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• Ways to gain a deeper understanding of programming concepts?

  - by MrPlow

  I'm a marketer and have been messing around in PHP/MySQL for years. Recently (the last several months) I've been making my own scripts/programs in Python and I've really enjoyed the whole problem solving process. I've read(skimmed) some books and understand the basics of OOP, polymorphism, etc.. I have a general interest in AI and Natural Language in particular but it seems these things require a masters in Computer Science. My knowledge of math is poor. The last class I took was calculus, and I've forgotten the majority of it. Basically I'm looking for things to learn that will help me think in a more analytic way, and maybe see solutions where I didn't before. Improving my ability to program in Python would be nice too. I don't need to learn a specific language or something for employment, just enjoyment. Although my work often involves web development so some utility would be nice. I don't like learning concepts by just reading them. I need to apply them, even if the examples are contrived. A recommendation of a couple good books or other resources would be nice. :) Apologies if this is too vague/misplaced...

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• RFC: Whitespace's Assembly Mnemonics

  - by Noctis Skytower

  Request For Comment regarding Whitespace's Assembly Mnemonics What follows in a first generation attempt at creating mnemonics for a whitespace assembly language. STACK ===== push number copy copy number swap away away number MATH ==== add sub mul div mod HEAP ==== set get FLOW ==== part label call label goto label zero label less label back exit I/O === ochr oint ichr iint In the interest of making improvements to this small and simple instruction set, this is a second attempt. hold N Push the number onto the stack copy Duplicate the top item on the stack copy N Copy the nth item on the stack (given by the argument) onto the top of the stack swap Swap the top two items on the stack drop Discard the top item on the stack drop N Slide n items off the stack, keeping the top item add Addition sub Subtraction mul Multiplication div Integer Division mod Modulo save Store load Retrieve L: Mark a location in the program call L Call a subroutine goto L Jump unconditionally to a label if=0 L Jump to a label if the top of the stack is zero if<0 L Jump to a label if the top of the stack is negative return End a subroutine and transfer control back to the caller exit End the program print chr Output the character at the top of the stack print int Output the number at the top of the stack input chr Read a character and place it in the location given by the top of the stack input int Read a number and place it in the location given by the top of the stack What is the general consensus on the following revised list for Whitespace's assembly instructions? They definitely come from thinking outside of the box and trying to come up with a better mnemonic set than last time. When the previous python interpreter was written, it was completed over two contiguous, rushed evenings. This rewrite deserves significantly more time now that it is the summer. Of course, the next version of Whitespace (0.4) may have its instructions revised even more, but this is just a redesign of what originally was done in a few hours. Hopefully, the instructions make more sense to those new to programming jargon.

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• Http Digest Authentication, Handle different browser char-sets...

  - by user160561

  Hi all, I tried to use the Http Authentication Digest Scheme with my php (apache module) based website. In general it works fine, but when it comes to verification of the username / hash against my user database i run into a problem. Of course i do not want to store the user´s password in my database, so i tend to store the A1 hashvalue (which is md5($username . ':' . $realm . ':' . $password)) in my db. This is just how the browser does it too to create the hashes to send back. The Problem: I am not able to detect if the browser does this in ISO-8859-1 fallback (like firefox, IE) or UTF-8 (Opera) or whatever. I have chosen to do the calculation in UTF-8 and store this md5 hash. Which leads to non-authentication in Firefox and IE browsers. How do you solve this problem? Just do not use this auth-scheme? Or Store a md5 Hash for each charset? Force users to Opera? (Terms of A1 refer to the http://php.net/manual/en/features.http-auth.php example.) (for digest access authentication read the according wikipedia entry)

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• BindingList<T> and reflection!

