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• Looking for an Open Source Project in need of help

  - by hvidgaard

  Hi StackOverflow! I'm a CS student on well on my way to graduate. I have had a difficult time of finding relevant student jobs (they seems to be taken merely hours after the notice gets on the board) , so instead I'm looking for an open source project in need of help. I'm aware that I should choose one that I use, but I'm not aware of any OS-project that I use that needs help. That's why I'm asking you. I don't have any deep experience, but I here are some of my biggest projects so far: BitTorrent-ish client in Python (a subset of BitTorrent) HTTP 1.1 webserver in Java Compiler from a subset of Java to run on JRE Flash-framework project to model an iPad look and feel (not to run actual iPad programs) complete with an API for programs. Complete MySQL database for a booking system, with departure and arrival times, so you could only book valid tickets (with a Java frontend). I know, Java and languages like AS3 and C# feels natural per se, Python, and have done a fair bit of hacking around in C, but I don't feel very comfortable with it. Mostly I'm afraid to make a fuckup because I have such a high degree of control. I would like to think I'm well aware of good software design practices, but in reality what I do is ask myself "would I like to use/maintain this?", and I love to refactor my code because I see optimizations. I love algorithms and to make them run in the best possible time. I don't have any preferred domain to work in, but I wouldn't mind it to be graphics or math heavy. Ideally I'm looking for a project in C++ to learn the in's and out's of it, but I'm well aware that I don't know that language very well. I would like to have a mentor-like figure until I'm confident enough to stand on my own, not one to review all my code (I'm sure someone will to start with anyway), but to ask questions about the project and language in question. I do have a wife and two children, so don't expect me to put in 10+ hours every week. In return I can work on my own, I strive to program modular and maintainable code. Know how to read an API, use Google, StackOverflow and online resources in general. If you have any questions, shoot. I'm looking forward to your suggestions.

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• Incompatible library creating new project with Aptana

  - by Phil Rice

  I am a ruby and rails newbie, so my abilities to debug this are somewhat limited. I have just added the eclipse plugin which failed, then downloaded the latest aptana studio which also failed. The failure was the same in both cases. The nature of the failure is that when I create a new rails project, I get an error message about an incompatible library version "C:/Ruby193/lib/ruby/gems/1.9.1/gems/mongrel-1.1.5-x86-mswin32-60/lib/http11.so". The project is actually created, along with directories and files. Google searches around this error message have only returned a couple of hits, which were not very helpful I am wondering if this is about 64 bit libraries. My software stack is: Windows 7 home premium 64bit Aptana RadRails, build: 2.0.5.1278709071 Ruby1.9.3 gem 1.8.24 The console shows: "4320" C:/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require': iconv will be deprecated in the future, use String#encode instead. C:/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require': incompatible library version - C:/Ruby193/lib/ruby/gems/1.9.1/gems/mongrel-1.1.5-x86-mswin32-60/lib/http11.so (LoadError) from C:/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:156:in `block in require' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:521:in `new_constants_in' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:156:in `require' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/mongrel-1.1.5-x86-mswin32-60/lib/mongrel.rb:12:in `<top (required)>' from C:/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:60:in `require' from C:/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:60:in `rescue in require' from C:/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:35:in `require' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:156:in `block in require' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:521:in `new_constants_in' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/activesupport-2.3.4/lib/active_support/dependencies.rb:156:in `require' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.0.0/lib/rack/handler/mongrel.rb:1:in `<top (required)>' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.0.0/lib/rack/handler.rb:17:in `const_get' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.0.0/lib/rack/handler.rb:17:in `block in get' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.0.0/lib/rack/handler.rb:17:in `each' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/rack-1.0.0/lib/rack/handler.rb:17:in `get' from C:/Ruby193/lib/ruby/gems/1.9.1/gems/rails-2.3.4/lib/commands/server.rb:45:in `<top (required)>' from C:/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require' from C:/Ruby193/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:36:in `require' from script/server:3:in `<top (required)>' from -e:2:in `load' from -e:2:in `<main>'

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• Google Code + SVN or GitHub + Git

  - by Nazgulled

  Let me start by telling you that I never used anything besides SVN and I'm also a Windows user. I have a couple of simple projects that are open-source, others are on there way when I'm happy enough to release their source code but either way, I was thinking of using Google Code and SVN to share the source code of my projects instead of providing a link to the source on my website. This as always been a pain cause I had to update the binaries and the code every time I released a new version. This would also help me out to have a backup of my code some where instead of just my local machine (I used to have a local Subversion server running). What I want from a service like this is very simple... I just want a place to store my source code that people can download if they want, allows me to control revisions and provide a simple and easy issue system so people can submit bugs and stuff like that. I guess both of them have this. But I don't want to host any binaries in their websites, I want this to be hosted on my website so I can control download statistics with my own scripts, I also don't have the need for wiki pages as I prefer to have all the documentation in my own website. Does anyone of this services provide a way to "disable" features like wiki and downloads and don't show them at all for my project(s)? Now, I'm sure there are lots of pros and cons about using Google Code with SVN and GitHub with Git (of course) but here's what it's important for me on each one and why I like them: Google Code: As with any Google page, the complexity is almost non-existent Everyone (or almost) as a Google account and this is nice if people want to report problems using the issues system GitHub: May (or may not) be a little more complex (not a problem for me though) than Google's pages but... ...has a much prettier interface than Google's service It needs people to be registered on GitHub to post about issues I like the fact that with Git, you have your own revisions locally (can I use TortoiseGit for this or?) Basically that's it, not much I know... What other, most common, pros and cons can you tell me about each site/software? Keep in mind that my projects are simple, I'm probably the only one who will ever develop these projects on these repositories (or maybe not, for now I will)

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• Release management with a distributed version control system

  - by See Sharp Cheddar

  We're considering a switch from SVN to a distributed VCS at my workplace. I'm familiar with all the reasons for wanting to using a DVCS for day-to-day development: local version control, easier branching and merging, etc., but I haven't seen that much that's compelling in terms of managing software releases. Here's our release process: Discover what changes are available for merging. Run a query to find the defects/tickets associated with these changes. Filter out changes associated with "open" tickets. In our environment, tickets must be in a closed state in order to merged with a release branch. Filter out changes we don't want in the release branch. We are very conservative when it comes to merging changes. If a change isn't absolutely necessary, it doesn't get merged. Merge available changes, preferably in chronological order. We group changes together if they're associated with the same ticket. Block unwanted changes from the release branch (svnmerge block) so we don't have to deal with them again. Sometimes we can be juggling 3-5 different milestones at a time. Some milestones have very different constraints, and the block list can get quite long. I've been messing around with git, mercurial and plastic, and as far as I can tell none of them address this model very well. It seems like they would work very well when you have only one product you're releasing, but I can't imagine using them for juggling multiple, very different products from the same codebase. For example, cherry-picking seems to be an afterthought in mercurial. (You have to use the 'transplant' command). After you cherry-pick a change into a branch it still shows up as an available integration. Cherry-picking breaks the mercurial way of working. DVCS seems to be better suited for feature branches. There's no need for cherry-picking if you merge directly from a feature branch to trunk and the release branch. But who wants to do all that merging all the time? And how do you query for what's available to merge? And how do you make sure all the changes in a feature branch belong together? It sounds like total chaos. I'm torn because the coder in me wants DVCS for day-to-day work. I really want it. But I fear the day when I have to put the release manager hat and sort out what needs to be merged and what doesn't. I want to write code, I don't want to be a merge monkey.

