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• What is the best software to capture full-screen 3h programming session in Windows?

  - by Hugo S Ferreira

  Hi, I'm planning a laboratorial experiment to assess behavior of groups when programming using some tools under study. For that, I'll need to capture their entire screen to disk. Mostly, what will be displayed is code, so I'm not to worried with image quality. However, it's paramount that the team is not able to stop the recording by accident, and the tool should be rebust enough to hold at least 3h of video. If possible, it would be nice for researchers in other rooms to "watch" the video as it is recording. Actually, this last requirement reminded me that I could use a VNC recording software, and install a VNC client in each laboratory computer. Anyway, what is your experience with this? Which software do you recommend? Thanks.

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• Teaching high school kids ASP.NET programming

  - by dotneteer

  During the 2011 Microsoft MVP Global Summit, I have been talking to people about teaching kids ASP.NET programming. I want to work with volunteer organizations to provide kids volunteer opportunities while learning technical skills that can be applied elsewhere. The goal is to teach motivated kids enough skill to be productive with no more than 6 hours of instruction. Based on my prior teaching experience of college extension courses and involvement with high school math and science competitions, I think this is quite doable with classic ASP but a challenge with ASP.NET. I don’t want to use ASP because it does not provide a good path into the future. After some considerations, I think this is possible with ASP.NET and here are my thoughts: · Create a framework within ASP.NET for kids programming. · Use existing editor. No extra compiler and intelligence work needed. · Using a subset of C# like a scripting language. Teaches data type, expression, statements, if/for/while/switch blocks and functions. Use existing classes but no class creation and OOP. · Linear rendering model. No complicated life cycle. · Bare-metal html with some MVC style helpers for widget creation; ASP.NET control is optional. I want to teach kids to understand something and avoid black boxes as much as possible. · Use SQL for CRUD with a helper class. Again, I want to teach understanding rather than black boxes. · Provide a template to encourage clean separation of concern. · Provide a conversion utility to convert the code that uses template to ASP.NET MVC. This will allow kids with AP Computer Science knowledge to step up to ASP.NET MVC. Let me know if you have thoughts or can help.

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• insert or update on table violates foreign key constraint

  - by sprasad12

  Hi, I have two tables entitytype and project. Here are the create table statements: Create table project ( pname varchar(20) not null, primary key(pname) ); create table entitytype( entityname varchar(20) not null, toppos char(100), leftpos char(100), pname varchar(20) not null, primary key(entityname), foreign key(pname) references project(pname) on delete cascade on update cascade ); Now when i try to insert any values into entitytype table i am getting the following error: ERROR: insert or update on table "entitytype" violates foreign key constraint "entitytype_pname_fkey" Detail: Key (pname)=(494) is not present in table "project". Can someone please shed some light on what i am doing wrong. Any input will be of great help. Thank you.

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• Programming Practice/Test Contest?

  - by Emmanuel

  My situation: I'm on a programming team, and this year, we want to weed out the weak link by making a competition to get the best coder from our group of candidates. Focus is on IEEExtreme-like contests. What I've done: I've been trying already for 2 weeks to get a practice or test site, like UVa or codechef. The plan after I find one: Send them (the candidates) a list of direct links to the problems (making them the "contest's problem list) get them to email me their correct answers' code at the time the judge says they have solved it and accept the fastest one into the team. Issues: We had practiced on UVa already (on programming challenges too), so our former teammate (which will be in the candidate group) already has an advantage if we used it. Codechef has all it's answers public, and since it shows the latest ones it will be extremely hard to verify if the answer was copied. And I've found other sites, like SPOJ, but they share at least some problems with codechef, making them inherit the issue of Codechef So, what alternatives do you think there are? Any site that may work? Any place to get all stuff to set up a Mooshak or similar contest (as in the stuff to get the problems, instructions to set up the server itself are easy to google)? Any other idea?

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• DDD - Validation of unique constraint

  - by W3Max

  In DDD you should never let your entities enter an invalid state. That being said, how do you handle the validation of a unique constraint? The creation of an entity is not a real problem. But let say you have an entity that must have a unique name and there is a thousand instances of this entity type - they are not in memory but stored in a database. Now let say you want to rename an instance. You can't just use a setter... the object could enter an invalid state - you have to validate against the database. How do you handle this scenario in a web environment?

