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  • Why exactly is eval evil?

    - by Jay
    I know that Lisp and Scheme programmers usually say that eval should be avoided unless strictly necessary. I´ve seen the same recommendation for several programming languages, but I´ve not yet seen a list of clear arguments against the use of eval. Where can I find an account of the potential problems of using eval? For example, I know the problems of GOTO in procedural programming (makes programs unreadable and hard to maintain, makes security problems hard to find, etc), but I´ve never seen the arguments against eval. Interestingly, the same arguments against GOTO should be valid against continuations, but I see that Shemers, for example, won´t say that continuations are "evil" -- you should just be careful when using them. They´re much more likely to frown upon code using eval than upon code using continuations (as far as I can see -- I could be wrong).

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  • What (kind of) project could I create to learn JavaScript?

    - by Aziz Light
    Hello, I started learning JavaScript a while ago. It's a fairly easy programming language considering that I learned Java in university, that I know php pretty well and that I already played around with python and ruby. The problem is that to properly learn a programming language I usually create a project. In javascript, I just don't know what kind of project I could create - that is, a project that is not web-based or related to the web browser. Can I create javascript shell scripts? Where is javascript commonly used beside the web browsers? So, can someone actually give me some ideas please?

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  • Why is RAISERROR misspelled? Or is it not?

    - by Jason
    Why isn't RAISERROR spelled RAISEERROR? Where is the second E? I could understand if it were some ancient keyword length constraint, but I wouldn't expect it to be a nine-character limit. Is RAIS or RROR a technical word such that "raise-error" is just a mis-reading? Are its (immediate) origins in a different language? I've searched Google but not finding much on the subject.

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  • How to access a SIM card programatically?

    - by mawg
    Just any old GSM compatible SIM card (bonus for 3G USIM). I presume I need some hardware? Can anyone recommend something cheap for hobbyist, and something more professional? I presume that there will be full docs of an API with the h/w, so maybe this should be tagged "no-programming-related"? Sorry, if so. Any good URLs or books (I am conversant with the 3GPP standards). I'm not (black hat) hacking, don't worry, just not pleased with the likes of SIM Card Secretary, Data Doctor Recovery, etc, so would like to code my own, but might turn it commercial, or offer SIM card programming services (data recover from damaged card, etc) as a sideline.

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  • Does Objective-C have a Standard Library?

    - by Roman A. Taycher
    Most somewhat modern programming languages have a standard library? It is my impression is that there isn't a decent sized standard library for Obj-C , rather that it relies mostly/all on Cocoa and that (plus people not wanting to use GNUstep) is why Obj-C is only used on macs)? Is this true/to what extent? Are there any standard obj-c collections? (note I haven't done any Obj-C programming and am not to likely to try it in the near future, I'm just curious). P.S. are there a any decent non-Cocoa/Gnustep Libraries? are they non-apple, are they open source, well documented?

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  • What should every programmer know?

    - by Matt Lacey
    Regardless of programming language(s) or operating system(s) used or the environment they develop for, what should every programmer know? Some background: I'm interested in becoming the best programmer I can. As part of this process I'm trying to understand what I don't know and would benefit me a lot if I did. While there are loads of lists around along the lines of "n things every [insert programming language] developer should know", I have yet to find anything similar which isn't limited to a specific language. I also expect this information to be of interest and benefit to others.

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  • What is the current state of Unit testing support in the R language

    - by PaulHurleyuk
    R is a statistics programming language. Part of R is the use of Packages, which themselves are written in the R language. Programming best practice includes the use of unit-testing to test the functions within these packages while they are being written and when they are used. I am aware of a few packages for unit testing within R, these being RUnit Svunit Testthat I'm interested to know; Are there any other packages out there ? Given peoples experience, do these packages excel at different things ? What's the current state of the art in unit testing for R ?

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  • How to Delete all data from a table which contain self referencing foreign key

    - by Shantanu Gupta
    I have a table which has employee relationship defined within itself. i.e. EmpID Name SeniorId ----------------------- 1 A NULL 2 B 1 3 C 1 4 D 3 and so on... Where Senior ID is a foreign key whose primary key table is same with refrence column EmpId I want to clear all rows from this table without removing any constraint. How can i do this? Deletion need to be performed like this 4, 3 , 2 , 1 How can I do this

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  • Good development themes/environments for Gnome/kde/whatever?

