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  • SQL language drawbacks, The Third Manifesto

    - by David Portabella
    Sometime ago I read about SQL language drawbacks (the basic language specification, not vendor specific), and one of the drawbacks was that the language does not allow to create a set of tuples that don't come from a table. For instance, SELECT firstName, lastName from people; this creates a set of tuples coming from the table people. Now, if I don't have this table people, and I want to return a constant, I'd need something like this to return a set of two tuples (this would not require to have a table): SELECT VALUES('james', 'dean'), ('tom', 'cruisse'); Why I would need that? Because of the same reasons that we can define constants (not only basic types, but objects and arrays also) in any advanced programming language. Workarounds, Yes, I could create a temporal table, fill the data, and SELECT from that table. This is a hack, to overcome the drawbacks of the poor SQL language. I think that I read about this somewhere in "The Third Manifesto", but I don't find the paragraph/example talking about this concrete drawback anymore. Do you know a reference about it?

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  • Excel annoyance: How to maintain formulas in a ledger?

    - by davidcl
    A common use of Excel is to create a spreadsheet which functions as a transaction ledger of some kind, where one or more fields in each row is calculated by adding a value or values from the current row to a value from the previous row. For example, if column C holds the value of a transaction and column D holds the balance, then the formula in row D3 might be =D2+C3. This formula would be repeated for every row in the ledger. A common annoyance when maintaining this type of spreadsheet is that if you insert a row into the middle of such a ledger, that row may be skipped when calculating the balance-- the formulas in the subsequent row have to be updated along with the formulas in the inserted row. Do you have any techniques for avoiding these problems?

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  • Experience with MQ File Transfer Edition?

    - by mfinni
    We've got several processes that move files across servers - SFTP, FTP, SCP; Windows, Linux, AIX; there is a workflow component (usually require a control file with filenames and hash values to move a batch of related files). The action is often initiated on our servers to get the files, so we need to make sure they're done being written. We have some homegrown scripts to do this, but they don't always work properly, and troubleshooting, maintenance, and log review is not easy this way. There's a lot of servers, and our scripts don't have central logging or a dashboard/console/etc. We're looking into commercial products to do this. Has anyone used MQ File Transfer Edition? Another team in our company is using Aspera, does anyone have any thoughts on that, or other favored products? I have no idea what our budget is for this, yet. Just trying to get a handle on the product space from the perspective of other admins.

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  • Facebook Payments & Credits vs. Real-World & Charities

    - by Adam Tannon
    I am having a difficult time understanding Facebook's internal "e-commerce microcosm" and what it allows Facebook App developers to do (and what it restricts them from doing). Two use cases: I'm an e-com retailer selling clothes and coffee mugs (real-world goods) on my website; I want to write a Facebook App that allows Facebook users to buy my real-world goods from inside of Facebook using real money ($ USD) I'm highschool student trying to raise money for my senior class trip and want to build a Facebook App that allows Facebook users to donate to our class using real money ($ USD) Are these two scenarios possible? If not, why (what Facebook policies prohibit me from doing so)? If so, what APIs do I use: Payments or Credits? And how (specifically) would it work? Do Facebook Users have to first buy "credits" (which are mapped to $ USD values under the hood) and pay/donate with credits, or can they whip out their credit card and pay/donate right through my Facebook App? I think that last question really summarizes my confusion: can Facebook users enter their credit card info directly into Facebook Apps, or do you have to go through Payments/Credits APIs as a "middleman"?

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  • Removing ocurrances of characters in a string

    - by DmainEvent
    I am reading this book, programming Interviews exposed by John Wiley and sons and in chapter 6 they are discussing removing all instances of characters in a src string using a removal string... so removeChars(string str, string remove) In there writeup they sey the steps to accomplish this are to have a boolean lookup array with all values initially set to false, then loop through each character in remove setting the corresponding value in the lookup array to true (note: this could also be a hash if the possible character set where huge like Unicode-16 or something like that or if str and remove are both relatively small... < 100 characters I suppose). You then iterate through the str with a source and destination index, copying each character only if its corresponding value in the lookup array is false... Which makes sense... I don't understand the code that they use however... They have for(src = 0; src < len; ++src){ flags[r[src]] == true; } which is turning the flag value at the remove string indexed at src to true... so if you start out with PLEASE HELP as your str and LEA as your remove you will be setting in your flag table at 0,1,2... t|t|t but after that you will get an out of bounds exception because r doesn't have have anything greater than 2 in it... even using there example you get an out of bounds exception... Am is there code example unworkable?

