenGL or DirectX (or whatever). Way way back ('98? '99?) I had tried and failed to really grasp Stroustrup's The C++ Programming Language. I know that this book is often not recommended for the beginner. Anyway, I picked it back up (in a much more recent printing) and I'm actually getting it and enjoying it. I also have a copy of his textbook, Programming: Principles and Practice Using C++, which, as I understand it, is really geared toward teaching programming, not necessarily C++. I'm certainly not arrogant enough to claim I don't have anything more to learn about programming, data structures, algoriths, etc., however I'm not a novice there either. So my question is, with the goal of gaining the broader and more real-world-useful understanding of C++ and given my background, on which should I focus? The denser (as I perceive it) TCPPPL or the gentler Programming? EDIT: I thank everyone for the responses. However, I've got a personal choice here to make between these two books. Granted there are other very good books out there, but I'm already a good length into both of the books I mention and I'd like to finish one. So, can anyone respond on which would be the better and why? Time is not an issue; I'm not looking (at this point) at an "accelerated" read.

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  • JDBC call not executing

    - by dbyrne
    I am working on one of the DAOs for a medium sized web application. Unfortunately, it contains very convoluted logic, and makes hundreds of JDBC stored proc calls in loops. This is out of my control. I am working on a method inside the DAO which makes a single JDBC call. The simplified version of what this method looks like is this: DriverManager.registerDriver(new com.sybase.jdbc2.jdbc.SybDriver()); Connection con = DriverManager.getConnection((String)connectionDetails.get("DATABASE_URL") (String)connectionDetails.get("USERID"), (String)connectionDetails.get("PASSWORD")); String sqlToExecute = "{call " + STORED_PROC + "(?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)}"; CallableStatement stmt = con.prepareCall(sqlToExecute); //Maybe I should try calling clearParameters here? stmt.setString(1,someData); //....Set of parameters.... if (!stmt.execute()) { //execute method never returns false } stmt.close(); Its pretty much a textbook JDBC call. All this stored proc does is insert a single row. Here is where things get crazy: This code works when you run it through a debugger line by line, but fails when you run it "full speed". Not only does it fail, but it doesn't throw any exception! The execute method always returns true. It just breezes right through the JDBC call without inserting a row to the database. If you go through the log files, copy the stored proc call and run it manually, it works (just like it does in debug mode). Whats strange is that the rest of the DAO, with all its hundreds of looped stored proc calls, works fine. My thinking is that Connection or CallableStatement is caching some value behind the scenes that is screwing things up. Has anyone ever seen anything like this before? A JDBC call failing with no exceptions? I know it will be impossible to provide a complete solution to this without seeing the whole application, I am just looking for suggestions on possible issues to investigate.

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  • C# Virtual method call in constructor - how to refactor?

    - by Cristi Diaconescu
    I have an abstract class for database-agnostic cursor actions. Derived from that, there are classes that implement the abstract methods for handling database-specific stuff. The problem is, the base class ctor needs to call an abstract method - when the ctor is called, it needs to initialize the database-specific cursor. I know why this shouldn't be done, I don't need that explanation! This is my first implementation, that obviously doesn't work - it's the textbook "wrong way" of doing it. The overridden method accesses a field from the derived class, which is not yet instantiated: public abstract class CursorReader { private readonly int m_rowCount; protected CursorReader() { m_rowCount = CreateCursor(sqlCmd); //virtual call ! } protected abstract int CreateCursor(string sqlCmd); } public class SqlCursorReader : CursorReader { private SqlConnection m_sqlConnection; public SqlCursorReader(string sqlCmd, SqlConnection sqlConnection) { m_sqlConnection = sqlConnection; //field initialized here } protected override int CreateCursor(string sqlCmd) { //uses not-yet-initialized member *m_sqlConnection* //so this throws a NullReferenceException var cursor = new CustomCursor(sqlCmd, m_sqlConnection); return cursor.Count(); } } I will follow up with an answer on my attempts to fix this...

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  • Attaching methods to prototype from within constructor function

    - by Matthew Taylor
    Here is the textbook standard way of describing a 'class' or constructor function in JavaScript, straight from the Definitive Guide to JavaScript: function Rectangle(w,h) { this.width = w; this.height = h; } Rectangle.prototype.area = function() { return this.width * this.height; }; I don't like the dangling prototype manipulation here, so I was trying to think of a way to encapsulate the function definition for area inside the constructor. I came up with this, which I did not expect to work: function Rectangle(w,h) { this.width = w; this.height = h; this.constructor.prototype.area = function() { return this.width * this.height; }; } I didn't expect this to work because the this reference inside the area function should be pointing to the area function itself, so I wouldn't have access to width and height from this. But it turns out I do! var rect = new Rectangle(2,3); var area = rect.area(); // great scott! it is 6 Some further testing confirmed that the this reference inside the area function actually was a reference to the object under construction, not the area function itself. function Rectangle(w,h) { this.width = w; this.height = h; var me = this; this.constructor.prototype.whatever = function() { if (this === me) { alert ('this is not what you think');} }; } Turns out the alert pops up, and this is exactly the object under construction. So what is going on here? Why is this not the this I expect it to be?

