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• Can the Visual Studio (2010) Command Window handle "external tools" with project/solution relative p

  - by ee

  I have been playing with the Command Window in Visual Studio (View-Other Windows-Command Window). It is great for several mouse-free scenarios. (The autocompleting file "Open" command rocks in a non-trivial solution.) That success got me thinking and experimenting: Possibility 1.1: You can use the Alias commands to create custom commands Possibility 1.2: You can use the Shell command to run arbitrary executables and specify parameters (and pipe the result to the output or command windows) Possibility 2: A previously setup external tool definition (with project-relative path variables) could be run from the command window What I am stuck on is: There doesn't appear to be a way to send parameters to an aliased command (and thus the underlying Shell call) There doesn't appear to be a way to use project/solution relative paths ($SolutionDir/$ProjectDir) on a Shell call Using absolute paths in Shell works, but is fragile and high-maintenance (one alias for each needed use case). Typically you want the command to run against a file relative to your project/solution. It seems you can't run the traditional external tools (Tools-External Tools...) in the command window Ultimately I want the external tool functionality in the command window in some way. Can anyone see a way to do this? Or am I barking up the wrong tree? So my questions: Can an "external tool" of some sort (using relative project/solution path parameters) be used in the Command Window? If yes, How? If no, what might be a suitable alternative?

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• How combine TabBar + Navigation with XCode

  - by mamcx

  I'm triying to combine a TabBar + Navigation app. I have 5 tab bars, 4 are listing of stuff and drill down to details views. I try to follow this tutorial: http://www.iphonedevforums.com/forum/iphone-sdk-development/124-view-controller-problem.html But always get a blank view. This is what I do, with a clean project: I start with a TabBar template app. I put 5 tab bar buttons. I create a controller like: @interface FirstViewController : UINavigationController { } I put the main window.xib on tree mode & change the selected first view to FirstViewController I select the TabBar Controller in Interface builder, go to TabBar Attributes & change the class to navigation controler. Select the fist view & put the nib name "SecondView" In response, I get a blank screen. I must add that I wanna navigate from the details views, no from the main windows. i.e in the main window tab bar 1 is the list of people. I select a person then wanna navigate to the detail window.

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• Trouble swapping values as keys in generic java BST class

  - by user1729869

  I was given a generic binary search tree class with the following declaration: public class BST<K extends Comparable<K>, V> I was asked to write a method that reverses the BST such that the values become the keys and keys become values. When I call the following method (defined in the class given) reverseDict.put(originalDict.get(key), key); I get the following two error messages from Netbeans: Exception in thread "main" java.lang.RuntimeException: Uncompilable source code - Erroneous sym type: BST.put And also: no suitable method found for put(V,K) method BST.put(BST<K,V>.Node,K,V) is not applicable (actual and formal argument lists differ in length) method BST.put(K,V) is not applicable (actual argument V cannot be converted to K by method invocation conversion) where V,K are type-variables: V extends Object declared in method <K,V>reverseBST(BST<K,V>) K extends Comparable<K> declared in method <K,V>reverseBST(BST<K,V>) From what the error messages are telling me, since my values do not extend Comparable I am unable to use them as keys. If I am right, how can I get around that without changing the class given (maybe a cast)?

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• ActionListener isn't Implementing

  - by Nick Gibson

  JFrameWithPanel is not abstract and does not override abstract method actionPerformed(java.awt.event.ActionEvent) in java.awt.event.ActionListener public class JFrameWithPanel extends JFrame implements ActionListener I Don't get this code. Book and Java site tells me this is the syntax for the method, but again this error shows up constantly. import javax.swing.*; import javax.swing.JOptionPane; import java.awt.*; import java.awt.event.*; import java.lang.Math.*; import java.lang.Integer.*; import java.util.*; import java.util.Random; import java.io.*; import java.text.*; import java.text.DecimalFormat.*; public class JFrameWithPanel extends JFrame implements ActionListener { JButton button = new JButton("Exit"); public JFrameWithPanel() { super("JFrame with Panel"); JComboBox packageChoice = new JComboBox(); packageChoice.addItem("A+ Certification"); packageChoice.addItem("Network+ Certification "); packageChoice.addItem("Security+ Certifictation"); packageChoice.addItem("CIT Full Test Package"); packageChoice.addActionListener(this); setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JPanel pane = new JPanel(); pane.add(button); pane.add(packageChoice); setContentPane(pane); setSize(200,100); setVisible(true); } } then later public class CreateJFrameWithPanel { public static void main(String[] args) { JFrameWithPanel panel = new JFrameWithPanel(); } }

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• Simple HTML interface to XSD?

