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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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  • "SQLSTATE[23000]: Integrity constraint violation" in Doctrine

    - by rags
    Hi, i do get an Integrity constraint violation for Doctrine though i really can't see why. Schema.yml User: columns: id: type: integer primary: true autoincrement: true username: type: varchar(64) notnull: true email: type: varchar(128) notnull: true password: type: varchar(128) notnull: true relations: Websites: class: Website local: id foreign: owner type: many foreignType: one onDelete: CASCADE Website: columns: id: type: integer primary: true autoincrement: true active: type: bool owner: type: integer notnull: true plz: type: integer notnull: true longitude: type: double(10,6) notnull: true latitude: type: double(10,6) notnull: true relations: Owner: type: one foreignType: many class: User local: owner foreign: id And here's my data Fixtures (data.yml) Model_User: User_1: username: as email: as****.com password: ***** Model_Website: Website_1: active: true plz: 34222 latitude: 13.12 longitude: 3.56 Owner: User_1

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  • So my employer wants me to do less programming and focus on IT support

    - by Rich
    I was hired into a non tech company's IT department as a programmer a few years back, and after several rounds of lay offs, we're down to a skeleton crew. I've saved the company hundreds of thousands of dollars with my projects and management has been happy with them (although most of the stakeholders have since left the company). Management now wants me to limit the programming that I do and spend most of my time on IT support: putting out fires, dealing with vendors, outsourced contractors, supporting company systems, managing projects, etc. I am a little burnt out on programming since I've been pushed pretty hard for the past several years. However, I'm not sure if this is a good career move in the long run. I'm a decent programmer (and also good with databases) but not obsessed with it to the point of coding outside of work. I'm approaching my mid 30s and there's potential ageism to deal with down the line. While I'm fortunate to have survived the lay offs, it sorta feels like my job is being "dumbed down". I have both good technical skills and people skills...but it doesn't take a genius to do what I'm doing now. And my success is being increasingly linked to others' performance rather than my own... Just looking for some advice. Is it time to move on? That's not really an easy thing to do since I'd likely have to move to another area to find another comparable tech job. Should I go after another pure technical role? Or should I stay and try to make this work? People say do what you "enjoy" but it doesn't really matter to me as long as I'm getting paid. Also the ageism thing is on the horizon and could be an issue eventually. I'm making a decent (but not great) salary. Should I chase money and maximize my income while I still have a chance? Or be happy with a moderate salary and 40 hour work week?

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  • Unique constraint with nullable column

    - by Álvaro G. Vicario
    I have a table that holds nested categories. I want to avoid duplicate names on same-level items (i.e., categories with same parent). I've come with this: CREATE TABLE `category` ( `category_id` int(10) unsigned NOT NULL AUTO_INCREMENT, `category_name` varchar(100) NOT NULL, `parent_id` int(10) unsigned DEFAULT NULL, PRIMARY KEY (`category_id`), UNIQUE KEY `category_name_UNIQUE` (`category_name`,`parent_id`), KEY `fk_category_category1` (`parent_id`,`category_id`), CONSTRAINT `fk_category_category1` FOREIGN KEY (`parent_id`) REFERENCES `category` (`category_id`) ON DELETE SET NULL ON UPDATE CASCADE ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_spanish_ci Unluckily, category_name_UNIQUE does not enforce my rule for root level categories (those where parent_id is NULL). Is there a reasonable workaround?

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  • Grails Unique Constraint for Groups

    - by WaZ
    Hi there, I have the following requirement I have 3 domains namely: class Product { String productName static constraints = { productName(unique:true,blank:false) } class SubType { String subTypeName static constraints = { subTypeName(unique:true,blank:false) } String toString() { "${subTypeName}" } } class CLType { String TypeName static belongsTo = Car static hasMany = [car:Cars] static constraints = { } String toString() { "${TypeName}" } class CLines implements Serializable { Dealer dealer CLType clType SubType subType Product product static constraints = { dealer(nullable:false,blank:false,unique:['subType','product','clType']) clType(blank:false,nullable:false) subType(nullable:true) product(nullable:true) } } I want to achieve this combination: A user can assign dealer a CLType. But cannot have duplicates. As an example consider this scenario Please let me know what to mention in my unqiue constraint to make this possible? Thanks, Much Appreciated.

