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  • boost::spirit::karma using the alternatives operator (|) with conditions

    - by Ingemar
    I'm trying to generate a string from my own class called Value using boost::spirit::karma, but i got stuck with this. I've tried to extract my problem into a simple example. I want to generate a String with karma from instances of the following class: class Value { public: enum ValueType { BoolType, NumericType }; Value(bool b) : type_(BoolType), value_(b) {} Value(const double d) : type_(NumericType), value_(d) {}; ValueType type() { return type_; } operator bool() { return boost::get<bool>(value_); } operator double() { return boost::get<double>(value_); } private: ValueType type_; boost::variant<bool, double> value_; }; Here you can see what I'm tying to do: int main() { using karma::bool_; using karma::double_; using karma::rule; using karma::eps; std::string generated; std::back_insert_iterator<std::string> sink(generated); rule<std::back_insert_iterator<std::string>, Value()> value_rule = bool_ | double_; Value bool_value = Value(true); Value double_value = Value(5.0); karma::generate(sink, value_rule, bool_value); std::cout << generated << "\n"; generated.clear(); karma::generate(sink, value_rule, double_value); std::cout << generated << "\n"; return 0; } The first call to karma::generate() works fine because the value is a bool and the first generator in my rule also "consumes" a bool. But the second karma::generate() fails with boost::bad_get because karma tries to eat a bool and calls therefore Value::operator bool(). My next thought was to modify my generator rule and use the eps() generator together with a condition but here i got stuck: value_rule = (eps( ... ) << bool_) | (eps( ... ) << double_); I'm unable to fill the brackets of the eps generator with sth. like this (of course not working): eps(value.type() == BoolType) I've tried to get into boost::phoenix, but my brain seems not to be ready for things like this. Please help me! here is my full example (compiling but not working): main.cpp

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  • Using a boost::fusion::map in boost::spirit::karma

    - by user1097105
    I am using boost spirit to parse some text files into a data structure and now I am beginning to generate text from this data structure (using spirit karma). One attempt at a data structure is a boost::fusion::map (as suggested in an answer to this question). But although I can use boost::spirit::qi::parse() and get data in it easily, when I tried to generate text from it using karma, I failed. Below is my attempt (look especially at the "map_data" type). After some reading and playing around with other fusion types, I found boost::fusion::vector and BOOST_FUSION_DEFINE_ASSOC_STRUCT. I succeeded to generate output with both of them, but they don't seem ideal: in vector you cannot access a member using a name (it is like a tuple) -- and in the other solution, I don't think I need both ways (member name and key type) to access the members. #include <iostream> #include <string> #include <boost/spirit/include/karma.hpp> #include <boost/fusion/include/map.hpp> #include <boost/fusion/include/make_map.hpp> #include <boost/fusion/include/vector.hpp> #include <boost/fusion/include/as_vector.hpp> #include <boost/fusion/include/transform.hpp> struct sb_key; struct id_key; using boost::fusion::pair; typedef boost::fusion::map < pair<sb_key, int> , pair<id_key, unsigned long> > map_data; typedef boost::fusion::vector < int, unsigned long > vector_data; #include <boost/fusion/include/define_assoc_struct.hpp> BOOST_FUSION_DEFINE_ASSOC_STRUCT( (), assocstruct_data, (int, a, sb_key) (unsigned long, b, id_key)) namespace karma = boost::spirit::karma; template <typename X> std::string to_string ( const X& data ) { std::string generated; std::back_insert_iterator<std::string> sink(generated); karma::generate_delimited ( sink, karma::int_ << karma::ulong_, karma::space, data ); return generated; } int main() { map_data d1(boost::fusion::make_map<sb_key, id_key>(234, 35314988526ul)); vector_data d2(boost::fusion::make_vector(234, 35314988526ul)); assocstruct_data d3(234,35314988526ul); std::cout << "map_data as_vector: " << boost::fusion::as_vector(d1) << std::endl; //std::cout << "map_data to_string: " << to_string(d1) << std::endl; //*FAIL No 1* std::cout << "at_key (sb_key): " << boost::fusion::at_key<sb_key>(d1) << boost::fusion::at_c<0>(d1) << std::endl << std::endl; std::cout << "vector_data: " << d2 << std::endl; std::cout << "vector_data to_string: " << to_string(d2) << std::endl << std::endl; std::cout << "assoc_struct as_vector: " << boost::fusion::as_vector(d3) << std::endl; std::cout << "assoc_struct to_string: " << to_string(d3) << std::endl; std::cout << "at_key (sb_key): " << boost::fusion::at_key<sb_key>(d3) << d3.a << boost::fusion::at_c<0>(d3) << std::endl; return 0; } Including the commented line gives lots of pages of compilation errors, among which notably something like: no known conversion for argument 1 from ‘boost::fusion::pair’ to ‘double’ no known conversion for argument 1 from ‘boost::fusion::pair’ to ‘float’ Might it be that to_string needs the values of the map_data, and not the pairs? Though I am not good with templates, I tried to get a vector from a map using transform in the following way template <typename P> struct take_second { typename P::second_type operator() (P p) { return p.second; } }; // ... inside main() pair <char, int> ff(32); std::cout << "take_second (expect 32): " << take_second<pair<char,int>>()(ff) << std::endl; std::cout << "transform map_data and to_string: " << to_string(boost::fusion::transform(d1, take_second<>())); //*FAIL No 2* But I don't know what types am I supposed to give when instantiating take_second and anyway I think there must be an easier way to get (iterate over) the values of a map (is there?) If you answer this question, please also give your opinion on whether using an ASSOC_STRUCT or a map is better.

