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  • Best way to check for null values in Java?

    - by Arty-fishL
    I need to check whether the function of an object returns true or false in Java, but that object may be null, so obviously then the function would throw a NullPointerException. This means I need to check if the object is null before checking the value of the function. What is the best way to go about this? I've listed some methods I considered, I just want to know the most sensible one, the one that is best programming practice for Java (opinion?). // method 1 if (foo != null) { if (foo.bar()) { etc... } } // method 2 if (foo != null ? foo.bar() : false) { etc... } // method 3 try { if (foo.bar()) { etc... } } catch (NullPointerException e) { } // method 4 // would this work all the time, would it still call foo.bar()? if (foo != null && foo.bar()) { etc... }

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  • How stable or unstable is symfony 2.0 ?

    - by Doron
    Well, I know it's a preview, and I know it says that it's not yet ready for production, and yet I dare ask the question. I need to start building a pretty big application, which is planned to go live at around sep-oct 2010. Lets say I will not release the application to production until the stable version of symfony 2.0 will be released - is it a good idea (well, I'll settle for a viable idea) for me to start building the application using the 2.0 version ? How big is the chance I will need to rewrite/replace code I've written due to core changes in the framework ? Thanks. Edit: the other option right now, is to use symfony 1.4. I have thought and tried Zend Framework, but I refuse to re-invent each and every module, which will cost me a lot of programming hours (if not days/weeks).

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  • In what language was MSDOS originally written in?

    - by nebukadnezzar
    In what language was MSDOS originally written in? The Wikipedia Article implies either C, QBasic or Pascal, but: * C was invented to write UNIX, so I don't believe it was used to write MSDOS * Pascal seems popular to teach programming, but not really popular to write Operating systems in * QBasic didn't seem to be very popular for Operating Systems at the time MSDOS was developed (or was *BASIC ever very popular to write Operating Systems in it?) Except these three languages there is also Assembly, but I assume that Microsoft already switched from Assembly to a "higher" level language? Since C was originally invented for UNIX, I still wouldn't think Microsoft is using C... although the Microsoft API is written in C (I find this kind-of oxymoronic, actually). Can anyone enlighten me on this topic?

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  • Consolidate loan, purchase & sale 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. Each transaction will be assigned a unique transaction number [serial]. 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, whenever possible. This implies denormalization.

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  • Hidden Features and Dark Corners of STL?

    - by Andrei
    C++ developers, all know the basics of C++: Declarations, conditionals, loops, operators, etc. Some of us even mastered the stuff like templates, object model, complex I/O, etc. But what are the most hidden features or tricks or dark corners of C++/STL that even C++ fans, addicts, and experts barely know? I am talking about a seasoned C++ programmer (be she/he a developer, student, fan, all three, etc), who thinks (s)he knows something 99% of us never heard or dreamed about. Something that not only makes his/her work easier, but also cool and hackish. After all, C++ is one of the most used programming languages in the world, thus it should have intricacies that only a few privileged know about and want to share with us. Boost is welcome too! One per post with an example please P.S Examples are important for other developers to copy and paste!

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  • Resources for TDD aimed at Python Web Development

    - by Null Route
    I am a hacker not and not a full-time programmer but am looking to start my own full application development experiment. I apologize if I am missing something easy here. I am looking for recommendations for books, articles, sites, etc for learning more about test driven development specifically compatible with or aimed at Python web application programming. I understand that Python has built-in tools to assist. What would be the best way to learn about these outside of RTFM? I have searched on StackOverflow and found the Kent Beck's and David Astels book on the subject. I have also bookmarked the Wikipedia article as it has many of these types of resources. Are there any particular ones you would recommend for this language/application?

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  • In what language was MSDOS originally written?

