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  • Why does the Java compiler complain about a local variable not having been initialized here?

    - by pele
    int a = 1, b; if(a > 0) b = 1; if(a <= 0) b = 2; System.out.println(b); If I run this, I receive: Exception in thread "main" java.lang.Error: Unresolved compilation problem: The local variable b may not have been initialized at Broom.main(Broom.java:9) I know that the local variables are not initialized and is your duty to do this, but in this case, the first if doesn't initialize the variable?

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  • Should the argument be passed by reference in this .net example?

    - by Hamish Grubijan
    I have used Java, C++, .Net. (in that order). When asked about by-value vs. by-ref on interviews, I have always done well on that question ... perhaps because nobody went in-depth on it. Now I know that I do not see the whole picture. I was looking at this section of code written by someone else: XmlDocument doc = new XmlDocument(); AppendX(doc); // Real name of the function is different AppendY(doc); // ditto When I saw this code, I thought: wait a minute, should not I use a ref in front of doc variable (and modify AppendX/Y accordingly? it works as written, but made me question whether I actually understand the ref keyword in C#. As I thought about this more, I recalled early Java days (college intro language). A friend of mine looked at some code I have written and he had a mental block - he kept asking me which things are passed in by reference and when by value. My ignorant response was something like: Dude, there is only one kind of arg passing in Java and I forgot which one it is :). Chill, do not over-think and just code. Java still does not have a ref does it? Yet, Java hackers seem to be productive. Anyhow, coding in C++ exposed me to this whole by reference business, and now I am confused. Should ref be used in the example above? I am guessing that when ref is applied to value types: primitives, enums, structures (is there anything else in this list?) it makes a big difference. And ... when applied to objects it does not because it is all by reference. If things were so simple, then why would not the compiler restrict the usage of ref keyword to a subset of types. When it comes to objects, does ref serve as a comment sort of? Well, I do remember that there can be problems with null and ref is also useful for initializing multiple elements within a method (since you cannot return multiple things with the same easy as you would do in Python). Thanks.

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  • C++ variable alias - what's that exactly, and why is it better to turn if off?

    - by Poni
    I've read the essay Surviving the Release Version. Under the "Aliasing bugs" clause it says: You can get tighter code if you tell the compiler that it can assume no aliasing.... I've also read Aliasing (computing). What exactly is a variable alias? I understand it means using a pointer to a variable is an alias, but, how/why does it affect badly, or in other words - why telling the compiler that it can assume no aliasing would get me a "tighter code"

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  • Updated SOA Documents now available in ITSO Reference Library

