questions - Page 354 - Developer IT

Can I compose a WCF callback contract out of multiple interfaces?

- by mafutrct

Followup question to http://stackoverflow.com/questions/2502930/how-can-i-compose-a-wcf-contract-out-of-multiple-interfaces. I tried to merge multiple callback interfaces in a single interface. This yields an InvalidOperationException claiming that the final interface contains no operations. Technically, this is true, however, the inherited interfaces do contain operations. How can I fix this? Or is this a limitation of WCF? Edit: interface A { [OperationContract]void X(); } interface B { [OperationContract]void Y(); } interface C: A, B {} // this is the public callback contract

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Should I use "id" or "unique username"?

- by roa3

I am using PHP, AS3 and mysql. I have a website. A flash(as3) website. The flash website store the members' information in mysql database through php. In "members" table, i have "id" as the primary key and "username" as a unique field. Now my situation is: When flash want to display a member's profile. My questions: Should Flash pass the member "ID" or "username" to php to process the mysql query? Is there any different passing the "id" or "username"? Which one is more secure? Which one you recommend? I would like to optimize my website in terms of security and performance.

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SAS(Statistical Analysis System) Career As a computer science student

- by Renju

Hi. I have completed MSc in Computer science this academic year. So I am fresher... While I am doing graduation and post graduation I did many projects using PHP and MySQL. Now I got opportunity to get into SAS(Statistical Analysis System) career, and I heard that SAS having better career growth than PHP developement. For the past 4 days, I was working with SAS and I feel interested in working. My questions are, Since i am a computer science student whether i will have any problem in my career growth in SAS? I am ready to learn statistics also, is there anything else I have to do? Doing certification in SAS will make any changes? Is it a bad idea to get into SAS with only CSc backgrond? So please guide me for my career...

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Do bit operations cause programs to run slower?

- by flashnik

I'm dealing with a problem which needs to work with a lot of data. Currently its values are represented as an unsigned int. I know that real values do not exceed a limit of 1000. Questions I can use unsigned short to store it. An upside to this is that it'll use less storage space to store the value. Will performance suffer? If I decided to store data as short but all the calling functions use int, it's recognized that I need to convert between these datatypes when storing or extracting values. Will performance suffer? Will the loss in performance be dramatic? If I decided to not use short but just 10 bits packed into an array of unsigned int. What will happen in this case comparing with previous ones?

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Python editor/IDE for OS X

- by TheJuice

As a (reasonably) new Python programmer, what IDEs or editors would you recommend for Python programming on OS X and why (i.e. what features/capabilities/workflow techniques really help)? I've used Xcode and played a bit with TextMate but I can't really say that either have really hit the spot for me (although TextMate's code completion is pretty neat, I think i've been spoilt with code-completion facilities provided by editors for statically-typed languages so maybe i'm subconsciously comparing apples and oranges) I'm looking to increase my efficacy with Python and any tips would be appreciated. I know people have asked similar questions for Python IDEs in general but I am specifically concentrating on OS X and the 'Mac way'. If Xcode or TextMate are thought highly of, perhaps some suggestions as to how I could get the most benefit from the tools would help.

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What are the exact versions of stuff you have to install in order to be able to step-debug a Scala p

- by Alex R

How do YOU debug a Scala program? I mean YOU as in the person posting the Answer :) Please answer only from personal experience, not from stuff you've heard or read on the Internet. You should not believe everything you read on the Internet, especially tales of complex open-source software configurations that actually work :-) The are many Java tools which claim to support Scala in some way or another, but I have so far struck out in trying to get any one of them to actually let me set a breakpoint in Scala code and step through it. These are big, major open-source IDEs I'm talking about here. The main problem in getting a debugger to work seems to be the "version hell" with fast-changing IDEs, Plug-Ins, JDKs, and the Scala language itself. Hence, the more detailed re-statement of the question is appropriate: What is the exact version number of the IDE, Plug-In, JDK, Scala, and even Operating System, that you are successfully using? My question is related to this one, but wider in scope: http://stackoverflow.com/questions/2272705/how-to-debug-scala-code-when-outside-of-an-ide Thanks

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"Introduction to Computer Science and Programming" for a beginner.