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• approximating log10[x^k0 + k1]

  - by Yale Zhang

  Greetings. I'm trying to approximate the function Log10[x^k0 + k1], where .21 < k0 < 21, 0 < k1 < ~2000, and x is integer < 2^14. k0 & k1 are constant. For practical purposes, you can assume k0 = 2.12, k1 = 2660. The desired accuracy is 5*10^-4 relative error. This function is virtually identical to Log[x], except near 0, where it differs a lot. I already have came up with a SIMD implementation that is ~1.15x faster than a simple lookup table, but would like to improve it if possible, which I think is very hard due to lack of efficient instructions. My SIMD implementation uses 16bit fixed point arithmetic to evaluate a 3rd degree polynomial (I use least squares fit). The polynomial uses different coefficients for different input ranges. There are 8 ranges, and range i spans (64)2^i to (64)2^(i + 1). The rational behind this is the derivatives of Log[x] drop rapidly with x, meaning a polynomial will fit it more accurately since polynomials are an exact fit for functions that have a derivative of 0 beyond a certain order. SIMD table lookups are done very efficiently with a single _mm_shuffle_epi8(). I use SSE's float to int conversion to get the exponent and significand used for the fixed point approximation. I also software pipelined the loop to get ~1.25x speedup, so further code optimizations are probably unlikely. What I'm asking is if there's a more efficient approximation at a higher level? For example: Can this function be decomposed into functions with a limited domain like log2((2^x) * significand) = x + log2(significand) hence eliminating the need to deal with different ranges (table lookups). The main problem I think is adding the k1 term kills all those nice log properties that we know and love, making it not possible. Or is it? Iterative method? don't think so because the Newton method for log[x] is already a complicated expression Exploiting locality of neighboring pixels? - if the range of the 8 inputs fall in the same approximation range, then I can look up a single coefficient, instead of looking up separate coefficients for each element. Thus, I can use this as a fast common case, and use a slower, general code path when it isn't. But for my data, the range needs to be ~2000 before this property hold 70% of the time, which doesn't seem to make this method competitive. Please, give me some opinion, especially if you're an applied mathematician, even if you say it can't be done. Thanks.

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• Unlimited SMS API/Gateway (Sending and Receiving)

  - by Naif

  I am creating a chat application which requires that users be able to send and receive sms messages through a web interface. It would be somewhat similar to the text messaging service available in yahoo mail or in aol instant messenger. The situation is this: Given the high quantity of messages that would be sent and received, paying on a per message basis is not economically feasible. How is it that sites such as yahoo, aim, and twitter can send and receive unlimited sms messages? Essentially, I am looking for a way to send and receive unlimited sms from my computer. Below is a list of some approaches I've come up with but have run into problems with as well. If just one of the approaches can be utilized effectively, then I am fine. As a note on the nature of my application: I will only be sending messages to users that explicitly sign up for the service and permit the receiving of messages. They can unsubscribe at any time. This is to prevent spam. I am aware of software such as Kannel which allows one to connect to a providers smsc gateway. However, this adds the risk of not being approved by the provider which would be unacceptable. Is there any way to significantly mitigate this risk? Utilizing a gateway provider eliminates this risk, but adds the issue of per message pricing. I am also aware of email to sms. However, I have done some testing with that and it appears that this method results in many messages being undelivered or delivered VERY late. If it weren't for that, this approach would have been ideal. Is there any way to negotiate with carriers to remove me from their filters (considering the nature of my service as stated before)? I could use a gsm modem, but even with an "unilimited" plan on a sim card, there are still limits (around 100,000 messages or so). Furthermore, from my understanding, gsm modems are capable of only sending out around a dozen messages per minute. I need to be able to send out as much as several hundred messages per second. During the first 2 months, around 10 messages per second would suffice. There are ways to send out ads with messages to cover the per message costs. However, this is a deal-breaker since it has a high chance of tarnishing the quality of service. Furthermore, I know it is possible to do it without such ads since yahoo, aim, and twitter do not send ads with their messages.

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• Schema to support dynamic properties

  - by Johan Fredrik Varen

  Hi people. I'm working on an editor that enables its users to create "object" definitions in real-time. A definition can contain zero or more properties. A property has a name a type. Once a definition is created, a user can create an object of that definition and set the property values of that object. So by the click of a mouse-button, the user should ie. be able to create a new definition called "Bicycle", and add the property "Size" of type "Numeric". Then another property called "Name" of type "Text", and then another property called "Price" of type "Numeric". Once that is done, the user should be able to create a couple of "Bicycle" objects and fill in the "Name" and "Price" property values of each bike. Now, I've seen this feature in several software products, so it must be a well-known concept. My problem started when I sat down and tried to come up with a DB schema to support this data structure, because I want the property values to be stored using the appropriate column types. Ie. a numeric property value is stored as, say, an INT in the database, and a textual property value is stored as VARCHAR. First, I need a table that will hold all my object definitions: Table obj_defs id | name | ---------------- 1 | "Bicycle" | 2 | "Book" | Then I need a table for holding what sort of properties each object definition should have: Table prop_defs id | obj_def_id | name | type | ------------------------------------ 1 | 1 | "Size" | ? | 2 | 1 | "Name" | ? | 3 | 1 | "Price" | ? | 4 | 2 | "Title" | ? | 5 | 2 | "Author" | ? | 6 | 2 | "ISBN" | ? | I would also need a table that holds each object: Table objects id | created | updated | ------------------------------ 1 | 2011-05-14 | 2011-06-15 | 2 | 2011-05-14 | 2011-06-15 | 3 | 2011-05-14 | 2011-06-15 | Finally, I need a table that will hold the actual property values of each object, and one solution is for this table to have one column for each possible value type, such as this: Table prop_vals id | prop_def_id | object_id | numeric | textual | boolean | ------------------------------------------------------------ 1 | 1 | 1 | 27 | | | 2 | 2 | 1 | | "Trek" | | 3 | 3 | 1 | 1249 | | | 4 | 1 | 2 | 26 | | | 5 | 2 | 2 | | "GT" | | 6 | 3 | 2 | 159 | | | 7 | 4 | 3 | | "It" | | 8 | 5 | 3 | | "King" | | 9 | 6 | 4 | 9 | | | If I implemented this schema, what would the "type" column of the prop_defs table hold? Integers that each map to a column name, varchars that simply hold the column name? Any other possibilities? Would a stored procedure help me out here in some way? And what would the SQL for fetching the "name" property of object 2 look like?

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• Curl Wrapper Class does not return any data even though it worked previously?

