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  • Python 2.6 and 3.1.1, earlier version compatibility

    - by Todd
    I ordered three books to start teaching myself Python - a beginning programming book, a computer science book that uses Python for all of its code references, and a book on Python network programming. Unfortunately, I was a little too quick on ordering them, because I hadn't noticed the version differences. The beginner book is for python 3.1, the CS book is Python 2.3, and the last is Python 2.6. The CS book is also oriented towards beginners. My question is, will the different versions be too different at this level for me to effectively use all three, or will I likely be able to get by learning from the 3.1 beginners book and then sort of teach myself from the 2.3 CS book, and be able to comprehend 2.6 code? That probably didn't make sense. I hope it did.

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  • Issuing native system commands in Scala

    - by Tony
    I want to issue a native system command from a Scala program, and perhaps trap the output. ("ls" comes to mind. There may be other ways to get directory information without issuing the command, but that's beside the point of my question.) It would correspond to os.system(...) in Python. I've looked in "Programming in Scala". I've looked in O'Reilly's "Programming Scala". I've Googled several combinations of terms. No luck yet. Can someone out there give me an example, or point me at a resource where I can find an example?

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  • Best computer-science universities in Europe?

    - by Tom
    I am in 11th grade and only one year left when I finish my school. I am sure I want to dedicate my life to programming. In my country the education's level is not so high as in Europe, so I want to emigrate and study not just for a diploma, but for knowledge too. So, what universities would you suggest me which has subject Computer-Science? I prefer web programming. Please do not delete this message though it is quite offtopic, but it's the best place for me to get suggestions from advanced programmers who have already finished their university. And I hope here comes also teenagers who can make the best decision choosing university. Thank you. Please read the whole my message before voting to close this thread, thanks.

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  • Is Python appropriate for algorithms focused on scientific computing?

    - by gmatt
    My interests in programming lie mainly in algorithms, and lately I have seen many reputable researchers write a lot of their code in python. How easy and convenient is python for scientific computing? Does it have a library of algorithms that compares to matlab's? Is Python a scripting language or does it compile? Is it a great language for prototyping an algorithm? How long would it take me to learn enough of it to be productive provided I know C well and OO programming somewhat? Is it OO based? Sorry for the condensed format of questions, but I'm very curious and was hoping a more experienced programmer could help me out.

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  • Caffeine and Stimulant Usage

    - by Jon Purdy
    Let's see how many of us fit the old stereotype, shall we? Do you typically use caffeine when programming? During the day or at night? How frequently do you pull all-nighters? Do you use caffeine when you do stay up late? Do you prefer to have a large amount of caffeine all at once, or small amounts over a longer period of time? Do you use energy drinks, 5-hour energy shots, coffee, tea, or caffeine pills? How about other stimulants such as amphetamines? For instance, I've known a programmer who dabbled in speed because they believed it increased their ability to focus on programming, though happily they're clean now and quite honest about the whole experience. Share, discuss, find the Ballmer Peak of caffeine, enjoy. Happy Easter.

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  • Is it any desktop wysiwyg editors for mediawiki / wiki available?

    - by Eye of Hell
    Hello. Mediawiki is very good, but for programming tasks editing it via web is not very handy since wysiwyg is very limited, pressing 'edit' + 'publish' on any small change and waiting for page loading kins of annoying. I have seen alot of desktop wikis (personal wikis) that are free from such problems. The best example is a 'wikidpad' that has a usage patter of 'focus, edit wiki in-place, minimize'. This is very handy for programming work where you need to make small changes to wiki and documentation during development, and documentation is written much more often than readed :). But all such desktops wikies are personal - they don't have any wiki sharing (or marginally limited support for it). So, maybe it's a desktop application exists that can connect to mediawiki and allows to view and edit it via a rich wysiwyg editor? Any hints are welcomed.

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  • Postgresql 9.1: ERROR: type "citext" does not exist

    - by gotuskar
    I am trying to execute following query through PgAdmin utility. CREATE TABLE svcr."EventLogs" ("eventId" BIGINT NOT NULL, "eventTime" TIMESTAMP WITH TIME ZONE NOT NULL, "userid" CITEXT, "realmid" CITEXT NOT NULL, "onUserid" CITEXT, "description" TEXT, CONSTRAINT eventlogs_pkey PRIMARY KEY ("eventId")); And I get following error - ERROR: type "citext" does not exist SQL state: 42704 Character: 120 However, following query runs fine - CREATE TABLE svcr."CategoryMap" ("category" INT NOT NULL, "userData" INT NOT NULL); What is wrong with the first query?