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  • Best (functional?) programming language to learn coming from Mathematica

    - by Will Robertson
    As a mechanical engineering PhD student, I haven't had a great pedigree in programming as part of my “day job”. I started out in Matlab (having written some Hypercard and Applescript back in the day, and being introduced to Ada, of all things, in my 1st undergrad year), learned to program—if you can call it that—in (La)TeX; and finally discovered and fell for Mathematica. Now I'm interested in learning a "real" programming language that I can enjoy in the same sort of style as Mathematica, which tries to stress functional programming since it seems to map more nicely to how certain kinds of mathematics can be written algorithmically. So which functional language should I learn? I guess the obvious answer is “as many as possible”, but let's start out humble and give a single, well-considered option a good crack. I've heard good things about, say, Haskell and Scala, but I wonder if (given my non–computer science background) I'd be better off starting in more “grounded” territory and going with Ruby or Python (the latter having the big advantage of being used for Sage, which I'd also like to investigate…after my PhD). Well, I guess this is pretty subjective, so perhaps I could rephrase: would it be better to start looking at Haskell (say) straight after an ad-hoc education to functional programming in Mathematica, or will I get more out of learning Python (say) first? In reference to the question "what do I want to do with it?", I guess my answer is "fun, and learning more". I've got this list of languages that I'd like to look at, and I don't know how to trim them down. And I'd rather start with something a little higher-level than C simply so that I can be somewhat productive without having to re-invent many wheels for any code I'd like to write.

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  • What's the benefit to learn Java programming?

    - by user30139
    I'm from the PHP world. Recently I'm trying to learn about Java. Because simply I'm a bit interested in Android development. Learning about Java gives more control about my cellphone. Say I could fine tune some applications to fit my personal requirements or even make my own ones. Still Java is a new world to me. I guess I'm already too comfortable with weak typed languages such as PHP. Honestly I think application development of no matter which kind wouldn't make too much difference. Because just as web development mostly framework based, what the developer do is to fill the blanks meaning to follow the protocols the given by the framework. Most of the code is still about business logic, that's what application development all about, right? The big difference seems to lie on the programming languages. Comparing to PHP, Java holds a whole package of constraints and practices. At this point, what are the benefits to learn programming in it?

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  • Review - Professional Android Programming with Mono for Android and .NET/C#

    - by Wallym
    Mike Riley of Dev Pro Connections Magazine has a review of our Mono for Android book.  You can read the full review on their siteMono for Android has been available for more than a year. The documentation for the product is adequate and has been improving over time, but until recently, finding a good book about the technology was difficult. Such a constraint has been lifted thanks to Wiley's Professional Android Programming with Mono for Android and .NET/C#. Written under the Wrox imprint by several contributors (Wallace B. McClure, Nathan Blevins, John J. Croft, Jonathan Dick, and Chris Hardy), the book is one of the most comprehensive and helpful Mono for Android titles currently on the market. Please buy 8-10 copies of our book for the ones you love, they make great romantic gifts.

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  • Why do some programmers think there is a contrast between theory and practice?

    - by Giorgio
    Comparing software engineering with civil engineering, I was surprised to observe a different way of thinking: any civil engineer knows that if you want to build a small hut in the garden you can just get the materials and go build it whereas if you want to build a 10-storey house you need to do quite some maths to be sure that it won't fall apart. In contrast, speaking with some programmers or reading blogs or forums I often find a wide-spread opinion that can be formulated more or less as follows: theory and formal methods are for mathematicians / scientists while programming is more about getting things done. What is normally implied here is that programming is something very practical and that even though formal methods, mathematics, algorithm theory, clean / coherent programming languages, etc, may be interesting topics, they are often not needed if all one wants is to get things done. According to my experience, I would say that while you do not need much theory to put together a 100-line script (the hut), in order to develop a complex application (the 10-storey building) you need a structured design, well-defined methods, a good programming language, good text books where you can look up algorithms, etc. So IMO (the right amount of) theory is one of the tools for getting things done. So my question is why do some programmers think that there is a contrast between theory (formal methods) and practice (getting things done)? Is software engineering (building software) perceived by many as easy compared to, say, civil engineering (building houses)? Or are these two disciplines really different (apart from mission-critical software, software failure is much more acceptable than building failure)?

