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• Python design mistakes

  - by Andrea

  A while ago, when I was learning Javascript, I studied Javascript: the good parts, and I particularly enjoyed the chapters on the bad and the ugly parts. Of course, I did not agree with everything, as summing up the design defects of a programming language is to a certain extent subjective - although, for instance, I guess everyone would agree that the keyword with was a mistake in Javascript. Nevertheless, I find it useful to read such reviews: even if one does not agree, there is a lot to learn. Is there a blog entry or some book describing design mistakes for Python? For instance I guess some people would count the lack of tail call optimization a mistake; there may be other issues (or non-issues) which are worth learning about.

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• Drawing unfilled rectangle shape in c++ openGL

  - by Bahaa

  I want to draw unfilled rectangle shape in openGL using c++ programming language but when I used the glBegin(GL_QUADS) or glBegin(GL_POLYGON), the resulted shape is filled but I want to be unfilled. How I can draw unfilled rectangle. void draweRect(void) { glClear(GL_COLOR_BUFFER_BIT); glColor3f(0.0,0.0,1.0); glLineWidth(30); glBegin(GL_POLYGON); glVertex2i(50,90); glVertex2i(100,90); glVertex2i(100,150); glVertex2i(50,150); glEnd(); glFlush(); }

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• Reference variable to an object instantiated/initialized in another class in Java

  - by Alex

  The reason I'm asking is because I'm getting NullPointerException. I now this is very easy but I'm pretty new programming and find this a bit confusing. So say I have initialized an object in a class and want to access that same object from another class. Like now for instance I'm working on a small Chess game, in my model Game class I have an instance of Board, an object. Board, in turn, has an array of Squares. Square[][]. Game has board, board has Square[][]. Now if I want to access the Square[][] through the object board (in Game) of type Board. Do I just declare a variable with the same name and type or do I have to initialize it again? Board board OR Board board = new Board(); Note, I have already initialized board in the class Game so if I do it again, won't they be two totally different Board objects?

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• How to handle huge table ?

  - by misha-moroshko

  I would like to display to user a table which contains ~500,000 rows. The table should be calculated based on a file (i.e. the table is known at the beginning, and does not change). I guess that building the HTML text of this table is not a good idea in terms of memory performance. So how can I build such table ? I would like user to be able to scroll the table using a vertical scroll bar. Is it possible to build on the fly only the visible part of the table ? I'm afraid to see delays because of this. Is it a better idea to use server side programming rather than Javascript ? Any advise would be appreciated.

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• Expected symbol problems with this function declaration

  - by Derek

  I am just getting back into the C programming realm and I am having an issue that I think is linker related. I am using cmake for the first time as well, so that could be adding to my frustration. I have included a third party header file that contains a typedef that my code is trying to use, and it has this line: typedef struct a a_t so my code has a_t *var; //later..... var->member;// this line throws the error which throws the error: dereferencing pointer to incomplete type So am I just missing another include file, or is this a linker issue? I am building this code in QtCreator and using cmake. I can dive on a_t to see that typedef declaration in the included header, but I can't seem to dive on "struct a" itself to see where it's coming from. Thanks

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• How compiling circular dependencies works?

  - by Fabio F.

  I've made the example in Java but I think (not tested) that it works in other (all?) languages. You have 2 files M.java that says public class MType{ XType x; MType(){ x = null;} } and another file XType.java (in the same directory) public class XType{ MType m; public XType(MType m){ this.m=m;} } Ok it's BAD programming , but.. if you run javac XType it compiles: compiles even MTypes because XType needs it. But.. MType needs XType.. how it works? How does the compiler know what is happening? Probably is a stupid question, but I would like to know how the compiler (javac or other compilers if you know.) manages that situation, not how to avoid it. I'm asking because i'm writing a precompiler and I would like to manage that situation.. Thank you

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• Consolidating separate Loan, Purchase & Sales tables into one transaction table.