  - by Visage

  I'm writing an app that, at its heart, uses a hierarchical tree of nodes in XML, it looks like this: <node> <name>Node1</name> <Attribute1>Something</Attribute1> <Attribute2>SomethingElse</Attribute2> <child>Node2</child> <child>Node4</child> <child>Node7</child> </node> And so on (all child elements must refer to an existing node, though the node inquestion doesnt have to precede the first reference to it) For a simple structure like this is there a simple tool to generate a html page that will allow a user to enter Nodes and dynamically update a server-side xml file? Im basically writing a tool that will use such a file, but the people who's job it is to create the file arent especially techno-literate, so creating the XML by hand is a no-no. I could hand-crank one fairly quickly, but if I can get a tool to do it, even better (especially as the format may change in future)....

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• 3 questions about JSON-P format.

  - by Tristan

  Hi, I have to write a script which will be hosted on differents domains. This script has to get information from my server. So, stackoverflow's user told me that i have to use JSON-P format, which, after research, is what i'm going to do. (the data provided in JSON-P is for displaying some information hosted on my server on other website) How do I output JSON-P from my server ? Is it the same as the json_encode function from PHP How do i design the tree pattern for the output JSON-P (you know, like : ({"name" : "foo", "id" : "xxxxx", "blog" : "http://xxxxxx.com"}); can I steal this from my XML output ? (http://bit.ly/9kzBDP) Each time a visitor browse a website on which my widget is it'll make a request on my server, requesting the JSON-P data to display on the client side. It'll increase dramatically the CPU load (1 visitor on the website who will have the script = 1 SQL request on my server to output data), so is there any way to 'caching' the JSON-P information output to refresh it only one or twice a day and stores it into a 'file' (in which extension?). BUT on the other hand i would say that requesting the JSON-P data directly (without caching it) is a plus, because, websites which will integrates the script only want to display THEIR information and not the whole data. So, making a script with something like that: jQuery.getJSON("http://www.something.com/json-p/outpout?filter=5&callback=?", function(data) { ................); }); Where filter= the information the website wants to display What do you think ? Thank you very much ;)

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• Running Sitecore Production Site under a Virtual Directory

  - by danswain

  We are using Sitecore 6 on a Windows Server 2003 (32bit) dev machine. I know it's not recommended for the CMS editing site, but we've been told it is possible to get the front-end Sitecore websites to run from within a virtual directory. Here's the issue: we'd like to achieve what the below poor mans diagram shows. We have a website (.net 1.1) /WebSiteRoot (.net 1.1) | | |---- Custom .net 1.1 Web Application | |---- SiteCore frontend WebApplication (.net 2.0) | |---- Custom .net 2.0 WebApplication The Sitecore webApplication would contain the Sitecore pipeline in its web.config and we'd make use of the section to configure the virtual folder to allow for where our Sitecore app sits and point it to the appropriate place in the Content Tree. Is it possible to pull this off? This is just the customer facing website, there will be no CMS editing functionality on these servers, that will be done from a more standard Sitecore install inside the firewall on a different server. The errors we're encountering are centered around loading the the various config files in the App_Config folder. It seems to do a Server.MapPath on "/" initially (which is wrong for us) so we've tried putting absolute paths in the web.config and still no joy (I think there must be some hardcoded piece that looks for the Include directory). Any help would be greatly appreciated. Thanks

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• Bash script not working on a new dedicated server

