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  • When is it better to use a method versus a property for a class definition?

    - by ccomet
    Partially related to an earlier question of mine, I have a system in which I have to store complex data as a string. Instead of parsing these strings as all kinds of separate objects, I just created one class that contains all of those objects, and it has some parser logic that will encode all properties into strings, or decode a string to get those objects. That's all fine and good. This question is not about the parser itself, but about where I should house the logic for the parser. Is it a better choice to put it as a property, or as a method? In the case of a property, say public string DataAsString, the get accessor would house the logic to encode all of the data into a string, while the set accessor would decode the input value and set all of the data in the class instance. It seems convenient because the input/output is indeed a string. In the case of a method, one method would be Encode(), which returns the encoded string. Then, either the constructor itself would house the logic for the decoding a string and require the string argument, or I write a Decode(string str) method which is called separately. In either case, it would be using a method instead of a property. So, is there a functional difference between these paths, in terms of the actual running of the code? Or are they basically equivalent and it then boils down to a choice of personal preference or which one looks better? And in that kind of question... which would look cleaner anyway?

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  • Uncaught exception while using xdebug

    - by rich97
    I'm not too great with xdebug so forgive me if this is a stupid question. But I installed it on a separate machine and it performed some magic for me like formating my var_dump() output and catching any uncaught exceptions. It also fails to format the stack traces, outputting plain text which is extremely hard to read. As I am learning the Lithium PHP Framework I am required to use php5.3, on my other machine I compiled from the source but on this machine I'm using the precompiled packages from dotdeb.org. As far as I can tell the only difference is that this is a slightly newer version of php and it comes with the Suhosin patch. The other odd thing is that the xdebug functions such as xdebug_var_dump() work, aside from poor formatting. This is an Ubuntu machine, so I don't know if it could be anything to do with the dotdep packages, but I have installed xdebug through pecl, the downloadable tarball and from the SVN repository. But to no avail. You can see my php.ini and output of php -i in the following gist. I copied php.ini from /etc/php5/apache2/php.ini over to /etc/php5/cli/php.ini so php -i should reflect my apache setup. http://gist.github.com/391675 Any help is appreciated. Rich

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  • Insert a datetime value with GetDate() function to a SQL server (2005) table?

    - by David.Chu.ca
    I am working (or fixing bugs) on an application which was developed in VS 2005 C#. The application saves data to a SQL server 2005. One of insert SQL statement tries to insert a time-stamp value to a field with GetDate() TSQL function as date time value. Insert into table1 (field1, ... fieldDt) values ('value1', ... GetDate()); The reason to use GetDate() function is that the SQL server may be at a remove site, and the date time may be in a difference time zone. Therefore, GetDate() will always get a date from the server. As the function can be verified in SQL Management Studio, this is what I get: SELECT GetDate(), LEN(GetDate()); -- 2010-06-10 14:04:48.293 19 One thing I realize is that the length is not up to the milliseconds, i.e., 19 is actually for '2010-06-10 14:04:48'. Anyway, the issue I have right now is that after the insert, the fieldDt actually has a date time value up to minutes, for example, '2010-06-10 14:04:00'. I am not sure why. I don't have permission to update or change the table with a trigger to update the field. My question is that how I can use a INSERT T-SQL to add a new row with a date time value ( SQL server's local date time) with a precision up to milliseconds?

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  • Windows-1251 file inside UTF-8 site?