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  • Notes from a short presentation on NodeJs

    - by Aligned
    Originally posted on: http://geekswithblogs.net/Aligned/archive/2014/05/30/notes-from-a-short-presentation-on-nodejs.aspxI volunteered myself to give a short 30 minute presentation at a work lunch and learn on NodeJs. With my limited experience I see using Node as a great tool for build process improvement, scaffolding with yeoman, and running tests with Karma. I haven’t looked into using as a full server or development stack. I guess I’m too stuck on IIS and Visual Studio :-). Here are my notes, that aren’t very well formatted, but I wanted to share it anyways. What is it? "Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices." Why should you be interested? another popular tool that can help you get the job done you can use the command prompt! can be run at build or release time to automate tasks What are some uses? https://www.npmjs.org/ - NuGet for Node packages http://bower.io/ - NuGet for UI JavaScript libraries (jQuery, Bootstrap, Angular, etc) http://yeoman.io/ "Our workflow is comprised of three tools for improving your productivity and satisfaction when building a web app: yo (the scaffolding tool), grunt (the build tool) and bower (for package management)." -> yeoman asks which components you want alternative - http://joakimbeng.eu01.aws.af.cm/slush-replacing-yeoman-with-gulp/ https://www.npmjs.org/package/generator-cg-angular - phantom js, less, // git is needed for bower http://git-scm.com/ run installer in Windows before you can use bower // select Run Git from the Windows Command Prompt in the installer // requires a reboot http://stackoverflow.com/questions/20069297/bower-git-not-in-the-path-error npm install -g git npm install -g yo npm install -g generator-cg-angular mkdir myapp cd myapp yo cg-angular npm install -g bower npm install -g grunt-cli yo bower grunt serve grunt test grunt build // there are many generators (generator-angular) is another one // I like the Nuget HotTowel-Angular from John Papa myself // needed IIS Node for Express -> prompt from WebMatrix Karma bat to startup Karma - see below image compression - https://www.npmjs.org/search?q=optimize+images, https://github.com/heldr/node-smushit - do it from the command line LESS compiling js and css combine and minification at build with Gulp for requireJS apps quick lightweight HTTP server - "Express" Build pipeline with Grunt or Gulp http://www.johnpapa.net/gulp-and-grunt-at-anglebrackets/ Gulp is the newer and improved over Grunt. Supposed to be easier to use, but Grunt is more established. https://github.com/johnpapa/ng-demos/tree/master/grunt-gulp https://github.com/assetgraph/assetgraph-builder Does a lot of the minimizing, combining, image optimization etc using Node. Looks interesting.... http://nodejs.org http://nodeschool.io/ http://sub.watchmecode.net/getting-started-with-nodejs-installing-and-writing-your-first-code/ https://stormpath.com/blog/build-a-killer-node-dot-js-client-for-your-rest-plus-json-api/ https://codio.com/ http://www.hanselman.com/blog/ItsJustASoftwareIssueEdgejsBringsNodeAndNETTogetherOnThreePlatforms.aspx run unit tests - Karma in msBuild karma-start.bat @echo off cd %~dp0\.. REM 604800 is to make sure we only update once every 7 days call npm install --cache-min 604800 -g grunt-cli call npm install --cache-min 604800 call npm install --cache-min 604800 -g karma-cli karma start UnitTests\karma.conf.js REM karma start UnitTests\karma.conf.js --single-run REM see karma-start.bat and karam.config.js REM jsHint comes from Nuget