  - by Scott Faisal

  We changed servers and installed all necessary software and just cannot seem to pin point what is going on. A simple CURL request does not return anything. Command Line CURL commands work just fine. We are using a wrapper for CURL utilizing streams. Do PHP streams require any out of the ordinary configuration? We are using the latest Lamp stack. This is the var_dump: object(cURL_Response)#180 (14) { ["cURL:private"]= resource(288) of type (curl) ["data_stream:private"]= object(elTempStream)#178 (1) { ["fp"]= resource(290) of type (stream) } ["request_header:private"]= NULL ["response_header:private"]= object(cURL_Headers)#179 (1) { ["headers:private"]= string(0) "" } ["response_headers:private"]= array(1) { [0]= object(cURL_Headers)#179 (1) { ["headers:private"]= string(0) "" } } ["error:private"]= string(0) "" ["errno:private"]= int(0) ["info:private"]= array(21) { ["url"]= string(21) "http://www.yahoo.com/" ["content_type"]= string(23) "text/html;charset=utf-8" ["http_code"]= int(200) ["header_size"]= int(1195) ["request_size"]= int(1153) ["filetime"]= int(-1) ["ssl_verify_result"]= int(0) ["redirect_count"]= int(1) ["total_time"]= float(0.486924) ["namelookup_time"]= float(0.003692) ["connect_time"]= float(0.005709) ["pretransfer_time"]= float(0.005714) ["size_upload"]= float(0) ["size_download"]= float(28509) ["speed_download"]= float(58549) ["speed_upload"]= float(0) ["download_content_length"]= float(211) ["upload_content_length"]= float(0) ["starttransfer_time"]= float(0.149365) ["redirect_time"]= float(0.312743) ["request_header"]= string(973) "GET / HTTP/1.0 User-Agent: cURL_ClientBase (PHP v/5.2.6-1+lenny4) Host: www.yahoo.com Accept: / Accept-Encoding: gzip, deflate, compress Referer: http://yahoo.com Cookie: B=e5iber15t7u05&b=3&s=ie; fpc_s=d=GGX6WCTIR29HWsjgLxFejKc_YJWxRqm3jYdEd6lu7W5ophpuAHBm6JGtNvhv97anG4VtaIMHQBPg3JAMOZGq59Lz_tRn_TFXgUT8T_at5HdCktVJLycy&v=2; fpt=d=nt1OT7HPe9wVIkHbMkpzQOgbP3.mQ3o1SPX7k5ztrFrWeeSWK5IgQooRY.8KtTeRMiaSEZ0kv3sO1MWtEsAzjVlRCDAZBoxqOs17v6PaZbPRqmDc92ivoMia.CqjufRs4_guOO4AyhRZ7_ml8rzxFrYeexpR2jLN0oPMyEWT0nbEf6Sdf._Bkh0HMfmI7KBnEx5uZBEEmV.wTfGRLG7zSd9sA4itOFv.r6AjP39CnogSn7NTJnqg_kEcKoiCM.lR5w_MqMc8IgWMBgSAZZgGEZpfmvxlQGnUzPwNh2pSpTe2wxFS3v1zPopDgoo2VsO3uzeyA3A_j7Hlk1P8T08DHbfr6ApDMUcr7d0QIt4pGYIxVV45XzfgpT7mgUdMei6VZrD9ozVQF0oqxrs1Ufri.XzPdB3NdQ--&v=1; fpc=d=sRPCfUfBTW96.RGiQn4hSkfi3p7WnPCAqYl5YoHecI7zjg7gH7PolscoPcq1Esm8dR.Rg1.AbQCpo2WBPXn1St96PpcjeCC.pj2.Upb3mKSRQkYPIVP1vQcL9nL7J8s9Z0VIXjiBFgSUcxyzDeUdP4us2YbVO3PbaVIwaIEfFsX3WI7YgiTbkrTGtwnFgoSYq6l8tnw-&v=2" } ["info_flagged:private"]= array(20) { [1048577]= string(21) "http://www.yahoo.com/" [2097154]= int(200) [2097166]= int(-1) [3145731]= float(0.486924) [3145732]= float(0.003692) [3145733]= float(0.005709) [3145734]= float(0.005714) [3145745]= float(0.149365) [3145747]= float(0.312743) [3145735]= float(0) [3145736]= float(28509) [3145737]= float(58549) [3145738]= float(0) [2097163]= int(1195) [2]= string(973) "GET / HTTP/1.0 User-Agent: cURL_ClientBase (PHP v/5.2.6-1+lenny4) Host: www.yahoo.com Accept: / Accept-Encoding: gzip, deflate, compress Referer: http://yahoo.com Cookie: B=e5iber15t7u05&b=3&s=ie; fpc_s=d=GGX6WCTIR29HWsjgLxFejKc_YJWxRqm3jYdEd6lu7W5ophpuAHBm6JGtNvhv97anG4VtaIMHQBPg3JAMOZGq59Lz_tRn_TFXgUT8T_at5HdCktVJLycy&v=2; fpt=d=nt1OT7HPe9wVIkHbMkpzQOgbP3.mQ3o1SPX7k5ztrFrWeeSWK5IgQooRY.8KtTeRMiaSEZ0kv3sO1MWtEsAzjVlRCDAZBoxqOs17v6PaZbPRqmDc92ivoMia.CqjufRs4_guOO4AyhRZ7_ml8rzxFrYeexpR2jLN0oPMyEWT0nbEf6Sdf._Bkh0HMfmI7KBnEx5uZBEEmV.wTfGRLG7zSd9sA4itOFv.r6AjP39CnogSn7NTJnqg_kEcKoiCM.lR5w_MqMc8IgWMBgSAZZgGEZpfmvxlQGnUzPwNh2pSpTe2wxFS3v1zPopDgoo2VsO3uzeyA3A_j7Hlk1P8T08DHbfr6ApDMUcr7d0QIt4pGYIxVV45XzfgpT7mgUdMei6VZrD9ozVQF0oqxrs1Ufri.XzPdB3NdQ--&v=1; fpc=d=sRPCfUfBTW96.RGiQn4hSkfi3p7WnPCAqYl5YoHecI7zjg7gH7PolscoPcq1Esm8dR.Rg1.AbQCpo2WBPXn1St96PpcjeCC.pj2.Upb3mKSRQkYPIVP1vQcL9nL7J8s9Z0VIXjiBFgSUcxyzDeUdP4us2YbVO3PbaVIwaIEfFsX3WI7YgiTbkrTGtwnFgoSYq6l8tnw-&v=2" [2097164]= int(1153) [2097165]= int(0) [3145743]= float(211) [3145744]= float(0) [1048594]= string(23) "text/html;charset=utf-8" } ["request_url:private"]= string(16) "http://yahoo.com" ["response_url:private"]= string(21) "http://www.yahoo.com/" ["status_code:private"]= int(200) ["cookies:private"]= array(0) { } ["request_headers"]= string(973) "GET / HTTP/1.0 User-Agent: cURL_ClientBase (PHP v/5.2.6-1+lenny4) Host: www.yahoo.com Accept: / Accept-Encoding: gzip, deflate, compress Referer: http://yahoo.com Cookie: B=e5iber15t7u05&b=3&s=ie; fpc_s=d=GGX6WCTIR29HWsjgLxFejKc_YJWxRqm3jYdEd6lu7W5ophpuAHBm6JGtNvhv97anG4VtaIMHQBPg3JAMOZGq59Lz_tRn_TFXgUT8T_at5HdCktVJLycy&v=2; fpt=d=nt1OT7HPe9wVIkHbMkpzQOgbP3.mQ3o1SPX7k5ztrFrWeeSWK5IgQooRY.8KtTeRMiaSEZ0kv3sO1MWtEsAzjVlRCDAZBoxqOs17v6PaZbPRqmDc92ivoMia.CqjufRs4_guOO4AyhRZ7_ml8rzxFrYeexpR2jLN0oPMyEWT0nbEf6Sdf._Bkh0HMfmI7KBnEx5uZBEEmV.wTfGRLG7zSd9sA4itOFv.r6AjP39CnogSn7NTJnqg_kEcKoiCM.lR5w_MqMc8IgWMBgSAZZgGEZpfmvxlQGnUzPwNh2pSpTe2wxFS3v1zPopDgoo2VsO3uzeyA3A_j7Hlk1P8T08DHbfr6ApDMUcr7d0QIt4pGYIxVV45XzfgpT7mgUdMei6VZrD9ozVQF0oqxrs1Ufri.XzPdB3NdQ--&v=1; fpc=d=sRPCfUfBTW96.RGiQn4hSkfi3p7WnPCAqYl5YoHecI7zjg7gH7PolscoPcq1Esm8dR.Rg1.AbQCpo2WBPXn1St96PpcjeCC.pj2.Upb3mKSRQkYPIVP1vQcL9nL7J8s9Z0VIXjiBFgSUcxyzDeUdP4us2YbVO3PbaVIwaIEfFsX3WI7YgiTbkrTGtwnFgoSYq6l8tnw-&v=2" }