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  • alot questings since i wanted to make a new SSB game or mario game(that use 3d models) [closed]

    - by user20465
    i have just started to study programming and i know already ppl will say why make a so big project like as a SSB game for a noob game development? cuz i always wanted a SSB engine like as Mugen is a fighter game engine but is not like as SSB´s gameplay + is not using 3d models too so i will call it SSBmugen(until i find a better title for it i got afew ideas for titles) also i wanted to make this game so it can use SSBbrawl files(models+animations mainly) the moveset+Stage coding files i wanted to redo cuz so anything can be possible like make a teleporter or a pipe teleporter(like as Super mario bros game) on a stag e or make some stuff there is impossible in SSBbrawl for moveset coding but is not in SSBmugen like make so a char. summon a Clone and the clone will do a attack and then is gone or some attacks/moves also i will make a moveset/stage Coding editor so it will be really easy to make moveset/stages coding for yours 3d models/animations moveset+stage Coding i mean: hitboxes/hurtboxes/moving Stuff/moving bones like cape or hair bones that is moving by wind effects or falling or other stuff like that/other stuff that needed to be coded i have planed to make a editor(for moveset/char. coding) or add the editor in brawlbox for my game so other ppl can easy make moveset/stages Coding to they´s models/animations so it will be easy so even kids can make a custom movesets/stages why using SSBbrawl files?: cuz ppl have made alot of models or textures/custom movesets/custom stages like goku/other anime/not brawl stuff for super smash bros brawl hacking(a.k.a modding) so ppl dont have to redo anything if they wanted to have the custom models or textures/custom movesets/custom stages from SSBbrawl to SSBmugen +there is the program named brawlbox that can open brawl files like model/animations and can edit models or animations and import models from 3ds max to be the right model format for SSBbrawl and i also wanted it so easy to add(a.k.a installer) Recolours or alt. models(like as oneslot doctor mario model over mario´s boneset) or textures/Movesets/new char. slots/new stages so easy so you only needing to download themplace them in right foldername them the right nameStart the gameRecolours or alt. models or textures/Movesets/new char. slots/new stages works an loading right so you wont needing to edit any files for add something so kids/not so smart ppl can easy use the mods other ppl is making/uploading for this game here is the file format i wanted to know if they can be readed/opened if making a game that use these files: .mld0(brawl model file) .chr0(model animation for moving/scale/rota the bones) .srt0(animations for texture like moving eyes or blinking) .vis0(Animations for get polygons to hide/show with visibilitybones on the model there is also some polygons there ) .brres(a file format where stuff like model files or textures or animations is inside) .pac(a file format where the .brres is inside to keep model+textures+model for the shadow in 1 file) .wav (for SoundFX effects or voices to char. or stages) i am sure that one is possible the .wav files is inside a other file format for brawl but that file can´t you add more .wav files inside only replace so i wanted the .wav files outside so its easy to add/replace/remove SoundFX effects or voices to char. or stages .brstm(brawl music file so the music is looped perfect so it loop in middel of the music and not start over again then the music is done) afew more file formats (mainly for the Graphics effects like fire/aura/hit effects if not needing to redo them)so only coding in the editor i will make is needed to be done for port a SSBB hack(a.k.a mod)(moveset/stage coding) to this game wanted the game to be able to load these files and load them right like if loading wait1.chr0(idle animation) it will also load at same time wait1.srt0/wait1.vis0 and all kinda of animations is inside the same .brres file i am needing since it to be able to load the file format i wanted cuz: -the animations can´t be converted to any other animation file format and i dont think ppl want to redo these animations(inc. me for Goku to SSBbrawl) -models can be converted but then they lose all the shader/materials stuff like a shine effect or lighting on the model -.brstm can be converted to .wav but then there will be no loop so i prefer it can load this file format too for the music to stage/menu -brawlbox is really easy to use for make animation for the char. and import models from 3ds max so even around "not too stupid" 10 year kids can make SSBB mods(not try to be rude but to say how easy it is) also i wanted the folder setup for characters/stages/moveset/other stuff to be like this: https://www.dropbox.com/s/2oolm5z5ri234tz/SSBmugen%20Folder%20setup.txt just uploaded a txt file since it is a wall of text and this post is already a wall of test so it easy to place stuff (if not i do a program for to that so it auto place the stuff on right place) not 100% sure what to use of game engine to make this possible but i got a dll file from that brawlbox program