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  • How do I remedy "Error: Cannot find module 'child-process-close'"?

    - by Tyler Sloan
    I was going about business as usual and about to checkout generator-angular-fullstack. I got no red errors but a message a the end saying Error: Cannot find module 'child-process-close'. I tried many a-thing–uninstalling node, reinstalling, manually getting rid of files and directories in local and/or global paths and tried to make sure Homebrew was the one who installed everything and somehow I've made things worse. (Also, I initially saw errors regarding karma. Everything looked right but it doesn't seem I did any good by throwing commands at it.) I am at a loss. All the stackoverflow questions have been clicked and I'm afraid I've probably tried too many of the suggestions. I cannot install any Yeoman generator. I cannot install anything with npm. When inside the project directory when I run npm install it throws the error. I really have no clue. Is there a way I can basically start over all together? A simple uninstall and install isn't cutting it. Something in the system needs to change but I don't know what. Any ideas?

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  • Isolating a computer in the network

    - by Karma Soone
    I've got a small network and want to isolate one of the computers from the whole network. My Network: <----> Trusted PC 1 ADSL Router --> Netgear dg834g <----> Trusted PC 2 <----> Untrusted PC I want to isolate this untrusted PC in the network. That means the network should be secure against : * ARP Poisoning * Sniffing * Untrusted PC should not see / reach any other computers within the network but can go out the internet. Static DHCP and switch usage solves the problem of sniffing/ARP poisoning. I can enable IPSec between computers but the real problem is sniffing the traffic between the router and one of the trusted computers. Against getting a new IP address (second IP address from the same computer) I need a firewall with port security (I think) or I don't think my ADSL router supports that. To summarise I'm looking for a hardware firewall/router which can isolate one port from the rest of the network. Could you recommend such a hardware or can I easily accomplish that with my current network?

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  • ubuntu's average load never below "0.00 0.01 0.05"

    - by Karma Fusebox
    I have several ubuntu 12.04 VMs running on a ubuntu 12.04 KVM host. Those of the virtual machines that are totally idle with no services (except syslog and the other "small" standard stuff of a fresh installation) show a constant load of "0.00 0.01 0.05" in top/htop as average 1/5/15. When there are "real" applications running, the load averages behave perfectly normal but they never fall below the mentioned values. While this doesn't affect performance at all and could easily be ignored, it screws up the monitoring graphs in a very annoying way: (Notice how load15 behaves nicely if 0.05 for a short time in the right half of the pic) Unfortunately I don't know what diagnostic outputs might be helpful for you, so here's some default stuff: # top top - 16:31:01 up 1:05, 1 user, load average: 0.00, 0.01, 0.05 Tasks: 62 total, 1 running, 61 sleeping, 0 stopped, 0 zombie Cpu(s): 0.2%us, 0.2%sy, 0.0%ni, 99.2%id, 0.5%wa, 0.0%hi, 0.0%si, 0.0%st Mem: 1019464k total, 73452k used, 946012k free, 6140k buffers Swap: 0k total, 0k used, 0k free, 22504k cached . # free -m total used free shared buffers cached Mem: 995 72 923 0 6 21 -/+ buffers/cache: 43 951 Swap: 0 0 0 . # iostat -x /dev/vda Linux 3.2.0-32-virtual (vm3) 11/15/2012 _x86_64_ (2 CPU) avg-cpu: %user %nice %system %iowait %steal %idle 0.25 0.00 0.65 0.20 0.24 98.66 Device: rrqm/s wrqm/s r/s w/s rkB/s wkB/s avgrq-sz avgqu-sz await r_await w_await svctm %util vda 0.14 0.12 0.51 0.22 6.74 1.46 22.50 0.02 23.26 20.64 29.30 7.63 0.56 Need something else? Has anyone ever seen this behavior? Might this be a bug in kvm/ubuntu/kernel 3.x in the end? Thanks a lot!