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• Programming as a minor

  - by Tomas Cokis

  Hello Everyone! I've never asked a question here at programmers, and for reasons which will become obvious later I've never answered one here, but I do poke around in short bursts. Anyway, I'm 15 right now, and I've been programming in C++ for 4 years, just working on my own projects that are aim so high as to never be finished. I've been working on a single project for the last year, and every 3 months, I add a new system into it. It might be a value tabling directory enabled log system, or a render system, or a class to load up xml files, whatever it is, I don't mind too much that the overall project (a 3d engine) isn't ever going to get finished, I just get some satisfaction from getting what I have done building and running. I don't know what I want to do when I grow up, although I suspect I'll go into some form of engineering, but I was interested in knowing if I do choose to go into a career as a developer, what kind of material I could look at to push myself up and get myself experience that might help my career later. I'm not talking about books in particular, I'm more interested in subjects areas that will get me access to good job opportunities, or that will give me a hand-up if I do computer science and software related courses at uni. One of the things I was thinking of doing was designing some of the logic gate components of a small computer - which I started briefly over the holidays, working out integer addition, subtraction and multiplication. That kind of stuff interests me, but is it really useful - or more useful then just more programming? But anyway, Any advice? Should I continue on my perpetual 3d engine? Are there any other projects or particular accomplishments that would help my education? Perhaps I should mention that I live in Perth, Australia, so local software companies are likely to be more scarce then usual.

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• Getting into game/game engine programming

  - by Darkslash

  So I am interested in learning game programming, but I really have an interest in the lower level engineering in games. I have openGL experience, and I am really interested in learning more about implementing AI, Physics, etc. I have a computer science degree, so I really like getting into technical stuff. Many times when I ask about this sort of thing, I get a lot of "Use an engine", "Use Unity3d", "Why waste your time writing code that already exists", etc etc. My idea was to use simpler libraries such as SFML or XNA so that I could learn how to implement the more complex systems. The thing is, although I do want to write games, I want to learn things that using something like Unity simply doesnt teach you. My goal is not to make a current generation quality 3D game to sell, I just want to make some cool smaller games and learn all I can about the programming side of game development. Is this something that people just do not do anymore? It seems like everywhere I turn people are using Unity or UDK or GameMaker. I fully understand why you would use a tool like these, but I cant see how they would suit my purposes. So where does someone like myself turn? Am I trying to learn something that people just do not bother doing anymore? Is the innovation in this area gone and just all about gameplay now? Im sorry if this question seems silly, but I am genuinely interested in knowing more about this and meeting more people who are interested in this sort of thing.

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• Is a Model Driven Architecture in Language Oriented Programming (MPS) feasible at this time

  - by Steven Jeuris

  As a side project I am developing some sort of DSL where I describe a data model, and generate desired code files from it. I believe this is called Model Driven Architecture. My partial existing implementation uses C#, CodeDOM, XML and XSLT to do this manually. I discovered there already exist better environments to do this in. The one which fascinated me the most is called MPS, which follows the Language Oriented Programming paradigm. This article, written by a cofounder of JetBrains was a real eye opener for me. I truly believe LOP has a very good chance of becoming the next big programming paradigm once it has broader support. From my short experience with MPS, I noticed it is still mainly Java-oriented. My question is, how feasible is it to generate code files for other (multiple) languages instead of just Java. I don't need full language support from the start, so preferably, I need to be able to implement a language in a agile way. E.g. first support only one type, add access modifiers, ... Perhaps some other (free) environment already provides this out of the box. P.S.: I find it important to have a lot of control over the naming conventions and such of the generated code. This is one of the reasons why I started my own implementation.