that can open/read/edit these file formats if that helps i also got open source of brawlbox i have kinda learned programming(since its kinda the same thing but still not 100% same) from Super smash bros modding/hacking like coding a moveset for the new animations/models + have readed alittle about it but i am soon starting for real to study it for ppl who is alittle confuse for what i am asking for here is the list: -what game engine should i use to make a SSB clone? but at same time to make all this stuff i just said possible so ppl can make they own mods and share them and use the already made mods from SSBbrawl? and easy to use aswell so noob programmors can use it? -where to learning programming on internet to be even more ready to make a game like this? and dont wanted to start in the small like making small boring 2d games that no one care about anyway ps. i am also planing a other project like as SSBmugen but it will be Super mario bros open (again tittle unsure but open means open source) i will make a Mario game engine that also use 3d models and can have 2d or 3d gameplay with any mario powerups/gameplay(from any mario platform games) there is ever made multiplayer like as in New super mario bros wii maybe multiplay over lan or online but for now over 1 PC also alittle planed for that to my SSBmugen a Level/world map editor for it too(easy to use so even kids can use it and make levels for it) so it just place the objects/enemies and options for them enemies since they are not 100% same AI in all mario game like to choose a goomba have AI from SM64 the Editor will be able to change the gameplay on a level while have a other gameplay on a other level like this: 1 level have Super mario bros 3 gameplay (then it will be a 3d model remake) a other level have super mario galaxy gameplay but in a Super mario 3d land level yet a other level have super mario 64 gameplay but with powerups from a other mario game like powerups from mario 3d land or can ride on Yoshi so you can easy remake your fav. level from a old mario game in this mario engine/editor or just make a custom one with yours fav. mario gameplay/powerups so it will be like turn off/on: walljump/triple jump/other kinda or jumps/2x punch and 1 kick+Air kick/SMG spin attack/Fludd/other stuff like that so you can make the gameplay from the first mario game to the newest or make custom gameplay on a level also the star(from 64/sunshine/galaxy) will be replaced with the flag from new super mario bros/mario 3d land since the game is not so much about getting stars its more about making/download the levels you wanted and share them to other ppl and play these level so after have killed like the boss from SM64 bomb omb field(if one have made that) you will get the flag instead of star since i wanted it to be simple to make levels in the editor to make the bosses/new enemies/new powerups/custom char. idk what to do to make that simple yet also thinking the mario game will use brawl files since it almost already got all needed animations/models for this since i dont wanted to redo animations/models and if needing more animations i can just make them easy in brawlbox since thats the program i am most used to make animations but that will be after my SSBmugen project if not this game will be easyer then SSBmugen to make since i am planing then 1 of them is done i use the that game as base to make the other (since both is kinda platfrom games and possible using same file format for both) also wanted to ask what is best to start with out of these 2 games? also will maybe make a DLC site(or ingame) for both of these games if they get done so it wont end up like as Mugen where you needing to look all over the internet to find the stuff you wanted but for my game all the mods for my game is on same place not sure about online mode for SSBmugen or super mario bros open but i can always add that then i get better at programming both games also need to have options on controls/if using joystick also that i have planed these game for a long time and got even more ideas for them but first i wanted to get them to work so i can add the other stuff later(like DLC or online mode or some other stuff later) right now i know 0,0001% to programming(in my option) maybe i know more then that since i have been study it alittle but i learning while making stuff like this that was also my plan for make these game learn while making them and get better to programming so again i say it i kinda dont want to hear dont do these projects cuz i already know it will be hard so dont wanted so much to heard stuff like: you can´t do it since you just started learning programming or this project will fail since somewhere i needing to get started with programming and this is where i want to start to make my dream games(possible other´s dream games too) and i dont think this project will fail if i work hard on it (as i possible will) and ppl will maybe help i think this was all my questing/ideas for now (sorry for it sounds more like ideas then questings) but i needing to say my ideas so you ppl can see what i needing to use for make this possible

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  • Fixed-Function vs Shaders: Which for beginner?