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  • Is this iptables NAT exploitable from the external side?

    - by Karma Fusebox
    Could you please have a short look on this simple iptables/NAT-Setup, I believe it has a fairly serious security issue (due to being too simple). On this network there is one internet-connected machine (running Debian Squeeze/2.6.32-5 with iptables 1.4.8) acting as NAT/Gateway for the handful of clients in 192.168/24. The machine has two NICs: eth0: internet-faced eth1: LAN-faced, 192.168.0.1, the default GW for 192.168/24 Routing table is two-NICs-default without manual changes: Destination Gateway Genmask Flags Metric Ref Use Iface 192.168.0.0 0.0.0.0 255.255.255.0 U 0 0 0 eth1 (externalNet) 0.0.0.0 255.255.252.0 U 0 0 0 eth0 0.0.0.0 (externalGW) 0.0.0.0 UG 0 0 0 eth0 The NAT is then enabled only and merely by these actions, there are no more iptables rules: echo 1 > /proc/sys/net/ipv4/ip_forward /sbin/iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE # (all iptables policies are ACCEPT) This does the job, but I miss several things here which I believe could be a security issue: there is no restriction about allowed source interfaces or source networks at all there is no firewalling part such as: (set policies to DROP) /sbin/iptables -A FORWARD -i eth0 -o eth1 -m state --state RELATED,ESTABLISHED -j ACCEPT /sbin/iptables -A FORWARD -i eth1 -o eth0 -j ACCEPT And thus, the questions of my sleepless nights are: Is this NAT-service available to anyone in the world who sets this machine as his default gateway? I'd say yes it is, because there is nothing indicating that an incoming external connection (via eth0) should be handled any different than an incoming internal connection (via eth1) as long as the output-interface is eth0 - and routing-wise that holds true for both external und internal clients that want to access the internet. So if I am right, anyone could use this machine as open proxy by having his packets NATted here. So please tell me if that's right or why it is not. As a "hotfix" I have added a "-s 192.168.0.0/24" option to the NAT-starting command. I would like to know if not using this option was indeed a security issue or just irrelevant thanks to some mechanism I am not aware of. As the policies are all ACCEPT, there is currently no restriction on forwarding eth1 to eth0 (internal to external). But what are the effective implications of currently NOT having the restriction that only RELATED and ESTABLISHED states are forwarded from eth0 to eth1 (external to internal)? In other words, should I rather change the policies to DROP and apply the two "firewalling" rules I mentioned above or is the lack of them not affecting security? Thanks for clarification!

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  • Can I join two tables whereby the joined table is sorted by a certain column?

    - by Ferdy
    I'm not much of a database guru so I need some help on a query I'm working on. In my photo community project I want to richly visualize tags by not only showing the tag name and counter (# of images inside them), I also want to show a thumb of the most popular image inside the tag (most karma). The table setup is as follow: Image table holds basic image metadata, important is the karma field Imagefile table holds multiple entries per image, one for each format Tag table holds tag definitions Tag_map table maps tags to images In my usual trial and error query authoring I have come this far: SELECT * FROM (SELECT tag.name, tag.id, COUNT(tag_map.tag_id) as cnt FROM tag INNER JOIN tag_map ON (tag.id = tag_map.tag_id) INNER JOIN image ON tag_map.image_id = image.id INNER JOIN imagefile on image.id = imagefile.image_id WHERE imagefile.type = 'smallthumb' GROUP BY tag.name ORDER BY cnt DESC) as T1 WHERE cnt > 0 ORDER BY cnt DESC [column clause of inner query snipped for the sake of simplicity] This query gives me somewhat what I need. The outer query makes sure that only tags are returned for which there is at least 1 image. The inner query returns the tag details, such as its name, count (# of images) and the thumb. In addition, I can sort the inner query as I want (by most images, alphabetically, most recent, etc) So far so good. The problem however is that this query does not match the most popular image (most karma) of the tag, it seems to always take the most recent one in the tag. How can I make sure that the most popular image is matched with the tag?