    - by nebukadnezzar
    In what language was MSDOS originally written in? The Wikipedia Article implies either C, QBasic or Pascal, but: C was invented to write UNIX, so I don't believe it was used to write MSDOS Pascal seems popular to teach programming, but not really popular to write Operating systems in QBasic didn't seem to be very popular for Operating Systems at the time MSDOS was developed (or was *BASIC ever very popular to write Operating Systems in it?) Except these three languages there is also Assembly, but I assume that Microsoft already switched from Assembly to a "higher" level language? Since C was originally invented for UNIX, I still wouldn't think Microsoft is using C... although the Microsoft API is written in C (I find this kind-of oxymoronic, actually). Can anyone enlighten me on this topic?

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  • Parallel Assignment operator in Ruby

    - by Bragaadeesh
    Hi, I was going through an example from Programming in Ruby book. This is that example def fib_up_to(max) i1, i2 = 1, 1 # parallel assignment (i1 = 1 and i2 = 1) while i1 <= max yield i1 i1, i2 = i2, i1+i2 end end fib_up_to(100) {|f| print f, " " } The above program simply prints the fibonacci numbers upto 100. Thats fine. My question here is when i replace the parallel assignment with something like this, i1 = i2 i2 = i1+i2 I am not getting the desired output. My question here is, is it advisable to use parallel assignments? (I come from Java background and it feels really wierd to see this type of assignment) One more doubt is : Is parallel assignment an operator?? Thanks

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  • Best way to return a user-generated file, AJAX or Forms?

    - by Bill Zimmerman
    Hi, I'm new to web programming, so I need some help. I am writing a custom file-creation app for my site. A user visits the page, clicks on some various options and toggles some checkboxes, and the presses a 'download now' link. I have a PHP backend which will be processing the submission, and generating a PDF file. After the user presses the download link, I want the download to start like it would for any static link. My question is: What is the best way to do this? From my limited understanding, I have a choice between using AJAX or somehow using forms to submit the data. What are the advantages/disadvantages of each? Does anyone have any good links to examples? Thanks

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  • CMS common Architecture

    - by Shalan
    Hi there, I know this is a weird question to ask, but I would like to know if there is any documentation/blog-article out there that explains the architecture of a Website content management system? More particularly, I am interested to learn more about how "widgets" are implemented. I can't remember which system it was that I've seen tis one, but in the "Page Layout view" it had the ability to allow the end user to select a widget (thumbnail gallery, contact form, etc) from a list, and drag and drop it onto custom areas of the page. I know that this is not directly a programming question, but please could I seek advice/feedback on this. Thanks!

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  • Good way to cache data during Android application lifecycle?

    - by sniurkst
    Hello, keeping my question short, I have creating application with 3 activities, where A - list of categories, B - list of items, C - single item. Data displayed in B and C is parsed from online XML. But, if I go trough A - B1 - C, then back to A and then back to B1 I would like to have it's data cached somewhere so I wouldn't have to request XML again. I'm new to Android and Java programming, I've googled a lot and still can't find (or simply do not have an idea where to look) a way to do what I want. Would storing all received data in main activity A (HashMaps? ContentProviders?) and then passing to B and C (if they get same request that was before) be a good idea?

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  • verilog or systemc for testbench

    - by Alphaneo
    I am assigned with the task of verifying some verilog based RTL code. Now, coding the RTL testbench using verilog seems to be very difficult (for me). So I would like to try one of the following. - Try providing a PLI interface to the RTL and thereby invoke 'C functions for testing - Using system 'C for interfacing the 'C functions PS: I already have a extensive 'C code that was used for testing the behavioral model. I am new to the world of hardware programming. Any pointers would be greatly appreciated.

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  • printing uid of a file on linux system

    - by neo730
    i am learning c programming. I am trying to make my own program similar to ls command but with less options.what i am doing is taking input directory/file name as argument and then gets all directory entry with dirent struct(if it is directory) . After it i use stat() to take all information of the file but here is my problem when i use write() to print these value its fine but when i want to print these with printf() i get warninng : format ‘%ld’ expects type ‘long int’, but argument 2 has type ‘__uid_t’. I don't know what should use at place of %ld and also for other special data types.

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  • What tech stack/platform to use for a project?