    - by Bob Rhubart
    Nine documents within the IT Strategies from Oracle (ITSO) reference library have recently been updated. (Access to the ITSO collection is free to registered Oracle.com members -- and that membership is free.) All nine documents fall within the Service Oriented Architecture section of the ITSO collection, and cover the following topics: SOA Practitioner Guides Creating an SOA Roadmap (PDF, 54 pages, published: February 2012) The secret to successful SOA is to build a roadmap that can be successfully executed. SOA offers an opportunity to adopt an iterative technique to deliver solutions incrementally. This document offers a structured, iterative methodology to help you stay focused on business results, mitigate technology and organizational risk, and deliver successful SOA projects. A Framework for SOA Governance (PDF, 58 pages, published: February 2012) Successful SOA requires a strong governance strategy that designs-in measurement, management, and enforcement procedures. Enterprise SOA adoption introduces new assets, processes, technologies, standards, roles, etc. which require application of appropriate governance policies and procedures. This document offers a framework for defining and building a proper SOA governance model. Determining ROI of SOA through Reuse (PDF, 28 pages, published: February 2012) SOA offers the opportunity to save millions of dollars annually through reuse. Sharing common services intuitively reduces workload, increases developer productivity, and decreases maintenance costs. This document provides an approach for estimating the reuse value of the various software assets contained in a typical portfolio. Identifying and Discovering Services (PDF, 64 pages, published: March 2012) What services should we build? How can we promote the reuse of existing services? A sound approach to answer these questions is a primary measure for the success of a SOA initiative. This document describes a pragmatic approach for collecting the necessary information for identifying proper services and facilitating service reuse. Software Engineering in an SOA Environment (PDF, 66 pages, published: March 2012) Traditional software delivery methods are too narrowly focused and need to be adjusted to enable SOA. This document describes an engineering approach for delivering projects within an SOA environment. It identifies the unique software engineering challenges faced by enterprises adopting SOA and provides a framework to remove the hurdles and improve the efficiency of the SOA initiative. SOA Reference Architectures SOA Foundation (PDF, 70 pages, published: February 2012) This document describes they key tenets for SOA design, development, and execution environments. Topics include: service definition, service layering, service types, the service model, composite applications, invocation patterns, and standards. SOA Infrastructure (PDF, 86 pages, published: February 2012) Properly architected, SOA provides a robust and manageable infrastructure that enables faster solution delivery. This document describes the role of infrastructure and its capabilities. Topics include: logical architecture, deployment views, and Oracle product mapping. SOA White Papers and Data Sheets Oracle's Approach to SOA (white paper) (PDF, 14 pages, published: February 2012) Oracle has developed a pragmatic, holistic approach, based on years of experience with numerous companies to help customers successfully adopt SOA and realize measureable business benefits. This executive datasheet and whitepaper describe Oracle's proven approach to SOA. Oracle's Approach to SOA (data sheet) (PDF, 3 pages, published: March 2012) SOA adoption is complex and success is far from assured. This is why Oracle has developed a pragmatic, holistic approach, based on years of experience with numerous companies, to help customers successfully adopt SOA and realize measurable business benefits. This data sheet provides an executive overview of Oracle's proven approach to SOA.

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  • Set environment variable in Ubuntu

    - by Junho Park
    In Ubuntu, I'd like to switch my JAVA_HOME environment variable back and forth between Java 5 and 6. I open a terminal and type in the following to set the JAVA_HOME environment variable: export JAVA_HOME=/usr/lib/jvm/java-1.5.0-sun And in that same terminal window, I type the following to check that the environment variable has been updated: echo $JAVA_HOME And I see /usr/lib/jvm/java-1.5.0-sun which is what I'm expecting to see. In addition, I modify ~/.profile and set the JAVA_HOME environment variable to /usr/lib/jvm/java-1.5.0-sun. And now for the problem--when I open a new terminal window and I check my JAVA_HOME environment variable by typing in echo $JAVA_HOME I see that my JAVA_HOME environment variable has been reverted back to Java 6. When I reboot my machine (or log out and back in, I suppose) the JAVA_HOME environment variable is set to Java 5 (presumably because of the modification I made in my ~/.profile). Is there a way around this so that I can change my JAVA_HOME environment without having to log out and back in (AND make that environment variable change stick in all new terminal windows)?

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  • call value inside a JS variable as a JS function name

    - by user1640668
    Hello I have a function to perform actions but name of the function is inside a variable... below code will get the URL's hashed part example: #JHON and remove # and store it inside URLHASH variable..example: JHON var urlhash = document.location.hash; urlhash = urlhash.replace(/^.*#/, ''); always there is a function name from that value inside variable and i want to call value inside that variable as a function name window.onload=function() { Value inside URLHASH variable should run as a name of a variable. example: jhon(); }; Is it possible ? I tried some codes but it calls variable name as a function not value inside the variable..help me..

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  • How to improve variable overriding/overwriting in XSL?

    - by ChrisBenyamin
    I want to do the following: Declare a variable Go into a if-statement Overwrite the variable XSL says I can't declare a variable twice, so what can I do to improve this step? Another approach was to check if a variable is set at all. I did this, because i skipped the first step and declared the variable in the if-statement. In another if-statement I wanted to check if the variable exists at all.