- by Richard

Hi everyone! Im new here and also new to developing software and programming, and with new I mean 0 experience or schooling for it. As Im currently studying medicine via internet and I use a computer on an average of about 8-9 hours a day, this has lead me to get very interested in programming. I got a link from a fellow Redditor and I got some questions before I dive into this project. http://ocw.mit.edu/OcwWeb/Electrical-Engineering-and-Computer-Science/6-00Fall-2008/CourseHome/index.htm Is this too much/hard for a beginner? Is Python™ programming language the way to go or would I be better off learning some other kind of language to begin with? What other ways of learning basic programming by myself is there? Are there any better ways for a complete beginner to start off? Thank you for your time!

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MVC design pattern - who loads view initially

- by enableDeepak

This query is about MVC design pattern in general and not ASP.net MVC framework I understand in MVC (desktop application): 1. User clicks something in view 2. this is passed on to controller to manage 3. controller makes some changes in Model 4. Model calls method on view which has the logic to refresh UI Questions around these: Q1) Can controller also modify View or Model only updates View? Q2) When screen loads for the first time, there is no Model change. Then, who fetches data from model and populates view? View directly calls Model and populates itself OR controller gets data and passes to view method OR some dummy event is raised at Model which updates View?

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How to dynamically change fields in an .NET ORM

- by rsteckly

I'm working in ASP.NET in an application where often users want to add fields or change field names. I'd like to be able to have an xml schema in place that is parsed and a dynamic object model created from it that can be accessed throughout the application. My initial reaction is that this is not realistic. I think there is flexibility about the dynamic nature of it. I think the people I'm trying to build this for wouldn't mind recompiling. Even if the app recompiled, I don't know how to abstract away enough in my code access the data to allow for users changing property names, etc. How can you write LINQ when the properties might change? In short, there's two questions here: 1) is there a way to dynamically generate an object model of the database and 2) is there a way to abstract away enough so that code accessing the database doesn't break when properties change?

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Writing Resources from filesystem in Android

- by Markus

Hi, as I need to get a specific Frame from a Website I want to display in an WebView, I decided to grab the .html from the net and save it under file:///data/data//files/file.html. Stroed there I can edit it using regex or String methods. Now two questions: Is there a way to bind this file to an resource. e.g. to /res/raw/file.html and get it updated dynamically as i edit it? Or can i write the File directly to the resources? Is this whole stuff I do there any good or performant at all? I mean maybe there is a better way to get the .html code between two tags from a Webpage and display it via WebView. Kind regards Markus

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On Memory Allocation and C++

- by Arpan

And I quote from MSDN http://msdn.microsoft.com/en-us/library/aa366533(VS.85).aspx: The malloc function has the disadvantage of being run-time dependent. The new operator has the disadvantage of being compiler dependent and language dependent. Now the questions folks: a) What do we mean that malloc is run-time dependent? What kind of dynamic memory allocation functions can be independent of run-time? This statement sounds real strange. b) new is language dependent? Of course it should be right? Are HeapAlloc, LocalAlloc etc language independent? c) From a pure performance perspective are the MSVC provided routines preferable? Arpan

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Vim: Replacing a line with another one yanked before

- by duddle

At least once per day i have the following situation: A: This line should also replace line X ... X: This is line should be replaced I believe that I don't perform that task efficiently. What I do: Go to line A: AG Yank line A: yy Go to line X: XG Paste line A: P Move to old line: j Delete old line: dd This has the additional disadvantage that line X is now in the default register, which is annoying if I find another line that should be replaced with A. Yanking to and pasting from an additional register ("ayy, "aP) makes this simple task even less efficient. My Questions: Did I miss a built-in Vim command to replace a line yanked before? If not, how can I bind my own command that leaves (or restores) the yanked line in the default register?

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LINQ - Using where or join - Performance difference ?

- by Patrick Säuerl

Hi Based on this question: http://stackoverflow.com/questions/3013034/what-is-difference-between-where-and-join-in-linq My question is following: Is there a performance difference in the following two statements: from order in myDB.OrdersSet from person in myDB.PersonSet from product in myDB.ProductSet where order.Persons_Id==person.Id && order.Products_Id==product.Id select new { order.Id, person.Name, person.SurName, product.Model,UrunAdi=product.Name }; and from order in myDB.OrdersSet join person in myDB.PersonSet on order.Persons_Id equals person.Id join product in myDB.ProductSet on order.Products_Id equals product.Id select new { order.Id, person.Name, person.SurName, product.Model,UrunAdi=product.Name }; I would always use the second one just because it´s more clear. My question is now, is the first one slower than the second one? Does it build a cartesic product and filters it afterwards with the where clauses ? Thank you.