    - by danny z
    Hey guys, This is a bit of a weird meta-programming question, but I've realized that my new project doesn't need a full MVC framework, and being a rails guy, I'm not sure what to use now. To give you a gist of the necessary functionality; this website will display static pages, but users will be able to log in and 'edit their current plans'. All purchasing and credit card editing is being handled by a recurring payment subscriber, I just need a page to edit their current plan. All of that will be done through (dynamic) XML API calls, so no database is necessary. Should I stick with my typical rails/nginx stack, or is there something I could use that would lighten the load, since I don't need the Rails heft. I'm familiar with python and PHP but would prefer not to go that route. Is Sinatra a good choice here? tl;dr: What's a good way to quickly serve mostly static pages, preferably in Ruby, with some pages requiring dynamic XML rendering?

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  • Is there any advantages to integrate Smarty with Zend?

    - by keisimone
    Hi, i am quite familiar with Smarty and recently decided to use Zend framework in implementation. because i am aware of the various advantages of Smarty, i insisted my contractor to integrate Smarty in. But now, i am questioning my assumptions. Should I integrate Smarty in with Zend framework? simply because I am familiar with Smarty syntax? I am also involved with the programming. I got the contractor to help in the architecture and with the prototype.

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  • Cross-platform GUI toolkits with WPF-style composition capabilities

    - by Alexey Romanov
    A huge advantage of WPF over, say, WinForms is its composability. To quote Programming WPF: One level up, WPF provides its “content model,” which allows any control to host any group of other controls. You don’t have to build special BitmapButton or IconComboBox classes; you put as many images, shapes, videos, 3D models, or whatever into a Button (or a ComboBox, ListBox, etc.) as suit your fancy. Are there any cross-platform GUI frameworks (preferably with Java bindings) out there which also let you do this?

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  • Redirect print in Python: val = print(arg) to output mixed iterable to file

    - by emcee
    So lets say I have an incredibly nested iterable of lists/dictionaries. I would like to print them to a file as easily as possible. Why can't I just redirect print to a file? val = print(arg) gets a SyntaxError. Is there a way to access stdinput? And why does print take forever with massive strings? Bad programming on my side for outputting massive strings, but quick debugging--and isn't that leveraging the strength of an interactive prompt? There's probably also an easier way than my gripe. Has the hive-mind an answer?

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  • A compiler for automata theory

    - by saadtaame
    I'm designing a programming language for automata theory. My goal is to allow programmers to use machines (DFA, NFA, etc...) as units in expressions. I'm confused whether the language should be compiled, interpreted, or jit-compiled! My intuition is that compilation is a good choice, for some operations might take too much time (converting NFA's to equivalent DFA's can be expensive). Translating to x86 seems good. There is one issue however: I want the user to be able to plot machines. Any ideas?

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  • Refreshing metadata on user functions t-SQL

    - by luckyluke
    I am doing some T-SQL programming and I have some Views defines on my database. The data model is still changing these days and I have some table functions defined. Sometimes i deliberately use select * from MYVIEW in such a table function to return all columns. If the view changes (or table) the function crashes and I need to recompile it. I know it is in general good thing so that it prevents from hell lotta errors but still... Is there a way to write such functions so the dont' blow up in my face everytime I change something on the underlying table? Or maybe I am doing something completely wrong... Thanks for help

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  • Why the "mutable default argument fix" syntax is so ugly, asks python newbie

    - by Cawas
    Now following my series of "python newbie questions" and based on another question. Go to http://python.net/~goodger/projects/pycon/2007/idiomatic/handout.html#other-languages-have-variables and scroll down to "Default Parameter Values". There you can find the following: def bad_append(new_item, a_list=[]): a_list.append(new_item) return a_list def good_append(new_item, a_list=None): if a_list is None: a_list = [] a_list.append(new_item) return a_list So, question here is: why is the "good" syntax over a known issue ugly like that in a programming language that promotes "elegant syntax" and "easy-to-use"? Why not just something in the definition itself, that the "argument" name is attached to a "localized" mutable object like: def better_append(new_item, a_list=[].local): a_list.append(new_item) return a_list I'm sure there would be a better way to do this syntax, but I'm also almost positive there's a good reason to why it hasn't been done. So, anyone happens to know why?