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• Generate lags R

  - by Btibert3

  Hi All, I hope this is basic; just need a nudge in the right direction. I have read in a database table from MS Access into a data frame using RODBC. Here is a basic structure of what I read in: PRODID PROD Year Week QTY SALES INVOICE Here is the structure: str(data) 'data.frame': 8270 obs. of 7 variables: $ PRODID : int 20001 20001 20001 100001 100001 100001 100001 100001 100001 100001 ... $ PROD : Factor w/ 1239 levels "1% 20qt Box",..: 335 335 335 128 128 128 128 128 128 128 ... $ Year : int 2010 2010 2010 2009 2009 2009 2009 2009 2009 2010 ... $ Week : int 12 18 19 14 15 16 17 18 19 9 ... $ QTY : num 1 1 0 135 300 270 300 270 315 315 ... $ SALES : num 15.5 0 -13.9 243 540 ... $ INVOICES: num 1 1 2 5 11 11 10 11 11 12 ... Here are the top few rows: head(data, n=10) PRODID PROD Year Week QTY SALES INVOICES 1 20001 Dolie 12" 2010 12 1 15.46 1 2 20001 Dolie 12" 2010 18 1 0.00 1 3 20001 Dolie 12" 2010 19 0 -13.88 2 4 100001 Cage Free Eggs 2009 14 135 243.00 5 5 100001 Cage Free Eggs 2009 15 300 540.00 11 6 100001 Cage Free Eggs 2009 16 270 486.00 11 7 100001 Cage Free Eggs 2009 17 300 540.00 10 8 100001 Cage Free Eggs 2009 18 270 486.00 11 9 100001 Cage Free Eggs 2009 19 315 567.00 11 10 100001 Cage Free Eggs 2010 9 315 569.25 12 I simply want to generate lags for QTY, SALES, INVOICE for each product but I am not sure where to start. I know R is great with Time Series, but I am not sure where to start. I have two questions: 1- I have the raw invoice data but have aggregated it for reporting purposes. Would it be easier if I didn't aggregate the data? 2- Regardless of aggregation or not, what functions will I need to loop over each product and generate the lags as I need them? In short, I want to loop over a set of records, calculate lags for a product (if possible), append the lags (as they apply) to the current record for each product, and write the results back to a table in my database for my reporting software to use. Any help you can provide will be greatly appreciated! Many thanks in advance, Brock

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• Need Help About Using XPathNavigator in C#?

  - by Nano HE

  Hello. My XML file as below. It mixed schema and normal elements. <?xml version="1.0" encoding="utf-8"?> <!-- R1 --> <ax:root xmlns:ax="http://amecn/software/realtime/ax"> <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:element name="EquipmentConstants"> <xsd:complexType> <xsd:sequence> <xsd:element minOccurs="0" maxOccurs="unbounded" ref="EquipmentConstant" /> </xsd:sequence> </xsd:complexType> <xsd:unique name="id"> <xsd:selector xpath=".//EquipmentConstant" /> <xsd:field xpath="@id" /> </xsd:unique> </xsd:element> ...... ...... </xsd:schema> <EquipmentConstants xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <EquipmentConstant id="0"> <Name>SerialNumber</Name> <Group>SYSTEM</Group> <Data> <Value min="0" max="10000000" scale_factor="0" unit="U_NO_UNITS" permission="NolimitedAndNoChangeable" type="xsd_string" enum="" flag="0">0</Value> </Data> <Description>Serial Number</Description> </EquipmentConstant> ..... ..... </EquipmentConstants> </ax:root> My C# code as below. I want to loop the elements from <EquipmentConstants xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> XPathDocument doc = new XPathDocument("test.xml"); XPathNavigator navigator = doc.CreateNavigator(); navigator.MoveToRoot(); // <?xml version="1.0" encoding="utf-8"?> //navigator.MoveToFirstChild(); // <!-- R1 --> // 1st, I tried to use MoveToChield(), But I failed to move there. navigator.MoveToChild("EquipmentConstants"); // Then, I also tried to use SelectSingleNode(). But I failed too. navigator.SelectSingleNode("ax/EquipmentConstants"); while (navigator.MoveToNext()) { // do something. } Could you please give me some suggestion. Thank you.

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• Inserting checkbox values

  - by rabeea

  hey i have registration form that has checkboxes along with other fields. i cant insert the selected checkbox values into the data base. i have made one field in the database for storing all checked values. this is the code for checkbox part in the form: Websites, IT and Software Writing and Content <pre><input type="checkbox" name="expertise[]" value="Design and Media"> Design and Media <input type="checkbox" name="expertise[]" value="Data entry and Admin"> Data entry and Admin </pre> <pre><input type="checkbox" name="expertise[]" value="Engineering and Skills"> Engineering and Science <input type="checkbox" name="expertise[]" value="Seles and Marketing"> Sales and Marketing </pre> <pre><input type="checkbox" name="expertise[]" value="Business and Accounting"> Business and Accounting <input type="checkbox" name="expertise[]" value="Others"> Others </pre> and this is the corresponding php code for inserting data $checkusername=mysql_query("SELECT * FROM freelancer WHERE fusername='{$_POST['username']}'"); if (mysql_num_rows($checkusername)==1) { echo "username already exist"; } else { $query = "insert into freelancer(ffname,flname,fgender,femail,fusername,fpwd,fphone,fadd,facc,facc_name,fbank_details,fcity,fcountry,fexpertise,fprofile,fskills,fhourly_rate,fresume) values ('".$_POST['first_name']."','".$_POST['last_name']."','".$_POST['gender']."','".$_POST['email']."','".$_POST['username']."','".$_POST['password']."','".$_POST['phone']."','".$_POST['address']."','".$_POST['acc_num']."','".$_POST['acc_name']."','".$_POST['bank']."','".$_POST['city']."','".$_POST['country']."','".implode(',',$_POST['expertise'])."','".$_POST['profile']."','".$_POST['skills']."','".$_POST['rate']."','".$_POST['resume']."')"; $result = ($query) or die (mysql_error()); this code inserts data for all fields but the checkbox value field remains empty???

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• Trying to run multiple HTTP requests in parallel, but being limited by Windows (registry)

  - by Nailuj

  I'm developing an application (winforms C# .NET 4.0) where I access a lookup functionality from a 3rd party through a simple HTTP request. I call an url with a parameter, and in return I get a small string with the result of the lookup. Simple enough. The challenge is however, that I have to do lots of these lookups (a couple of thousands), and I would like to limit the time needed. Therefore I would like to run requests in parallel (say 10-20). I use a ThreadPool to do this, and the short version of my code looks like this: public void startAsyncLookup(Action<LookupResult> returnLookupResult) { this.returnLookupResult = returnLookupResult; foreach (string number in numbersToLookup) { ThreadPool.QueueUserWorkItem(lookupNumber, number); } } public void lookupNumber(Object threadContext) { string numberToLookup = (string)threadContext; string url = @"http://some.url.com/?number=" + numberToLookup; WebClient webClient = new WebClient(); Stream responseData = webClient.OpenRead(url); LookupResult lookupResult = parseLookupResult(responseData); returnLookupResult(lookupResult); } I fill up numbersToLookup (a List<String>) from another place, call startAsyncLookup and provide it with a call-back function returnLookupResult to return each result. This works, but I found that I'm not getting the throughput I want. Initially I thought it might be the 3rd party having a poor system on their end, but I excluded this by trying to run the same code from two different machines at the same time. Each of the two took as long as one did alone, so I could rule out that one. A colleague then tipped me that this might be a limitation in Windows. I googled a bit, and found amongst others this post saying that by default Windows limits the number of simultaneous request to the same web server to 4 for HTTP 1.0 and to 2 for HTTP 1.1 (for HTTP 1.1 this is actually according to the specification (RFC2068)). The same post referred to above also provided a way to increase these limits. By adding two registry values to [HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Internet Settings] (MaxConnectionsPerServer and MaxConnectionsPer1_0Server), I could control this myself. So, I tried this (sat both to 20), restarted my computer, and tried to run my program again. Sadly though, it didn't seem to help any. I also kept an eye on the Resource Monitor (see screen shot) while running my batch lookup, and I noticed that my application (the one with the title blacked out) still only was using two TCP connections. So, the question is, why isn't this working? Is the post I linked to using the wrong registry values? Is this perhaps not possible to "hack" in Windows any longer (I'm on Windows 7)? Any ideas would be highly appreciated :) And just in case anyone should wonder, I have also tried with different settings for MaxThreads on ThreadPool (everyting from 10 to 100), and this didn't seem to affect my throughput at all, so the problem shouldn't be there either.