  - by Aren B

  Background Working in .NET 2.0 Here, reflecting lists in general. I was originally using t.IsAssignableFrom(typeof(IEnumerable)) to detect if a Property I was traversing supported the IEnumerable Interface. (And thus I could cast the object to it safely) However this code was not evaluating to True when the object is a BindingList<T>. Next I tried to use t.IsSubclassOf(typeof(IEnumerable)) and didn't have any luck either. Code /// <summary> /// Reflects an enumerable (not a list, bad name should be fixed later maybe?) /// </summary> /// <param name="o">The Object the property resides on.</param> /// <param name="p">The Property We're reflecting on</param> /// <param name="rla">The Attribute tagged to this property</param> public void ReflectList(object o, PropertyInfo p, ReflectedListAttribute rla) { Type t = p.PropertyType; //if (t.IsAssignableFrom(typeof(IEnumerable))) if (t.IsSubclassOf(typeof(IEnumerable))) { IEnumerable e = p.GetValue(o, null) as IEnumerable; int count = 0; if (e != null) { foreach (object lo in e) { if (count >= rla.MaxRows) break; ReflectObject(lo, count); count++; } } } } The Intent I want to basically tag lists i want to reflect through with the ReflectedListAttribute and call this function on the properties that has it. (Already Working) Once inside this function, given the object the property resides on, and the PropertyInfo related, get the value of the property, cast it to an IEnumerable (assuming it's possible) and then iterate through each child and call ReflectObject(...) on the child with the count variable.

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• Dragging a copy of all selected elements from a select box--possible?

  - by Sean

  I have a picklist web interface: a pair of select elements with a pair of buttons (a left-pointing arrow and a right-pointing arrow) between them. Users can move items between the two columns by, eg, selecting one of options in the left column and clicking on the right-pointing arrow. Now I have an enhancement request: someone wants to be able to drag-and-drop items between the two columns instead of clicking a button. The problem with my initial two-select-box setup is that as soon as I click one of the highlighted options to initiate a drag, all of the other selected options are deselected. Using jQuery, I've attached mousedown event handlers to both the select boxes and each individual option that just call preventDefault() on the event object, but this isn't sufficient. On Firefox 3 the clicked-on option loses focus immediately, but all other options are still deseleted, and on IE6 (which I regrettably still have to support) it makes no difference at all. So I thought I could maybe create a reasonable facsimile of a select box using list elements or divs or something. I can create something reasonable-looking that works on Firefox, but on IE6, if I shift-click on an element of my pseudo-select object (in order to select a range of options), IE selects all of the text between where I click and the last place I clicked. Again, I've attached preventDefault-ing mousedown, mouseup, and click handlers to all of the elements involved, but it doesn't help. I've even tried overlaying transparent divs over both my original select boxes and my pseudo-select objects, thinking to intercept mouse clicks and manage the selections manually, but I can't make it work on IE. If I use a select box, I can't prevent clicks from changing the selection, and if I use text that just looks like a select element, I can't prevent it from selecting a range of text on a shift-click. Is there some general solution, or am I just out of luck?

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• Who architected / designed C++'s IOStreams, and would it still be considered well-designed by today'

  - by stakx

  First off, it may seem that I'm asking for subjective opinions, but that's not what I'm after. I'd love to hear some well-grounded arguments on this topic. In the hope of getting some insight into how a modern streams / serialization framework ought to be designed, I recently got myself a copy of the book Standard C++ IOStreams and Locales by Angelika Langer and Klaus Kreft. I figured that if IOStreams wasn't well-designed, it wouldn't have made it into the C++ standard library in the first place. After having read various parts of this book, I am starting to have doubts if IOStreams can compare to e.g. the STL from an overall architectural point-of-view. Read e.g. this interview with Alexander Stepanov (the STL's "inventor") to learn about some design decisions that went into the STL. What surprises me in particular: It seems to be unknown who was responsible for IOStreams' overall design (I'd love to read some background information about this — does anyone know good resources?); Once you delve beneath the immediate surface of IOStreams, e.g. if you want to extend IOStreams with your own classes, you get to an interface with fairly cryptic and confusing member function names, e.g. getloc/imbue, uflow/underflow, snextc/sbumpc/sgetc/sgetn, pbase/pptr/epptr (and there's probably even worse examples). This makes it so much harder to understand the overall design and how the single parts co-operate. Even the book I mentioned above doesn't help that much (IMHO). Thus my question: If you had to judge by today's software engineering standards (if there actually is any general agreement on these), would C++'s IOStreams still be considered well-designed? (I wouldn't want to improve my software design skills from something that's generally considered outdated.)