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  • How can I test to see if a class contains a particular attribute?

    - by BryanWheelock
    How can I test to see if a class contains a particular attribute? In [14]: user = User.objects.get(pk=2) In [18]: user.__dict__ Out[18]: {'date_joined': datetime.datetime(2010, 3, 17, 15, 20, 45), 'email': u'[email protected]', 'first_name': u'', 'id': 2L, 'is_active': 1, 'is_staff': 0, 'is_superuser': 0, 'last_login': datetime.datetime(2010, 3, 17, 16, 15, 35), 'last_name': u'', 'password': u'sha1$44a2055f5', 'username': u'DickCheney'} In [25]: hasattr(user, 'username') Out[25]: True In [26]: hasattr(User, 'username') Out[26]: False I'm having a weird bug where more attributes are showing up than I actually define. I want to conditionally stop this. e.g. if not hasattr(User, 'karma'): User.add_to_class('karma', models.PositiveIntegerField(default=1))

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  • Darth Vader Wins Big [Humorous Comic]

    - by Asian Angel
    Everyone’s favorite Star Wars villain receives a notice in the mail saying he won a contest, but did he really hit it big or is karma dishing out some payback? Note: Make sure to take a close look at the letter shown in the second panel for an additional laugh! Darth Vader Wins Big (Dorkly) [via Neatorama] HTG Explains: Why Linux Doesn’t Need Defragmenting How to Convert News Feeds to Ebooks with Calibre How To Customize Your Wallpaper with Google Image Searches, RSS Feeds, and More

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  • Multiple site URLs now showing up in SERPs

    - by Scott Helme
    Recently when you search for me on Google several URLs from my blog have started showing up, instead of just the main URL. 1) https://scotthelme.co.uk/ 2) https://scotthelme.co.uk/category/wifi-pineapple-2/? 3) https://scotthelme.co.uk/wifi-pineapple-karma-sslstrip/ Is there a reason this starts happening? I have contemplated doing something to remove them but is it better to occupy the top 3 spots instead of just the top spot? Should I just leave them there?

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  • A Digg-like rotating homepage of popular content, how to include date as a factor?

    - by Ferdy
    I am building an advanced image sharing web application. As you may expect, users can upload images and others can comments on it, vote on it, and favorite it. These events will determine the popularity of the image, which I capture in a "karma" field. Now I want to create a Digg-like homepage system, showing the most popular images. It's easy, since I already have the weighted Karma score. I just sort on that descendingly to show the 20 most valued images. The part that is missing is time. I do not want extremely popular images to always be on the homepage. I guess an easy solution is to restrict the result set to the last 24 hours. However, I'm also thinking that in order to keep the image rotation occur throughout the day, time can be some kind of variable where its offset has an influence on the image's sorting. Specific questions: Would you recommend the easy scenario (just sort for best images within 24 hours) or the more sophisticated one (use datetime offset as part of the sorting)? If you advise the latter, any help on the mathematical solution to this? Would it be best to run a scheduled service to mark images for the homepage, or would you advise a direct query (I'm using MySQL) As an extra note, the homepage should support paging and on a quiet day should include entries of days before in order to make sure it is always "filled" I'm not asking the community to build this algorithm, just looking for some advise :)

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  • Freeware local proxy engine for Windows?

    - by Tomalak
    Is there a nice and small, freeware proxy application that runs in the system tray? It should support HTTP and HTTPS proxy connections, NTLM authentication and configurable rules (different proxy servers for different hosts). Bonus karma if it can NTLM-authenticate anonymous requests passing through it.