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• How best to modernize the 2002-era J2EE app?

  - by user331465

  I have this friend.... I have this friend who works on a java ee application (j2ee) application started in the early 2000's. Currently they add a feature here and there, but have a large codebase. Over the years the team has shrunk by 70%. [Yes, the "i have this friend is". It's me, attempting to humorously inject teenage high-school counselor shame into the mix] Java, Vintage 2002 The application uses EJB 2.1, struts 1.x, DAO's etc with straight jdbc calls (mixture of stored procedures and prepared statements). No ORM. For caching they use a mixture of OpenSymphony OSCache and a home-grown cache layer. Over the last few years, they have spent effort to modernize the UI using ajax techniques and libraries. This largely involves javascript libaries (jquery, yui, etc). Client Side On the client side, the lack of upgrade path from struts1 to struts2 discouraged them from migrating to struts2. Other web frameworks became popular (wicket, spring , jsf). Struts2 was not the "clear winner". Migrating all the existing UI from Struts1 to Struts2/wicket/etc did not seem to present much marginal benefit at a very high cost. They did not want to have a patchwork of technologies-du-jour (subsystem X in Struts2, subsystem Y in Wicket, etc.) so developer write new features using Struts 1. Server Side On the server side, they looked into moving to ejb 3, but never had a big impetus. The developers are all comfortable with ejb-jar.xml, EJBHome, EJBRemote, that "ejb 2.1 as is" represented the path of least resistance. One big complaint about the ejb environment: programmers still pretend "ejb server runs in separate jvm than servlet engine". No app server (jboss/weblogic) has ever enforced this separation. The team has never deployed the ejb server on a separate box then the app server. The ear file contains multiple copies of the same jar file; one for the 'web layer' (foo.war/WEB-INF/lib) and one for the server side (foo.ear/). The app server only loads one jar. The duplications makes for ambiguity. Caching As for caching, they use several cache implementations: OpenSymphony cache and a homegrown cache. Jgroups provides clustering support Now What? The question: The team currently has spare cycles to to invest in modernizing the application? Where would the smart investor spend them? The main criteria: 1) productivity gains. Specifically reducing the time to develope new subsystems features and reduced maintenance. 2) performance/scalability. They do not care about fashion or techno-du-jour street cred. What do you all recommend? On the persistence side Switch everything (or new development only) to JPA/JPA2? Straight hibernate? Wait for Java EE 6? On the client/web-framework side: Migrate (some or all) to struts2? wicket? jsf/jsf2? As for caching: terracotta? ehcache? coherence? stick with what they have? how best to take advantage of the huge heap sizes that the 64-bit jvms offer? Thanks in advance.

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• Data Warehouse ETL slow - change primary key in dimension?

  - by Jubbles

  I have a working MySQL data warehouse that is organized as a star schema and I am using Talend Open Studio for Data Integration 5.1 to create the ETL process. I would like this process to run once per day. I have estimated that one of the dimension tables (dimUser) will have approximately 2 million records and 23 columns. I created a small test ETL process in Talend that worked, but given the amount of data that may need to be updated daily, the current performance will not cut it. It takes the ETL process four minutes to UPDATE or INSERT 100 records to dimUser. If I assumed a linear relationship between the count of records and the amount of time to UPDATE or INSERT, then there is no way the ETL can finish in 3-4 hours (my hope), let alone one day. Since I'm unfamiliar with Java, I wrote the ETL as a Python script and ran into the same problem. Although, I did discover that if I did only INSERT, the process went much faster. I am pretty sure that the bottleneck is caused by the UPDATE statements. The primary key in dimUser is an auto-increment integer. My friend suggested that I scrap this primary key and replace it with a multi-field primary key (in my case, 2-3 fields). Before I rip the test data out of my warehouse and change the schema, can anyone provide suggestions or guidelines related to the design of the data warehouse the ETL process how realistic it is to have an ETL process INSERT or UPDATE a few million records each day will my friend's suggestion significantly help If you need any further information, just let me know and I'll post it. UPDATE - additional information: mysql> describe dimUser; Field Type Null Key Default Extra user_key int(10) unsigned NO PRI NULL auto_increment id_A int(10) unsigned NO NULL id_B int(10) unsigned NO NULL field_4 tinyint(4) unsigned NO 0 field_5 varchar(50) YES NULL city varchar(50) YES NULL state varchar(2) YES NULL country varchar(50) YES NULL zip_code varchar(10) NO 99999 field_10 tinyint(1) NO 0 field_11 tinyint(1) NO 0 field_12 tinyint(1) NO 0 field_13 tinyint(1) NO 1 field_14 tinyint(1) NO 0 field_15 tinyint(1) NO 0 field_16 tinyint(1) NO 0 field_17 tinyint(1) NO 1 field_18 tinyint(1) NO 0 field_19 tinyint(1) NO 0 field_20 tinyint(1) NO 0 create_date datetime NO 2012-01-01 00:00:00 last_update datetime NO 2012-01-01 00:00:00 run_id int(10) unsigned NO 999 I used a surrogate key because I had read that it was good practice. Since, from a business perspective, I want to keep aware of potential fraudulent activity (say for 200 days a user is associated with state X and then the next day they are associated with state Y - they could have moved or their account could have been compromised), so that is why geographic data is kept. The field id_B may have a few distinct values of id_A associated with it, but I am interested in knowing distinct (id_A, id_B) tuples. In the context of this information, my friend suggested that something like (id_A, id_B, zip_code) be the primary key. For the large majority of daily ETL processes (80%), I only expect the following fields to be updated for existing records: field_10 - field_14, last_update, and run_id (this field is a foreign key to my etlLog table and is used for ETL auditing purposes).

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• Mercurial local repository backup

  - by Ricket

  I'm a big fan of backing things up. I keep my important school essays and such in a folder of my Dropbox. I make sure that all of my photos are duplicated to an external drive. I have a home server where I keep important files mirrored across two drives inside the server (like a software RAID 1). So for my code, I have always used Subversion to back it up. I keep the trunk folder with a stable copy of my application, but then I create a branch named with my username, and inside there is my working copy. I make very few changes between commits to that branch, with the understanding that the code in there is my backup. Now I'm looking into Mercurial, and I must admit I haven't truly used it yet so I may have this all wrong. But it seems to me that you have a server-side repository, and then you clone it to a working directory in the form of a local repository. Then as you work on something, you make commits to that local repository, and when things are in a state to be shared with others, you hg push to the parent repository on the server. Between pushes of stable, tested, bug-free code, where is the backup? After doing some thinking, I've come to the conclusion that it is not meant for backup purposes and it assumes you've handled that on your own. I guess I need to keep my Mercurial local repositories in my dropbox or some other backed-up location, since my in-progress code is not pushed to the server. Is this pretty much it, or have I missed something? If you use Mercurial, how do you backup your local repositories? If you had turned on your computer this morning and your hard drive went up in flames (or, more likely, the read head went bad, or the OS corrupted itself, ...), what would be lost? If you spent the past week developing a module, writing test cases for it, documenting and commenting it, and then a virus wipes your local repository away, isn't that the only copy? So then on the flip side, do you create a remote repository for every local repository and push to it all the time? How do you find a balance? How do you ensure your code is backed up? Where is the line between using Mercurial as backup, and using a local filesystem backup utility to keep your local repositories safe?