  - by Frank Computer

  INFORMIX-SE with ISQL 7.3: I have separate tables for Loan, Purchase & Sales transactions. Each tables rows are joined to their respective customer rows by: customer.id [serial] = loan.foreign_id [integer]; = purchase.foreign_id [integer]; = sale.foreign_id [integer]; I would like to consolidate the three tables into one table called "transaction", where a column "transaction.trx_type" [char(1)] {L=Loan, P=Purchase, S=Sale} identifies the transaction type. Is this a good idea or is it better to keep them in separate tables? Storage space is not a concern, I think it would be easier programming & user=wise to have all types of transactions under one table.

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• python: find and replace numbers < 1 in text file

  - by hjp

  I'm pretty new to Python programming and would appreciate some help to a problem I have... Basically I have multiple text files which contain velocity values as such: 0.259515E+03 0.235095E+03 0.208262E+03 0.230223E+03 0.267333E+03 0.217889E+03 0.156233E+03 0.144876E+03 0.136187E+03 0.137865E+00 etc for many lines... What I need to do is convert all the values in the text file that are less than 1 (e.g. 0.137865E+00 above) to an arbitrary value of 0.100000E+01. While it seems pretty simple to replace specific values with the 'replace()' method and a while loop, how do you do this if you want to replace a range? thanks

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• Good real-world uses of metaclasses (e.g. in Python)

  - by Carles Barrobés

  I'm learning about metaclasses in Python. I think it is a very powerful technique, and I'm looking for good uses for them. I'd like some feedback of good useful real-world examples of using metaclasses. I'm not looking for example code on how to write a metaclass (there are plenty examples of useless metaclasses out there), but real examples where you have applied the technique and it was really the appropriate solution. The rule is: no theoretical possibilities, but metaclasses at work in a real application. I'll start with the one example I know: Django models, for declarative programming, where the base class Model uses a metaclass to fill the model objects of useful ORM functionality from the attribute definitions. Looking forward to your contributions.

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• Keeping track of threads when creating them recursively

  - by 66replica

  I'm currently working on some code for my Programming Languages course. I can't post the code but I'm permitted to talk about some high level concepts that I'm struggling with and receive input on them. Basically the code is a recursive DFS on a undirected graph that I'm supposed to convert to a concurrent program. My professor already specified that I should create my threads in the recursive DFS method and then join them in another method. Basically, I'm having trouble thinking of how I should keep track of the threads I'm creating so I can join all of them in the other method. I'm thinking an array of Threads but I'm unsure how to add each new thread to the array or even if that's the right direction.

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• the use of private keyword

  - by LAT

  Hi everyone I am new to programming. I am learning Java now, there is something I am not really sure, that the use of private. Why programmer set the variable as private then write , getter and setter to access it. Why not put everything in public since we use it anyway. public class BadOO { public int size; public int weight; ... } public class ExploitBadOO { public static void main (String [] args) { BadOO b = new BadOO(); b.size = -5; // Legal but bad!! } } I found some code like this, and i saw the comment legal but bad. I don't understand why, please explain me.

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• Is It Worth Using Bitwise Operators In Methods?

  - by user1626141

  I am very new to Java (and programming in general, my previous experience is with ActionScript 2.0 and some simple JavaScript), and I am working my way slowly and methodically through Java: A Beginner's Guide by Herbert Schildt. It is an incredible book. For one thing, I finally understand more-or-less what bitwise operators (which I first encountered in ActionScript 2.0) do, and that they are more efficient than other methods for certain sums. My question is, is it more efficient to use a method that uses, say, a shift right, to perform all your divisions/2 (or divisions/even) for you in a large program with many calculations (in this case, a sprawling RPG), or is it more efficient to simply use standard mathematical operations because the compiler will optimise it all for you? Or, am I asking the wrong question entirely?

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• What is an instance of a field called?