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How to Debug Java Application using VIM/GVIM?

- by Techmaddy

I asked this question previously: http://stackoverflow.com/questions/495268/any-good-tutorial-for-moving-from-eclipse-to-vim From the inputs, I started using GVIM instead of Eclipse. I added ctags to it and I am able to navigate now comfortably. Only problem left for me is "Debugging"? I tried searching for some links, and couldn't a useful one? If anyone using or familiar with Java Debugging using vim/Gvim, can provide there inputs/ links/ tutorials, it would be very helpful. Thanks in advance.

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C++ Typing and OOP child classes

- by Zack

I'm a bit confused: If I have a base class A, and a class B which extends A, can a variable of the type A hold a value of the type B and vice versa? If yes, why? Aren't they completely different even if B is derived from A? How about type-safety? If this is possible, what things do I have to mind when taking use of this? How would this work out in terms of performance? Note: Sorry if I asked too many questions, just ignore them and just look out for those "marked" with the list decoration dot :) Also, this is not my homework. I'm a hobby programmer and have skills in scripting languages with OOP, yet I'm relatively new to OOP typing in C++.

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C++'s unordered_map / hash_map / Google's dense_hash - how to input binary data (buf+len) and insert

- by shlomif

Hi all, I have two questions about Google's dense_hash_map, which can be used instead of the more standard unordered_map or hash_map: How do I use an arbitrary binary data memory segment as a key: I want a buffer+length pair, which may still contain some NUL (\0) characters. I can see how I use a NUL-terminated char * string , but that's not what I want. How do I implement an operation where I look if a key exists, and if not - insert it and if it does return the pointer to the existing key and let me know what actually happened. I'd appreciate it if anyone can shed any light on this subject. Regards, -- Shlomi Fish

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An MP3 parser to extract numbered frames?

- by Xepoch

I am writing a streaming application for MP3 (CBR). It is all passthru, meaning I don't have to decode/encode, I just need to pass on the data as I see it come through. I want to be able to count the MP3 frames as they passthru (and some other stuff like throughput calculations). According to the MP3 frame header spec, the sync word appears to be 11 bits of 1s, however I notice (naturally) that the frame payload which I should safely assume to be binary and thus it is not odd at all to see 11 1s in sequence. My questions: Is there a Unix/Linux MP3 parser utility (dd-style) that can pull numbered frames from an MP3 file/pipe? Any perl wisdom here? How does one delineate an MP3 header block from any other binary payload data? and lastly: Is a constant bitrate (CBR) MP3 defined by payload bytes or are the header bytes included in the aggregate # of bytes/bits per any given timeslice? Thanks,

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Ruby method Array#<< not updating the array in hash

- by Mladen Jablanovic

Inspired by http://stackoverflow.com/questions/2552363/how-can-i-marshal-a-hash-with-arrays I wonder what's the reason that Array#<< won't work properly in the following code: h = Hash.new{Array.new} #=> {} h[0] #=> [] h[0] << 'a' #=> ["a"] h[0] #=> [] # why?! h[0] += ['a'] #=> ["a"] h[0] #=> ["a"] # as expected Does it have to do with the fact that << changes the array in-place, while Array#+ creates a new instance?

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Best practice for handling memory leaks in large Java projects?

- by knorv

In almost all larger Java projects I've been involved with I've noticed that the quality of service of the application degrades with the uptime of the container. This is most probably due to memory leaks in the code. The correct way to solve this problem is obviously to trace back to the root cause of the problem and fix the leaks in the code. The quick and dirty way of solving the problem is simply restarting Tomcat (or whichever servlet container you're using). These are my three questions: Assume that you choose to solve the problem by tracing the root cause of the problem (the memory leaks), how would you collect data to zoom in on the problem? Assume that you choose the quick and dirty way of speeding things up by simply restarting the container, how would you collect data to choose the optimal restart cycle? Have you been able to deploy and run projects over an extended period of time without ever restarting the servlet container to regain snappiness? Or is an occasional servlet restart something that one has to simply accept?