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• compiling and running java on windows

  - by artur grzesiak

  I thought the task should be fairly easy, but my understanding of javac and java in general is rather poor. I am using Windows8 and would like to compile a single file.java that makes use of other classes. I successfully (at least without any warnings) compiled my file by calling: javac -cp relative_path_to_needed_classes relative_path_to_file_java\file.java Now if I want to run the result of compilation (file.class) by calling: java -cp relative_path_to_needed_classes relative_path_to_file_java\file I get: Error: Could not find or load main class relative_path_to_file_java\file I was trying a lot of combination to modify the -cp (eg. by adding .\;relative_path_to_file;) but still the closest where I get is: Exception in thread "main" java.lang.NoClassDefFoundError : relative_path_to_file\file (wrong name: file) The file from (wrong name: file) is the name of the file and the name of the public class within the file. I was reading a lot on SO and other sources but could not figure out what is wrong. Btw. as a result of compilation some other classes were created: file$1.class file$name1.class file$name2.class (where name1 and name2 are names of private classes within file.java) My questions are: What is (the most) probably source of my error / what am I doing wrong? What is the purpose of file$1.class? What is the minimum I should specify in -cp? May encoding play any role? Do every java class have to reside in a package? (rather not directly related to my issue) Do order of paths specified in -cp play any role in runtime?

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• _Painless_ integration of Eclipse with Vim?

  - by Adnan

  Hi, Has anyone managed to get Vim integrated into Eclipse painlessly? I just want to use Vim for the editor while retaining the general Eclipse interface. I have tried using Eclim plugin but the editor seemed to crash more often than work (the site said that the editor replacement functionality is still beta). On the flip side, is there any IDE which matches Eclipse's functionality -- mainly the integration with SVN, ant, etc. -- and is also able to use Vim? I mostly use eclipse for SAS SCL, Java and Javascript programming and find the eclipse editor too "mouse-y". I'd also like, in a perfect world, to use vimdiff as a diff viewer for SVN (we use TortoiseSVN) while checking for diffs or conflicts during merge etc. I admit I havent spent a lot of time trying to get these things to work. I feel guilty about spending too much time on potential wild-goose-chases while my other team members are working away at their code, perfectly content with all that eclipse has to offer. Edit: Just found this while desperately browsing around: Vim plugin.. Any experience using this? Its saturday afternoon in Kiwi land, so I'll try it later and update if no one has an opinion. From the claims on the site, it sounds perfect.

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• export and import utf8 data in mysql: best practices

  - by ChrisRamakers

  We're often faced with the need to send a data file to one of our clients with data from the database he/she needs to translate. Most of the time this export is CSV or XLS. Most of the time we create a csv dump with phpmyadmin and get an xls file in return with the translated data. The problem is that most of the time the data is UTF8 and when the file is returned as xls each and every time we load the data into mysql again we end up with utf8 problems, characters not being displayed properly, etc ... We've already doublechecked everything in mysql from my.conf to column charactersets and everything is set correctly to UTF8. My question is not how to fix the encoding issue since that's been solved but how we would best proceed in the future handling this situation? What export format should we hand over? How should we import (just mysql load data infile or our own processing scripts). What is the general consensus on how to handle this situation? We would like to continue using excel if possible since that's the format almost everybody expects including our clients' translation agencies. Our clients' ease of use is the most important factor here, without overloading us with major issues each time. The best of both worlds :)

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• Simple Java Applet not loading in FireFox / Safari on MacOS