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  • update terminal title from standard output of long running command?

    - by Sam Hasler
    I'd like to change the title of a terminal window during a long running command (for example: git svn fetch) with values greped from the output, whilst still writing to standard output. Is this possible using named pipes or tee and xargs? I'm thinking something like git svn fetch | sed "s/^\(r\d*\).*$/ \"\\\033]0;\"\1\"\\\007\"/" | xargs -l1 echo -ne based on: http://tldp.org/HOWTO/Xterm-Title-3.html Update: getting this to work would be enough: (echo "r9" ; echo "r10") | sed "s/^\(r\d*\).*$/ \"\\\033]0;\"\1\"\\\007\"/" | xargs -l1 echo -ne Update 2: This almost does what I want. I see r10, but not r9: (echo "r9" ; sleep 1 ; echo "r10") | sed "s/^\(r[0-9]*\)\.*$/\\\033]0;\1\\\007/" | xargs -0 echo -ne

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  • How to understand cpu family/model/stepping fields in /proc/cpuinfo

    - by Victor Sorokin
    I have following in cpuinfo: processor : 0 vendor_id : AuthenticAMD cpu family : 15 model : 107 model name : AMD Athlon(tm) 64 X2 Dual Core Processor 5600+ stepping : 2 According to Wikipedia page there are two kinds of 5600+ -- one of 90nm technology, another of 65nm. How can I understand which one I have? There seem to be no direct correspondence between contents of cpuinfo and info on Wikipedia page. AMD site seems to use some other naming scheme for processors too. How can I map values of family, model and stepping from cpuinfo to the data available on Wikipedia/AMD?

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  • How can I ensure my Collada model fits on an iPhone screen?

    - by rakeshNS
    Hi I am new to game development. I see many examples and tried myself like displaying triangle, cube etc. Now I am looking to render a Collada object. So I created a Collada object using Google Sketch up and trying to render that now. But the thing I am not understanding is, in all examples the vertices are between -1.0 and +1.0 values. But when I looked into that Collada file, the vertices were ranging from -30.0 to 90.0. I know any vertices greater than 1.0 will not display on iPhone. So can you pleas tell my the secret behind converting Object coordinate to normalized vector coordinate? My previous triangle defined as struct Vertex{ float Position[3]; float Color[4]; }; const Vertex Vertices[] = { {{-0.5, -0.866}, {1, 1, 0.5f, 1}}, {{0.5, -0.866}, {1, 1, 0.5, 1}}, {{0, 1}, {1, 1, 0.5, 1}}, {{-0.5, -0.866}, {0.5f, 0.5f, 0.5f}}, {{0.5, -0.866}, {0.5f, 0.5f, 0.5f}}, {{0, -0.4f}, {0.5f, 0.5f, 0.5f}}, }; And now triangle from collada is const Vertex Vertices[] = { {{39.4202092, 90.1263924, 0.0000000}, {1, 1, 0.5f, 1}}, {{-20.2205588, 90.1263924, 0.0000000}, {1, 1, 0.5, 1}}, {{-20.2205588, 176.3763924, 0.0000000}, {1, 1, 0.5, 1}}, {{-20.2205588, 176.3763924, 0.0000000}, {1, 1, 0.5, 1}}, {{-20.2205588, 90.1263924, 0.0000000}, {1, 1, 0.5, 1}}, {{39.4202092, 90.1263924, 0.0000000}, {1, 1, 0.5, 1}}, };

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  • Data Validation of a Comma Delimited List

    - by Brad
    I need a simple way of taking a comma seperated list in a cell, and providing a drop down box to select one of them. For Example, the cell could contain: 24, 32, 40, 48, 56, 64 And in a further cell, using Data Validation, I want to provide a drop-down list to select ONE of those values I need to do this without VBA or Macros please. Apolgies, I want this to work with Excel 2010 and later. I have been playing around with counting the number of commas in the list and then trying to split this into a number of rows of single numbers etc with no joy yet.