    - by Spoonk
    Hello everyone Masters Of Web Delevopment :) I have a piece of PHP script that fetches last 10 played songs from my winamp. This script is inside file (lets call it "lastplayed.php") which is included in my site with php include function inside a "div". My site is on UTF-8 encoding. The problem is that some songs titles are in Windows-1251 encoding. And in my site they displays like "??????"... Is there any known way to tell to this div with included "lastplayed.php" in it, to be with windows-1251 encoding? Or any other suggestions? P.S: The file with fetching script a.k.a. "lastplayed.php", is converted to UTF-8. But if it is ANCII it's the same result. I try to put and meta tag with windows-1251 between head tag but nothing happens again. P.P.S: Script that fetches the Winamp's data (lastplayed.php): <?php /****** * You may use and/or modify this script as long as you: * 1. Keep my name & webpage mentioned * 2. Don't use it for commercial purposes * * If you want to use this script without complying to the rules above, please contact me first at: [email protected] * * Author: Martijn Korse * Website: http://devshed.excudo.net * * Date: 08-05-2006 ***/ /** * version 2.0 */ class Radio { var $fields = array(); var $fieldsDefaults = array("Server Status", "Stream Status", "Listener Peak", "Average Listen Time", "Stream Title", "Content Type", "Stream Genre", "Stream URL", "Current Song"); var $very_first_str; var $domain, $port, $path; var $errno, $errstr; var $trackLists = array(); var $isShoutcast; var $nonShoutcastData = array( "Server Status" => "n/a", "Stream Status" => "n/a", "Listener Peak" => "n/a", "Average Listen Time" => "n/a", "Stream Title" => "n/a", "Content Type" => "n/a", "Stream Genre" => "n/a", "Stream URL" => "n/a", "Stream AIM" => "n/a", "Stream IRC" => "n/a", "Current Song" => "n/a" ); var $altServer = False; function Radio($url) { $parsed_url = parse_url($url); $this->domain = isset($parsed_url['host']) ? $parsed_url['host'] : ""; $this->port = !isset($parsed_url['port']) || empty($parsed_url['port']) ? "80" : $parsed_url['port']; $this->path = empty($parsed_url['path']) ? "/" : $parsed_url['path']; if (empty($this->domain)) { $this->domain = $this->path; $this->path = ""; } $this->setOffset("Current Stream Information"); $this->setFields(); // setting default fields $this->setTableStart("<table border=0 cellpadding=2 cellspacing=2>"); $this->setTableEnd("</table>"); } function setFields($array=False) { if (!$array) $this->fields = $this->fieldsDefaults; else $this->fields = $array; } function setOffset($string) { $this->very_first_str = $string; } function setTableStart($string) { $this->tableStart = $string; } function setTableEnd($string) { $this->tableEnd = $string; } function getHTML($page=False) { if (!$page) $page = $this->path; $contents = ""; $domain = (substr($this->domain, 0, 7) == "http://") ? substr($this->domain, 7) : $this->domain; if (@$fp = fsockopen($domain, $this->port, $this->errno, $this->errstr, 2)) { fputs($fp, "GET ".$page." HTTP/1.1\r\n". "User-Agent: Mozilla/4.0 (compatible; MSIE 5.5; Windows 98)\r\n". "Accept: */*\r\n". "Host: ".$domain."\r\n\r\n"); $c = 0; while (!feof($fp) && $c <= 20) { $contents .= fgets($fp, 4096); $c++; } fclose ($fp); preg_match("/(Content-Type:)(.*)/i", $contents, $matches); if (count($matches) > 0) { $contentType = trim($matches[2]); if ($contentType == "text/html") { $this->isShoutcast = True; return $contents; } else { $this->isShoutcast = False; $htmlContent = substr($contents, 0, strpos($contents, "\r\n\r\n")); $dataStr = str_replace("\r", "\n", str_replace("\r\n", "\n", $contents)); $lines = explode("\n", $dataStr); foreach ($lines AS $line) { if ($dp = strpos($line, ":")) { $key = substr($line, 0, $dp); $value = trim(substr($line, ($dp+1))); if (preg_match("/genre/i", $key)) $this->nonShoutcastData['Stream Genre'] = $value; if (preg_match("/name/i", $key)) $this->nonShoutcastData['Stream Title'] = $value; if (preg_match("/url/i", $key)) $this->nonShoutcastData['Stream URL'] = $value; if (preg_match("/content-type/i", $key)) $this->nonShoutcastData['Content Type'] = $value; if (preg_match("/icy-br/i", $key)) $this->nonShoutcastData['Stream Status'] = "Stream is up at ".$value."kbps"; if (preg_match("/icy-notice2/i", $key)) { $this->nonShoutcastData['Server Status'] = "This is <span style=\"color: red;\">not</span> a Shoutcast server!"; if (preg_match("/ultravox/i", $value)) $this->nonShoutcastData['Server Status'] .= " But an <a href=\"http://ultravox.aol.com/\" target=\"_blank\">Ultravox</a> Server"; $this->altServer = $value; } } } return nl2br($htmlContent); } } else return $contents; } else { return False; } } function getServerInfo($display_array=null, $very_first_str=null) { if (!isset($display_array)) $display_array = $this->fields; if (!isset($very_first_str)) $very_first_str = $this->very_first_str; if ($html = $this->getHTML()) { // parsing the contents $data = array(); foreach ($display_array AS $key => $item) { if ($this->isShoutcast) { $very_first_pos = stripos($html, $very_first_str); $first_pos = stripos($html, $item, $very_first_pos); $line_start = strpos($html, "<td>", $first_pos); $line_end = strpos($html, "</td>", $line_start) + 4; $difference = $line_end - $line_start; $line = substr($html, $line_start, $difference); $data[$key] = strip_tags($line); } else { $data[$key] = $this->nonShoutcastData[$item]; } } return $data; } else { return $this->errstr." (".$this->errno.")"; } } function createHistoryArray($page) { if (!in_array($page, $this->trackLists)) { $this->trackLists[] = $page; if ($html = $this->getHTML($page)) { $fromPos = stripos($html, $this->tableStart); $toPos = stripos($html, $this->tableEnd, $fromPos); $tableData = substr($html, $fromPos, ($toPos-$fromPos)); $lines = explode("</tr><tr>", $tableData); $tracks = array(); $c = 0; foreach ($lines AS $line) { $info = explode ("</td><td>", $line); $time = trim(strip_tags($info[0])); if (substr($time, 0, 9) != "Copyright" && !preg_match("/Tag Loomis, Tom Pepper and Justin Frankel/i", $info[1])) { $this->tracks[$c]['time'] = $time; $this->tracks[$c++]['track'] = trim(strip_tags($info[1])); } } if (count($this->tracks) > 0) { unset($this->tracks[0]); if (isset($this->tracks[1])) $this->tracks[1]['track'] = str_replace("Current Song", "", $this->tracks[1]['track']); } } else { $this->tracks[0] = array("time"=>$this->errno, "track"=>$this->errstr); } } } function getHistoryArray($page="/played.html") { if (!in_array($page, $this->trackLists)) $this->createHistoryArray($page); return $this->tracks; } function getHistoryTable($page="/played.html", $trackColText=False, $class=False) { $title_utf8 = mb_convert_encoding($trackArr ,"utf-8" ,"auto"); if (!in_array($page, $this->trackLists)) $this->createHistoryArray($page); if ($trackColText) $output .= " <div class='lastplayed_top'></div> <div".($class ? " class=\"".$class."\"" : "").">"; foreach ($this->tracks AS $title_utf8) $output .= "<div style='padding:2px 0;'>".$title_utf8['track']."</div>"; $output .= "</div><div class='lastplayed_bottom'></div> <div class='lastplayed_title'>".$trackColText."</div> \n"; return $output; } } // this is needed for those with a php version < 5 // the function is copied from the user comments @ php.net (http://nl3.php.net/stripos) if (!function_exists("stripos")) { function stripos($haystack, $needle, $offset=0) { return strpos(strtoupper($haystack), strtoupper($needle), $offset); } } ?> And the calling script outside the lastplayed.php: include "lastplayed.php"; $radio = new Radio($ip.":".$port); echo $radio->getHistoryTable("/played.html", "<b>Last played:</b>", "lastplayed_content");