  - by Scott

  Recently I have migrated to the new dedicated server which is running on the same operating system - FreeBSD 8.2. I got a root account access and all permissions have been set properly. My problem is that, the bash script I was running on the old server doesn't works on the new machine, the only error appearing while running the script is: # sh script.sh script.sh: 3: Syntax error: word unexpected (expecting ")") Here is the code itself: #!/usr/local/bin/bash PORTS=(7777:GAME 11000:AUTH 12000:DB) MESSG="" for i in ${PORTS[@]} ; do PORT=${i%%:*} DESC=${i##*:} CHECK=`sockstat -4 -l | grep :$PORT | awk '{print $3}' | head -1` if [ "$CHECK" -gt 1 ]; then echo $DESC[$PORT] "is up ..." $CHECK else MESSG=$MESSG"$DESC[$PORT] wylaczony...\n" if [ "$DESC" == "AUTH" ]; then MESSG=$MESSG"AUTH is down...\n" fi if [ "$DESC" == "GAME" ]; then MESSG=$MESSG"GAME is down...\n" fi if [ "$DESC" == "DB" ]; then MESSG=$MESSG"DB is down...\n" fi fi done if [ -n "$MESSG" ]; then echo -e "Some problems ocurred:\n\n"$MESSG | mail -s "Problems" [email protected] fi I don't really code in bash, so I don't know why this happend...

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• How do I use XPath with a default namespace with no prefix?

  - by Scott Stafford

  What is the XPath (in C# API to XDocument.XPathSelectElements(xpath, nsman) if it matters) to query all MyNodes from this document? <?xml version="1.0" encoding="utf-8"?> <configuration> <MyNode xmlns="lcmp" attr="true"> <subnode /> </MyNode> </configuration I tried /configuration/MyNode which is wrong because it ignores the namespace. I tried /configuration/lcmp:MyNode which is wrong because lcmp is the URI, not the prefix. I tried /configuration/{lcmp}MyNode which failed because Additional information: '/configuration/{lcmp}MyNode' has an invalid token. EDIT: I can't use mgr.AddNamespace("df", "lcmp"); as some of the answerers have suggested. That requires that the XML parsing program know all the namespaces I plan to use ahead of time. Since this is meant to be applicable to any source file, I don't know which namespaces to manually add prefixes for. It seems like {my uri} is the XPath syntax, but Microsoft didn't bother implementing that... true?

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• Measure text size in JavaScript

  - by kayahr

  I want to measure the size of a text in JavaScript. So far this isn't so difficult because I can simply put a temporary invisible div into the DOM tree and check the offsetWidth and offsetHeight. The problem is, I want to do this BEFORE the DOM is ready. Here is a stub: <html> <head> <script type="text/javascript"> var text = "Hello world"; var fontFamily = "Arial"; var fontSize = 12; var size = measureText(text, fontSize, fontFamily); function measureText(text, fontSize, fontFamily) { // TODO Implement me! } </script> </head> <body> </body> </html> Again: I KNOW how to do it asynchronously when DOM (or body) signals that it is ready. But I want to do it synchronously right in the header as shown in the stub above. Any ideas how I can accomplish this? My current opinion is that this is impossible but maybe someone has a crazy idea.

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• How to reliably get size of C-style array?

  - by Frank

  How do I reliably get the size of a C-style array? The method often recommended seems to be to use sizeof, but it doesn't work in the foo function, where x is passed in: #include <iostream> void foo(int x[]) { std::cerr << (sizeof(x) / sizeof(int)); // 2 } int main(){ int x[] = {1,2,3,4,5}; std::cerr << (sizeof(x) / sizeof(int)); // 5 foo(x); return 0; } Answers to this question recommend sizeof but they don't say that it (apparently?) doesn't work if you pass the array around. So, do I have to use a sentinel instead? (I don't think the users of my foo function can always be trusted to put a sentinel at the end. Of course, I could use std::vector, but then I don't get the nice shorthand syntax {1,2,3,4,5}.)

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• Best way to parse this particular string using awk / sed?