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• Check For Duplicate Records VS try/catch Unique Key Constraint

  - by Jed

  I have a database table that has a Unique Key constraint defined to avoid duplicate records from occurring. I'm curious if it is bad practice to NOT manually check for duplicate records prior to running an INSERT statement on the table. In other words, should I run a SELECT statement using a WHERE clause that checks for duplicate values of the record that I am about to INSERT. If a record is found, then do not run the INSERT statement, otherwise go ahead and run the INSERT.... OR Just run the INSERT statement and try/catch the exception that may be thrown due to a Unique Key violation. I'm weighing the two perspectives and can't decide which is best- 1. Don't waste a SELECT call to check for duplicates when I can just trap for an exception VS 2. Don't be lazy by implementing ugly try/catch logic VS 3. ???Your thoughts here??? :)

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• eBook editions of programming books

  - by Jon Hopkins

  (I'll get my justification for why this is on topic in early: programming books tend to have fairly specific formatting needs - code samples, tables, images and graphs - which are not common to all book types and are not necessarily well handled by eBook readers. Similarly they're used in different ways - you often dip in and out rather than read cover to cover.) I've just noticed that Don't Make Me Think by Steve Krug is available as an eBook edition for the Kindle (and presumably also for other readers) which set me thinking. There are certain advantages to eBook readers for tech books - primarily that you can carry a massive library of what would be heavy physical books around very easily. The downside is that certain eBook readers allegedly aren't particularly well equipped to cope with tables, code samples and so on and a book like Don't Make Me Think presumably makes extensive use of these sorts of things. So, the question, what are your experiences of reading and using programming books on an eBook reader and would you recommend it? I'm specifically interested in the latest generation Kindle but happy to hear about all devices - might be useful to state which one you use in the answer.

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• Programming and Ubiquitous Language (DDD) in a non-English domain

  - by Sandor Drieënhuizen

  I know there are some questions already here that are closely related to this subject but none of them take Ubquitous Language as the starting point so I think that justifies this question. For those who don't know: Ubiquitous Language is the concept of defining a (both spoken and written) language that is equally used across developers and domain experts to avoid inconsistencies and miscommunication due to translation problems and misunderstanding. You will see the same terminology show up in code, conversations between any team member, functional specs and whatnot. So, what I was wondering about is how to deal with Ubiquitous Language in non-English domains. Personally, I strongly favor writing programming code in English completely, including comments but ofcourse excluding constants and resources. However, in a non-English domain, I'm forced to make a decision either to: Write code reflecting the Ubiquitous Language in the natural language of the domain. Translate the Ubiquitous Language to English and stop communicating in the natural language of the domain. Define a table that defines how the Ubiquitous Language translates to English. Here are some of my thoughts based on these options: 1) I have a strong aversion against mixed-language code, that is coding using type/member/variable names etc. that are non-English. Most programming languages 'breathe' English to a large extent and most of the technical literature, design pattern names etc. are in English as well. Therefore, in most cases there's just no way of writing code entirely in a non-English language so you end up with a mixed languages. 2) This will force the domain experts to start thinking and talking in the English equivalent of the UL, something that will probably not come naturally to them and therefore hinders communication significantly. 3) In this case, the developers communicate with the domain experts in their native language while the developers communicate with each other in English and most importantly, they write code using the English translation of the UL. I'm sure I don't want to go for the first option and I think option 3 is much better than option 2. What do you think? Am I missing other options?

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• NHibernate Unique Constraint on Name and Parent Object fails because NH inserts Null

  - by James

  Hi, I have an object as follows Public Class Bin Public Property Id As Integer Public Property Name As String Public Property Store As Store End Class Public Class Store Public Property Id As Integer Public Property Bins As IEnumerable(Of Bin) End Class I have a unique constraint in the database on Bin.Name and BinStoreID to ensure unique names within stores. However, when NHibernate persists the store, it first inserts the Bin records with a null StoreID before performing an update later to set the correct StoreID. This violates the Unique Key If I persist two stores with a Bin of the same name because The Name columns are the same and the StoreID is null for both. Is there something I can add to the mapping to ensure that the correct StoreID is included in the INSERT rather than performing an update later? We are using HiLo identity generation so we are not relying on DB generated identity columns Thanks James

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• Has anyone else read "Programming video games for the Evil Genius"