  - by Sleepless

  Hello all, I'm probably missing something very basic here. I'm trying to get my first applet to run inside a local HTML page in Firefox 3.6 on Mac OS 10.5.8. Here's the applet's code: package SimpleApplet; import java.applet.Applet; import java.awt.*; public class MyApplet extends Applet { private static final long serialVersionUID = 1L; public void init() { } public void stop() { } public void paint(Graphics g) { g.drawString("Tweedle-Dee!",20,40); } } Here's the HTML page: <html> <body> Here's the applet: <br/> <applet code="MyApplet.class" width="300" height="150"> </applet> </body> </html> Both files (.class and .html) are in the same folder on my local machine. Now when I load the .html file into Firefox, a rectangle with a red X gets displayed. The applet works when started from Eclipse (using JRE 1.5 BTW). Also, it's not a general problem with my browser, as several pages with applets (e.g. http://java.sun.com/applets/jdk/1.4/demo/applets/Blink/example1.html) work. This is also difficult to troubleshoot because there is no output at all on the Java console... Any suggestions are appreciated!

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• Efficient way to create a large number of SharePoint folders

  - by BeraCim

  Hi all: I'm currently creating a large number of SharePoint folders within a list (e.g. ~800 folders), with each folder containing a different number of items. The way it is currently done is that it programmatically reads off the content types, items, event listeners and the likes off the same folder from another web, then creates the same folder in the current web. That ran reasonably fine and fast on a dev environment. However when it goes to an environment with WFEs and farms, it slowed down a lot. I have checked that there are no leaks in the code, and that the code follows SharePoint coding best practices. At the moment I'm looking at it at the code level. From your experience, are there any efficient ways of creating a large number of SharePoint folders, lists and items? EDIT: I'm currently using SharePoint API, but will be looking at moving to using Web Service in the future. I'm interested in looking at both options though. Code wise, its just the general reading of a folder and its content types plus items and their details, then create the same folder in the same list with the same content types, then copy over the items using patch update. I want to know whether there are more efficient ways of doing the above. Thanks.

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• belongs_to with multiple models

  - by julie p

  Hi there! I am a Rails noob and have a question. I have a feed aggregator that is organized by this general concept: Feed Category (books, electronics, etc) Feed Site Section (home page, books page, etc) Feed (the feed itself) Feed Entry So: class Category < ActiveRecord::Base has_many :feeds has_many :feed_entries, :through => :feeds, :limit => 5 validates_presence_of :name attr_accessible :name, :id end class Section < ActiveRecord::Base has_many :feeds has_many :feed_entries, :through => :feeds, :limit => 5 attr_accessible :name, :id end class Feed < ActiveRecord::Base belongs_to :categories belongs_to :sections has_many :feed_entries validates_presence_of :name, :feed_url attr_accessible :name, :feed_url, :category_id, :section_id end class FeedEntry < ActiveRecord::Base belongs_to :feed belongs_to :category belongs_to :section validates_presence_of :title, :url end Make sense? Now, in my index page, I want to basically say... If you are in the Category Books, on the Home Page Section, give me the feed entries grouped by Feed... In my controller: def index @section = Section.find_by_name("Home Page") @books = Category.find_by_name("Books") end In my view: <%= render :partial => 'feed_list', :locals => {:feed_group => @books.feeds} -%> This partial will spit out the markup for each feed entry in the @books collection of Feeds. Now what I need to do is somehow combine the @books with the @section... I tried this: <%= render :partial => 'feed_list', :locals => {:feed_group => @books.feeds(:section_id => @section.id)} -%> But it isn't limiting by the section ID. I've confirmed the section ID by using the same code in the console... Make sense? Any advice? Thanks!