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  • The ABC of Front End Web Development

    - by Geertjan
    And here it is, the long awaited "ABC" of front end web development, in which the items I never knew existed until I was looking to fill the gaps link off to the sites where more info can be found on them. A is for Android and AngularJS B is for Backbone.js and Bower C is for CSS and Cordova D is for Docker E is for Ember.js and Ext JS F is for Frisby.js G is for Grunt H is for HTML I is for Ionic and iPhone J is for JavaScript, Jasmine, and JSON K is for Knockout.js and Karma L is for LESS M is for Mocha N is for NetBeans and Node.js O is for "Oh no, my JS app is unmaintainable!" P is for PHP, Protractor, and PhoneGap Q is for Queen.js R is for Request.js S is for SASS, Selenium, and Sublime T is for TestFairy U is for Umbrella V is for Vaadin W is for WebStorm X is for XML Y is for Yeoman Z is for Zebra

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  • AdWords test with two different agencies - can I track their results without them being aware of each other

    - by Drew
    Currently going through a process of testing two AdWords ppc providers at the same time from two separate AdWords accounts. However they will require access to my GA account for linking and ecommerce tracking. Which means that they will be able to see each others results. I dont want this; Is it possible to set up GA so that; Company A only sees Adwords results associated to their AdWords management via GA Company B only sees Adwords results associated to their AdWords management via GA And each company never sees the other company's Adwords results? 100 positive karma points to anyone who can shed some light on this. Cheers.

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  • How to add a link group to update-alternatives?

    - by Kurtosis
    Is it possible to add a custom link group to update-alternatives that is not already there by default? For example, I want to add Scala and all its supporting binaries as a link group 'scala'. I'm trying using this script, but keep getting the error: update-alternatives: error: unknown argument `' I'm not sure what that means, but after troubleshooting the script a bit with no luck, I'm wondering if update-alternatives has a hard-coded list of link groups, that can't be added to, and that doesn't include scala. PS - any chance someone with higher karma can create an update-alternatives tag? Seems this topic gets a decent number of questions, but no tag for it.

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  • What options should I consider for a modern Web/Mobile development stack? [on hold]

    - by jimmy_terra
    I'm a long time server side dev who has been tasked with building a bleeding edge web UI (go figure), so apologies for the very broad nature of the question. What are the best modern libraries, tools, languages and patterns for building a dynamic web application that will run seamlessly on mobiles also? My requirements are that it must be dynamic (push updates), support automated testing, and should allow 'componentization' (a team of devs will be working on this). What should I check out and why? I will start off with some of the things I'm looking at already: Front-end HTML5 CSS3 JavaScript AngularJs Testing Karma Testem Jasmine Patterns Single Page Applications

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  • What to choose for beginner: PHP/Python/Ruby

    - by Nai
    I'm a beginner teaching myself to code but I would like he insight of the PSE community and helping choose where to start. My main objective is to be able to create a basic website to first test my business idea and from there iterate on it quickly to minimise my learning time. The most important criteria for me is speed. An example of speed would be pre-built components available open source and not having to write one from scratch. From my research, this seems to be a death match between the following languages and frameworks: PHP and CakePHP Python and Django Ruby and Rails Assumptions: I am going to be equally good (or bad) in all 3. It is going to be equally easy to find competent developers in either language. I know this to be false already by lets assume that it is. This question is not meant to karma whore as I've seen how passionate some of these standoff questions have been and I'll be happy to turn it into a community wiki.

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  • Why do people still use Vi and Emacs?