    - by EvanAlm
    I've searched forever for good themes or customized versions of any type of x-server that is designed for development in terms of web productions/programming for all kind of stuffs. Features such as simplified workspace overviews, good tabbing support etc. For multimedia "UbuntuStudio" exists, and something like that but for programming instead. I know that it's possible to customize it by myself but I don't have the skills to make it all happen. Another reason why it's hard for me to customize it is that I simply do not know everything that would make it good for me. I've looked into gnome-shell and it has (according to me) superb workspace overview functions, but lacks in other spaces instead. Any help in finding a good solution for me in this case is appreciated. If some of you also have had this problem and found a solution that works for you, please tell me how you did :) Would love to solve this for once!

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  • Combining the UNIQUE and CHECK constraints

    - by Bobby
    I have a table with columns a b and c, and if c is false then I only want to allow insertions if columns a and b are unique, but if c is true then a and b do not need to be unique. Example: There can only be one (foo, bar, false) in the table, but no limit on how many (foo, bar, true) there can be. I tried something like CONSTRAINT blah UNIQUE (a,b) AND CHECK (C is TRUE) but I can't figure out the correct syntax.

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  • Real world example of Unification in First Order Logic?

    - by Sebi
    I know this is only part of a programming question, but at the moment, I'm doing a little bit of logic programming. One thing I still don't understand correctly is Unification in First Order Logic. I read the Wikipedia article and it is more or less clear that the purpose is searching a term that unifies two sentences... There are also examples in this article but I just don't get the point why this should be useful. Can anyone give an example with real world objects instead of A, B, C,, etc.? I hope this will help me to understand. Thanks

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  • FluentNHibernate Many-To-One References where Foreign Key is not to Primary Key and column names are

    - by Todd Langdon
    I've been sitting here for an hour trying to figure this out... I've got 2 tables (abbreviated): CREATE TABLE TRUST ( TRUSTID NUMBER NOT NULL, ACCTNBR VARCHAR(25) NOT NULL ) CONSTRAINT TRUST_PK PRIMARY KEY (TRUSTID) CREATE TABLE ACCOUNTHISTORY ( ID NUMBER NOT NULL, ACCOUNTNUMBER VARCHAR(25) NOT NULL, TRANSAMT NUMBER(38,2) NOT NULL POSTINGDATE DATE NOT NULL ) CONSTRAINT ACCOUNTHISTORY_PK PRIMARY KEY (ID) I have 2 classes that essentially mirror these: public class Trust { public virtual int Id {get; set;} public virtual string AccountNumber { get; set; } } public class AccountHistory { public virtual int Id { get; set; } public virtual Trust Trust {get; set;} public virtual DateTime PostingDate { get; set; } public virtual decimal IncomeAmount { get; set; } } How do I do the many-to-one mapping in FluentNHibernate to get the AccountHistory to have a Trust? Specifically, since it is related on a different column than the Trust primary key of TRUSTID and the column it is referencing is also named differently (ACCTNBR vs. ACCOUNTNUMBER)???? Here's what I have so far - how do I do the References on the AccountHistoryMap to Trust??? public class TrustMap : ClassMap<Trust> { public TrustMap() { Table("TRUST"); Id(x => x.Id).Column("TRUSTID"); Map(x => x.AccountNumber).Column("ACCTNBR"); } } public class AccountHistoryMap : ClassMap<AccountHistory> { public AccountHistoryMap() { Table("TRUSTACCTGHISTORY"); Id (x=>x.Id).Column("ID"); References<Trust>(x => x.Trust).Column("ACCOUNTNUMBER").ForeignKey("ACCTNBR").Fetch.Join(); Map(x => x.PostingDate).Column("POSTINGDATE"); ); I've tried a few different variations of the above line but can't get anything to work - it pulls back AccountHistory data and a proxy for the Trust; however it says no Trust row with given identifier. This has to be something simple. Anyone? Thanks in advance.

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  • Are all languages used within .net Equally performant?

    - by WeNeedAnswers
    I know the "Sales pitch" answer is yes to this question, but is it technically true. The Common Language Runtime (CLR) is designed as an intermediate language based on Imperative Programming (IP), but this has obvious implications when dealing with Declarative Programming (DP). So how efficient is a language based on a different paradigm than the Imperative Style when implemented in the CLR? I also get the feeling that the step to DP would incur an extra level of abstraction that might not model at all performant, would this be a fair comment? I have done some simple tests using F# and it all looks great, but am I missing something if the programs get more complex?