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  • Compressing/compacting messages over websocket on Node.js

    - by icelava
    We have a websocket implementation (Node.js/Sock.js) that exchanges data as JSON strings. As our use cases grow, so have the size of the data transmitted across the wire. The websocket protocol does not natively offer any compression feature, so in order to reduce the size of our messages we'd have to manually do something about the serialisation. There appear to be a variety of LZW implementations in Javascript, some which confuses me on their compatibility for in-browser use only versus transmission across the wire due to my lack of understanding on low-level encodings. More importantly, all of them seem to take a noticeable performance drag when Javascript is the engine doing the compression/decompression work, which is not desirable for mobile devices. Looking instead other forms of compact serialisation, MessagePack does not appear to have any active support in Javascript itself; BSON does not have any Javascript implementation; and an alternative BISON project that I tested does not deserialise everything back to their original values (large numbers), and it does not look like any further development will happen either. What are some other options others have explored for Node.js?

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  • Excel 2010: Copy row conditionaly

    - by TimothyHeyden
    I've searched for a similar question here, but haven't been able to find something that answers my issue. I'm a mediocre user of Excel 2010 with no experience in macro's. I have a dataset where each row represents a data entry. Let's say each row can be for each of its values (the columns) the maximum or minimum of the entire dataset. How can I create a row at the top where the, for instance, maximum row is shown dynamicly? So when extra data is added to the bottom of the dataset, the new maximum (if applicable) is shown in that row at the top. Thank you in advance!

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  • Why is rvalue write in shared memory array serialised?

    - by CJM
    I'm using CUDA 4.0 on a GPU with computing capability 2.1. One of my device functions is the following: device void test(int n, int* itemp) // itemp is shared memory pointer { const int tid = threadIdx.x; const int bdim = blockDim.x; int i, j, k; bool flag = 0; itemp[tid] = 0; for(i=tid; i<n; i+=bdim) { // { code that produces some values of "flag" } } itemp[tid] = flag; } Each thread is checking some conditions and producing a 0/1 flag. Then each thread is writing flag at the tid-th location of a shared int array. The write statement "itemp[tid] = flag;" gets serialized -- though "itemp[tid] = 0;" is not. This is causing huge performance lag which technically should not be there -- I want to avoid it. Please help.

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  • Mobile Web Framework that will only control rendering and page transitions

    - by rlemon
    I have been using jQueryMobile for a bit now, and there are some things I like about it and others I do not. First I will give a bit of background. I have a light weight mobile application that has a few configurations and 6 pages. Ideally I Would like to load all pages into the DOM (they interact with each other quite often and pages will be switched in the same frequency). The application will post for some JSON every n seconds and refresh the values on the page (yes it is primarily a information display app). with the jQuery Mobile framework the only real thing I like is how easy it is to have a standardized UI a crossed all devices and browsers, I'm really not using too much else out of the framework other than the basic page navigation (if you are familiar with the framework; a bare-bone multi-page design is all i need). Why I want to step away from jQueryMobile is how weighty it is. Not only do you need to include the mobile library, but also the base jQuery libraries. This I do not like because I'm not using jQuery anywhere else on the site. Any suggestions on light-weight mobile frameworks that have a similar rendering as jQueryMobile?

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  • Writing Java in Java

    - by Skeith
    I have been using Java for several months at work now and am becoming mildly competent in it. The problem I think I am having is that I program C++ in Java . By that I mean I have always used C++ and am treating Java as a simple syntax change instead of appreciate if for its own language. For instance a static variable in C++ is the same as a normal variable in Java as Java is all classes so they maintain there values between function calls. Little things like this are tripping me up constantly as I am self taught. What I want is to invest the time to become a good java programmer not just a C++ programmer that can write in Java. The problem is I do not know how to do this. I have tried reading the Java doc pages but I find them very clinical and hard to understand. So what I am looking for is recommendations on how I can learn to think in Java. Books that teach Java concepts not Java syntax, online tutorials that I can work through that give it a context, established Java traditions/best practices and any other thing that you could recommend.