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  • Why Does This Maintainability Index Increase?

    - by Timothy
    I would be appreciative if someone could explain to me the difference between the following two pieces of code in terms of Visual Studio's Code Metrics rules. Why does the Maintainability Index increase slightly if I don't encapsulate everything within using ( )? Sample 1 (MI score of 71) public static String Sha1(String plainText) { using (SHA1Managed sha1 = new SHA1Managed()) { Byte[] text = Encoding.Unicode.GetBytes(plainText); Byte[] hashBytes = sha1.ComputeHash(text); return Convert.ToBase64String(hashBytes); } } Sample 2 (MI score of 73) public static String Sha1(String plainText) { Byte[] text, hashBytes; using (SHA1Managed sha1 = new SHA1Managed()) { text = Encoding.Unicode.GetBytes(plainText); hashBytes = sha1.ComputeHash(text); } return Convert.ToBase64String(hashBytes); } I understand metrics are meaningless outside of a broader context and understanding, and programmers should exercise discretion. While I could boost the score up to 76 with return Convert.ToBase64String(sha1.ComputeHash(Encoding.Unicode.GetBytes(plainText))), I shouldn't. I would clearly be just playing with numbers and it isn't truly any more readable or maintainable at that point. I am curious though as to what the logic might be behind the increase in this case. It's obviously not line-count.

