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• How can a language be interpreted by itself (like Rubinius)?

  - by japancheese

  I've been programming in Ruby for a while now with just the standard MRI implementation of Ruby, but I've always been curious about the other implementations I hear so much about. I was reading about Rubinius the other day, a Ruby interpreter written in Ruby. I tried looking it up in various places, but I was having a hard time figuring out exactly how something like this works. I've never had much experience in compilers or language writing but I'm really interested to figure it out. How exactly can a language be interpreted by itself? Is there a basic step in compiling that I don't understand where this makes sense? Can someone explain this to me like I'm an idiot (because that wouldn't be too far off base anyways)

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• Java: How can I create good looking class docs with Javadoc?

  - by Cheeso

  I'd like to create HTNML documentation for a Java class library that includes programming guide information - beyond just a class reference code examples in the reference doc collapsible regions I want it to look well-styled. Something like this: I think that Javadoc exposes a doclet API that allows other parties to provide doc generation integrated in Javadoc. Is there a doclet option that I can use (for free) that does something a little nicer than the standard javadoc output? I tried googling for this but no luck. Suggestions?

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• How does exactly Qt works?

  - by Somebody still uses you MS-DOS

  I have seen that you can write your application in Qt, and it can be run in different operating systems. And - correct me if I'm wrong - you don't need to have Qt already installed in all of these platforms. How exactly this approach works? Does Qt compiles to the desired platform, does it bundle some "dlls" (libs), how does it do it? Is different from programming a Java application for the sake of cross-platform? If you use Python to write a Qt application with Python bindings, does the final user needs to have Python installed?

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• Searching for a complex and well-designed PHP OOP application to learn from

  - by Raveren

  Basically, I am diving ever deeper into complex programming practices. I've almost no friends that are experienced (or more experienced than me) programmers to learn from, so I am looking for the next best thing - learning from the work of strangers. Can anyone recommend a real world finished and working application written well and OOP-centered. I'd like to take and analyze its source. Bonus if it's based on Zend Framework. What I am interested most in is objects that unlike desktop applications, have only one real operation done to them (or to their representation in DB or session) during their lifetime (or pageload), like user-logIn(). I'm interested in optimal and reusable design patterns and their real life implementations.

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• GoTo statements and alternatives in VB.NET

  - by qais

  I've posted a code snippet on another forum asking for help and people pointed out to me that using GoTo statements is very bad programming practice. I'm wondering: why is it bad? What alternatives to GoTo are there to use in VB.NET that would be considered generally more of a better practice? Consider this snippet below where the user has to input their date of birth. If the month/date/year are invalid or unrealistic(using if statements checking the integer inputs size, if there's a better way to do this, I'd appreciate if you could tell me that also :D) How would I be able to loop back to ask the user again? retryday: Console.WriteLine("Please enter the day you were born : ") day = Console.ReadLine If day > 31 Or day < 1 Then Console.WriteLine("Please enter a valid day") GoTo retryday End If

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• Django: Data corrupted after loading? (possible programmer error)

  - by Rosarch

  I may be loading data the wrong way. excerpt of data.json: { "pk": "1", "model": "myapp.Course", "fields": { "name": "Introduction to Web Design", "requiredFor": [9], "offeringSchool": 1, "pre_reqs": [], "offeredIn": [1, 5, 9] } }, I run python manage.py loaddata -v2 data: Installed 36 object(s) from 1 fixture(s) Then, I go to check the above object using the Django shell: >>> info = Course.objects.filter(id=1) >>> info.get().pre_reqs.all() [<Course: Intermediate Web Programming>] # WRONG! There should be no pre-reqs >>> from django.core import serializers >>> serializers.serialize("json", info) '[{"pk": 1, "model": "Apollo.course", "fields": {"pre_reqs": [11], "offeredIn": [1, 5, 9], "offeringSchool": 1, "name": "Introduction to Web Design", "requiredFor": [9]}}]' The serialized output of the model is not the same as the input that was given to loaddata. The output has a non-empty pre_req list, whereas the input's pre_reqs field is empty. What am I doing wrong?