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  • B-trees, databases, sequential inputs, and speed.

    - by IanC
    I know from experience that b-trees have awful performance when data is added to them sequentially (regardless of the direction). However, when data is added randomly, best performance is obtained. This is easy to demonstrate with the likes of an RB-Tree. Sequential writes cause a maximum number of tree balances to be performed. I know very few databases use binary trees, but rather used n-order balanced trees. I logically assume they suffer a similar fate to binary trees when it comes to sequential inputs. This sparked my curiosity. If this is so, then one could deduce that writing sequential IDs (such as in IDENTITY(1,1)) would cause multiple re-balances of the tree to occur. I have seen many posts argue against GUIDs as "these will cause random writes". I never use GUIDs, but it struck me that this "bad" point was in fact a good point. So I decided to test it. Here is my code: SET ANSI_NULLS ON GO SET QUOTED_IDENTIFIER ON GO CREATE TABLE [dbo].[T1]( [ID] [int] NOT NULL CONSTRAINT [T1_1] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO CREATE TABLE [dbo].[T2]( [ID] [uniqueidentifier] NOT NULL CONSTRAINT [T2_1] PRIMARY KEY CLUSTERED ([ID] ASC) ) GO declare @i int, @t1 datetime, @t2 datetime, @t3 datetime, @c char(300) set @t1 = GETDATE() set @i = 1 while @i < 2000 begin insert into T2 values (NEWID(), @c) set @i = @i + 1 end set @t2 = GETDATE() WAITFOR delay '0:0:10' set @t3 = GETDATE() set @i = 1 while @i < 2000 begin insert into T1 values (@i, @c) set @i = @i + 1 end select DATEDIFF(ms, @t1, @t2) AS [Int], DATEDIFF(ms, @t3, getdate()) AS [GUID] drop table T1 drop table T2 Note that I am not subtracting any time for the creation of the GUID nor for the considerably extra size of the row. The results on my machine were as follows: Int: 17,340 ms GUID: 6,746 ms This means that in this test, random inserts of 16 bytes was almost 3 times faster than sequential inserts of 4 bytes. Would anyone like to comment on this? Ps. I get that this isn't a question. It's an invite to discussion, and that is relevant to learning optimum programming.

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  • Best anti boss tricks to hide your private page navigation from your desktop.

    - by systempuntoout
    This question is slightly related to programming and it's kinda lame, i know; but i saw many funny things in these years and i'm looking for new tricks from you. I'm talking about methods to fast-hide\camouflage not job related web pages on your desktop when boss arrives like a ghost\ninja behind your shoulders. I know how much can be frustrating, programming hard for ten hours and then been caught by your boss watching XKCD during a 2 minutes break. I think the most common anti boss trick is the evergreen CTRL+TAB, but you have to be fast and your left hand has to be near the keyboard. I saw pitch black brightness on Lcd (how can you pretend to program on that?) or custom sized browser to fit a little space just below the IDE. My favourite one at the moment is using fire gesture plugin with FF; with a micro gesture you can hide FF to your tray in a blink of an eye. Do you have any trick to share?

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  • Where can I learn more about datastructure tricky questions?

    - by Sandbox
    I am relatively new to programming (around 1 year programming C#-winforms). Also, I come from a non CS background (no formal degree) Recently, while being interviewed for a job, I was asked about implementing a queue using a stack. I fumbled and wan't able to answer the question. After, the interview I could do it(had to spend some time). I have learnt (and think that I know it well) basic algorithms in datastructures using the book Data Structures: A Pseudocode Approach with C - Richard F. Gilberg (Author) . I want to know about sites/ books which have such questions along with answers. I think this will allow me to develop my CS specific problem solving skills. Any help is appreciated. BOUNTY: I am looking at some blog/website with datastructure and algorithms Q&A.

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  • MySQL won't use index for query?

    - by Jack Sleight
    I have this table: CREATE TABLE `point` ( `id` INT(11) NOT NULL AUTO_INCREMENT, `siteid` INT(11) NOT NULL, `lft` INT(11) DEFAULT NULL, `rgt` INT(11) DEFAULT NULL, `level` SMALLINT(6) DEFAULT NULL, PRIMARY KEY (`id`), KEY `point_siteid_site_id` (`siteid`), CONSTRAINT `point_siteid_site_id` FOREIGN KEY (`siteid`) REFERENCES `site` (`id`) ON DELETE CASCADE ) ENGINE=INNODB AUTO_INCREMENT=35 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci And this query: SELECT * FROM `point` WHERE siteid = 1; Which results in this EXPLAIN information: +----+-------------+-------+------+----------------------+------+---------+------+------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+------+----------------------+------+---------+------+------+-------------+ | 1 | SIMPLE | point | ALL | point_siteid_site_id | NULL | NULL | NULL | 6 | Using where | +----+-------------+-------+------+----------------------+------+---------+------+------+-------------+ Question is, why isn't the query using the point_siteid_site_id index?