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  • Conflict between variable substitution and CJK characters in BASH

    - by AndreasT
    I encountered a problem with variable substitution in the BASH shell. Say you define a variable a. Then the command $> echo ${a//[0-4]/} prints its value with all the numbers ranged between 0 and 4 removed: $> a="Hello1265-3World" $> echo ${a//[0-4]/} Hello65-World This seems to work just fine, but let's take a look at the next example: $> b="?1265-3?" $> echo ${b//[0-4]/} ?1265-3? Substitution did not take place: I assume that is because b contains CJK characters. This issue extends to all cases in which square brackets are involved. Surprisingly enough, variable substitution without square brackets works fine in both cases: $> a="Hello1265-3World" $> echo ${a//2/} Hello165-3World $> b="?1265-3?" $> echo ${b//2/} ?165-3? Is it a bug or am I missing something? I use Lubuntu 12.04, terminal is lxterminal and echo $BASH_VERSION returns 4.2.24(1)-release. EDIT: Andrew Johnson in his comment stated that with gnome-terminal 4.2.37(1)-release the command works fine. I wonder whether it is a problem of lxterminal or of its specific 4.2.24(1)-release version.

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  • Variable naming conventions?

    - by Ziv
    I've just started using ReSharper (for C#) and I kind of like its code smells finder, it shows me some things about my writing that I meant to fix a long time ago (mainly variable naming conventions). It caused me to reconsider some of my naming conventions for methods and instance variables. ReSharper suggests that instance variable be lower camel case and begin with an underscore. For a while I meant to make all my local variables lower camel case but is the underscore necessary? Do you find it comfortable? I don't like this convention but I also haven't tried it yet, what is you opinion of it? The second thing it prompted me to re-evaluate is my naming conventions for GUI event handlers. I usually use the VS standard of ControlName_Action and my controls usually use hungarian notation (as a suffix, to help clarify in code what is visible to the user and what isn't when dealing with similarly named variable) so I end up with OK_btn_Click(), what is your opinion of that? Should I succumb to the ReSharper convention or there are other equally valid options?

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  • Need help with the naming convention for an incremental variable [closed]

    - by iStryker
    I am using a voting module, that allows you vote either up or down [or reset]. If you vote up, the value is +1. If you vote down, the value is -1. If you vote up then down, the value is -1. I want to extend this module to allow you to vote multiple times, and the votes to be incremental. Examples Up, Up = +1, +1 = +2 Up, Up, Down = +1, +1, -1 = +1 I want to create a new boolean variable. If FALSE/NULL then use the old system +1/-1. If TRUE, voting will be incremental. What should be the name of this variable be? I feel 'incremental' is not the correct name. This module is part of an open-source project and is used on 3,177+ websites, so I want to get the naming convention right. Naturally, I'll be setting an upper and lower limit the variable be. [ie 5 & 0] Side-question: Is there a mathematics term to describe something being either +1/-1?

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  • Where can I find a quick reference for standard Basic?

    - by Steve314
    The reason? Pure nostalgia. Anyway, there was a standard for Basic that was published in the late 80s or early 90s. It was probably ISO/IEC 10279:1991, but I don't have access to that and cannot be sure. Whatever this standard was, some of the syntax made its way into Borlands Turbo Basic and Microsofts Visual Basic. I never learned any significant amount of VB, but Turbo Basic is one of those things I played with in my mis-spent youth. At one time, my main reference was an article published in one of the main programming periodicals - maybe Personal Computer World, maybe Byte. A scan of that article (if anyone can even identify it) would be great, but all I really want is a few pages quick reference of that standard syntax. Must be free (I'm not that nostalgic), but it must describe the standard syntax - the whole point is to sort out what is standard as opposed to VB or whatever. EDIT The more I think about this, the more convinced I am that this standard was available around 1987 or 1988. Maybe it was the earlier non-full version of the standard above, or maybe it was pre-acceptance of the standard.