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  • Malloc to a CGPoint Pointer throwing EXC_BAD_ACCESS when accessing

    - by kdbdallas
    I am trying to use a snippet of code from a Apple programming guide, and I am getting a EXC_BAD_ACCESS when trying to pass a pointer to a function, right after doing a malloc. (For Reference: iPhone Application Programming Guide: Event Handling - Listing 3-6) The code in question is really simple: CFMutableDictionaryRef touchBeginPoints; UITouch *touch; .... CGPoint *point = (CGPoint *)CFDictionaryGetValue(touchBeginPoints, touch); if (point == NULL) { point = (CGPoint *)malloc(sizeof(CGPoint)); CFDictionarySetValue(touchBeginPoints, touch, point); } Now when the program goes into the if statement it assigns the 'output' of malloc into the point variable/pointer. Then when it tries to pass point into the CFDictionarySetValue function it crashes the application with: Program received signal: “EXC_BAD_ACCESS”. Someone suggested not doing the malloc and pass the point var/pointer as: &point, however that still gave me a EXC_BAD_ACCESS. What I am (and it looks like Apple) doing wrong??? Thanks in advance.

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  • Finding the time to program in your spare time?

    - by Omar Kooheji
    I've got about a dozen programming projects bouncing about my head, and I'd love to contribute to some open source projects, the problem I have is that having spent the entire day staring at Visual Studio and or Eclipse (Sometimes both at the same time...) the last thing I feel like doing when I go home is program. How do you build up the motivation/time to work on your own projects after work? I'm not saying that I don't enjoy programming, it's just that I enjoy other things to and it can be hard to even do something you enjoy if you've spent all day already doing it. I think that if I worked at a chocolate factory the last thing I'd want to see when I got home was a Wonka bar.... Related: How do you keep a balance between working, training, health and family?

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  • Cancel draggable dragging

    - by JohnM2
    I have a draggable (jquery-ui) element. I subscribe to it's 'drag' event. How can I cancel current draggig based on some constraints? So I want to constraint possible moves of this draggable element, but it is more custom then only based on axis or parent (containment). How can I do that?

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  • NHibernate - does it work well with database-level cascading deletions on foreign key constraints

    - by Nelson LaQuet
    Dose nHibernate play well with database level cascading deletions? What I mean is that if I have a constraint set at the RDBMS level to cascade delete all orphans, will nHibernate invoke any custom delete logic at the application level if I were to delete an entity though nHibernate? Or should I remove the cascading deletions from the RDBMS level and just use the cascading delete feature of nHibernate itself by defining that behavior though its configuration? Thanks

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  • The unmentioned parts of COBOL's history

    - by be nice to me.
    I'm very curious about old programming languages, especially COBOL, and as Wikipedia couldn't really tell me much about this topic, I decided to ask it here: Was COBOL the first programming language really being used in financial, stock and banking systems? Where exactly was COBOL used? Was it used more frequently than Fortran or BASIC, for example? I don't know if you lived at that time, but how did people react to the rising COBOL? Did they expect it to be the future? When has COBOL actually stopped being used to create new, big systems? Are you sure that there are still important legacy apps written in COBOL out there? I can't believe that somehow.

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  • Linq to Entities and outer joins issue

    - by Robert Koritnik
    Can somebody tell me, why does Linq to Entities translate many to 1 relationships to left outer joins instead of inner joins? It relation was many to 0..1. There's referential constraint on DB itself, that ensures there's a record in the right table, so inner join should be used instead. Is it possible to write LINQ in a way so they will translate to inner joins rather than left outer joins. It would speed query execution a lot.

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  • Access block level storage via kernel

    - by N 1.1
    How to access block level storage via the kernel (w/o using scsi libraries)? My intent is to implement a block level storage protocol over network for learning purpose, almost the same way SCSI works. Requests will be generated by initiator and sent to target (both userspace program) which makes call to kernel module and returns the data using TCP protocol to initiator. So far, I have managed to build a simple "Hello" module and run it (I am new at kernel programming), but unable to proceed with block access. After searching a lot, I found struct buffer_head * bread(int dev,int block) in linux/fs.h, but the compiler throws error. error: implicit declaration of function ‘bread’ Please help, also feel free to advice on starting with kernel programming. Thank you!