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problem-configure-jboss-to-work-with-jndi(3)

- by Spiderman

Sorry for opening new thread every time for the same problem. It's just that I'd like to refine my question during my investigation and it's hard to do it in stackoverflow structure on the same question (maybe on purpose). Anyway, in continuation to this thread http://stackoverflow.com/questions/2843218/problem-configure-jboss-to-work-with-jndi2 I discovered that when running an application that is deployed on my JBoss 4.2.3.GA, when I perform: Context initialContext = new InitialContext(); Object dataSource = initialContext.lookup("java:/DefaultDS"); I get null as a return value even though DefaultDS is the default datasource that comes with Jboss installation. and generally, how come initialContext return null value? if the datasource is not found it should throw NamingException and in other case it should return real object. What can I do with null? isn't it a bad error handling of javax.naming.InitialContext ???

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Click-Once deployment is leaving multiple versions (yes, more than 2)

- by Clyde

I've got a click once application that is leaving all old versions on my disk. It's an internal corporate application that gets frequent updates, so this is a disaster for rapidly inflating our backup size. According to the docs and other SO questions, it is supposed to only leave the current and previous versions on disk. However, each time I deploy the project and upgrade a client, I get another copy of all exe/dll/data files. I'm making no changes whatsoever to the application, just pushing deploy again in Visual Studio. Any ideas? Updates: The problem seems to happen on both Windows 7 and XP. 64 bit windows and 32. I've done a diff of the folders where the version is installed and the following files are different: MyApp.exe.manifest MyApp.exe.cdf-ms MyDll1.cdf-ms MyDll2.cdf-ms No actual executable files are different, nor the MyApp.manifest, MyDll1.manifest, etc.

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mysql_real_escape_string and search data in mySql DB

- by ryrysz

I have problem with php function : mysql_real_escape_string My test string: @,&!#$%^*()_+' "\/ I add this data to mySql database, like that (in short): $str = mysql_real_escape_string($str); $sql = "INSERT INTO table(company) VALUES('".$str. "')"; In DB is stored as: @,&!#$%^*()_+\' \"\\/ But problem is with find this data by SELECT statement. I want find, company where name is like ' " My SELECT's: SELECT company FROM table WHERE company LIKE '%\' "%'; SELECT company FROM table WHERE company LIKE '%\\' \\"%'; ; not working. This works: SELECT `company` FROM `table` WHERE `company` LIKE '%\\\' \\\\"%'; and SELECT `company` FROM `table` WHERE `company` LIKE '%\\\\\\\' \\\\\\\"%' But I dont know why this work :(. My questions are: why must add so many slashes ? how I can make correct query in PHP: $query = '\' "'; '%'.mysql_real_escape_string($query).'%' result is : '%\' \"%' '%'.mysql_real_escape_string(mysql_real_escape_string($query)).'%' result is : '%\\\' \\\"%' '%'.mysql_real_escape_string(mysql_real_escape_string(mysql_real_escape_string($query))).'%' result is : '%\\\\\\\' \\\\\\\"%' Only last one works good.

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Creating Bordless Windows with custom visual

- by RHaguiuda

Hi I'd like to create a custom window using WPF that doesn't look like the regular window. The window I want to create is similar to MacOs window, with title centered (with dropshadow effect), and controls button on left side of the window. I did create a bordless window, but some questions I have: 1 - How can I set it functionality of maximize, minimize and close buttons in XAML (if it's possible)? 2 - How can I define a window template so every new window I create have the same look and feel? 3 - Is it possible to create the Aqua maximize, minimize and close buttons using only elements from WPF (without using images)? How? 4 - How can I make the window move when dragged? Thanks for all help.

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What Programming Book would you NOT recommend to Developers?

- by Ender

Like a lot of people on Stack Overflow I love to read books about programming, almost as much as I love to read the lists that people add onto their websites, Blog's and this very website. However, for every gem there are a thousand turds, and to one developer a gem could just be a shiny turd to another. Whilst there are hundreds of book questions on this website asking users to recommend books that they have loved I have decided (after looking for a similar question and not finding it) to create a list of books that users have detested. After all, if we're going to fork out money for these books it'd be a good idea to get both positive and negative aspects out there. Please refer to a specific book, and with it add an image of either the latest version or the version you have read. Also, if you have the time please comment on the answers to provide your experiences with the books.

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