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  • configuration issue with respect to .htaccess file on ubuntu

    - by Registered User
    I am building an application tshirtshop I have following configuration in /etc/apache2/sites-enabled/tshirtshop <VirtualHost *:80> ServerAdmin webmaster@localhost DocumentRoot /var/www/tshirtshop <Directory /var/www/tshirtshop> Options Indexes FollowSymLinks AllowOverride All Order allow,deny allow from all </Directory> ErrorLog ${APACHE_LOG_DIR}/error.log # Possible values include: debug, info, notice, warn, error, crit, # alert, emerg. LogLevel warn CustomLog ${APACHE_LOG_DIR}/access.log combined </VirtualHost> and following in .htaccess file in location /var/www/tshirtshop/.htaccess <IfModule mod_rewrite.c> # Enable mod_rewrite RewriteEngine On # Specify the folder in which the application resides. # Use / if the application is in the root. RewriteBase /tshirtshop #RewriteBase / # Rewrite to correct domain to avoid canonicalization problems # RewriteCond %{HTTP_HOST} !^www\.example\.com # RewriteRule ^(.*)$ http://www.example.com/$1 [R=301,L] # Rewrite URLs ending in /index.php or /index.html to / RewriteCond %{THE_REQUEST} ^GET\ .*/index\.(php|html?)\ HTTP RewriteRule ^(.*)index\.(php|html?)$ $1 [R=301,L] # Rewrite category pages RewriteRule ^.*-d([0-9]+)/.*-c([0-9]+)/page-([0-9]+)/?$ index.php?DepartmentId=$1&CategoryId=$2&Page=$3 [L] RewriteRule ^.*-d([0-9]+)/.*-c([0-9]+)/?$ index.php?DepartmentId=$1&CategoryId=$2 [L] # Rewrite department pages RewriteRule ^.*-d([0-9]+)/page-([0-9]+)/?$ index.php?DepartmentId=$1&Page=$2 [L] RewriteRule ^.*-d([0-9]+)/?$ index.php?DepartmentId=$1 [L] # Rewrite subpages of the home page RewriteRule ^page-([0-9]+)/?$ index.php?Page=$1 [L] # Rewrite product details pages RewriteRule ^.*-p([0-9]+)/?$ index.php?ProductId=$1 [L] </IfModule> the site is working on localhost and is working as if there is no .htaccess rule specified i.e. if I were to view a page as http://localhost/tshirtshop/nature-d2 then I get a 404 Error but if I view the same page as http://localhost/tshirtshop/index.php?DepartmentId=2 then I can view it. sudo apache2ctl -M Loaded Modules: core_module (static) log_config_module (static) logio_module (static) mpm_prefork_module (static) http_module (static) so_module (static) alias_module (shared) auth_basic_module (shared) authn_file_module (shared) authz_default_module (shared) authz_groupfile_module (shared) authz_host_module (shared) authz_user_module (shared) autoindex_module (shared) cgi_module (shared) deflate_module (shared) dir_module (shared) env_module (shared) mime_module (shared) negotiation_module (shared) php5_module (shared) reqtimeout_module (shared) rewrite_module (shared) setenvif_module (shared) status_module (shared) Syntax OK What is the mistake if any one can point out in above configuration, or else I need to check any thing else?

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  • What did Rich Hickey mean when he said, "All that specificity [of interfaces/classes/types] kills your reuse!"

    - by GlenPeterson
    In Rich Hickey's thought-provoking goto conference keynote "The Value of Values" at 29 minutes he's talking about the overhead of a language like Java and makes a statement like, "All those interfaces kill your reuse." What does he mean? Is that true? In my search for answers, I have run across: The Principle of Least Knowledge AKA The Law of Demeter which encourages airtight API interfaces. Wikipedia also lists some disadvantages. Kevlin Henney's Imperial Clothing Crisis which argues that use, not reuse is the appropriate goal. Jack Diederich's "Stop Writing Classes" talk which argues against over-engineering in general. Clearly, anything written badly enough will be useless. But how would the interface of a well-written API prevent that code from being used? There are examples throughout history of something made for one purpose being used more for something else. But in the software world, if you use something for a purpose it wasn't intended for, it usually breaks. I'm looking for one good example of a good interface preventing a legitimate but unintended use of some code. Does that exist? I can't picture it.

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  • How to pass one float as four unsigned chars to shader by glVertexPointAttrib?