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  • iPhone application update (using Core Data on Sqlite)

    - by owen
    I have an app which is using Core Data on Sqlite, Now I have a update which has some DB structure changes say adding a new table I know when an app get updated, it updates the app binary only, nothing on document directory will be changed. When the app gets updated and launchs at the first time and run [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]]; It will find the difference between the data model and DB structure in Sqlite and will throw an exception and quit. Error: "The model used to open the store is incompatible with the one used to create the store" So, can anyone here give me some idea how to update an app when there is a DB structure change? I think we can run a DB script to create that new table when it launchs the update at the first time. But if there are other changes like changing the type of some fields or deleting some fields, and we need to migrate the old data, this is really a headache. In this case, Is the only way to do is creating a new app? Is there anyone tried something similar like this?

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  • iPhone Development - Location Accuracy

    - by Mustafa
    I'm using following conditions in-order to make sure that the location i get has adequate accuracy, In my case kCLLocationAccuracyBest. But the problem is that i still get inaccurate location. // Filter out nil locations if(!newLocation) return; // Make sure that the location returned has the desired accuracy if(newLocation.horizontalAccuracy < manager.desiredAccuracy) return; // Filter out points that are out of order if([newLocation.timestamp timeIntervalSinceDate:oldLocation.timestamp] < 0) return; // Filter out points created before the manager was initialized NSTimeInterval secondsSinceManagerStarted = [newLocation.timestamp timeIntervalSinceDate:locationManagerStartDate]; if(secondsSinceManagerStarted < 0) return; // Also, make sure that the cached location was not returned by the CLLocationManager (it's current) - Check for 5 seconds difference if([newLocation.timestamp timeIntervalSinceReferenceDate] < [[NSDate date] timeIntervalSinceReferenceDate] - 5) return; When i activate the GPS, i get inaccurate results before i actually get an accurate result. What methods do you use to get accurate/precise location information?

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  • mySQL not saving data?

    - by tony noriega
    i have a PHP contact form that submits data, and an email...: <?php $dbh=mysql_connect ("localhost", "username", "password") or die ('I cannot connect to the database because: ' . mysql_error()); mysql_select_db ("guest"); if (isset($_POST['submit'])) { if (!$_POST['name'] | !$_POST['email']) { echo"<div class='error'>Error<br />Please provide your Name and Email Address so we may properly contact you.</div>"; } else { $age = $_POST['age']; $name = $_POST['name']; $gender = $_POST['gender']; $email = $_POST['email']; $phone = $_POST['phone']; $comments = $_POST['comments']; $query = "INSERT INTO contact_us (age,name,gender,email,phone,comments) VALUES ('$age','$name','$gender','$email','$phone','$comments')"; mysql_query($query); mysql_close(); $yoursite = "Mysite "; $youremail = $email; $subject = "Website Guest Contact Us Form"; $message = "$name would like you to contact them Contact PH: $phone Email: $email Age: $age Gender: $gender Comments: $comments"; $email2 = "[email protected]"; mail($email2, $subject, $message, "From: $email"); echo"<div class='thankyou'>Thank you for contacting us,<br /> we will respond as soon as we can.</div>"; } } ?> The email is coming through fine, but the data is not storing the dbase... am i missing something? Its the same script as i use on another contact us page, only difference is instead of parsing the data on teh same page, i now send this data to a "thankyou.php" page... i tried changing $_POST to $_GET but that killed the page... what am i doing wrong?

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  • Help with possible Haskell type inference quiz questions

    - by Linda Cohen
    foldr:: (a -> b -> b) -> b -> [a] -> b map :: (a -> b) -> [a] -> [b] mys :: a -> a (.) :: (a -> b) -> (c -> a) -> c -> b what is inferred type of: a.map mys :: b.mys map :: c.foldr map :: d.foldr map.mys :: I've tried to create mys myself using mys n = n + 2 but the type of that is mys :: Num a => a -> a What's the difference between Num a = a - a and just a - a? Or what does 'Num a =' mean? Is it that mys would only take Num type? So anyways, a) I got [a] - [a] I think because it would just take a list and return it +2'd according to my definition of mys b) (a - b) - [a] - [b] I think because map still needs take both arguments like (*3) and a list then returns [a] which goes to mys and returns [b] c) I'm not sure how to do this 1. d) I'm not sure how to do this 1 either but map.mys means do mys first then map right? Are my answers and thoughts correct? If not, why not? THANKS!