  - by Jack

  Hi, I need to get a particular version string from a file (call it version.lst) and use it to compare another in a shell script. For example sake, the file contains lines that look like this: V1.000 -- build date and other info here -- APP1 V1.000 -- build date and other info here -- APP2 V1.500 -- build date and other info here -- APP3 .. and so on. Let's say I am trying to grab the first version (in this case, V1.000) from APP1. Obviously, the versions can change and I want this to be dynamic. What I have right now works: var = `cat version.lst | grep " -- APP1" | grep -Eo V[0-9].[0-9]{3}` Pipe to grep will get the line containing APP1 and the second pipe to grep will get the version string. However, I hear grep is not the way to do this so I'd like to learn the best way using awk or sed. Any ideas? I am new to both and haven't found a tutorial easy enough to learn the syntax of it. Do they support egrep? Thanks!

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• Using placeholders/variables in a sed command

  - by jesse_galley

  I want to store a specific part of a matched result as a variable to be used for replacement later. I would like to keep this in a one liner instead of finding the variable I need before hand. when configuring apache, and use mod_rewrite, you can specificy specific parts of patterns to be used as variables,like this: RewriteRule ^www.example.com/page/(.*)$ http://www.example.com/page.php?page=$1 [R=301,L] the part of the pattern match that's contained inside the parenthesis is stored as $1 for use later. So if the url was www.example.com/page/home, it would be replaced with www.example.com/page.php?page=home. So the "home" part of the match was saved in $1 because it was the part of the pattern inside the parenthesis. I want something like this functionality with a sed command, I need to automatically replace many strings in a SQL dump file, to add drop table if exist commands before each create table, but I need to know the table name to do this, so if the dump file contains something like: ... CREATE TABLE `orders` ... I need to run something like: cat dump.sql | sed "s/CREATE TABLE `(.*)`/DROP TABLE IF EXISTS $1\N CREATE TABLE `$1`/g" to get the result of: ... DROP TABLE IF EXISTS `orders` CREATE TABLE `orders` ... I'm using the mod_rewrite syntax in the sed command as a logical example of what I'm trying to do. Any suggestions?

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• shell script stopped working --- need to rewrite?

  - by OopsForgotMyOtherUserName

  The script below worked on my Mac OS X. I'm now using Ubuntu OS, and the script is no longer working. I'm wondering if there's something that I need to change here? I did change the first line from #!/bin/bash to #!/bin/sh, but it's still throwing up an error.... Essentially, I get an error when I try to run it: Syntax error: end of file unexpected (expecting ")") #!/bin/sh REMOTE='ftp.example.com' USER='USERNAME' PASSWORD='PASSWORD' CMDFILE='/jtmp/rc.ftp' FTPLOG='/jtmp/ftplog' PATTERN='SampFile*' date > $FTPLOG rm $CMDFILE 2>/dev/null LISTING=$(ftp -in $REMOTE <<EOF user $USER $PASSWORD cd download ls $PATTERN quit EOF ) echo "open $REMOTE" >> $CMDFILE echo "user $USER $PASSWORD" >> $CMDFILE echo "verbose" >> $CMDFILE echo "bin" >> $CMDFILE echo "cd download" >> $CMDFILE for FILE in $LISTING do echo "get $FILE" >> $CMDFILE done echo "quit" >> $CMDFILE ftp -in < $CMDFILE >> $FTPLOG 2>&1 rm $CMDFILE

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• transforming 1d (1column) into 5d(5column) matrix through copy paste or other