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• Recommendations, Asp.Net ObjectDataSource bind result of webservice call

  - by DerDres

  I need recommendations on how to solve / structure a solution to the following problem. In an asp.net web application i'll have to visualise results returned from a web service call. Im planning to use a repeater server control and bind this with an objectdatasource. The service returns a result of the form: public class SearchResult : IExtensibleDataObject { [DataMember] public Guid SearchId { get; set; } [DataMember] public DateTime Timestamp { get; set; } [DataMember] public int Offset { get; set; } [DataMember] public int TotalResults { get; set; } [DataMember] public IList<ResultDocumentData> Documents { get; set; } It is the collection of Documents that I need to visualise with a repeater which will be associated with an ObjectDataSource. The datasource should work on the type ResultDocumentData; the collection property in the class SearchResult. I think I need to wrap the call to the webservice in a dataaccess layer class, that will have a getDocuments method returning an IList, that the ObjectDataSource can use as its SelectMethod. I think I could make this work, but I would like to know how to do it in an elegant way. Can you give me general recommendations and/or recommendations for the following: WebProject Folderstructure + naming Naming conventions for the name of the service wrapper class Creating the service reference

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• Can Haskell's Parsec library be used to implement a recursive descent parser with backup?

  - by Thor Thurn

  I've been considering using Haskell's Parsec parsing library to parse a subset of Java as a recursive descent parser as an alternative to more traditional parser-generator solutions like Happy. Parsec seems very easy to use, and parse speed is definitely not a factor for me. I'm wondering, though, if it's possible to implement "backup" with Parsec, a technique which finds the correct production to use by trying each one in turn. For a simple example, consider the very start of the JLS Java grammar: Literal: IntegerLiteral FloatingPointLiteral I'd like a way to not have to figure out how I should order these two rules to get the parse to succeed. As it stands, a naive implementation like this: literal = do { x <- try (do { v <- integer; return (IntLiteral v)}) <|> (do { v <- float; return (FPLiteral v)}); return(Literal x) } Will not work... inputs like "15.2" will cause the integer parser to succeed first, and then the whole thing will choke on the "." symbol. In this case, of course, it's obvious that you can solve the problem by re-ordering the two productions. In the general case, though, finding things like this is going to be a nightmare, and it's very likely that I'll miss some cases. Ideally, I'd like a way to have Parsec figure out stuff like this for me. Is this possible, or am I simply trying to do too much with the library? The Parsec documentation claims that it can "parse context-sensitive, infinite look-ahead grammars", so it seems like something like I should be able to do something here.

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• Reasons for & against a Database

  - by dbemerlin

  Hi, i had a discussion with a coworker about the architecture of a program i'm writing and i'd like some more opinions. The Situation: The Program should update at near-realtime (+/- 1 Minute). It involves the movement of objects on a coordinate system. There are some events that occur at regular intervals (i.e. creation of the objects). Movements can change at any time through user input. My solution was: Build a server that runs continously and stores the data internally. The server dumps a state-of-the-program at regular intervals to protect against powerfailures and/or crashes. He argued that the program requires a Database and i should use cronjobs to update the data. I can store movement information by storing startpoint, endpoint and speed and update the position in the cronjob (and calculate collisions with other objects there) by calculating direction and speed. His reasons: Requires more CPU & Memory because it runs constantly. Powerfailures/Crashes might destroy data. Databases are faster. My reasons against this are mostly: Not very precise as events can only occur at full minutes (wouldn't be that bad though). Requires (possibly costly) transformation of data on every run from relational data to objects. RDBMS are a general solution for a specialized problem so a specialized solution should be more efficient. Powerfailures (or other crashes) can leave the Data in an undefined state with only partially updated data unless (possibly costly) precautions (like transactions) are taken. What are your opinions about that? Which arguments can you add for any side?