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  • Is there a language with native pass-by-reference/pass-by-name semantics, which could be used in mod

    - by Bubba88
    Hi! This is a reopened question. I look for a language and supporting platform for it, where the language could have pass-by-reference or pass-by-name semantics by default. I know the history a little, that there were Algol, Fortran and there still is C++ which could make it possible; but, basically, what I look for is something more modern and where the mentioned value pass methodology is preferred and by default (implicitly assumed). I ask this question, because, to my mind, some of the advantages of pass-by-ref/name seem kind of obvious. For example when it is used in a standalone agent, where copyiong of values is not necessary (to some extent) and performance wouldn't be downgraded much in that case. So, I could employ it in e.g. rich client app or some game-style or standalone service-kind application. The main advantage to me is the clear separation between identity of a symbol, and its current value. I mean when there is no reduntant copying, you know that you're working with the exact symbol/path you have queried/received. And intristing boxing of values will not interfere with the actual logic of program. I know that there is C# ref keyword, but it's something not so intristic, though acceptable. Equally, I realize that pass-by-reference semantics could be simulated in virtually any language (Java as an instant example) and so on.. not sure about pass by name :) What would you recommend - create a something like DSL for such needs wherever it be appropriate; or use some languages that I already know? Maybe, there is something that I'm missing? Thank you!

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  • Reference remotely located assembly (web uri) from locally installed application?

    - by moonground.de
    Hi Stackoverflowers! :) We have a .NET application for Windows which is installed locally by Microsoft Installer. Now we have the need to use additional assemblies which are located online at our Web Servers. We'd like to refer to a remote uri like https://www.ourserver.com/OurProductName/ExternalLib.dll and reveal additional functionality, which is described roughly by a known common ("AddIn/Plugin") Interface. These are not 3rd Party Plugins, we just want be able to exchange parts of the application frequently, without the need to have frequent software updates. Our first idea was to add some kind of "remote refence" in Visual Studio by setting the path to the remote assembly uri. But Visual Studio downloaded the assembly immediately to a temporary directory, adding a reference to it. Our second attempt then, is simply using a WebRequest (or WebClient) to retrieve a binary stream of the Assembly, loading it "from image" by using Assembly.Load(...). This actually works, but is not very elegant and requires more additional programming for verification etc. We hoped Clickonce would provide useful techniques but apparently it's suitable for standalone applications only. (Correct me?) Is there a way (.net native or by framework/api) to reference remotely located assemblies? Thanks in advance and have a happy easter!

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  • How can I pass an array resulting from a Perl method by reference?

    - by arareko
    Some XML::LibXML methods return arrays instead of references to arrays. Instead of doing this: $self->process_items($xml->findnodes('items/item')); I want to do something like: $self->process_items(\$xml->findnodes('items/item')); So that in process_items() I can dereference the original array instead of creating a copy: sub process_items { my ($self, $items) = @_; foreach my $item (@$items) { # do something... } } I can always store the results of findnodes() into an array and then pass the array reference to my own method, but let's say I want to try a reduced version of my code. Is that the correct syntax for passing the method results or should I use something different? Thanks! EDIT: Now suppose I want to change process_items() to process_item() so I can do stuff on a single element of the referenced array inside a loop. Something like: $self->process_item($_) for ([ $xml->findnodes('items/item') ]); This doesn't work as process_item() is executed only once because a single value is passed to the for loop (the reference to the array from findnodes()). What's the proper way of using $_ in this case?

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  • Is method reference caching a good idea in Java 8?

    - by gexicide
    Consider I have code like the following: class Foo { Y func(X x) {...} void doSomethingWithAFunc(Function<X,Y> f){...} void hotFunction(){ doSomethingWithAFunc(this::func); } } Consider that hotFunction is called very often. Would it then be advisable to cache this::func, maybe like this: class Foo { Function<X,Y> f = this::func; ... void hotFunction(){ doSomethingWithAFunc(f); } } As far as my understanding of java method references goes, the Virtual Machine creates an object of an anonymous class when a method reference is used. Thus, caching the reference would create that object only once while the first approach creates it on each function call. Is this correct? Should method references that appear at hot positions in the code be cached or is the VM able to optimize this and make the caching superfluous? Is there a general best practice about this or is this highly VM-implemenation specific whether such caching is of any use?