  - by Curious

  Ex. I want to take the column with 12345..... and order 5 columns across as seen. next 5 numbers in column will be next row. However my code creates a 4 row gap in between each successive row. I dont know what additional logic (possibly if then statement) I can embed into do loop to may make it cleaner. I am new to this, so showing as much sample code to learn the syntax would be most beneficial. thanks in advance. Below is the Result of my code. VBA code is below result. 1 1 2 3 4 5 2 3 4 5 6 6 7 8 9 10 7 8 9 10 11 11 12 13 14 15 12 13 14 15 16 16 17 17 Sub Working_Code() ' Working_Code Macro Do ActiveCell.Select Selection.Copy ActiveCell.Offset(0, 5).Select ActiveSheet.Paste ActiveCell.Offset(1, -5).Select Selection.Copy ActiveCell.Offset(-1, 6).Select ActiveSheet.Paste ActiveCell.Offset(2, -6).Select Selection.Copy ActiveCell.Offset(-2, 7).Select ActiveSheet.Paste ActiveCell.Offset(3, -7).Select Selection.Copy ActiveCell.Offset(-3, 8).Select ActiveSheet.Paste ActiveCell.Offset(4, -8).Select Selection.Copy ActiveCell.Offset(-4, 9).Select ActiveSheet.Paste ActiveCell.Offset(5, -9).Select Loop Until IsEmpty(ActiveCell.Offset(0, -1)) End Sub

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• Python lists/arrays: disable negative indexing wrap-around

  - by wim

  While I find the negative number wraparound (i.e. A[-2] indexing the second-to-last element) extremely useful in many cases, there are often use cases I come across where it is more of an annoyance than helpful, and I find myself wishing for an alternate syntax to use when I would rather disable that particular behaviour. Here is a canned 2D example below, but I have had the same peeve a few times with other data structures and in other numbers of dimensions. import numpy as np A = np.random.randint(0, 2, (5, 10)) def foo(i, j, r=2): '''sum of neighbours within r steps of A[i,j]''' return A[i-r:i+r+1, j-r:j+r+1].sum() In the slice above I would rather that any negative number to the slice would be treated the same as None is, rather than wrapping to the other end of the array. Because of the wrapping, the otherwise nice implementation above gives incorrect results at boundary conditions and requires some sort of patch like: def ugly_foo(i, j, r=2): def thing(n): return None if n < 0 else n return A[thing(i-r):i+r+1, thing(j-r):j+r+1].sum() I have also tried zero-padding the array or list, but it is still inelegant (requires adjusting the lookup locations indices accordingly) and inefficient (requires copying the array). Am I missing some standard trick or elegant solution for slicing like this? I noticed that python and numpy already handle the case where you specify too large a number nicely - that is, if the index is greater than the shape of the array it behaves the same as if it were None.

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• How can I store and access a filehandle in a Perl class?

  - by Haiyuan Zhang

  please look at the following code first. #! /usr/bin/perl package foo; sub new { my $pkg = shift; my $self = {}; my $self->{_fd} = undef; bless $self, $pkg; return $self; } sub Setfd { my $self = shift; my $fd = shift; $self_->{_fd} = $fd; } sub write { my $self = shift; print $self->{_fd} "hello word"; } my $foo = new foo; My intention is to store a file handle within a class using hash. the file handle is undefined at first, but can be initilized afterwards by calling Setfd function. then write can be called to actually write string "hello word" to a file indicated by the file handle, supposed that the file handle is the result of a success "write" open. but, perl compiler just complains that there are syntax error in the "print" line. can anyone of you tells me what's wrong here? thanks in advance.

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• Jquery passing an HTML element into a function

  - by christian

  I have an HTML form where I am going to copy values from a series of input fields to some spans/headings as the user populates the input fields. I am able to get this working using the following code: $('#source').keyup(function(){ if($("#source").val().length == 0){ $("#destinationTitle").text('Sample Title'); }else{ $("#destinationTitle").text($("#source").val()); } }); In the above scenario the html is something like: Sample Title Basically, as the users fills out the source box, the text of the is changed to the value of the source input. If nothing is input in, or the user deletes the values typed into the box some default text is placed in the instead. Pretty straightforward. However, since I need to make this work for many different fields, it makes sense to turn this into a generic function and then bind that function to each 's onkeyup() event. But I am having some trouble with this. My implementation: function doStuff(source,target,defaultValue) { if($(source).val().length == 0){ $(target).text(defaultValue); }else{ $(target).text($(source).val()); } } which is called as follows: $('#source').keyup(function() { doStuff(this, '"#destinationTitle"', 'SampleTitle'); }); What I can't figure out is how to pass the second parameter, the name of the destination html element into the function. I have no problem passing in the element I'm binding to via "this", but can't figure out the destination element syntax. Any help would be appreciated - many thanks!