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• Is there a c++ library that provides functionality to execute an external program and read its outpu

  - by BD at Rivenhill

  Basically, I'm looking for something that will allow me to replicate the following Perl code: my $fh = new FileHandle; $fh->open("foo |"); while (<$fh>) { # Do something with this line of data. } This is in the context of Linux, so a library that is specific to Windows will not help. I know how to write a program that does fork/exec/dup2 and all that basic shell-type jazz, but there are some fiddly details involving terminals that I don't feel like messing around with (and I don't have a copy of "Advanced Programming in the UNIX Environment" or a similar reference handy), so I'm hoping that someone has already solved this problem.

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• Conditionally setting the font color of an item in a drop down box in JSF

  - by Greg

  I'm a newbie to web programming, so please bear with me. I am using JSF 1.2 and I want to conditionally set the color of the items in my drop down list. In other words, I have a collection of items that, along with a key and a value, also have a boolean property, warning, that is dynamically set by user action. I want the drop down to show all of the items, but those whose warning property is set to true should be displayed in red. I assume I have to extend the SelectItem class to add in the boolean property. How do I then conditionally set the color of the font of those items whose warning property is set to true in my JSP pages? Thanks in advance

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• How is fseek() implemented in the filesystem?

  - by pajton

  This is not a pure programming question, however it impacts the performance of programs using fseek(), hence it is important to know how it works. A little disclaimer so that it doesn't get closed. I am wondering how efficient it is to insert data in the middle of the file. Supposing I have a file with 1MB data and then I insert something at the 512KB offset. How efficient would that be compared to appending my data at the end of the file? Just to make the example complete lets say I want to insert 16KB of data. I understand the answer varies depending on the filesystem, however I assume that the techniques used in common filesystems are quite similar and I just want to get the right notion of it.

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• C# (With .NET & Visual Studio) WebForms - How can I get the title of a page ..?

  - by Ashley Davies

  Prety long question; How can I do the following in C#: Open a webpage (Prefferably not visible) Check whether the page redirects to a different page (Site is down, 404, etc.) Check if the title is not equal to a said string Then seperately, (They need to click a confirm button) open their browser, and go to the adress of the first (It'll be the only one) hyperlink on the site. I literally have been looking on google for ages and haven't found anything similar to what I need. Whether you give me a link to a site with a tutorial on this area of programming or actual source code doesn't make a difference to me.

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• I need to pad IP addresses with Zeroes for each octet

  - by Felipe Alvarez

  Starting with a string of an unspecified length, I need to make it exactly 43 characters long (front-padded with zeroes). It is going to contain IP addresses and port numbers. Something like: ### BEFORE # Unfortunately includes ':' colon 66.35.205.123.80-137.30.123.78.52172: ### AFTER # Colon removed. # Digits padded to three (3) and five (5) # characters (for IP address and port numbers, respectively) 066.035.05.123.00080-137.030.123.078.52172 This is similar to the output produced by tcpflow. Programming in Bash. I can provide copy of script if required. If it's at all possible, it would be nice to use a bash built-in, for speed. Is printf suitable for this type of thing?

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• Convert a string representation of a hex dump to a byte array using Java?

  - by ravigad

  I am looking for a way to convert a long string (from a dump), that represents hex values into a byte array. I couldn't have phrased it better than the person that posted the same question here: http://www.experts-exchange.com/Programming/Programming_Languages/Java/Q_21062554.html But to keep it original, I'll phrase it my own way: suppose I have a string "00A0BF" that I would like interpreted as the byte[] {0x00,0xA0,0xBf} what should I do? I am a Java novice and ended up using BigInteger and watching out for leading hex zeros. But I think it is ugly and I am sure I am missing something simple...