    - by Rob Hays
    I'm currently going to college for computer science. Although I do plan on utilizing an existing engine at some point to create a small game, my aim right now is towards learning the fundamentals: namely, 3D programming. I've already done some research regarding the choice between DirectX and OpenGL, and the general sentiment that came out of that was that whether you choose OpenGL or DirectX as your training-wheels platform, a lot of the knowledge is transferrable to the other platform. Therefore, since OpenGL is supported by more systems (probably a silly reason to choose what to learn), I decided that I'm going to learn OpenGL first. After I made this decision to learn OpenGL, I did some more research and found out about a dichotomy that I was somewhere unaware of all this time: fixed-function OpenGL vs. modern programmable shader-based OpenGL. At first, I thought it was an obvious choice that I should choose to learn shader-based OpenGL since that's what's most commonly used in the industry today. However, I then stumbled upon the very popular Learning Modern 3D Graphics Programming by Jason L. McKesson, located here: http://www.arcsynthesis.org/gltut/ I read through the introductory bits, and in the "About This Book" section, the author states: "First, much of what is learned with this approach must be inevitably abandoned when the user encounters a graphics problem that must be solved with programmability. Programmability wipes out almost all of the fixed function pipeline, so the knowledge does not easily transfer." yet at the same time also makes the case that fixed-functionality provides an easier, more immediate learning curve for beginners by stating: "It is generally considered easiest to teach neophyte graphics programmers using the fixed function pipeline." Naturally, you can see why I might be conflicted about which paradigm to learn: Do I spend a lot of time learning (and then later unlearning) the ways of fixed-functionality, or do I choose to start out with shaders? My primary concern is that modern programmable shaders somehow require the programmer to already understand the fixed-function pipeline, but I doubt that's the case. TL;DR == As an aspiring game graphics programmer, is it in my best interest to learn 3D programming through fixed-functionality or modern shader-based programming?

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  • An ideal way to decode JSON documents in C?

    - by AzizAG
    Assuming I have an API to consume that uses JSON as a data transmission method, what is an ideal way to decode the JSON returned by each API resource? For example, in Java I'd create a class for each API resource then initiate an object of that class and consume data from it. for example: class UserJson extends JsonParser { public function UserJson(String document) { /*Initial document parsing goes here...*/ } //A bunch of getter methods . . . . } The probably do something like this: UserJson userJson = new UserJson(jsonString);//Initial parsing goes in the constructor String username = userJson.getName();//Parse JSON name property then return it as a String. Or when using a programming language with associative arrays(i.e., hash table) the decoding process doesn't require creating a class: (PHP) $userJson = json_decode($jsonString);//Decode JSON as key=>value $username = $userJson['name']; But, when I'm programming in procedural programming languages (C), I can't go with either method, since C is neither OOP nor supports associative arrays(by default, at least). What is the "correct" method of parsing pre-defined JSON strings(i.e., JSON documents specified by the API provider via examples or documentation)? The method I'm currently using is creating a file for each API resource to parse, the problem with this method is that it's basically a lousy version of the OOP method, as it looks exactly like the OOP method but doesn't provide any OOP benefits(e.g., can't pass an object of the parser, etc.). I've been thinking about encapsulating each API resource parser file in a publicly accessed structure(pointing all functions/publicly usable variables to the structure) then accessing the parser file code from within the structure(parser.parse(), parser.getName(), etc.). As this way looks a bit better than the my current method, it still just a rip off the OOP way, isn't it? Any suggestions for methods to parse JSON documents on procedural programming lanauges? Any comments on the methods I'm currently using(either 3 of them)?

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  • What language and topics should be covered when teaching non-CS college students how to program?

    - by michaelcarrano
    I have been asked by many of my non-computer science friends to teach them how to program. I have agreed to hold a seminar for them that will last for approximately 1 to 2 hours. My thoughts are to use Python as the language to teach them basic programming skills. I figured Python is relatively easier to learn from what I have researched. It is also a language I want to learn which will make holding this seminar all the more enjoyable. The topics I plan to cover are as followed: Variables / Arrays Logic - If else statements, switch case, nested statements Loops - for, while, do-while and nested loops Functions - pass by value, pass by reference (is this the correct terms for Python? I am mostly a C/C++ person) Object Oriented Programming Of course, I plan to have code examples for all topics and I will try to have each example flow into each other so that at the end of the seminar everyone will have a complete working program. I suppose my question is, if you were given 1 to 2 hours to teach a group of college students how to program, what language would you choose and what topics would you cover? Update: Thank you for the great feedback. I should have mentioned in my earlier post above that a majority of the students attending the seminar have some form of programming experience whether it was with Java or using Matlab. Most of these students are 3rd/4th year Engineering students who want to get a refresher on programming before they graduate.