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• Running OpenMPI on Windows XP

  - by iamweird

  Hi there. I'm trying to build a simple cluster based on Windows XP. I compiled OpenMPI-1.4.2 successfully, and tools like mpicc and ompi_info work too, but I can't get my mpirun working properly. The only output I can see is Z:\orterun --hostfile z:\hosts.txt -np 2 hostname [host0:04728] Failed to initialize COM library. Error code = -2147417850 [host0:04728] [[8946,0],0] ORTE_ERROR_LOG: Error in file ..\..\openmpi-1.4.2 \orte\mca\ess\hnp\ess_hnp_module.c at line 218 -------------------------------------------------------------------------- It looks like orte_init failed for some reason; your parallel process is likely to abort. There are many reasons that a parallel process can fail during orte_init; some of which are due to configuration or environment problems. This failure appears to be an internal failure; here's some additional information (which may only be relevant to an Open MPI developer): orte_plm_init failed -- Returned value Error (-1) instead of ORTE_SUCCESS -------------------------------------------------------------------------- [host0:04728] [[8946,0],0] ORTE_ERROR_LOG: Error in file ..\..\openmpi-1.4.2 \orte\runtime\orte_init.c at line 132 -------------------------------------------------------------------------- It looks like orte_init failed for some reason; your parallel process is likely to abort. There are many reasons that a parallel process can fail during orte_init; some of which are due to configuration or environment problems. This failure appears to be an internal failure; here's some additional information (which may only be relevant to an Open MPI developer): orte_ess_set_name failed -- Returned value Error (-1) instead of ORTE_SUCCESS -------------------------------------------------------------------------- [host0:04728] [[8946,0],0] ORTE_ERROR_LOG: Error in file ..\..\..\..\openmpi -1.4.2\orte\tools\orterun\orterun.c at line 543 Where z:\hosts.txt appears as follows: host0 host1 Z: is a shared network drive available to both host0 and host1. What my problem is and how do I fix it? Upd: Ok, this problem seems to be fixed. It seems to me that WideCap driver and/or software components causes this error to appear. A "clean" machine runs local task successfully. Anyway, I still cannot run a task within at least 2 machines, I'm getting following message: Z:\mpirun --hostfile z:\hosts.txt -np 2 hostname connecting to host1 username:cluster password:******** Save Credential?(Y/N) y [host0:04728] This feature hasn't been implemented yet. [host0:04728] Could not connect to namespace cimv2 on node host1. Error code =-2147024891 -------------------------------------------------------------------------- mpirun was unable to start the specified application as it encountered an error. More information may be available above. -------------------------------------------------------------------------- I googled a little and did all the things as described here: http://www.open-mpi.org/community/lists/users/2010/03/12355.php but I'm still getting the same error. Can anyone help me? Upd2: Error code -2147024891 might be WMI error WBEM_E_INVALID_PARAMETER (0x80041008) which occures when one of the parameters passed to the WMI call is not correct. Does this mean that the problem is in OpenMPI source code itself? Or maybe it's because of wrong/outdated wincred.h and credui.lib I used while building OpenMPI from the source code?

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• Is it possible to create a service like Feed My Inbox on my own server?

  - by Mark Bowen

  I was just wondering if it's at all possible to create a service like Feed My Inbox on my own server using PHP? Basically I have a site which has RSS feeds which are dynamic in nature and can search from thousands of posts based on many different criteria. I have the RSS feed working fine and bringing back data dynamically for whatever criteria I want so that bits fine. I am using the ExpressionEngine CMS to handle the site and there will be thousands of users on the site (currently there are around 2,0000) but that number is exponentially growing every single day. What I want to be able to do is allow the users to choose from certain criteria which will then build a dynamic RSS URL which will then be stored in a database table (one row for each user). This bit I will be able to do myself but then I want to be able to send out new RSS feed items via e-mail to each user. This is the part I'm a little stuck on. I'm guessing I would somehow need to run a cron job to hit a page which would check each users RSS feed and then if there are new items to send them to the user via e-mail. That's where I am totally stuck though and I'm just wondering what the best way to go about it would be? That or any software in PHP that already does this sort of thing would be great. I tried out phpList but it has severe problems working with RSS and I only ever got it to work once and now never again and I've read that lots of people have had this same problem so unfortunately it's not just me :-( I know there are services such as Feed My Inbox which I could easily set up so that users click a link and their RSS feed URL is added to go and use that service but I want to keep users from seeing the dynamic nature of the feed or they will easily be able to modify it to get at other items in the feed. I need this so that I can charge for access to the feeds but if people can see the URL of the feed then I will be totally unstuck as they will be able to get at whatever they want very easily. Therefore I'd like to be able to send the items out to them. Would really love to hear if anyone knows if this kind of thing is possible at all and what would be involved?

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• Android fill ImageView from URL

  - by Luke Batley

  Hi i'm trying to add an image to an ImageView from a URL i have tried loading it as a bitmap but nothing is showing. so does anyone know what the best method to do this is or what i'm doing wrong? heres my code @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); //Check Preferences which sets UI setContentView(R.layout.singlenews); TextView headerText = (TextView) findViewById(R.id.header_text); headerText.setText("Latest News"); PostTask posttask; posttask = new PostTask(); posttask.execute(); } public void loadNews(){ newsStr = getIntent().getStringExtra("singleNews"); try { JSONObject obj = new JSONObject(newsStr); content = obj.getString("content"); title = obj.getString("title"); fullName = obj.getString("fullname"); created = obj.getString("created"); NewsImageURL = obj.getString("image_primary"); tagline = obj.getString("tagline"); meta = "posted by: " + fullName + " " + created; URL aURL = new URL("NewsImageURL"); URLConnection conn = aURL.openConnection(); conn.connect(); InputStream is = conn.getInputStream(); /* Buffered is always good for a performance plus. */ BufferedInputStream bis = new BufferedInputStream(is); /* Decode url-data to a bitmap. */ bm = BitmapFactory.decodeStream(bis); bis.close(); is.close(); /* Apply the Bitmap to the ImageView that will be returned. */ Log.v("lc", "content=" + content); Log.v("lc", "title=" + title); Log.v("lc", "fullname=" + fullName); Log.v("lc", "created=" + created); Log.v("lc", "NewsImage=" + NewsImageURL); Log.v("lc", "Meta=" + meta); Log.v("lc", "tagline=" + tagline); } catch (JSONException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } public class PostTask extends AsyncTask<Void, String, Boolean> { @Override protected Boolean doInBackground(Void... params) { boolean result = false; loadNews(); publishProgress("progress"); return result; } protected void onProgressUpdate(String... progress) { StringBuilder str = new StringBuilder(); for (int i = 1; i < progress.length; i++) { str.append(progress[i] + " "); } } @Override protected void onPostExecute(Boolean result) { super.onPostExecute(result); Log.v("BGThread", "begin fillin data"); fillData(); } } public void fillData(){ NewsView = LayoutInflater.from(getBaseContext()).inflate(R.layout.newsdetailact, null); TextView Title = (TextView) NewsView.findViewById(R.id.NewsTitle); Title.setText(title); TextView Tagline = (TextView) NewsView.findViewById(R.id.subtitle); Tagline.setText(tagline); TextView MetaData = (TextView) NewsView.findViewById(R.id.meta); MetaData.setText(meta); ImageView NewsImage = (ImageView)NewsView.findViewById(R.id.imageView2); NewsImage.setImageBitmap(bm); TextView MainContent = (TextView) NewsView.findViewById(R.id.maintext); MainContent.setText(content); Log.v("BGThread", "Filled results"); adapter = new MergeAdapter(); adapter.addView(NewsView); setListAdapter(adapter); } }