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• What are the things Java got right?

  - by hamletdarcy

  What are the things that Java (the language and platform) got categorically right? In other words, what things are more recent programming languages preserving and carrying forward? Some easy answer are: garbage collection, a VM, lack of pointers, classloaders, reflection(?) What about language based answers? Please don't list the things Java did wrong, just right. (note by Mark Harrison) This is an interesting and useful question, especially for those of us who don't use java regularly. I'm voting for reopening. Please don't close as argumentative, as it doesn't seem to be causing any arguments.

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• In Flash Actionscript 3.0 how do I create smooth keyboard controls for player movement?

  - by Reid

  I am a beginner in Flash Actionscript 3.0 programming. I am trying to create smooth keyboard controls for player movement in a game. I'm currently using addEventListener(KeyboardEvent.KEY_DOWN) listening for a keyboard key press and then within the handler function moving a graphic by adding a number to its .x or .y property. This creates a slow, sluggish jerk at the beginning. I know there's a smoother, more responsive way to do this but have no idea where to begin. Any help would be appreciated!

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• Convert Yes/No/Null from SQL to True/False in a DataTable

  - by Scott Chamberlain

  I have a Sql Database (which I have no control over the schema) that has a Column that will have the varchar value of "Yes", "No", or it will be null. For the purpose of what I am doing null will be handled as No. I am programming in c# net 3.5 using a data table and table adapter to pull the data down. I would like to directly bind the column using a binding source to a check box I have in my program however I do not know how or where to put the logic to convert the string Yes/No/null to boolean True/False; Reading a null from the SQL server and writing back a No on a update is acceptable behavior. Any help is greatly appreciated. EDIT -- This is being developed for windows.

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• How to program a connection pool?

  - by the_drow

  Is there a known algorithm for implementing a connection pool? If not what are the known algorithms and what are their trade-offs? What design patterns are common when designing and programming a connection pool? Are there any code examples implement a connection pool using boost.asio? Is it a good idea to use a connection pool for presisting connections (not http)? How is threading related to connection pooling? When do you need a new thread?

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• C++ -- return x,y; The point?

  - by Earlz

  Hello, I have been programming in C and C++ for a few years and now I'm taking a college course in it and our book had a function like this int foo(){ int x=0; int y=20; return x,y; //y is always returned } I have never seen such syntax. In fact, I never see the , operator used outside of parameter lists. If y is always returned though, then what is the point? Is there a case where a return statement would need to be created like this? (Also, I tagged C as well because it applies to both, though my book specifically is C++)

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• databind a DropDownList control with a list of all sub directories that exist in a particular direct

  - by sushant

  I am wanting to databind a DropDownList control with a list of all sub directories that exist in a particular directory on the server. The directory I want to search is in the root of the application. I am fairly new to programming and I'm not sure where to even start. I found this code on a website: Dim root As String = "C;\" Dim folders() As String = Directory.GetDirectories(root) Dim sb As New StringBuilder(2048) Dim f As String For Each f In folders Dim foldername As String = Path.GetFileName(f) sb.Append("<option>") sb.Append(foldername) sb.Append("</option>") Next Label3.Text = "<select runat=""sever"" id=""folderlist""" & sb.ToString() & "</select>" I guess this is vb. but my tool is in asp, so is their something similar in vbscript so that I can use it.

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• Xcode 3.2 not recompiling changed files

  - by Jason

  I've been programming a new iPhone application and everything has been chugging along fine, until this afternoon when I noticed that any changes I was making were not being reflected in the actual app! Even code that throws errors isn't getting picked up by the compiler. To get around this, I have taken to the following procedure: Finish making my edits, and add code to the file which will always throw a compiler error. Right-click the file I have just edited, and hit "Compile" to just compile that one file; it will throw the error. Remove the error-producing code, and again right-click and "Compile" the one file. Build the whole project This is quite annoying, and I can't figure out why this would suddenly happen to my Xcode project. Any thoughts on what could be causing this, and how to fix it?