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• response.Text is undefined when returning variable

  - by George

  Not sure if the problem is related to Ajax or something silly about JavaScript that I'm overlooking in general, but I have the following script where fox.html is just plain text that reads, "The quick brown fox jumped over the lazy dog." : function loadXMLDoc() { if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari xmlhttp=new XMLHttpRequest(); } else {// code for IE6, IE5 xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); } xmlhttp.open("GET","fox.html",true); xmlhttp.send(); xmlhttp.onreadystatechange=function() { if (xmlhttp.readyState==4 && xmlhttp.status==200) { fox = xmlhttp.responseText; alert(fox); } } } onload = loadXMLDoc; The above script alerts the contents of fox.html onload just fine. However if I change the script so that: { fox = xmlhttp.responseText; alert(fox); } becomes: { fox = xmlhttp.responseText; return fox; } and alert(loadXMLDoc()); onload I get 'undefined'. I'm wondering why this is so.

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• Updating join fields in an ORM command

  - by Jono

  I have a question about object relational updates on join fields. I am working on a project using codeigniter with datamapper dmz. But I think my problem is with general understanding of ORMs. So fell free to answer with any ORM you know. I have two tables, Goods and Tags. One good can have many tags. Everything is working, but I am looking for a way to merge tags. Meaning I decide I want to remove tag A and instead have everything that is tagged by it, now be tagged by tag B. I only have models for the goods and the tags. There is no separate model for the join relationship, as I believe these ORMs were designed to work. I know how to delete a tag. But I dont know how to reach into the join table to redirect the references since there is no model for the join table. I would rather use the ORM then issuing a raw SQL command.

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• Using authsmtp from a Grails server

  - by Simon

  This is quite a specific question, and I have had no luck on the grails nabble forum, so I thought I would post here. I am using the grails mail plug-in, but I think my question is a general one about using authsmtp as an email gateway from my server. I am having trouble sending mail from my app using authsmtp. I have installed and configured the mail plugin and was originally using my ISP's SMTP server to send mails. However when I deployed to AWS EC2 this failed because my elastic IP was blocked by the SMTP host. So I bought myself an authsmtp account and set up my server email address as an accepted one at authsmtp. I then changed my configuration in SecurityConfig.groovy to point to the authsmtp server that I had been designated... mailHost = "mail.authsmtp.com" mailUsername = "myusername" mailPassword = "mypassword" mailProtocol = "smtp" mailFrom = "[email protected]" mailPort = 2525 ...and I'm just trying to get this to work locally before I deploy back up to AWS. Sending mail fails and in my log I have this exception: 2010-02-13 10:59:44,218 [http-8080-1] ERROR service.EmailerService - Failed to send emails: Failed messages: com.sun.mail.smtp.SMTPSendFailedException: 513 5.0.0 Your email system must authenticate before sending mail. org.springframework.mail.MailSendException; nested exception details (1) are: Failed message 1: com.sun.mail.smtp.SMTPSendFailedException: 513 5.0.0 Your email system must authenticate before sending mail. at com.sun.mail.smtp.SMTPTransport.issueSendCommand(SMTPTransport.java:1388) at com.sun.mail.smtp.SMTPTransport.mailFrom(SMTPTransport.java:959) at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:583) I'm a bit lost since the username and password I provide in the configuration are definitely correct. A terse and not very helpful conversation with authsmtp support suggests that I need to MD5 and/or base64 encode my credentials before sending, so my question is in three parts... 1) any idea what's going on with the failure and why that message is appearing? 2) how would I encode the credentials to pass to authsmtp and how would I configure that for the mail plugin 3) has anyone successfully connected and sent mail through authsmtp from the mail plugin and specifically from AWS EC2?

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• Flex HttpService POST limited to 543 Byte per Form field?