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  • How to avoid geometric slowdown with large Linq transactions?

    - by Shaul
    I've written some really nice, funky libraries for use in LinqToSql. (Some day when I have time to think about it I might make it open source... :) ) Anyway, I'm not sure if this is related to my libraries or not, but I've discovered that when I have a large number of changed objects in one transaction, and then call DataContext.GetChangeSet(), things start getting reaalllly slooowwwww. When I break into the code, I find that my program is spinning its wheels doing an awful lot of Equals() comparisons between the objects in the change set. I can't guarantee this is true, but I suspect that if there are n objects in the change set, then the call to GetChangeSet() is causing every object to be compared to every other object for equivalence, i.e. at best (n^2-n)/2 calls to Equals()... Yes, of course I could commit each object separately, but that kinda defeats the purpose of transactions. And in the program I'm writing, I could have a batch job containing 100,000 separate items, that all need to be committed together. Around 5 billion comparisons there. So the question is: (1) is my assessment of the situation correct? Do you get this behavior in pure, textbook LinqToSql, or is this something my libraries are doing? And (2) is there a standard/reasonable workaround so that I can create my batch without making the program geometrically slower with every extra object in the change set?

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  • Exemplars of large document-centric applications with COM/XPCOM/.NET interfaces.

    - by Warren P
    I am looking for exemplars (design examples) showing the use of interfaces (aka 'protocols' for you smalltalkers) to design a document management architecture in a large Word Processor, Spreadsheet, vector graphic or publishing package, or office-productivity (non-database) application with support for as many of the following as possible: any open source project, will be ideal, and language of implementation is unimportant since I am looking for design examples, however an object oriented language with support for "interfaces" is a must. I know at least a dozen languages, and I'm willing to study any application's source. use of "interface" could loosely be applied to either XPCOM or COM interfaces, or .NET interfaces, or even the use of pure-virtual (virtual+abstract) base-classes for OOP languages that lack the ability to declare an interface distinct from a class. I am mostly looking for a robust, thorough and flexible implementation for a document, IDocument, various document views (IDocumentView), and whatever operations make sense in that case. I am particular interested in cases where the product in question is a real-world product. For example, if anybody familiar with OpenOffice can tell me if the code contains a good sample design. I am looking for design documentation that outlines the design of the interfaces for such an application. So for example, if the openoffice spreadsheet has such an interface design, then that might be the best case, because it is a widely used real-world design, with millions of users, rather than a textbook example, which is minimal, and contrived. I know that the Mozilla platform uses XPCOM, and its design is heavily "interface" oriented, but I am looking more for a "word processor" or "spreadsheet" type of document design, rather than a web-browser. I am particularly interested in the interfaces used to access to data and meta-data such as markup (attributes like bold, and italics, and font size), and the ability to search and look up named entities within a document.

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  • error catching exception while System.out.print

    - by user1702633
    I have 2 classes, one that implements a double lookup( int i); and one where I use that lookup(int i) in solving a question, or in this case printing the lookup values. This case is for an array. So I read the exception documentation or google/textbook and come with the following code: public double lookup(int i) throws Exception { if( i > numItems) throw new Exception("out of bounds"); return items[i]; } and take it over to my class and try to print my set, where set is a name of the object type I define in the class above. public void print() { for (int i = 0; i < set.size() - 1; i++) { System.out.print(set.lookup(i) + ","); } System.out.print(set.lookup(set.size())); } I'm using two print()'s to avoid the last "," in the print, but am getting an unhandled exception Exception (my exception's name was Exception) I think I have to catch my exception in my print() but cannot find the correct formatting online. Do I have to write catch exception Exception? because that gives me a syntax error saying invalid type on catch. Sources like http://docs.oracle.com/javase/tutorial/essential/exceptions/ are of little help to me, I'm can't seem to grasp what the text is telling me. I'm also having trouble finding sources with multiple examples where I can actually understand the coding in the examples. so could anybody give me a source/example for the above catch phrase and perhaps a decent source of examples for new Java programmers? my book is horrendous and I cannot seem to find an understandable example for the above catch phrase online.

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