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  • What kind of knowledge do you need to invent a new programming language?

    - by systempuntoout
    I just finished to read "Coders at works", a brilliant book by Peter Seibel with 15 interviews to some of the most interesting computer programmers alive today. Well, many of the interviewees have (co)invented\implemented a new programming language. Some examples: Joe Armstrong: Inventor of Erlang L. Peter Deutsch: implementer of Smalltalk-80 Brendan Eich: Inventor of JavaScript Dan Ingalls: Smalltalk implementor and designer Simon Peyton Jones: Coinventor of Haskell Guy Steele: Coinventor of Scheme Is out of any doubt that their minds have something special and unreachable, and i'm not crazy to think i will ever able to create a new language; i'm just interested in this topic. So, imagine a funny\grotesque scenario where your crazy boss one day will come to your desk to say "i want a new programming language with my name on it..take the time you need and do it", which is the right approach to studying this fascinating\intimidating\magic topic? What kind of knowledge do you need to model, design and implement a brand new programming language?

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  • What kind of knowledge you need to invent a new programming language?

    - by systempuntoout
    I just finished to read "coders at works", a brilliant book by Peter Seibel with 15 interviews to some of the most interesting computer programmers alive today. Well, many of the interviewees have (co)invented\implemented a new programming language. For example: * Joe Armstrong: Inventor of Erlang * L. Peter Deutsch: implementer of Smalltalk-80 * Brendan Eich: Inventor of JavaScript * Dan Ingalls: Smalltalk implementor and designer * Simon Peyton Jones: Coinventor of Haskell * Guy Steele: Coinventor of Scheme Is out of any doubt that their minds have something special and unreachable, and i'm not crazy to think i will ever able to create a new language; i'm just interested in this topic. So, imagine a funny\grotesque scenario where your crazy boss one day will come to your desk to say "i want a new programming language with my name on it..take the time you need and do it", what will you start to study? What kind of knowledge do you need to model, design and implement a brand new programming language?

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  • Can you help me think of problems for my programming language?

    - by I can't tell you my name.
    I've created an experimental toy programming language with a (now) working interpreter. It is turing-complete and has a pretty low-level instruction set. Even if everything takes four to six times more code and time than in PHP, Python or Ruby I still love programming all kinds of things in it. So I got the "basic" things that are written in many languages working: Hello World Input - Output Countdowns (not as easy as you think as there are no loops) Factorials Array emulation 99 Bottles of Beer (simple, wrong inflection) 99 Bottles of Beer (canonical) Conjatz conjecture Quine (that was a fun one!) Brainf*ck interpreter (To proof turing-completeness, made me happy) So I implemented all of the above examples because: They all used many different aspects of the language They are pretty interesting They don't take hours to write Now my problem is: I've run out of ideas! I don't find any more examples of what problems I could solve using my language. Do you have any programming problems which fit into some of the criteria above for me to work out?

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  • What theoretical and/or experimental programming-language features are there?

    - by Gary Rake
    I'm designing a programming language, purely for fun, and want to add as many experimental features as I can, just to make programming in it something completely different, and that not in a bad way like Brainf*ck or Malbolge. However, I seem to be quite bad at coming up with new things for it but I'm sure that there are tons of things out there that have been talked about but never really tried out. What experimental language features or concepts not implemented in mainstream languages are there at the moment? E.g: If I asked this in, let's say, 1960, an answer could be "Object-oriented programming". I'm sure that there are a lot of unimplemented ideas computer-scientists have (recently) come up with, at least I was told so.

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  • Which programming paradigm or language open most your mind?