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  • Type patterns and generic classes in Haskell

    - by finnsson
    I'm trying to understand type patterns and generic classes in Haskell but can't seem to get it. Could someone explain it in laymen's terms? In [1] I've read that "To apply functions generically to all data types, we view data types in a uniform manner: except for basic predefined types such as Float, IO, and ?, every Haskell data type can be viewed as a labeled sum of possibly labeled products." and then Unit, :*: and :+: are mentioned. Are all data types in Haskell automatically versions of the above mentioned and if so how do I figure out how a specific data type is represented in terms of :*:, etc? The users guide for generic classes (ch. 7.16) at haskell.org doesn't mention the predefined types but shouldn't they be handled in every function if the type patterns should be exhaustive? [1] Comparing Approaches to Generic Programming in Haskell, Ralf Hinze, Johan Jeuring, and Andres Löh

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  • How to get distinct values from a column with all its corresponding values in another column

    - by Vishnu
    I know the question is bit confusing. Please read below. I have a table table_categories (id INT(11), cname VARCHAR(25),survey_id INT(11)) I want to retrieve the values for the column cname without duplication, that is distinct values but with all the values in the other column. id cname survey_id -- -------- --------- 1 Trader 2 2 Beginner 2 25 Human 1 26 Human 2 From the above example I want to retrieve distinct cnames with all the values of the survey_id. I don't want to use any programming language. Is there any way by using a single query. Please give me a solution in MySQL.

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  • Where to start with C#

    - by RobertPitt
    Hello fellow programmers. Im a pretty experienced programmer in PHP and mainly web languages but today i have decided i want to start to learn a new language! Im only 21 and I feel as I will never make it in the programming industry without a great set of languages under my belt, So i decided to have a look at C#. The reason I have chosen C# is because some C programmers have told me that C# is the best language to learn for desktop applications. I think i need to get started with the Syntax / Structure of C#, What Development Environment to use, and other things that i might face along my new journey. I hope somebody can guide me Thanks.

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  • COM port - how to identify a device (.net/c#)

    - by argh
    Hi, I'm programming for Windows CE and I need to connect to a scanner. There is no problem - I know that it is on port COM0, but if I plug in another device earlier it gets another COM port... to get all com ports the easy way is: SerialPort.GetPortNames() But I don't know how to identify a device? Is there any standard way? I can't 'ping' it since there is one device that only sends data... it spams data all the time... and I don't know how to 'ping' a device...

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  • Why can't I install psycopg2? (Python 2.6.4, PostgreSQL 8.4, OS X 10.6)

    - by cojadate
    After running python setup.py install I get the following: Warning: Unable to find 'pg_config' filebuilding 'psycopg2._psycopg' extension gcc-4.0 -arch ppc -arch i386 -fno-strict-aliasing -fno-common -dynamic -DNDEBUG -g -O3 - DPSYCOPG_DEFAULT_PYDATETIME=1 -DPSYCOPG_VERSION="2.2.1 (dt dec ext pq3)" -DPSYCOPG_EXTENSIONS=1 -DPSYCOPG_NEW_BOOLEAN=1 -DHAVE_PQFREEMEM=1 -DHAVE_PQPROTOCOL3=1 -I/Library/Frameworks/Python.framework/Versions/2.6/include/python2.6 -I. -c psycopg/psycopgmodule.c -o build/temp.macosx-10.3-fat-2.6/psycopg/psycopgmodule.o unable to execute gcc-4.0: No such file or directory error: command 'gcc-4.0' failed with exit status 1 There's probably something screamingly obvious there to anyone who knows the first thing about back-end web programming, but unfortunately it's all gobbledegook to me. The psycopg2 documentation was not helpful.

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