  - by waxwing

  This might be an odd question, but it has actually caused me some headache. In Object oriented programming, there are accepted names for key concepts. In our model, we have classes with methods and fields. Now, going to the data world: An instance of a class is called an object. An instance of a field is called... what? A value? Isn't the term value a little broad for this? I have been offered "property" as well, but isn't property also part of the model and not the data? (This is not purely academic, I am actually coding these concepts.)

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• Magento quantity field doesn't work

  - by madmax

  Hi, i simply can't find a solution to my problem! The quantity field worked as it should. After a few months of programming on the whole shop, i wanted to test the quantity field and recognized that it doesn't function. I only can add one product to the cart although i typed “3” in the quantity field. I didn’t change anything in product/view.phtml and addtocart.phtml. Don't know where i have to search for this error. Maybe someone can give me a tip... greets max

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• Is there a server side API for Team Foundaion Server

  - by Ralph Shillington

  It would seem there is precious little documentation on programming against a TFS 2010 instance. What bits I have found, have next to nothing in the case of documentation beyond barebones listing of client access classes and their members, most likely autogenerated from the code comments. As I'm interested in building a silverlight client against TFS, I will need access to server side API (ideally the silverlight app will talk to my server (mainly for work items) and my server will in turn talk to the TFS server for the goods. Where is the doumentation (if any) for this kind of TFS integration?

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• Debugging ASP.NET in VS

  - by negligible

  A lot of what I'm doing at the moment is figuring out other peoples code and adding or adapting functions, so currently I am debugging more than I am writing code of my own. I'm still new to this, Junior Developer, and I am always finding new ways to improve what I am doing. For example I recently found This Guide which had some excellent tips, such as overriding the ToString() method in your classes so children are readable from their parents. So I am looking for any other tips or tricks to make my debugging more efficient, as I recognise it as a big part of programming, that you more experienced programmers may have picked up or found. Anything appreciated, I can read websites just fine so no need to explain it yourself if you have a good link!

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• How can I get the domain name for a user logged into a Mac via Active Directory

  - by Lawrence Johnston

  In my Cocoa app how can I get the current user's domain when they're logged in via Active Directory? I need to determine two things: 1. If the current user is logged on to an Active Directory domain (only need to handle Active Directory). 2. If 1, the domain of the user. I've found references to Directory Services and the Open Directory Programming Guide but the latter is 10.6 only (I must support 10.5+) and I could not find any examples for the former that gave me an idea of what I needed to do.

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• C++ code generation for repeted task

  - by sateesh

  Hi, I have something like below which will get repeated many times based on the function that get called for e.g acceptfunction() { inserter["quantity"] = sdd.getfloat(quantity); inserter["prodtype"] = sdd.getstring(prodtype); : : so on } Like accept above there are 20 more functions(reject,cancel etc) which will do the similar thing.But the parameteres they insert can differ based on function called. How can I automate this kind of code.So that I dont need to write new function from scratch.Basically what I need is if i provide parametres like ("quantity",prodtype) through some text file or xml, it should generate the required function with the input parametres. Is this task can be handled through C++ tempalte Meta programming or someother code generation tool will help me to do this?

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• Aside from performance concerns, is Java still chosen over Groovy/JRuby etc.?

  - by yar

  [This is an empirical question about the state-of-the-art: I am NOT asking if Java is cooler or less cool than the dynamic languages that work in the JVM.] Aside from cases where performance is a main decision factor, do companies/developers still willingly chose Java over Groovy, JRuby or JPython? Personal Note: The reason I am asking is that, while I do some subset of my professional work in Ruby (not JRuby, for now), in my personal projects I use Java. While I have written non-trivial apps in Groovy, I prefer Java, but I wonder if I should just get over it and do everything in Groovy. I like Java because I feel that static typing saves me time and aids refactoring. (No, I am not familiar with Scala.) However, I feel that this very empirical, on-topic programming question may inform my decision.

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• How can I declare a pointer structure using {}?