    - by Kog
    For each vertex I use two floats as position and four unsigned bytes as color. I want to store all of them in one table, so I tried casting those four unsigned bytes to one float, but I am unable to do that correctly... All in all, my tests came to one point: GLfloat vertices[] = { 1.0f, 0.5f, 0, 1.0f, 0, 0 }; glEnableVertexAttribArray(0); glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 2 * sizeof(float), vertices); // VER1 - draws red triangle // unsigned char colors[] = { 0xff, 0, 0, 0xff, 0xff, 0, 0, 0xff, 0xff, 0, 0, // 0xff }; // glEnableVertexAttribArray(1); // glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, GL_TRUE, 4 * sizeof(GLubyte), // colors); // VER2 - draws greenish triangle (not "pure" green) // float f = 255 << 24 | 255; //Hex:0xff0000ff // float colors2[] = { f, f, f }; // glEnableVertexAttribArray(1); // glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, GL_TRUE, 4 * sizeof(GLubyte), // colors2); // VER3 - draws red triangle int i = 255 << 24 | 255; //Hex:0xff0000ff int colors3[] = { i, i, i }; glEnableVertexAttribArray(1); glVertexAttribPointer(1, 4, GL_UNSIGNED_BYTE, GL_TRUE, 4 * sizeof(GLubyte), colors3); glDrawArrays(GL_TRIANGLES, 0, 3); Above code is used to draw one simple red triangle. My question is - why do versions 1 and 3 work correctly, while version 2 draws some greenish triangle? Hex values are one I read by marking variable during debug. They are equal for version 2 and 3 - so what causes the difference?

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  • How To Export/Import a Website in IIS 7.x

    - by Tray Harrison
    IIS 6 had a great feature called ‘Save Configuration to a File’ which would allow you to easily export a website’s configuration, to be later used to import either on the same server or another box.  This came in handy anytime you wanted to duplicate a site in order to do some testing without impacting the existing application.  So naturally, Microsoft decided to do away with this feature in IIS 7. The process to export/import a site is still fairly simple, though not as obvious as it was in previous versions.  Here are the steps: 1. Open a command prompt and navigate to C:\Windows\System32\inetsrv and run the following command: appcmd list site /name:<sitename> /config /xml > C:\output.xml So if you were wanting to export a website named EAC, you would run the following: If you’ll be setting up another copy of the site on the same server, you’ll now need to edit the output.xml file before importing it.  This is necessary in order to avoid conflicts such as bindings, Site ID, etc.  To do this, edit the XML and change the values.  Go ahead and make a copy of the home directory, and rename it to whatever folder name you specified in the output – /EAC2 in this example.  If you decide to change the app pool, make sure you go ahead and create the new app pool as well. Once these edits have been made, we are now ready to import the site.  To do that run: appcmd add sites /in < c:\output.xml So for our example it would look like this: That’s it.  You should now see your site listed when opening up Inet Manager.  If for some reason the site fails to start, that’s probably because you forgot to create the new app pool or there is a problem with one of the other parameters you changed.  Look at the System log to identify any issues like this.

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  • Lost WiFi after 12.10 upgrade