    - by Dom De Felice
    It is often said that some programming languages exist that once grasped can open your mind and change the way you write software. A sort of "software design enlightenment", we can say. I heard this about Lisp, Smalltalk, Haskell, pure functional programming in general.. What are your experiences about this? I know that the right language to use depends on your needs, but I would like to know the one that better improve your programming skills in general. What do you think would be the best language/paradigm to learn to end up being a better programmer in the long run?

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  • How to learn programming language (syntax rules, etc.) and remember easily? [closed]

    - by user239522
    I'm new to programming, and I always have a so call difficulty, that is, I always tend to forget the thing (syntax, rules, name, definition or anyting) of a programming language I've learnt. And I personally do feel that the way I learn it is wrong. Here is my method. Everyday I will spend approximately 1 or 2 hours on a programming e-book. I just follow the syllabus and teaching inside the books, of course I have try to code myself, alter the code inside the book, and did the exercises available. But everytime right after I finish a chapter and advanced myself to third or fourth chapter, I will forgot something I learnt in the first chapter. Is it the method I use wrong? Does learning through reading and coding not enough? Do I need to everytime make a small note (mind map for example) of things I've learnt by hand writing? Or do I sometime need to try coding using a pencil and a book, but not a computer?

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  • LINQ To SQL ignore unique constraint exception and continue

    - by Martin
    I have a single table in a database called Users Users ------ ID (PK, Identity) Username (Unique Index) I have setup a unique index on the Username table to prevent duplicates. I am then enumerating through a collection and creating a new user in the database for each item. What I want to do is just insert a new user and ignore the exception if the unique key constraint is violated (as it's clearly a duplicate record in that case). This is to avoid having to craft where not exists kind of queries. First off, is this going to be any more efficient or should my insert code be checking for duplicates instead? I'm drawn more to the database having that logic as this prevents any other type of client from inserting duplicate data. My other issue is related to LINQ To SQL. I have the following code: public class TestRepo { DatabaseDataContext database = new DatabaseDataContext(); public void Add(string username) { database.Users.InsertOnSubmit(new User() { Username = username }); } public void Save() { database.SubmitChanges(); } } And then I iterate over a collection and insert new users, ignoring any exceptions: TestRepo repo = new TestRepo(); foreach (var name in new string[] { "Tim", "Bob", "John" }) { try { repo.Add(name); repo.Save(); } catch { } } The first time this is run, great I have three users in the table. If I remove the second one and run this code again, nothing is inserted. I expected the first insert to fail with the exception, the second to succeed (as I just removed that item from the DB) and the third to then fail. What seems to be happening is that once the SqlException is thrown (even though the loop continues to iterate) all of the next inserts fail - even when there isn't a row in the table that would cause a unique violation. Can anyone explain this? P.S. The only workaround I could find was to instantiate the repo each time before the insert, then it worked exactly as excepted - indicating that it's something to do with the LINQ To SQL DataContext. Thanks.

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  • ASP MVC C#: LINQ Foreign Key Constraint conflicts

    - by wh0emPah
    I'm having a problem with LINQ. I have 2 tables (Parent-child relation) Table1: Events (EventID, Description) Table2: Groups (GroupID, EventID(FK), Description) Now i want to create an Event an and a child. Event e = new Event(); e.Description = "test"; Datacontext.Events.InsertOnSubmit(event) Group g = new Group(); g.Description = "test2"; g.EventID = e.EventID; Datacontext.Groups.InsertOnSubmit(g); Datacontext.SubmitChanges(); When i debug, i can see that after inserting the event. the EventID has gotten a new value (auto increment). But when Datacontext.SubmitChanges(); gets called. I get the following exception "The INSERT statement conflicted with the FOREIGN KEY constraint ... I know this can be solved by creating a relation in the LINQ diagram between Events and groups. And then setting the entity itself. But i don't want to load the events everytime i ask a list of groups. All i need is some way that when inserting the group fails, the event insert won't be comitted in the database. Sorry if this is a bit unclear, My english isn't really good. Thanks in advance!