    - by mawg
    This is not a subjective question. I am genuinely looking for techinccal reasons to do so. I will risk offending some folks (not intended as an offence – maybe as a goad) by saying that I have been coding for 30+ years and used to be religously attched to each of them, but as soone as I saw editor-cum-IDE which seemed to offer more, I moved on. Is there any compelling reason, in this day and age, to choose Vi / Emacs over – say- Eclipse for code editing? Even Notepad++ for win-doze users seems to offer more. Just sayin'

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  • Implementing a popularity algorithm in Django

    - by TheLizardKing
    I am creating a site similar to reddit and hacker news that has a database of links and votes. I am implementing hacker news' popularity algorithm and things are going pretty swimmingly until it comes to actually gathering up these links and displaying them. The algorithm is simple: Y Combinator's Hacker News: Popularity = (p - 1) / (t + 2)^1.5` Votes divided by age factor. Where` p : votes (points) from users. t : time since submission in hours. p is subtracted by 1 to negate submitter's vote. Age factor is (time since submission in hours plus two) to the power of 1.5.factor is (time since submission in hours plus two) to the power of 1.5. I asked a very similar question over yonder http://stackoverflow.com/questions/1964395/complex-ordering-in-django but instead of contemplating my options I choose one and tried to make it work because that's how I did it with PHP/MySQL but I now know Django does things a lot differently. My models look something (exactly) like this class Link(models.Model): category = models.ForeignKey(Category) user = models.ForeignKey(User) created = models.DateTimeField(auto_now_add = True) modified = models.DateTimeField(auto_now = True) fame = models.PositiveIntegerField(default = 1) title = models.CharField(max_length = 256) url = models.URLField(max_length = 2048) def __unicode__(self): return self.title class Vote(models.Model): link = models.ForeignKey(Link) user = models.ForeignKey(User) created = models.DateTimeField(auto_now_add = True) modified = models.DateTimeField(auto_now = True) karma_delta = models.SmallIntegerField() def __unicode__(self): return str(self.karma_delta) and my view: def index(request): popular_links = Link.objects.select_related().annotate(karma_total = Sum('vote__karma_delta')) return render_to_response('links/index.html', {'links': popular_links}) Now from my previous question, I am trying to implement the algorithm using the sorting function. An answer from that question seems to think I should put the algorithm in the select and sort then. I am going to paginate these results so I don't think I can do the sorting in python without grabbing everything. Any suggestions on how I could efficiently do this? EDIT This isn't working yet but I think it's a step in the right direction: from django.shortcuts import render_to_response from linkett.apps.links.models import * def index(request): popular_links = Link.objects.select_related() popular_links = popular_links.extra( select = { 'karma_total': 'SUM(vote.karma_delta)', 'popularity': '(karma_total - 1) / POW(2, 1.5)', }, order_by = ['-popularity'] ) return render_to_response('links/index.html', {'links': popular_links}) This errors out into: Caught an exception while rendering: column "karma_total" does not exist LINE 1: SELECT ((karma_total - 1) / POW(2, 1.5)) AS "popularity", (S... EDIT 2 Better error? TemplateSyntaxError: Caught an exception while rendering: missing FROM-clause entry for table "vote" LINE 1: SELECT ((vote.karma_total - 1) / POW(2, 1.5)) AS "popularity... My index.html is simply: {% block content %} {% for link in links %} karma-up {{ link.karma_total }} karma-down {{ link.title }} Posted by {{ link.user }} to {{ link.category }} at {{ link.created }} {% empty %} No Links {% endfor %} {% endblock content %} EDIT 3 So very close! Again, all these answers are great but I am concentrating on a particular one because I feel it works best for my situation. from django.db.models import Sum from django.shortcuts import render_to_response from linkett.apps.links.models import * def index(request): popular_links = Link.objects.select_related().extra( select = { 'popularity': '(SUM(links_vote.karma_delta) - 1) / POW(2, 1.5)', }, tables = ['links_link', 'links_vote'], order_by = ['-popularity'], ) return render_to_response('links/test.html', {'links': popular_links}) Running this I am presented with an error hating on my lack of group by values. Specifically: TemplateSyntaxError at / Caught an exception while rendering: column "links_link.id" must appear in the GROUP BY clause or be used in an aggregate function LINE 1: ...karma_delta) - 1) / POW(2, 1.5)) AS "popularity", "links_lin... Not sure why my links_link.id wouldn't be in my group by but I am not sure how to alter my group by, django usually does that.

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  • What is the best way to setup a public and private wireless access point on the same home network?