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  • What is causing this SQL 2005 Primary Key Deadlock between two real-time bulk upserts?

    - by skimania
    Here's the scenario: I've got a table called MarketDataCurrent (MDC) that has live updating stock prices. I've got one process called 'LiveFeed' which reads prices streaming from the wire, queues up inserts, and uses a 'bulk upload to temp table then insert/update to MDC table.' (BulkUpsert) I've got another process which then reads this data, computes other data, and then saves the results back into the same table, using a similar BulkUpsert stored proc. Thirdly, there are a multitude of users running a C# Gui polling the MDC table and reading updates from it. Now, during the day when the data is changing rapidly, things run pretty smoothly, but then, after market hours, we've recently started seeing an increasing number of Deadlock exceptions coming out of the database, nowadays we see 10-20 a day. The imporant thing to note here is that these happen when the values are NOT changing. Here's all the relevant info: Table Def: CREATE TABLE [dbo].[MarketDataCurrent]( [MDID] [int] NOT NULL, [LastUpdate] [datetime] NOT NULL, [Value] [float] NOT NULL, [Source] [varchar](20) NULL, CONSTRAINT [PK_MarketDataCurrent] PRIMARY KEY CLUSTERED ( [MDID] ASC )WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] ) ON [PRIMARY] - stackoverflow wont let me post images until my reputation goes up to 10, so i'll add them as soon as you bump me up, hopefully as a result of this question. ![alt text][1] [1]: http://farm5.static.flickr.com/4049/4690759452_6b94ff7b34.jpg I've got a Sql Profiler Trace Running, catching the deadlocks, and here's what all the graphs look like. stackoverflow wont let me post images until my reputation goes up to 10, so i'll add them as soon as you bump me up, hopefully as a result of this question. ![alt text][2] [2]: http://farm5.static.flickr.com/4035/4690125231_78d84c9e15_b.jpg Process 258 is called the following 'BulkUpsert' stored proc, repeatedly, while 73 is calling the next one: ALTER proc [dbo].[MarketDataCurrent_BulkUpload] @updateTime datetime, @source varchar(10) as begin transaction update c with (rowlock) set LastUpdate = getdate(), Value = t.Value, Source = @source from MarketDataCurrent c INNER JOIN #MDTUP t ON c.MDID = t.mdid where c.lastUpdate < @updateTime and c.mdid not in (select mdid from MarketData where LiveFeedTicker is not null and PriceSource like 'LiveFeed.%') and c.value <> t.value insert into MarketDataCurrent with (rowlock) select MDID, getdate(), Value, @source from #MDTUP where mdid not in (select mdid from MarketDataCurrent with (nolock)) and mdid not in (select mdid from MarketData where LiveFeedTicker is not null and PriceSource like 'LiveFeed.%') commit And the other one: ALTER PROCEDURE [dbo].[MarketDataCurrent_LiveFeedUpload] AS begin transaction -- Update existing mdid UPDATE c WITH (ROWLOCK) SET LastUpdate = t.LastUpdate, Value = t.Value, Source = t.Source FROM MarketDataCurrent c INNER JOIN #TEMPTABLE2 t ON c.MDID = t.mdid; -- Insert new MDID INSERT INTO MarketDataCurrent with (ROWLOCK) SELECT * FROM #TEMPTABLE2 WHERE MDID NOT IN (SELECT MDID FROM MarketDataCurrent with (NOLOCK)) -- Clean up the temp table DELETE #TEMPTABLE2 commit To clarify, those Temp Tables are being created by the C# code on the same connection and are populated using the C# SqlBulkCopy class. To me it looks like it's deadlocking on the PK of the table, so I tried removing that PK and switching to a Unique Constraint instead but that increased the number of deadlocks 10-fold. I'm totally lost as to what to do about this situation and am open to just about any suggestion. HELP!!

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  • Datamodel diagram-software

    - by megala
    I have nearly 20 tables.I want to draw datamodel diagram for this table.But it take more time.Is it possible to draw the diagram using any datamodel software.My constraint is i give dataonly it draw the diagram automatically,please suggest any softwsre related to my constraints

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