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  • Hibernate triggering constraint violations using orphanRemoval

    - by ptomli
    I'm having trouble with a JPA/Hibernate (3.5.3) setup, where I have an entity, an "Account" class, which has a list of child entities, "Contact" instances. I'm trying to be able to add/remove instances of Contact into a List<Contact> property of Account. Adding a new instance into the set and calling saveOrUpdate(account) persists everything lovely. If I then choose to remove the contact from the list and again call saveOrUpdate, the SQL Hibernate seems to produce involves setting the account_id column to null, which violates a database constraint. What am I doing wrong? The code below is clearly a simplified abstract but I think it covers the problem as I'm seeing the same results in different code, which really is about this simple. SQL: CREATE TABLE account ( INT account_id ); CREATE TABLE contact ( INT contact_id, INT account_id REFERENCES account (account_id) ); Java: @Entity class Account { @Id @Column public Long id; @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true) @JoinColumn(name = "account_id") public List<Contact> contacts; } @Entity class Contact { @Id @Column public Long id; @ManyToOne(optional = false) @JoinColumn(name = "account_id", nullable = false) public Account account; } Account account = new Account(); Contact contact = new Contact(); account.contacts.add(contact); saveOrUpdate(account); // some time later, like another servlet request.... account.contacts.remove(contact); saveOrUpdate(account); Result: UPDATE contact SET account_id = null WHERE contact_id = ? Edit #1: It might be that this is actually a bug http://opensource.atlassian.com/projects/hibernate/browse/HHH-5091

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  • Rails: Oracle constraint violation

    - by justinbach
    I'm doing maintenance work on a Rails site that I inherited; it's driven by an Oracle database, and I've got access to both development and production installations of the site (each with its own Oracle DB). I'm running into an Oracle error when trying to insert data on the production site, but not the dev site: ActiveRecord::StatementInvalid (OCIError: ORA-00001: unique constraint (DATABASE_NAME.PK_REGISTRATION_OWNERSHIP) violated: INSERT INTO registration_ownerships (updated_at, company_ownership_id, created_by, updated_by, registration_id, created_at) VALUES ('2006-05-04 16:30:47', 3, NULL, NULL, 2920, '2006-05-04 16:30:47')): /usr/local/lib/ruby/gems/1.8/gems/activerecord-oracle-adapter-1.0.0.9250/lib/active_record/connection_adapters/oracle_adapter.rb:221:in `execute' app/controllers/vendors_controller.rb:94:in `create' As far as I can tell (I'm using Navicat as an Oracle client), the DB schema for the dev site is identical to that of the live site. I'm not an Oracle expert; can anyone shed light on why I'd be getting the error in one installation and not the other? Incidentally, both dev and production registration_ownerships tables are populated with lots of data, including duplicate entries for country_ownership_id (driven by index PK_REGISTRATION_OWNERSHIP). Please let me know if you need more information to troubleshoot. I'm sorry I haven't given more already, but I just wasn't sure which details would be helpful.

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  • Namespace constraint with generic class decleration

    - by SomeGuy
    Good afternoon people, I would like to know if (and if so how) it is possible to define a namespace as a constraint parameter in a generic class declaration. What I have is this: namespace MyProject.Models.Entities <-- Contains my classes to be persisted in db namespace MyProject.Tests.BaseTest <-- Obvious i think Now the decleration of my 'BaseTest' class looks like so; public class BaseTest<T> This BaseTest does little more (at the time of writing) than remove all entities that were added to the database during testing. So typically I will have a test class declared as: public class MyEntityRepositoryTest : BaseTest<MyEntity> What i would LIKE to do is something similar to the following: public class BaseTest<T> where T : <is of the MyProject.Models.Entities namespace> Now i am aware that it would be entirely possible to simply declare a 'BaseEntity' class from which all entities created within the MyProject.Models.Entities namespace will inherit from; public class BaseTest<T> where T : MyBaseEntity but...I dont actually need to, or want to. Plus I am using an ORM and mapping entities with inheritance, although possible, adds a layer of complexity that is not required. So, is it possible to constrain a generic class parameter to a namespace and not a specific type ? Thank you for your time.

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  • "Parallel Programming Talk" show

    Over at the Intel Software Network Aaron Tersteeg runs a "Parallel Programming Talk" audio show on which I was invited as a guest (for the 55th episode) to talk about Microsoft's parallelism offerings in Visual Studio 2010. The call started at 7:45AM, so if my voice sounds croaky to you, now you know why ;)Check out the 20-minute chat (and related hyperlinks) on Aaron's blog. Comments about this post welcome at the original blog.

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