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• Passing C++ object to C++ code through Python?

  - by cornail

  Hi all, I have written some physics simulation code in C++ and parsing the input text files is a bottleneck of it. As one of the input parameters, the user has to specify a math function which will be evaluated many times at run-time. The C++ code has some pre-defined function classes for this (they are actually quite complex on the math side) and some limited parsing capability but I am not satisfied with this construction at all. What I need is that both the algorithm and the function evaluation remain speedy, so it is advantageous to keep them both as compiled code (and preferrably, the math functions as C++ function objects). However I thought of glueing the whole simulation together with Python: the user could specify the input parameters in a Python script, while also implementing storage, visualization of the results (matplotlib) and GUI, too, in Python. I know that most of the time, exposing C++ classes can be done, e.g. with SWIG but I still have a question concerning the parsing of the user defined math function in Python: Is it possible to somehow to construct a C++ function object in Python and pass it to the C++ algorithm? E.g. when I call f = WrappedCPPGaussianFunctionClass(sigma=0.5) WrappedCPPAlgorithm(f) in Python, it would return a pointer to a C++ object which would then be passed to a C++ routine requiring such a pointer, or something similar... (don't ask me about memory management in this case, though :S) The point is that no callback should be made to Python code in the algorithm. Later I would like to extend this example to also do some simple expression parsing on the Python side, such as sum or product of functions, and return some compound, parse-tree like C++ object but let's stay at the basics for now. Sorry for the long post and thx for the suggestions in advance.

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• [javascript] Populating jsTree based on XML data uploaded to server folder

  - by PFM

  tl:dr How can I populate jsTree based on a folder location instead of an exact XML url? I'm looking for a little direction on this project. Currently I am trying to copy file structures of hard drives as XML files and recreate them using jsTree on the webserver for a completely independent version of the file structure. I have some python script that outputs XML files that are formed to jsTree and automatically uploads to a folder on the server. The problem is now I am a little lost because I have to manually enter each XML file into jsTree code for it to display so I have multiple entries like this: $("#tree1") .jstree({ "plugins" : [ "themes", "xml_data", "ui", "search", "types" ], "xml_data" : { "ajax" : { "url" : "./XML_DATA/DRIVE1.xml" }, "xsl" : "nest" }, I see in the documentation that instead of populated by the direct file the folders are populated by "server.php" but no where in the php code does it point to any directories or files. After considering the problem I thought of a few solutions and could use some advice on them: Should I be trying to write php code to automatically look through my XML_DATA folder to upload each XML file? Should I just upload all the XML to mySQL and populate my tree based on that? Should the javascript be the code looking through the server's folder for XML files? All the XML is formed the same way but the number of XML files on the server will increase and will have to be refreshed as well as they will be overwritten with changes. Any direction would be appreciated, thanks.

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• Ruby - Writing Hpricot data to a file

  - by John

  Hey everyone, I am currently doing some XML parsing and I've chosen to use Hpricot because of it's ease of use and syntax, however I am running into some problems. I need to write a piece of XML data that I have found out to another file. However, when I do this the format is not preserved. For example, if the content should look like this: <dict> <key>item1</key><value>12345</value> <key>item2</key><value>67890</value> <key>item3</key><value>23456</value> </dict> And assuming that there are many entries like this in the document. I am iterating through the 'dict' items by using hpricot_element = Hpricot(xml_document_body) f = File.new('some_new_file.xml') (hpricot_element/:dict).each { |dict| f.write( dict.to_original_html ) } After using the above code, I would expect that the output look like the following exactly like the XML shown above. However to my surprise, the output of the file looks more like this: <dict>\n", " <key>item1</key><value>12345</value>\n", " <key>item2</key><value>67890</value>\n", " <key>item3</key><value>23456</value\n", " </dict> I've tried splitting at the "\n" characters and writing to the file one line at a time, but that didn't seem to work either as it did not recognize the "\n" characters. Any help is greatly appreciated. It might be a very simple solution, but I am having troubling finding it. Thanks!