  - by Y_Y

  This probably is one of the easiest question ever in C programming language... I have the following code: typedef struct node { int data; struct node * after; struct node * before; }node; struct node head = {10,&head,&head}; Is there a way I can make head to be *head [make it a pointer] and still have the availability to use '{ }' [{10,&head,&head}] to declare an instance of head and still leave it out in the global scope? For example: //not legal!!! struct node *head = {10,&head,&head};

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• What are the difference between Cygwin on windows and real UNIX environment

  - by Tarun

  Hi, I am a C/C++ developer. I have never done C++ programming on UNIX, I have done only on windows. I want to practice C++ on Unix. (Because all big companies ask C++ with Unix). I have a laptop on which i do not want to install any other OS (because i have installed very important software on it and i don't have setups) So, I searched and found CygWin which is Unix emulator for Windows. I am thinking to practice C++ on this. Please help me, how can I practice/learn in more close to the environment(Unix Environment) that is used in Big companies like IBM. What will be the difference between Unix and Cygwin?

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• How much more productive is an extra monitor?

  - by Sir Graystar

  I am mulling over whether to buy a new monitor, to go along side my current setup of two 24 (ish) inch monitors. What I want to know is whether this is worth the money (probably around £200)? I think most of us will agree that two monitors is much more productive than one when programming and developing (Jeff Atwood has said this many times on his blog, and I imagine that most of you are fans of his), but is three much more productive than two? What I'm worried about is that I will have so much space that one monitor will be used for things that are not related to the task (music, facebook etc.) and it will actually make me less productive.

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• How does lock(syncRoot) make sense on a static method?

  - by Rising Star

  The following code is excerpted from the (Windows Identity Foundation SDK) template that MS uses to create a new Security Token Service Web Site. public static CustomSecurityTokenServiceConfiguration Current { get { HttpApplicationState httpAppState = HttpContext.Current.Application; CustomSecurityTokenServiceConfiguration customConfiguration = httpAppState.Get( CustomSecurityTokenServiceConfigurationKey ) as CustomSecurityTokenServiceConfiguration; if ( customConfiguration == null ) { lock ( syncRoot ) { customConfiguration = httpAppState.Get( CustomSecurityTokenServiceConfigurationKey ) as CustomSecurityTokenServiceConfiguration; if ( customConfiguration == null ) { customConfiguration = new CustomSecurityTokenServiceConfiguration(); httpAppState.Add( CustomSecurityTokenServiceConfigurationKey, customConfiguration ); } } } return customConfiguration; } } I'm relatively new to multi-threaded programming. I assume that the reason for the lock statement is to make this code thread-safe in the event that two web requests arrive at the web site at the same time. However, I would have thought that using lock (syncRoot) would not make sense because syncRoot refers to the current instance that this method is operating on... but this is a static method? How does this make sense?

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• work question how to start working as a programmer what do i need!

  - by giorgo

  Hi i am learning java and php i have some projects from uni.(Gui,s in java with mysql and a web application in php with mysql ++ more things like this.) i have started learning mvc struts spring and i also lerning php +zend +++++ more stuff etc....you can't learn everything!!!!!!!!!!!!!!!!!!!!!!! I would like to ask how can i find a job as a programmer-software eng because i have send my cv in many companys but all of them said me that i need work expirience. How All of you started your programming expirience. Did you make some projects and send them did you you have somebody that help you ...??? i am totaly alone i do everything by my self. can anyone answer this?everybody starts from somewhere but what if this somewhere don't come?what to do ?? how to start !!!!!!! Thanks

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• Need help with some C# Counting Code

  - by kaywai

  Hi, I'm trying to code a counter in Ninjatrader which uses C# as its programming language. I would like this counter to commence counting upon the completion of the first counter and once it commences counting to consider only the new condition when counting. So, the first counter commences when Close[0] < Close[4]. The second counter commences ONLY after the first counter has reached 9 and its condition for counting is Close[0] <= Low[2]. I don't know how to write the part of the code where the second counter commences counting and its counts are independent of the first counter reaching 9.

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