    - by Steven Guillory
    I received my new Dell Vostro 2420 last week, and just got around to upgrading from 11.10 to 12.10. Unfortunately, like many others (after researching the issue), I no longer have WiFi. I have tried every sudo command given that worked for others, and still can't get my wireless to function. I am new to Linux, so any and all help is appreciated. Thanks in advance! Edit: I can connect via ethernet, just not via wifi. As a matter of fact, when I use Fn + F2 to turn on wifi, only my bluetooth comes on. lspci 00:00.0 Host bridge: Intel Corporation 2nd Generation Core Processor Family DRAM Controller (rev 09) 00:02.0 VGA compatible controller: Intel Corporation 2nd Generation Core Processor Family Integrated Graphics Controller (rev 09) 00:16.0 Communication controller: Intel Corporation Panther Point MEI Controller #1 (rev 04) 00:1a.0 USB controller: Intel Corporation Panther Point USB Enhanced Host Controller #2 (rev 04) 00:1b.0 Audio device: Intel Corporation Panther Point High Definition Audio Controller (rev 04) 00:1c.0 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 1 (rev c4) 00:1c.3 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 4 (rev c4) 00:1c.5 PCI bridge: Intel Corporation Panther Point PCI Express Root Port 6 (rev c4) 00:1d.0 USB controller: Intel Corporation Panther Point USB Enhanced Host Controller #1 (rev 04) 00:1f.0 ISA bridge: Intel Corporation Panther Point LPC Controller (rev 04) 00:1f.2 SATA controller: Intel Corporation Panther Point 6 port SATA Controller [AHCI mode] (rev 04) 00:1f.3 SMBus: Intel Corporation Panther Point SMBus Controller (rev 04) 07:00.0 Network controller: Broadcom Corporation Device 4365 (rev 01) 09:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd. RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 07) This is what I am getting... dpkg: error: --install needs at least one package archive file argument Type dpkg --help for help about installing and deinstalling packages [*]; Use dselect or aptitude for user-friendly package management; Type dpkg -Dhelp for a list of dpkg debug flag values; Type dpkg --force-help for a list of forcing options; Type dpkg-deb --help for help about manipulating *.deb files; Options marked [*] produce a lot of output - pipe it through less or more !

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  • How is determined an impact of a requirement change on the existing code?

    - by MainMa
    Hi, How companies working on large projects evaluate an impact of a single modification on an existing code? Since my question is probably not very clear, here's an example: Let's take a sample business application which deals with tasks. In the database, each task has a state, 0 being "Pending", ... 5 - "Finished". A new requirement adds a new state, between 2nd and 3rd one. It means that: A constraint on the values 1 - 5 in the database must be changed, Business layer and code contracts must be changed to add a new state, Data access layer must be changed to take in account that, for example the state StateReady is now 6 instead of 5, etc. The application must implement a new state visually, add new controls for it, new localized strings for tool-tips, etc. When an application is written recently by one developer, it's more or less easy to predict every change to do. On the other hand, when an application was written for years by many people, no single person can anticipate every change immediately, without any investigation. So since this situation (such changes in requirements) is very frequent, I imagine there are already some clever techniques and ways to predict the impact. Is there any? Do you know any books which deal about this subject? Note: my question is not related to How do you deal with changing requirements? question. In fact, I'm not interested in evaluating the cost of a change, but rather the way to predict the parts of an application which will be concerned by the change. What will be those changes and how difficult they are really doesn't matter in my question.

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  • foreign-architecture

    - by speedy-MACHO
    Always when I install something, I get the following error multiple times: Unknown configuration key 'foreign-architecture' found in your 'dpkg' configuration files. This warning will become a hard error at a later date, so please remove the offending configuration options and replace them with 'dpkg --add-architecture' invocations at the command line. When I try dpkg --add-architecture I get: Unknown configuration key `foreign-architecture' found in your `dpkg' configuration files. This warning will become a hard error at a later date, so please remove the offending configuration options and replace them with `dpkg --add-architecture' invocations at the command line. dpkg: error: --add-architecture takes one argument Type dpkg --help for help about installing and deinstalling packages [*]; Use `dselect' or `aptitude' for user-friendly package management; Type dpkg -Dhelp for a list of dpkg debug flag values; Type dpkg --force-help for a list of forcing options; Type dpkg-deb --help for help about manipulating *.deb files; Options marked [*] produce a lot of output - pipe it through `less' or `more' ! I've no problems yet, but since it says This warning will become a hard error at a later date I better do something about this. When I search 'foreign-architecture', I find an empty file, containing not a single byte. I somehow can't delete that file. Please help, it's a kind of creapy...