  - by Martin

  I bought this book called "Programming Video Games for the Evil Genius" by Ian Cinnamon. If there is anyone who has read or is familiar with this book I am wondering if they think it is worth reading. I am interested in making video games. I have already taken intro courses in C++, Java and Python and got through okay. I've been going through this book for about a month now(SLOWLY). All I have to do is type the code exactly in the book, BUT a lot of the code is not clearly explained. I do some research online but I usually still have some trouble answering my questions. Then I found stack overflow. It's been a ton of help. Right now I am trying to make a racing game right out of this book and I got to a point where the author left a bunch of errors in his code. One of the members of this website fixed it up for me, but added some stuff that I'm having trouble understanding. I spend more time trying to figure out the authors errors and fix them or get someone to help me fix them than I actually do learning code. I REALLY want to learn how to do this and I am ready and willing to put in the time, but I'm not sure if my time would be better spent learning from a different source. Are there any veterans out there that are familiar with this book and think it's worth it/not worth it? Should I try to move onto another book? Any advice for a fresh start for someone who wants to learn some video game programming?

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• HSQLDB Constraint Violation & SQL Query Log for an HSQLDB in-memory setup

  - by shipmaster

  We have a setup where we are using an embedded HSQLDB for backing Hibernate/JPA unit tests in java, and we are using the in-memory database mode since we simply want the database thrown away after the test run. My problem is that one of the tests is failing due to a constraint violation and HSQLDB lists the column as SYS_CT_286, and the query that appears in the log is the prepared statement where I cant see what the actual parameter values are (they are replaced by '?'). My questions are: 1- Is there a way in which I can see the actual SQL being executed? (like the mysql query log for example?). 2- What exactly is SYS_CT_286? it is not one of my columns, is it a generated column? is there something obvious that may be wrong with it? Thanks.

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• How to popularize Nemerle (or another programming language)?

  - by keykeeper

  Any .NET developer who is interested in different programming languages knows that F# is the most popular functional language for the .NET platform nowadays. The only fact describing the popularity of F# is the great support of Microsoft. But we are not limited with F# at all. There are some other functional languages on the .NET platform. I'm very disappointed with the fact that Nemerle isn't well-known. It's an awesome language which supports three paradigms: object-oriented, functional and meta- programming. I won't try to explain why I like it so much. The problem is that I can't use it at work. I think that only really brave companies can rely on Nemerle. It's almost unknown, that's why it's hard to find new developers for the project. Noone wants to make a first step with Nemerle if it can influence the budget what is reasonable. So, here is a question: what can I do to make Nemerle more popular? Here are my first ideas: implement open-source projects using Nemerle; make presentations on different conferences; write articles.

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• How would the 'Model' in a Rails-type webapp be implemented in a functional programming langauge?

  - by ceptorial

  In MVC web development frameworks such as Ruby on Rails, Django, and CakePHP, HTTP requests are routed to controllers, which fetch objects which are usually persisted to a backend database store. These objects represent things like users, blog posts, etc., and often contain logic within their methods for permissions, fetching and/or mutating other objects, validation, etc. These frameworks are all very much object oriented. I've been reading up recently on functional programming and it seems to tout tremendous benefits such as testability, conciseness, modularity, etc. However most of the examples I've seen for functional programming implement trivial functionality like quicksort or the fibonnacci sequence, not complex webapps. I've looked at a few 'functional' web frameworks, and they all seem to implement the view and controller just fine, but largely skip over the whole 'model' and 'persistence' part. (I'm talking more about frameworks like Compojure which are supposed to be purely functional, versus something Lift which conveniently seems to use the OO part of Scala for the model -- but correct me if I'm wrong here.) I haven't seen a good explanation of how functional programming can be used to provide the metaphor that OO programming provides, i.e. tables map to objects, and objects can have methods which provide powerful, encapsulated logic such as permissioning and validation. Also the whole concept of using SQL queries to persist data seems to violate the whole 'side effects' concept. Could someone provide an explanation of how the 'model' layer would be implemented in a functionally programmed web framework?