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• Assign value to list

  - by Kenneth B

  Hello First and foremost. I'm totally new to "programming" in Excel. I'm trying to make a price calculator, that calculates the price when I use my printer. I have made some lists so it's easy to perform the calculations. Single or duplex: Singlex/Duplex Format: SRA3 / A4 / SRA3 High Gloss The idea is that if I type in an amount of 100 prints, choose SRA3 format on the list, and choose Duplex on the other list. the calculation would look like this: This is how it's calculated: Paper + (print x sides) = Price of the print job Print prices Per page (singlex or duplex): 0,6 Paper format and price: A4 reg. paper: 0,2 SRA3 High Gloss: 1,25 SRA3 reg. paper: 1 Does anyone know about this???

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• Do most web 'programmers' (not designers) use WYSIWYG editors or hand code their HTML?

  - by John MacIntyre

  When I started programming web pages, it became immediately obvious that the WYSIWYG editors sucked. The HTML output was difficult to maintain, did things in ways you may not have agreed with, completely messed up existing pages if opened, couldn't handle code in the page, and was polluted with dead or irrelevant code like <font ...></font>. At that time, I didn't know a single programmer with more than 6 months experience who didn't hand code their HTML. Even now, most of the developers I know hand code their HTML. But, I also realize this was a decade ago, WYSIWYG editors have improved, and I may be seriously underproductive hand coding my HTML. Do you, as a web programmer, use WYSIWYG editors for your HTML? PS-I'm kind of thinking we can just vote either YES or NO, and put comments below.

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• Receive input over TCP/IP and use it to update HTML

  - by mawg

  This has got to be a FAQ, so can someone please just direct me to a "network programming for dummies" URL? The server wants to push information to a client or broadcast to all, when an event happens - as opposed to the clients constantly polling the server "just in case". The client then updates a browser page display. How do I do that? (toldya it was a n00b question) Should I have a thread which receives info on a socket and then writes it to a database which the browser display (PHP) can process with an HTML refresh tag, or what? Sorry to sound so dumb.

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• How the websocket bi-directional concept work?

  - by GMsoF

  I think the main difference between websocket and http streaming (I am not refering to polling and long polling) is websocket allows bi-directional communication which is similar to usual raw socket programming. (above is my understanding, could be wrong, feel free to correct me.) My question is how the web client (browser) continue to send another request in the already-opened websocket? Usual http request will treat another request as new socket connection, but websocket does not, that is why I am confused, how it achieve that? It should be handled in Server side or Client (browser) side?

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• Which is faster in memory, ints or chars? And file-mapping or chunk reading?

  - by Nick

  Okay, so I've written a (rather unoptimized) program before to encode images to JPEGs, however, now I am working with MPEG-2 transport streams and the H.264 encoded video within them. Before I dive into programming all of this, I am curious what the fastest way to deal with the actual file is. Currently I am file-mapping the .mts file into memory to work on it, although I am not sure if it would be faster to (for example) read 100 MB of the file into memory in chunks and deal with it that way. These files require a lot of bit-shifting and such to read flags, so I am wondering that when I reference some of the memory if it is faster to read 4 bytes at once as an integer or 1 byte as a character. I thought I read somewhere that x86 processors are optimized to a 4-byte granularity, but I'm not sure if this is true... Thanks!

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• Python recursive program

  - by mathboy

  I'm relatively newcomer on programming as I'm educated a mathematician and have no experience on Python. I would like to know how to solve this problem in Python which appeared as I was studying one maths problem on my own: Program asks a positive integer m. If m is of the form 2^n-1 it returns T(m)=n*2^{n-1}. Otherwise it writes m to the form 2^n+x, where -1 < x < 2^n, and returns T(m)=T(2^n-1)+x+1+T(x). Finally it outputs the answer.

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