  - by motto

  Hi, I am getting a FaultEvent when trying to send form fields through HTTPService that contain more than 542 chars. Initializing the HttpService: httpServ = new HTTPService(); httpServ.method = 'POST'; httpServ.url = ENDPOINT_URL; //http://localhost:3001/ReportError.aspx httpServ.resultFormat = HTTPService.RESULT_FORMAT_TEXT; httpServ.contentType = HTTPService.CONTENT_TYPE_FORM; httpServ.addEventListener(ResultEvent.RESULT, OnErrorSent); httpServ.addEventListener(FaultEvent.FAULT, OnFault); Sending the request: var params:Object = {}; //params["stack"] = e.stackTrace.slice(0, 542); //length 542 = works //params["stack2"] = e.stackTrace.slice(1, 543); //length 542 = works (just to show that it's not about the content itself) params["stack3"] = e.stackTrace.slice(0, 543); //length 543 = fails I also seem to be able to create many form fields (with 542 length) so that it's not a limit of the request itself but of the form field: var params:Object = {}; params["stack"] = e.stackTrace.slice(0, 542); //length 542 params["stack2"] = e.stackTrace.slice(1, 543); //length 542 params["stack3"] = e.stackTrace.slice(2, 544); //length 542 // Length > 1600 chars The receiving party is an ASP.NET 4 site on the same domain and port. I hope someone already came across a similar restrictions or has some general advice on how to trace this problem down further. Thanks in advance.

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• Writing catch block with cleanup operations in Java ...

  - by kedarmhaswade

  I was not able to find any advise on catch blocks in Java that involve some cleanup operations which themselves could throw exceptions. The classic example is that of stream.close() which we usually call in the finally clause and if that throws an exception, we either ignore it by calling it in a try-catch block or declare it to be rethrown. But in general, how do I handle cases like: public void doIt() throws ApiException { //ApiException is my "higher level" exception try { doLower(); } catch(Exception le) { doCleanup(); //this throws exception too which I can't communicate to caller throw new ApiException(le); } } I could do: catch(Exception le) { try { doCleanup(); } catch(Exception e) { //ignore? //log? } throw new ApiException(le); //I must throw le } But that means I will have to do some log analysis to understand why cleanup failed. If I did: catch(Exception le) { try { doCleanup(); } catch(Exception e) { throw new ApiException(e); } It results in losing the le that got me here in the catch block in the fist place. What are some of the idioms people use here? Declare the lower level exceptions in throws clause? Ignore the exceptions during cleanup operation?

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• Querying a database using Cocoa.

  - by S1syphus

  Hello everybody. Before I start a disclaimer, I should add a little disclaimer, that I am relatively new to Cocoa development and C in general. However I do have a copy of 'Cocoa Programming for Mac OS X 3rd edition' by Aaron Hillegass, which I am working through and using as a base, if anybody has a copy I am using the 'AmaZone' example on page 346 as a template and base. I trying to develop a small client app that takes a search string then displays results from a database accordingly. The database will contain a: list of files, their location, description & creation date, so for the moment the field number and types will remain the same. After looking around on SO, I saw something like: NSURL *myURL = [NSURL URLWithString:@"http://www.myserver.com/results.php"]; NSArray *sqlResults = [[NSArray alloc] initWithContentsOfURL:myURL]; I've worked with php before, so my current thinking after seeing this is create a php script on the server that queries the database, and creates an XML output. And with the XML response, just parse it. Would this be ok? as is there any major pitfalls anybody can see, that I can't. I know there are some database bundles, I've had a look at BaseTen for Postgres, but being relatively new to this, didn't want to get in over my head. Or if anybody else has any other suggestions and ideas, they would be greatly appreciated.

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• Shape object in Processing, translate individual shapes.

  - by Zain

  I am relatively new to Processing but have been working in Java for about 2 years now. I am facing difficulty though with the translate() function for objects as well as objects in general in processing. I went through the examples and tried to replicate the manners by which they instantiated the objects but cannot seem to even get the shapes to appear on the screen no less move them. I instantiate the objects into an array using a nested for loop and expect a grid of the objects to be rendered. However, nothing at all is rendered. My nested for loop structure to instantiate the tiles: for(int i=0; i<102; i++){ for(int j=0; j<102; j++){ tiles[i][j]=new tile(i,0,j); tiles[i][j].display(); } } And the constructors for the tile class: tile(int x, int y, int z){ this.x=x; this.y=y; this.z=z; beginShape(); vertex(x,y,z); vertex(x+1,y,z); vertex(x+1,y,z-1); vertex(x,y,z-1); endShape(); } Nothing is rendered at all when this runs. Furthermore, if this is of any concern, my translations(movements) are done in a method I wrote for the tile class called move which simply calls translate. Is this the correct way? How should one approach this? I can't seem to understand at all how to render/create/translate individual objects/shapes. Thanks for any help any of you are able to provide!