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  • Zend_Date and Zend Locale; can't get it to work ><

    - by Rick de Graaf
    Loving Zend Framework, hating Zend_Date... I'm buidling an app where one of the functions is to track the time one spends on a certain task. This works great. My previous question was my incapability to get the sum of all the timestamps (time spent on each task). Well that works as a charm, but when I echo this value, it adds one hour. Using gmdate() (just for checking) and the value turns out exactly as it's supposed to. I thought to solve this problem easeliy with Zend_Local, but I can't get the damn thing to work! This is my bootstrap code: protected function _initLocale() { $locale = new Zend_Locale('nl_NL'); $locale->setLocale($locale); Zend_Registry::set('Zend_Locale', $locale); } This is the code in my view file: $date = new Zend_Date($this->timequery, null, $locale); echo $date->toString(Zend_Date::HOUR.':'.Zend_Date::MINUTE.':'.Zend_Date::SECOND); The timestamp I'm processing is: 2632 which equals 00:43:52. The output I get is: 01:43:52 I know the extra hour comes from the time difference, but I can seem to solve this with Zend_Local and Zend_Date.

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  • Legitimate uses of the Function constructor

    - by Marcel Korpel
    As repeatedly said, it is considered bad practice to use the Function constructor (also see the ECMAScript Language Specification, 5th edition, § 15.3.2.1): new Function ([arg1[, arg2[, … argN]],] functionBody) (where all arguments are strings containing argument names and the last (or only) string contains the function body). To recapitulate, it is said to be slow, as explained by the Opera team: Each time […] the Function constructor is called on a string representing source code, the script engine must start the machinery that converts the source code to executable code. This is usually expensive for performance – easily a hundred times more expensive than a simple function call, for example. (Mark ‘Tarquin’ Wilton-Jones) Though it's not that bad, according to this post on MDC (I didn't test this myself using the current version of Firefox, though). Crockford adds that [t]he quoting conventions of the language make it very difficult to correctly express a function body as a string. In the string form, early error checking cannot be done. […] And it is wasteful of memory because each function requires its own independent implementation. Another difference is that a function defined by a Function constructor does not inherit any scope other than the global scope (which all functions inherit). (MDC) Apart from this, you have to be attentive to avoid injection of malicious code, when you create a new Function using dynamic contents. Lots of disadvantages and it is intelligible that ECMAScript 5 discourages the use of the Function constructor by throwing an exception when using it in strict mode (§ 13.1). That said, T.J. Crowder says in an answer that [t]here's almost never any need for the similar […] new Function(...), either, again except for some advanced edge cases. So, now I am wondering: what are these “advanced edge cases”? Are there legitimate uses of the Function constructor?

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  • MySQL table data transformation -- how can I dis-aggreate MySQL time data?

    - by lighthouse65
    We are coding for a MySQL data warehousing application that stores descriptive data (User ID, Work ID, Machine ID, Start and End Time columns in the first table below) associated with time and production quantity data (Output and Time columns in the first table below) upon which aggregate (SUM, COUNT, AVG) functions are applied. We now wish to dis-aggregate time data for another type of analysis. Our current data table design: +---------+---------+------------+---------------------+---------------------+--------+------+ | User ID | Work ID | Machine ID | Event Start Time | Event End Time | Output | Time | +---------+---------+------------+---------------------+---------------------+--------+------+ | 080025 | ABC123 | M01 | 2008-01-24 16:19:15 | 2008-01-24 16:34:45 | 2120 | 930 | +---------+---------+------------+---------------------+---------------------+--------+------+ Reprocessing dis-aggregation that we would like to do would be to transform table content based on a granularity of minutes, rather than the current production event ("Event Start Time" and "Event End Time") granularity. The resulting reprocessing of existing table rows would look like: +---------+---------+------------+---------------------+--------+ | User ID | Work ID | Machine ID | Production Minute | Output | +---------+---------+------------+---------------------+--------+ | 080025 | ABC123 | M01 | 2010-01-24 16:19 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:20 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:21 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:22 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:23 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:24 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:25 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:26 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:27 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:28 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:29 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:30 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:31 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:22 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:33 | 133 | | 080025 | ABC123 | M01 | 2010-01-24 16:34 | 133 | +---------+---------+------------+---------------------+--------+ So the reprocessing would take an existing row of data created at the granularity of production event and modify the granularity to minutes, eliminating redundant (Event End Time, Time) columns while doing so. It assumes a constant rate of production and divides output by the difference in minutes plus one to populate the new table's Output column. I know this can be done in code...but can it be done entirely in a MySQL insert statement (or otherwise entirely in MySQL)? I am thinking of a INSERT ... INTO construction but keep getting stuck. An additional complexity is that there are hundreds of machines to include in the operation so there will be multiple rows (one for each machine) for each minute of the day. Any ideas would be much appreciated. Thanks.