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  • Ridiculously Simple Erlang Question

    - by Aiden Bell
    Read (skimmed enough to get coding) through Erlang Programming and Programming Erlang. One question, which is as simple as it sounds: If you have a process Pid1 on machine m1 and a billion million messages are sent to Pid1, are messages handled in parallel by that process (I get the impression no) and is there any guarantee of order when processing messages? ie. Received in order sent? Coming from the whole C/Thread pools/Shared State background ... I want to get this concrete. I understand distributing an application, but want to ensure the 'raw bones' are what I expect before building processes and distributing workload. Also, am I right in thinking the whole world is currently flicking through Erlang texts ;)

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  • wxWidgets - Add items to sizer via DLL

    - by intl
    I have a GUI set up with wxWidgets (C++, MSVC) and part of the functionality is to add elements to the GUI via DLL's. Essentially, I would be passing in a sizer to the DLL which will in turn add the elements based on what is in the DLL. Could someone just point me in the right direction on how to get the DLL set up? I have looked, but don't see anything that's similar to what I'm looking for. The programming of the elements is fine with me, I just need to understand how to structure the DLL programming. Help appreciated.

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  • Many to Many delete in NHibernate two parents with common association

    - by Joshua Grippo
    I have 3 top level entities in my app: Circuit, Issue, Document Circuits can contain Documents and Issues can contain Documents. When I delete a Circuit, I want it to delete the documents associated with it, unless it is used by something else. I would like this same behavior with Issues. I have it working when the only association is in the same table in the db, but if it is in another table, then it fails due to foreign key constraints. ex 1(This will cascade properly, because there is only a foreign constraint from Circuit to Document) Document1 exists. Circuit1 exists and contains a reference to Document1. If I delete Circuit1 then it deletes Document1 with it. ex 2(This will cascade properly, because there is only a foreign constraint from Circuit to Document.) Document1 exists. Circuit1 exists and contains a reference to Document1. Circuit2 exists and contains a reference to Document1. If I delete Circuit1 then it is deleted, but Document1 is not deleted because Circuit2 exists. If I then delete Circuit2, then Document1 is deleted. ex 3(This will throw an error, because when it deletes the Circuit it sees that there are no other circuits that reference the document so it tries to delete the document. However it should not, because there is an Issue that has a foreign constraint to the document.) Document 1 exists. Circuit1 exists and contains a reference to Document1. Issue1 exists and contains a reference to Document1. If I delete Circuit1, then it fails, because it tries to delete Document1, but Issues1 still has a reference. DB: This think won't let upload an image, so here is the ERD to the DB: http://lh3.ggpht.com/_jZWhe7NXay8/TROJhOd7qlI/AAAAAAAAAGU/rkni3oEANvc/CircuitIssues.gif Model: public class Circuit { public virtual int CircuitID { get; set; } public virtual string CJON { get; set; } public virtual IList<Document> Documents { get; set; } } public class Issue { public virtual int IssueID { get; set; } public virtual string Summary { get; set; } public virtual IList<Model.Document> Documents { get; set; } } public class Document { public virtual int DocumentID { get; set; } public virtual string Data { get; set; } } Mapping Files: <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Model" assembly="Model"> <class name="Circuit" table="Circuit"> <id name="CircuitID"> <column name="CircuitID" not-null="true"/> <generator class="identity" /> </id> <property name="CJON" column="CJON" type="string" not-null="true"/> <bag name="Documents" table="CircuitDocument" cascade="save-update,delete-orphan"> <key column="CircuitID"/> <many-to-many class="Document"> <column name="DocumentID" not-null="true"/> </many-to-many> </bag> </class> </hibernate-mapping> <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Model" assembly="Model"> <class name="Issue" table="Issue"> <id name="IssueID"> <column name="IssueID" not-null="true"/> <generator class="identity" /> </id> <property name="Summary" column="Summary" type="string" not-null="true"/> <bag name="Documents" table="IssueDocument" cascade="save-update,delete-orphan"> <key column="IssueID"/> <many-to-many class="Document"> <column name="DocumentID" not-null="true"/> </many-to-many> </bag> </class> </hibernate-mapping> <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" namespace="Model" assembly="Model"> <class name="Document" table="Document"> <id name="DocumentID"> <column name="DocumentID" not-null="true"/> <generator class="identity" /> </id> <property name="Data" column="Data" type="string" not-null="true"/> </class> </hibernate-mapping> Code: using (ISession session = sessionFactory.OpenSession()) { var doc = new Model.Document() { Data = "Doc" }; var circuit = new Model.Circuit() { CJON = "circ" }; circuit.Documents = new List<Model.Document>(new Model.Document[] { doc }); var issue = new Model.Issue() { Summary = "iss" }; issue.Documents = new List<Model.Document>(new Model.Document[] { doc }); session.Save(circuit); session.Save(issue); session.Flush(); } using (ISession session = sessionFactory.OpenSession()) { foreach (var item in session.CreateCriteria<Model.Circuit>().List<Model.Circuit>()) { session.Delete(item); } //this flush fails, because there is a reference to a child document from issue session.Flush(); foreach (var item in session.CreateCriteria<Model.Issue>().List<Model.Issue>()) { session.Delete(item); } session.Flush(); }