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• Random Pairings that don't Repeat

  - by Andrew Robinson

  This little project / problem came out of left field for me. Hoping someone can help me here. I have some rough ideas but I am sure (or at least I hope) a simple, fairly efficient solution exists. Thanks in advance.... pseudo code is fine. I generally work in .NET / C# if that sheds any light on your solution. Given: A pool of n individuals that will be meeting on a regular basis. I need to form pairs that have not previously meet. The pool of individuals will slowly change over time. For the purposes of pairing, (A & B) and (B & A) constitute the same pair. The history of previous pairings is maintained. For the purpose of the problem, assume an even number of individuals. For each meeting (collection of pairs) and individual will only pair up once. Is there an algorithm that will allow us to form these pairs? Ideally something better than just ordering the pairs in a random order, generating pairings and then checking against the history of previous pairings. In general, randomness within the pairing is ok.

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• Table cell in a split-view controller - selected cell becomes deselected when called by reloadData

  - by bpapa

  I'm working on a universal app that uses a SplitViewController to present a master-detail view. In the iPad HIG on Split Views, Apple states: In general, indicate the current selection in the left pane in a persistent way. This behavior helps people understand the relationship between the item in the left pane and the contents of the right pane. This is important because the contents of the right pane can change, but they should always remain related to the item selected in the left pane. So I'm trying to maintain selection state on the left. Easy enough when the user taps, I just remove the deselectRowAtIndexPath:animated: message from tableView:didSelectRowAtIndexPath: implementation. But, I also want the selection state to show up by default (without a user tap). I wound up putting this in my tableView:cellForRowAtIndexPath: implementation: if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) { if (cellShouldBeSelected) cell.selected = YES; else cell.selected = NO; } The behavior I'm seeing, is that when the cells finall appear, for a fraction of a section the cell is indeed selected, but then the selection disappears without any user interaction. Any ideas? I set the new clearsSelectionOnViewWillAppear property to NO, but that doesn't seem to fix it, and it shouldn't really matter because I'm marking the cell as selected long after viewWillAppear is called - I'm actually doing it after some network activity and then sending the table view a reloadData message.

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• How large a role does subjectiveness play in programming?

  - by Bob

  I often read about the importance of readability and maintainability. Or, I read very strong opinions about which syntax features are bad or good. Or discussions about the values of certain paradigms, like OOP. Aside from that, this same question floats about in my mind whenever I read debates on SO or Meta about subjective questions. Or read questions about best practices and sometimes find myself or others disagreeing. What role does subjectiveness play within the programming realm? Sometimes I think it plays a large role. Software developers are engineers in a way, but also people. A large part of programming is dealing with code that's human readable. This is very different from Math or Physics or other disciplines with very exact and structured rules. Here the exact structure and rules are largely up in the air, changeable on a whim, and hence the amount of languages in existence. And one person may find one language very readable, and another person may find their own language the most comforting. The same with practices. One person may not like certain accepted practices. I myself find splitting classes into different files very unreadable, for instance. But, I can't say rules haven't helped in general. Certain practices have and do make life easier. And new languages have given rise to syntax and structure that make life easier. There's certainly been a progression towards code that is easier to read and maintain even given a largely diverse group of people. So maybe these things aren't as subjective as I thought. It reminds me, in a way, of UI design. Certainly it's subjective, but then there's an entire discipline involved in crafting good UI and it tends to work. Is there something non-subjective about the ideas behind maintainability, readability, and other best practices? Is there something tangible to grasp when one develops a new language or thinks of new practices?

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