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• Loosely coupled implicit conversion

  - by ltjax

  Implicit conversion can be really useful when types are semantically equivalent. For example, imagine two libraries that implement a type identically, but in different namespaces. Or just a type that is mostly identical, except for some semantic-sugar here and there. Now you cannot pass one type into a function (in one of those libraries) that was designed to use the other, unless that function is a template. If it's not, you have to somehow convert one type into the other. This should be trivial (or otherwise the types are not so identical after-all!) but calling the conversion explicitly bloats your code with mostly meaningless function-calls. While such conversion functions might actually copy some values around, they essentially do nothing from a high-level "programmers" point-of-view. Implicit conversion constructors and operators could obviously help, but they introduce coupling, so that one of those types has to know about the other. Usually, at least when dealing with libraries, that is not the case, because the presence of one of those types makes the other one redundant. Also, you cannot always change libraries. Now I see two options on how to make implicit conversion work in user-code: The first would be to provide a proxy-type, that implements conversion-operators and conversion-constructors (and assignments) for all the involved types, and always use that. The second requires a minimal change to the libraries, but allows great flexibility: Add a conversion-constructor for each involved type that can be externally optionally enabled. For example, for a type A add a constructor: template <class T> A( const T& src, typename boost::enable_if<conversion_enabled<T,A>>::type* ignore=0 ) { *this = convert(src); } and a template template <class X, class Y> struct conversion_enabled : public boost::mpl::false_ {}; that disables the implicit conversion by default. Then to enable conversion between two types, specialize the template: template <> struct conversion_enabled<OtherA, A> : public boost::mpl::true_ {}; and implement a convert function that can be found through ADL. I would personally prefer to use the second variant, unless there are strong arguments against it. Now to the actual question(s): What's the preferred way to associate types for implicit conversion? Are my suggestions good ideas? Are there any downsides to either approach? Is allowing conversions like that dangerous? Should library implementers in-general supply the second method when it's likely that their type will be replicated in software they are most likely beeing used with (I'm thinking of 3d-rendering middle-ware here, where most of those packages implement a 3D vector).

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• How do you place an Excel Sheet/Workbook onto a C# .NET Winform?

  - by incognick

  I am trying to create a stand alone application in Visual Studio 2008 C# .Net that will house Excel Workbooks (2007). I am using Office.Interop in order to create the Excel application and I open the workbooks via Workbooks.Open(...). The Interop does not provide any functionality to "move" the workbooks onto a form so I turned to P/Invoke Win32 library. I am able to move the entire excel application onto a WinForm with great success: // pseudo code to give you the idea excel = new Excel.ApplicationClass(); SetParent(excel.Hwnd, form.handle); This allows me to customize the form and control user input. All right click commands and formula editing work properly. Now, the issue I run into is when I want to open two workbooks in two separate forms. I do this by creating two excel application classes and placing each of those in their own form. When I try to reference one workbook to another workbook via =[Book2]Sheet1!A1, for example, it does not update. This is expected as each application is running under its own thread/process. Here are the alternatives I have tried. If you have any suggestions I would be greatly appreciative.(OLE is not an option. VSTO must be available) Create a single application class and move the workbook window into my form. Results: The window moves into my form and displays correctly, however, no right click or left click works on the form and it never gains focus. (I have tried to manually set focus and it does not work either). My guess is, by moving the window outside of the XLDESK application (viewable in Spy++ for Excel Application), the workbook application (EXCEL7) does not receive the correct window messages to gain focus and to behave properly. This leads me to: Move the XLDESK window handle into my form. Results: This allows the workbook to be click-able again but also has an undesired result of moving all child windows into the same form. Create a main excel application that creates workbooks. Create a new excel application for each new window. Move the workbook under the new excel application XLDESK window. Results: This also has the same effect of the 1st option. Unable to click in the workbook. This must mean that the thread that created the workbook is also responsible for the events. Create a windows hook that watches the WndProc procedure. Results: No events watched. The targeted thread must export the hook proc in a DLL export call. Excel does not do this and thus you cannot inject into it's DLL (unless someone can prove me wrong). I am able to watch all threads within my own process but not from an outside process. Excel is created as a separate process. Subclass NativeWindow. Results: Same as #4. After I move the window into my form, all events are captured up until the mouse is directly over the excel sheet making the sheet seem unclickable. One idea I haven't tried yet is just to continually save the excel sheet as the user edits it. This should update all references but I would feel this would cause poor system performance. There will be numerous chart references as well and I'm not sure if this solution would cause problems further down the road. I think in the end, all the workbooks need to be created by the same Excel Application and then moved to get the desired results but I can't seem to find the correct way to move the windows without disabling the user input in the process. Any suggestions?

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• In R, how do you get the best fitting equation to a set of data?

  - by Matherion

  I'm not sure wether R can do this (I assume it can, but maybe that's just because I tend to assume that R can do anything :-)). What I need is to find the best fitting equation to describe a dataset. For example, if you have these points: df = data.frame(x = c(1, 5, 10, 25, 50, 100), y = c(100, 75, 50, 40, 30, 25)) How do you get the best fitting equation? I know that you can get the best fitting curve with: plot(loess(df$y ~ df$x)) But as I understood you can't extract the equation, see Loess Fit and Resulting Equation. When I try to build it myself (note, I'm not a mathematician, so this is probably not the ideal approach :-)), I end up with smth like: y.predicted = 12.71 + ( 95 / (( (1 + df$x) ^ .5 ) / 1.3)) Which kind of seems to approximate it - but I can't help to think that smth more elegant probably exists :-) I have the feeling that fitting a linear or polynomial model also wouldn't work, because the formula seems different from what those models generally use (i.e. this one seems to need divisions, powers, etc). For example, the approach in Fitting polynomial model to data in R gives pretty bad approximations. I remember from a long time ago that there exist languages (Matlab may be one of them?) that do this kind of stuff. Can R do this as well, or am I just at the wrong place? (Background info: basically, what we need to do is find an equation for determining numbers in the second column based on the numbers in the first column; but we decide the numbers ourselves. We have an idea of how we want the curve to look like, but we can adjust these numbers to an equation if we get a better fit. It's about the pricing for a product (a cheaper alternative to current expensive software for qualitative data analysis); the more 'project credits' you buy, the cheaper it should become. Rather than forcing people to buy a given number (i.e. 5 or 10 or 25), it would be nicer to have a formula so people can buy exactly what they need - but of course this requires a formula. We have an idea for some prices we think are ok, but now we need to translate this into an equation.

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• PHP apache_request_headers() diagrees with reality (as confirmed by Firebug): why?