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• jquery how to access the an xml node by index?

  - by DS

  Hi, say I've an xml returned from server like this: <persons> <person> <firstname>Jon</firstname> </person> <person> <firstname>Jack</firstname> </person> <person> <firstname>James</firstname> </person> </persons> If I want to access the 3rd firstname node (passed dynamically and stored in i, assumed to be 3 here), how do I do that? My weird attempt follows: var i=3; $(xml).find('firstname').each(function(idx){ if (idx==i) alert($(this).text()); }); It does fetch me the right content... but it just feels wrong to me especially the looping part. Basically I'm looping through the whole tree using .each()! Is there any better approach than this? Something that'd take me to the nth node directly like: alert( $(xml).find('firstname')[idx].text() ); // where idx=n I'm new to jquery so please excuse my jquery coding approach.

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• File IO with Streams - Best Memory Buffer Size

  - by AJ

  I am writing a small IO library to assist with a larger (hobby) project. A part of this library performs various functions on a file, which is read / written via the FileStream object. On each StreamReader.Read(...) pass, I fire off an event which will be used in the main app to display progress information. The processing that goes on in the loop is vaired, but is not too time consuming (it could just be a simple file copy, for example, or may involve encryption...). My main question is: What is the best memory buffer size to use? Thinking about physical disk layouts, I could pick 2k, which would cover a CD sector size and is a nice multiple of a 512 byte hard disk sector. Higher up the abstraction tree, you could go for a larger buffer which could read an entire FAT cluster at a time. I realise with today's PC's, I could go for a more memory hungry option (a couple of MiB, for example), but then I increase the time between UI updates and the user perceives a less responsive app. As an aside, I'm eventually hoping to provide a similar interface to files hosted on FTP / HTTP servers (over a local network / fastish DSL). What would be the best memory buffer size for those (again, a "best-case" tradeoff between perceived responsiveness vs. performance).

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• how to do validations when composing object of a class in other class ?

  - by haansi

  Hi, I have an IPAddress class which has one property named ip and in its setter I am validating data coming and if data is invalid it throws an error. (Its code is as the following): private string ip; public string IP { get { return ip; } set { string PartsOfIP = value.Split('.'); if (PartsOfIP.Length == 4) { foreach (string part in PartsOfIP) { int a = 0; bool result = int.TryParse(part, out a); if (result != true) { throw new Exception("Invalid IP"); } else { ip = value; } } } else { throw new Exception("Invalid IP"); } } In User Class I want to compose an object of IPAddress class. I am doing validations for properties of User in User class and validations of Ip in IPAddress class. My question is how I will compose IPAddress object in UserClass and what will be syntax for this ? If I again mention get and set here with IPAddress object in User class will my earlier mentioned (in IPAddress class) getter and setter work ? plz advice me in details thanks

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• When is it possible to override top-level bindings in (R7RS) scheme?

  - by Marc

  I have read the current draft of the forthcoming R7RS scheme standard (small language), but I don't understand under which conditions it is not an error to redefine top-level bindings. I guess that it is possible to define or set! a binding that has been introduced at the top-level of a program a second time. But what about imported bindings from an external library? Is it possible to override these bindings by the standard? On page 26/27 of the report, it says: The top level of a program may also include import declarations. In a library declaration, it is an error to import the same identifier more than once with different bindings, or to redefine or mutate an imported binding with define, define-syntax or set!. However, a REPL should permit these actions. Does it mean that redefining is only an error when it does happen in libraries for imported bindings? I understand that it prohibits optimisations by compilers if the compiler does not know whether, say + still means the built-in addition or is any other user-specified error. But from this perspective, it does not make sense to restrict forbidding to rebind on the library level, when it would also make sense (at least) for imported bindings in programs. P.S.: As this is all about the environment of a scheme program: am I right in saying that environments are not first class citizens because one cannot get hold of the current environment? (Which, in turn, allows a compiled program to forget about the chosen names of the bindings.)

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