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  • Trasnfer of dirctory structure on network

    - by singh
    Hi I am designing a remote CD/DVD burner to address hardware constraint on my Machine. My design work like that :(Analogous to network paper printer) Unix Based Machine (acts as server) hosts a burner. Windows based machine acts as client. Client prepare data to be burn and transfer it to server. Server burn the data on CD/DVD. My Question is : . Which is the best protocol to transfer data over network (Keeping same Directory hierarchy) between different OS

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  • Time order of messages

    - by Aiden Bell
    Read (skimmed enough to get coding) through Erlang Programming and Programming Erlang. One question, which is as simple as it sounds: If you have a process Pid1 on machine m1 and a billion million messages are sent to Pid1, are messages handled in parallel by that process (I get the impression no) and(answered below) is there any guarantee of order when processing messages? ie. Received in order sent? If so, how is clock skew handled in high traffic situations for ordering? Coming from the whole C/Thread pools/Shared State background ... I want to get this concrete. I understand distributing an application, but want to ensure the 'raw bones' are what I expect before building processes and distributing workload. Also, am I right in thinking the whole world is currently flicking through Erlang texts ;)

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  • Delphi - online technical tests

    - by RBA
    I have searched for some online Delphi programming tests, and except the small test for Delphi certification and several tests on Delphi.about.com I did find nothing. Any ideas where I can find some Delphi online tests? LE: defining online Delphi programming tests: - technical questions about Delphi fundamentals,Data types,classes, libraries, generics, database concepts, etc. Examples here (Delphi Developer Certification Exam Study Guide) and here. LE2: tests to take after you have read all the articles from this question: Questions every good Delphi developer should be able to answer?

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  • How to use Unique Composite Key

    - by LifeH2O
    I have a table Item(ItemName*, ItemSize*, Price, Notes) I was making composite key of (ItemName,ItemSize) to uniquely identify item. And now after reading some answers on stackoverflow suggesting the use of UNIQUE i revised it as Item(ItemID*, ItemName, ItemSize, Price, Notes) But How to apply UNIQUE constraint on ItemName and ItemSize please correct if there is something wrong in question

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  • Which set(s) of video lectures for computer science?

    - by SebKom
    As most of you know a couple of top universities (MIT, Stanford, etc) around the world are now publishing videos of their lectures online. I am advancing to the third and final year of my computer science degree this September and I was thinking about spending some time during the summer to watch a couple of lectures, in order to improve my understanding of algorithms, complexity, programming, software engineering, etc. Now I don't have infinite time to spend so I can't watch all of the lectures from all of the universities so I was wondering if you could suggest me which sets to watch from each one (something like "Algorithms from MIT", "Programming from Yale", etc).

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  • Advanced example-driven C book with a lot of code.

    - by Inso Reiges
    Hello, I am looking for a book on advanced C programming that: Teaches how to effectively express one's solution in C when one already knows the language in depth. Shows some common design idioms expressed in C, like encapsulation, modularity and that kind of thing. Is example-driven with a lot of good-quality code. I already know the language itself so books like otherwise wonderful "Expert C Programming" by Peter van der Linden is not really what i am looking for. What i need is a book on how to express my design in C, what are the common idioms, best practices, etc. I would also like to note that i am primarily interested in C, not C++, C#, Objective-C or any other languages inspired by C-like syntax. Thank you.

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