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• Kids and programming: ScratchKara

  - by Mike Pagel

  Ever now and then I kept wondering how to share with my kids the excitement of creating something with your computer. Of course, today this is a bit more difficult, as they have seen 3D animation games and well-edited websites. I guess that's why they weren't all that hyped when I found my first computer model at our local recycling facilities (an 8-bit Laser VZ-200 with rubber keys). When I finally got it up and running with an old analog TV set they finally asked whether we could play soccer on it. Needless to say that my showing them how it remembers some BASIC commands and lists and executes them did not make any impression. So the question is for real: How do you get today's kids excited about programming? And just recently I looked again for environments that allow even young kids (mine are 7 and 9 years old now) to do something and have fun. Obviously any real, text-oriented programming language wouldn't work well. To cut it short: Something really nice was built by University of Oldenburg: ScratchKara. It is the perfect mixture of Kara, a simulation of a little ladybug and Scratch, an authoring environment from MIT. ScratchKara allows kids to initially simply explore how the bug moves and turns by pressing the action buttons, then move towards sequencing commands through drag & drop, and eventually end up building algorithms with procedures and functions. Even through it is built for kids and beginners, the environment comes with debugging and refactoring, which I found more than amazing. My kids love it and I have to admit I keep thinking about how to solve a bit more advanced problems with this language, which does not allow you to store any state information (other than your call stack). Yes, I am hooked, too... Once the language is understood you can then move to one of the original Kara versions, where you can define the bug's behavior through finite statemachines, Turing tables, Java and other textual languages. And from there, anything is possible.

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• add Constraint on database with trigger

  - by Am1rr3zA

  Hi, I have 3 tables (Student, Course, student_course_choose(have field grade)) I defined a view on these 3 tables that get me an Average of the each student. I want to have constraint(with trigger) on these view(or on the table that need it) to limit the average of each student between 13 and 18. I somewhere read that I must use foreach statement(instead of foreach row) on trigger because when I decrease some grade of special student and his/her average become less than 13 they don't give me error (because later I increase grade of another his/her course ). how must I wrote this Trigger? (I want to implement aprh for testing trigger) note:I can write it in SQL server, oracle or Mysql no diff for me.

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• how do you remember programming related stuff?

  - by dan leadgy

  How do you remember programming related stuff? Did you get the feeling you did encounter the error you have now a few years ago and you could swear you knew the cause but now you forgot it? Did you work with the xsl's string parsing some time ago but now you can't remember exactly which are the string functions altogether from xsl and you have to start from scratch? Or perhaps you forget about some feature from Apache Commons like "filtering a collection by some predicate" that you surely used in the past. So how do you do it? I tried having a blog but when I develop apps, I never find the time to update the blog or write about my experiences. Also, using a wiki is a nice thing but then I found it difficult to keep a clean separation between them since many times I needed to change a blog post to add new information about that topic. This made me think that I actually should have put this topic in the wiki instead of the blog. Do you have any systems that help you remember about your programming experience? What's your setup?

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• Reaching Intermediate Programming Status

  - by George Stocker

  I am a software engineer that's had positions programming in VBA (though I dare not consider that 'real' experience, as it was trial and error!), Perl w/ CGI, C#, and ASP.NET. The latter two are post-undergraduate, with my entrance into the 'real world'. I'm 2 years out of college, and have had 5 years of experience (total) across the languages I've mentioned. However, when it comes to my resume, I can only put 2 years down for C#, and less than a year down for ASP.NET. I feel like I know C#, but I still have to spend time going 'What does this method do?', whereas some of the more senior level engineers can immediately say, "Oh, Method X does this, without ever having looked at that method before." So I know empirically that there's a gulf there, but I'm not exactly sure how to bridge it. I've started programming in Project Euler, and I picked up a book on design patterns, but I still feel like I spend each day treading water, instead of moving forward. That isn't to say that I don't feel like I've made progress, it just means that as far as I come each day, I still see the mountain top way off in the distance. My question is this: How did you overcome this plateau? How long did it take you? What methods can you suggest to assist me in this? I've read through Code Complete, The Mythical Man Month, and CLR via C#, 2nd edition -- my question is: What do I do now? Edit: I just found this question on projects for an intermediate level programmer. I think it adds to the discussion (though it does not supplant my question). As such, I'm adding it to the question as a "For More Information".

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• How to declare a generic constraint that is a generic type

  - by HackedByChinese

  I have a two generic abstract types: Entity and Association. Let's say Entity looks like this: public class Entity<TId> { //... } and Association looks like this: public class Association<TEntity, TEntity2> { //... } How do I constrain Association so they can be of any Entity? I can accomplish it by the following: public class Association<TEntity, TId, TEntity2, TId2> where TEntity : Entity<TId> where TEntity2: Entity<TId2> { //... } This gets very tedious as more types derive from Association, because I have to keep passing down TId and TId2. Is there a simpler way to do this, besides just removing the constraint?