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  • Estimate angle to launch missile, maths question

    - by Jonathan
    I've been working on this for an hour or two now and my maths really isn't my strong suit which is definitely not a good thing for a game programmer but that shouldn't stop me enjoying a hobby surely? After a few failed attempts I was hoping someone else out there could help so here's the situation. I'm trying to implement a bit of faked intelligence when the A.I fires it's missiles at a target in a 2D game world. By predicting the likely position the target will be in given it's current velocity and the time it will take the missile to reach it's target. I created an image to demonstrate my thinking: http://i.imgur.com/SFmU3.png which also contains the logic I use for accelerating the missile after launch. The ship that fires the missile can fire within a total of 40 degree angle, 20 either side of itself, but this could likely become variable. My current attempt was to break the space between the two lines into segments which match the targets width. Then calculate the time it would take the missile to get to that location using the formula. So for each iteration of this we total up the values and that tells us the distance travelled, ad it would then just need compared to distance to the segment. startVelocity * ((startVelocity * acceleration)^(currentframe-1) So for example. If we start at a velocity of 1f/frame with an acceleration of 0.1f the formula, at frame 4, would be 1 * (1.1^3) = 1.331 But I quickly realized I was getting lost when trying to put this into practice. Does this seem like a correct starting point or am I going completely the wrong way about it? Any pointers would help me greatly. Maths really isn't my strong suit so I get easily lost in these matters and don't even really know a good phrase to search for with this. So I guess in summary my question is more about the correct way to approach this problem and any additional code samples on top of that would be great but I'm not averse to working out the complete code from helpful pointers.

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  • Understanding Application binary interface (ABI)

    - by Tim
    I am trying to understand the concept of Application binary interface (ABI). From The Linux Kernel Primer: An ABI is a set of conventions that allows a linker to combine separately compiled modules into one unit without recompilation, such as calling conventions, machine interface, and operating-system interface. Among other things, an ABI defines the binary interface between these units. ... The benefits of conforming to an ABI are that it allows linking object files compiled by different compilers. From Wikipedia: an application binary interface (ABI) describes the low-level interface between an application (or any type of) program and the operating system or another application. ABIs cover details such as data type, size, and alignment; the calling convention, which controls how functions' arguments are passed and return values retrieved; the system call numbers and how an application should make system calls to the operating system; and in the case of a complete operating system ABI, the binary format of object files, program libraries and so on. I was wondering whether ABI depends on both the instruction set and the OS. Are the two all that ABI depends on? What kinds of role does ABI play in different stages of compilation: preprocessing, conversion of code from C to Assembly, conversion of code from Assembly to Machine code, and linking? From the first quote above, it seems to me that ABI is needed for only linking stage, not the other stages. Is it correct? When is ABI needed to be considered? Is ABI needed to be considered during programming in C, Assembly or other languages? If yes, how are ABI and API different? Or is it only for linker or compiler? Is ABI specified for/in machine code, Assembly language, and/or of C?

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  • Dhcp clients fail after successful import of server to new machine

    - by Tathagata
    I transfered the configs of a dhcp server from one server to another both running Windows Server 2003 R2 following http [://] support.microsoft.com/kb/325473. The new server has a statically configured ip(outside the scope) like the old one. Stopped the server on the old, and started up in the new server (authorized too) - but when I ipconfig /renew from a client its network interface fails with all 0.0.0.0 (or 169...*). I read somewhere I need to reconcile the scope to sync the new registry values ('ll try this tomorrow). What other troubleshooting steps can I take other than these (which didn't help)? Things work fine when the old server resurrects and the new one is taken down. The new server showed there was no requests for offer.

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  • Generic rule parser for RPG board game rules - how to do it?

    - by burzum
    I want to build a generic rule parser for pen and paper style RPG systems. A rule can involve usually 1 to N entities 1 to N roles of a dice and calculating values based on multiple attributes of an entity. For example: Player has STR 18, his currently equipped weapon gives him a bonus of +1 STR but a malus of DEX -1. He attacks a monster entity and the game logic now is required to run a set of rules or actions: Player rolls the dice, if he gets for example 8 or more (base attack value he needs to pass is one of his base attributes!) his attack is successfully. The monster then rolls the dice to calculate if the attack goes through it's armor. If yes the damage is taken if not the attack was blocked. Besides simple math rules can also have constraints like applying only to a certain class of user (warrior vs wizzard for example) or any other attribute. So this is not just limited to mathematical operations. If you're familiar with RPG systems like Dungeon and Dragons you'll know what I'm up to. My issue is now that I have no clue how to exactly build this the best possible way. I want people to be able to set up any kind of rule and later simply do an action like selecting a player and a monster and run an action (set of rules like an attack). I'm asking less for help with the database side of things but more about how to come up with a structure and a parser for it to keep my rules flexible. The language of choice for this is php by the way.

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