  - by Peter Howe

  I have written a web app in PHP which makes use of Ajax requests (made using YUI.util.Connect.asyncRequest). Most of the time, this works fine. The request is sent with an X-Requested-With value of XMLHttpRequest. My PHP controller code uses apache_request_headers() to check whether an incoming request is Ajax or not and all works well. But not always. Intermittently, I'm getting a situation where the Ajax request is sent (and Firebug confirms for me that the headers on the request include an X-Requested-With of XMLHttpRequest) but apache_request_headers() is not returning that header in its list. The output from when I var_dump the apache_request_headers() is as follows (note the lack of X- 'Host' => string 'peterh.labs.example.com' (length=26) 'User-Agent' => string 'Mozilla/5.0 (X11; U; Linux i686; en-GB; rv:1.9.0.3) Gecko/2008101315 Ubuntu/8.10 (intrepid) Firefox/3.0.3' (length=105) 'Accept' => string 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' (length=63) 'Accept-Language' => string 'en-gb,en;q=0.5' (length=14) 'Accept-Encoding' => string 'gzip,deflate' (length=12) 'Accept-Charset' => string 'ISO-8859-1,utf-8;q=0.7,*;q=0.7' (length=30) 'Keep-Alive' => string '300' (length=3) 'Connection' => string 'keep-alive' (length=10) 'Referer' => string 'http://peterh.labs.example.com/qmail/' (length=40) 'Cookie' => string 'WORKFLOW_SESSION=55f9aff2051746851de453c1f776ad10745354f6' (length=57) 'Pragma' => string 'no-cache' (length=8) 'Cache-Control' => string 'no-cache' (length=8) But Firebug tells me: Request Headers: Host peterh.labs.example.com User-Agent Mozilla/5.0 (X11; U; Linux i686; en-GB; rv:1.9.0.3) Gecko/2008101315 Ubuntu/8.10 (intrepid) Firefox/3.0.3 Accept text/html,application/xhtml+xml,application/xml;q=0.9,**;q=0.8 Accept-Language en-gb,en;q=0.5 Accept-Encoding gzip,deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 300 Connection keep-alive X-Requested-With XMLHttpRequest Referer http://peterh.labs.example.com/qmail/ Cookie WORKFLOW_SESSION=55f9aff2051746851de453c1f776ad10745354f6 This mismatch is (apparently) intermittent when executing the same code. But I don't believe in "intermittent" when it comes to software! Help!

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• Refactoring Singleton Overuse

  - by drharris

  Today I had an epiphany, and it was that I was doing everything wrong. Some history: I inherited a C# application, which was really just a collection of static methods, a completely procedural mess of C# code. I refactored this the best I knew at the time, bringing in lots of post-college OOP knowledge. To make a long story short, many of the entities in code have turned out to be Singletons. Today I realized I needed 3 new classes, which would each follow the same Singleton pattern to match the rest of the software. If I keep tumbling down this slippery slope, eventually every class in my application will be Singleton, which will really be no logically different from the original group of static methods. I need help on rethinking this. I know about Dependency Injection, and that would generally be the strategy to use in breaking the Singleton curse. However, I have a few specific questions related to this refactoring, and all about best practices for doing so. How acceptable is the use of static variables to encapsulate configuration information? I have a brain block on using static, and I think it is due to an early OO class in college where the professor said static was bad. But, should I have to reconfigure the class every time I access it? When accessing hardware, is it ok to leave a static pointer to the addresses and variables needed, or should I continually perform Open() and Close() operations? Right now I have a single method acting as the controller. Specifically, I continually poll several external instruments (via hardware drivers) for data. Should this type of controller be the way to go, or should I spawn separate threads for each instrument at the program's startup? If the latter, how do I make this object oriented? Should I create classes called InstrumentAListener and InstrumentBListener? Or is there some standard way to approach this? Is there a better way to do global configuration? Right now I simply have Configuration.Instance.Foo sprinkled liberally throughout the code. Almost every class uses it, so perhaps keeping it as a Singleton makes sense. Any thoughts? A lot of my classes are things like SerialPortWriter or DataFileWriter, which must sit around waiting for this data to stream in. Since they are active the entire time, how should I arrange these in order to listen for the events generated when data comes in? Any other resources, books, or comments about how to get away from Singletons and other pattern overuse would be helpful.

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• Android Frame based animation memory problem

  - by madsleejensen

  Hi all Im trying to create a animation on top of a Camera Surface view. The animation if a box rotating, and to enable transparency i made a bunch of *.png files that i want to just switch out on top of the Camera view. The problem is Android wont allow me to allocate so many images (too much memory required) so the AnimationDrawable is not an option. Will i be able to allocate all the *.png bitmaps if i use OpenGL instead? then i would store all the *.png's as Textures and just make my own animation logic? is am i under the same restrictions there? Any ideas on how to solve this problem ? Ive made a Custom view that loads the image resource on every frame and discards it when next frame is to be displayed. But the performance is terrible. import android.app.Activity; import android.content.res.Resources; import android.graphics.drawable.Drawable; import android.os.SystemClock; import android.util.Log; import android.widget.ImageView; public class FrameAnimationView extends ImageView { private int mFramesPerSecond = 10; private int mTimeBetweenFrames = (1000 / mFramesPerSecond); private int mCurrentFrame = 1; private String[] mFrames; private Thread mAnimationThread; private Resources mResources; private String mIdentifierPrefix; private Activity mContext; private boolean mIsAnimating = false; private Integer[] mDrawableIndentifiers; public FrameAnimationView(Activity context, String[] frames) { super(context); mContext = context; mResources = context.getResources(); mFrames = frames; mIdentifierPrefix = context.getPackageName() + ":drawable/"; mDrawableIndentifiers = new Integer[frames.length]; } private void initAnimationThread() { mAnimationThread = new Thread(new Runnable() { @Override public void run() { while (mIsAnimating) { final int frameToShow = (mCurrentFrame - 1); //Log.e("frame", Integer.toString(frameToShow)); mContext.runOnUiThread(new Runnable() { @Override public void run() { if (mDrawableIndentifiers[frameToShow] == null) { String frameId = mFrames[frameToShow]; int drawableResourceId = mResources.getIdentifier(mIdentifierPrefix + frameId, null, null); mDrawableIndentifiers[frameToShow] = drawableResourceId; } Drawable frame = getResources().getDrawable(mDrawableIndentifiers[frameToShow]); setBackgroundDrawable(frame); if (mCurrentFrame < mFrames.length) { mCurrentFrame++; } else { mCurrentFrame = 1; } } }); try { Thread.sleep(mTimeBetweenFrames); } catch (InterruptedException e) { e.printStackTrace(); } } } }); } public void setFramesPerSecond(int fps) { mFramesPerSecond = fps; mTimeBetweenFrames = (1000 / mFramesPerSecond); } public void startAnimation() { if (mIsAnimating) return; mIsAnimating = true; initAnimationThread(); mAnimationThread.start(); } public void stopAnimation() { if (mIsAnimating) { Thread oldThread = mAnimationThread; mAnimationThread = null; oldThread.interrupt(); mIsAnimating = false; } } }

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• Generate A Simple Read-Only DAL?

  - by David

  I've been looking around for a simple solution to this, trying my best to lean towards something like NHibernate, but so far everything I've found seems to be trying to solve a slightly different problem. Here's what I'm looking at in my current project: We have an IBM iSeries database as a primary repository for a third party software suite used for our core business (a financial institution). Part of what my team does is write applications that report on or key off of a lot of this data in some way. In the past, we've been manually creating ADO .NET connections (we're using .NET 3.5 and Visual Studio 2008, by the way) and manually writing queries, etc. Moving forward, I'd like to simplify the process of getting data from there for the development team. Rather than creating connections and queries and all that each time, I'd much rather a developer be able to simply do something like this: var something = (from t in TableName select t); And, ideally, they'd just get some IQueryable or IEnumerable of generated entities. This would be done inside a new domain core that I'm building where these entities would live and the applications would interface with it through a request/response service layer. A few things to note are: The entities that correspond to the database tables should be generated once and we'd prefer to manually keep them updated over time. That is, if columns/tables are added to the database then we shouldn't have to do anything. (If some are deleted, of course, it will break, but that's fine.) But if we need to use a new column, we should be able to just add it to the necessary class(es) without having to re-gen the whole thing. The whole thing should be SELECT-only. We're not doing a full DAL here because we don't want to be able to break anything in the database (even accidentally). We don't need any kind of mapping between our domain objects and the generated entity types. The domain barely covers a fraction of the data that's in there, most of it we'll never need, and we would rather just create re-usable maps manually over time. I already have a logical separation for the DAL where my "repository" classes return domain objects, I'm just looking for a better alternative to manual ADO to be used inside the repository classes. Any suggestions? It seems like what I'm doing is just enough outside the normal demand for DAL/ORM tools/tutorials online that I haven't been able to find anything. Or maybe I'm just overlooking something obvious?

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