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  • Avoiding That Null Reference!

    - by TheJuice
    A coworker had this conversation with another of our developers. Names have been changed to protect the guilty. Clueless: hey! Clueless: I am using the ?? operator for null check below Nice Guy: hey Clueless: FundLoanRequestBoatCollateral boatCollateral = request.BoatCollateral ?? null; Nice Guy: that's not exactly how it works Clueless: I want to achive: FundLoanRequestBoatCollateral boatCollateral = request.BoatCollateral != null ? request.BoatCollateral : null; Clueless: isnt that equal to:  FundLoanRequestBoatCollateral boatCollateral = request.BoatCollateral ?? null; Nice Guy: that is functionally equivalent to FundLoanRequestBoatCollateral boatCollateral = request.BoatCollateral Nice Guy: you're checking if it's null and if so setting it to null Clueless: yeah Clueless: if its null I want to set it to null Nice Guy: if it's null then you're already going to set it to null, no special logic needed Clueless: I wanted to avoid a null reference if BoatCollateral is null   The sad part of all of this is that "Clueless" has been with our company for years and has a Master's in Computer Science.

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  • Add Reference with Search

    - by Daniel Cazzulino
    If you have been using VS2010 for any significant amount of time, you surely came across the awkward, slow and hard to use Add Reference dialog. Despite some (apparent) improvements over the VS2008 behavior, in its current form it's even LESS usable than before. A brief non-exhaustive summary of the typical grief with this dialog is: Scrolling a list of *hundreds* of entries? (300+ typically) No partial matching when typing: yes, you can type in the list to get to the desired entry, but the matching is performed in an exact manner, from the beginning of the assembly name. So, to get to the (say) "Microsoft.VisualStudio.Settings" assembly, you actually have to type the first two segments in their entirety before starting to type "Settings"....Read full article

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  • Comparing the Performance of Visual Studio&apos;s Web Reference to a Custom Class

    As developers, we all make assumptions when programming. Perhaps the biggest assumption we make is that those libraries and tools that ship with the .NET Framework are the best way to accomplish a given task. For example, most developers assume that using <a href="http://www.4guysfromrolla.com/articles/120705-1.aspx">ASP.NET's Membership system</a> is the best way to manage user accounts in a website (rather than rolling your own user account store). Similarly, creating a Web Reference to communicate with a <a href="http://www.4guysfromrolla.com/articles/100803-1.aspx">web service</a> generates markup that auto-creates a <i>proxy class</i>, which handles the low-level details of invoking the web service, serializing parameters,

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  • Python lower_case_with_underscores style convention: underscores not popular?

    - by squirrel
    PEP8 recommends using lowercase, with words separated by underscores as necessary to improve readability for variable and function names. I've seen this interpreted as lower_case_with_underscores by most people, although in practice and in Python's native methods it seems like lowercasewithoutunderscores is more popular. It seems like following PEP8 strictly would be awkward since it seems to suggest mixing both lower_case_with_underscores and lowercasewithoutunderscores, which would be inconsistent. What is your interpretation of PEP8's variable names, and what do you actually use in practice? (Personally, I like lowerCamelCase as a compromise between readability and ease of typing.)

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  • Strange problem with libc: undefined reference to `crypt'

    - by sorush-r
    I moved from Archlinux to Kubuntu 12.04 yesterday. I compiled buildroot 2012.08 on Archlinux without any problem. Though on Kubuntu libcrypt seems to be broken. sysvinit can't find it anywhere. glibc-dev and all dependencies are installed. How do I link to libcrypt? Or, which package containts that library? ... bc-gcc sulogin.o -o sulogin sulogin.o: In function `main': sulogin.c:(.text+0x49d): undefined reference to `crypt' collect2: ld returned 1 exit status

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