    - by Dougman
    For my home network (with internet provided from a cable modem) I would like to setup a secure wireless access point that I use for all of my personal connections (home PC, iPhone, Xbox, etc) and also another public access point that friends and folks in the neighborhood may connect to (for good karma). I want to ensure that my private traffic cannot be accessed from users of the public access point. I currently have one router that is running the Tomato firmware that I use with WPA security. What is the best way to accomplish this kind of setup securely (if it is possible in a home environment)?

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  • How many virtual processors or cores should I assign to my Guest OS?

    - by reidLinden
    I've just received an upgraded Host machine, and am looking to push some of those advances to my workstations Guest OS(s). In particular, I used to have a single processor, with 2 cores, so my Guest OS only had 1/1. Now, I've got a single processor with 8 cores, so I'm curious about what would be recommended for my Guest OS now? 1 processor/4 cores? 2 processors/2 cores? 4 processors/1 core? My instinct says to stick with the number of physical processors (or less), but, is that based on reality? I spent a good while looking for an answer to this, but perhaps my google-karma isn't in my favor today.

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  • Boost::Spirit::Qi autorules -- avoiding repeated copying of AST data structures

    - by phooji
    I've been using Qi and Karma to do some processing on several small languages. Most of the grammars are pretty small (20-40 rules). I've been able to use autorules almost exclusively, so my parse trees consist entirely of variants, structs, and std::vectors. This setup works great for the common case: 1) parse something (Qi), 2) make minor manipulations to the parse tree (visitor), and 3) output something (Karma). However, I'm concerned about what will happen if I want to make complex structural changes to a syntax tree, like moving big subtrees around. Consider the following toy example: A grammar for s-expr-style logical expressions that uses autorules... // Inside grammar class; rule names match struct names... pexpr %= pand | por | var | bconst; pand %= lit("(and ") >> (pexpr % lit(" ")) >> ")"; por %= lit("(or ") >> (pexpr % lit(" ")) >> ")"; pnot %= lit("(not ") >> pexpr >> ")"; ... which leads to parse tree representation that looks like this... struct var { std::string name; }; struct bconst { bool val; }; struct pand; struct por; struct pnot; typedef boost::variant<bconst, var, boost::recursive_wrapper<pand>, boost::recursive_wrapper<por>, boost::recursive_wrapper<pnot> > pexpr; struct pand { std::vector<pexpr> operands; }; struct por { std::vector<pexpr> operands; }; struct pnot { pexpr victim; }; // Many Fusion Macros here Suppose I have a parse tree that looks something like this: pand / ... \ por por / \ / \ var var var var (The ellipsis means 'many more children of similar shape for pand.') Now, suppose that I want negate each of the por nodes, so that the end result is: pand / ... \ pnot pnot | | por por / \ / \ var var var var The direct approach would be, for each por subtree: - create pnot node (copies por in construction); - re-assign the appropriate vector slot in the pand node (copies pnot node and its por subtree). Alternatively, I could construct a separate vector, and then replace (swap) the pand vector wholesale, eliminating a second round of copying. All of this seems cumbersome compared to a pointer-based tree representation, which would allow for the pnot nodes to be inserted without any copying of existing nodes. My question: Is there a way to avoid copy-heavy tree manipulations with autorule-compliant data structures? Should I bite the bullet and just use non-autorules to build a pointer-based AST (e.g., http://boost-spirit.com/home/2010/03/11/s-expressions-and-variants/)?

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  • recommendation for configuration for a multi-core guestOS

    - by reidLinden
    Hi there, I've just received an upgraded Host machine, and am looking to push some of those advances to my workstations Guest OS(s). In particular, I used to have a single processor, with 2 cores, so my guestOS only had 1/1. Now, I've got a single processor with 8 cores, so I'm curious about what would be recommended for my GuestOS now? 1 processor/4 cores? 2 processors/2Cores? 4 processors/1 core? My instinct says to stick with the number of physical processors (or less), but, is that based on reality? I spent a good while looking for an answer to this, but perhaps my google-karma isn't in my favor today. Suggestions?

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