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• Learning Programming during the job?

  - by Hossein

  Introduction: I have read and heard advice, about learning programming by accepting programming projects. I need real assistance to understand this, because: Problem: Although, it would seem to me that one would gain much more technical knowledge by doing, real world projects, if one doesn't know much about a technology, it would add much more risk to the actual delivery of the final product! Even the smallest of real world projects could be too much for a newbie. There is a contradiction here: You need to know the job to do it! and It's recommended to do the job, in order to learn it! Question: Any personal experiences in this case would be very pleasant to know while describing: How new was the subject to you? didn't have a clue at all? Or, did you have experience with similar technologies? Was it a solo project or were you in a team? If team, then did others help you with learning it? Did it work as expected? Did you deliver on time? Do you recommend this approach to others as well?

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• INSERT statement conflicted with the FOREIGN KEY constraint

  - by SmartestVEGA

  I am getting the following error. Could you please help me in ? Msg 547, Level 16, State 0, Line 1 The INSERT statement conflicted with the FOREIGN KEY constraint "FK_Sup_Item_Sup_Item_Cat". The conflict occurred in database "dev_bo", table "dbo.Sup_Item_Cat". The statement has been terminated. insert into sup_item (supplier_id,sup_item_id,name,sup_item_cat_id,status_code,last_modified_user_id,last_modified_timestamp,client_id) values(10162425,10,'jaiso','123123','a','12','2010-12-12','1062425') the last coulum "client_id" i am getting the conflict. I tried to put the value which already exists in the dbo.Sup_Item_Cat to the column corresponding to the sup_item.. but no joy :-(

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• "Programming error" exceptions - Is my approach sound?

  - by Medo42

  I am currently trying to improve my use of exceptions, and found the important distinction between exceptions that signify programming errors (e.g. someone passed null as argument, or called a method on an object after it was disposed) and those that signify a failure in the operation that is not the caller's fault (e.g. an I/O exception). As far as I understand, it makes little sense for an immediate caller to actually handle programming error exceptions, he should instead assure that the preconditions are met. Only "outer" exception handlers at task boundaries should catch them, so they can keep the system running if a task fails. In order to ensure that client code can cleanly catch "failure" exceptions without catching error exceptions by mistake, I create my own exception classes for all failure exceptions now, and document them in the methods that throw them. I would make them checked exceptions in Java. Now I have a few questions: Before, I tried to document all exceptions that a method could throw, but that sometimes creates an unwiedly list that needs to be documented in every method up the call chain until you can show that the error won't happen. Instead, I document the preconditions in the summary / parameter descriptions and don't even mention what happens if they are not met. The idea is that people should not try to catch these exceptions explicitly anyway, so there is no need to document their types. Would you agree that this is enough? Going further, do you think all preconditions even need to be documented for every method? For example, calling methods in IDisposable objects after calling Dispose is an error, but since IDisposable is such a widely used interface, can I just assume a programmer will know this? A similar case is with reference type parameters where passing null makes no conceivable sense: Should I document "non-null" anyway? IMO, documentation should only cover things that are not obvious, but I am not sure where "obvious" ends.

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• I'm looking for a constraint to prevent the insert of an empty string in MySQL

  - by Marga Keuvelaar

  Ok, in this question I learned how to prevent the insert of a NULL value. But, unfortunately, an empty string is being inserted anyway. Apart from preventing this on the PHP side, I'd like to use something like a database constraint to prevent this. Of course a check on the application side is necessary, but I'd like it to be on both sides. I am taught that whatever application is talking to your database, it should not be able to insert basically wrong data in it. So... CREATE TABLE IF NOT EXISTS tblFoo ( foo_id int(11) NOT NULL AUTO_INCREMENT, foo_test varchar(50) NOT NULL, PRIMARY KEY (foo_id) ); Would still allow me to do this insert: INSERT INTO tblFoo (foo_test) VALUES (''); Which I would like to prevent.

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