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  • Need a SQL statement focus on combination of tables but entries always with uinque ID

    - by Registered User KC
    Hi All, I need SQL code to solve the tables combination problem, described on below: Table old data: name version status lastupdate ID A 0.1 on 6/8/2010 1 B 0.1 on 6/8/2010 2 C 0.1 on 6/8/2010 3 D 0.1 on 6/8/2010 4 E 0.1 on 6/8/2010 5 F 0.1 on 6/8/2010 6 G 0.1 on 6/8/2010 7 Table new data: name version status lastupdate ID A 0.1 on 6/18/2010 #B entry deleted C 0.3 on 6/18/2010 #version_updated C1 0.1 on 6/18/2010 D 0.1 on 6/18/2010 E 0.1 off 6/18/2010 #status_updated F 0.1 on 6/18/2010 G 0.1 on 6/18/2010 H 0.1 on 6/18/2010 #new_added H1 0.1 on 6/18/2010 #new_added the difference of new data and old date: B entry deleted C entry version updated E entry status updated C1/H/H1 entry new added What I want is always keeping the ID - name mapping relationship in old data table no matter how data changed later, a.k.a the name always has a unique ID number bind with it. If entry has update, then update the data, if entry is new added, insert to the table then give a new assigned unique ID. However, I can only use SQL with simple select or update statement then it may too hard for me to write such code, then I hope someone with expertise can give direction, no details needed on the different of SQL variant, a standard sql code as sample is enough. Thanks in advance! Rgs KC

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  • Optimization in Python - do's, don'ts and rules of thumb.

    - by JV
    Well I was reading this post and then I came across a code which was: jokes=range(1000000) domain=[(0,(len(jokes)*2)-i-1) for i in range(0,len(jokes)*2)] I thought wouldn't it be better to calculate the value of len(jokes) once outside the list comprehension? Well I tried it and timed three codes jv@Pioneer:~$ python -m timeit -s 'jokes=range(1000000);domain=[(0,(len(jokes)*2)-i-1) for i in range(0,len(jokes)*2)]' 10000000 loops, best of 3: 0.0352 usec per loop jv@Pioneer:~$ python -m timeit -s 'jokes=range(1000000);l=len(jokes);domain=[(0,(l*2)-i-1) for i in range(0,l*2)]' 10000000 loops, best of 3: 0.0343 usec per loop jv@Pioneer:~$ python -m timeit -s 'jokes=range(1000000);l=len(jokes)*2;domain=[(0,l-i-1) for i in range(0,l)]' 10000000 loops, best of 3: 0.0333 usec per loop Observing the marginal difference 2.55% between the first and the second made me think - is the first list comprehension domain=[(0,(len(jokes)*2)-i-1) for i in range(0,len(jokes)*2)] optimized internally by python? or is 2.55% a big enough optimization (given that the len(jokes)=1000000)? If this is - What are the other implicit/internal optimizations in Python ? What are the developer's rules of thumb for optimization in Python? Edit1: Since most of the answers are "don't optimize, do it later if its slow" and I got some tips and links from Triptych and Ali A for the do's. I will change the question a bit and request for don'ts. Can we have some experiences from people who faced the 'slowness', what was the problem and how it was corrected? Edit2: For those who haven't here is an interesting read Edit3: Incorrect usage of timeit in question please see dF's answer for correct usage and hence timings for the three codes.

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  • _dl_runtime_resolve -- When do the shared objects get loaded in to memory?

    - by windfinder
    We have a message processing system with high performance demands. Recently we have noticed that the first message takes many times longer then subsequent messages. A bunch of transformation and message augmentation happens as this goes through our system, much of it done by way of external lib. I just profiled this issue (using callgrind), comparing a "run" of just one message with a "run" of many messages (providing a baseline of comparison). The main difference I see is the function "do_lookup_x" taking up a huge amount of time. Looking at the various calls to this function, they all seem to be called by the common function: _dl_runtime_resolve. Not sure what this function does, but to me this looks like the first time the various shared libraries are being used, and are then being loaded in to memory by the ld. Is this a correct assumption? That the binary will not load the shared libraries in to memory until they are being prepped for use, therefore we will see a massive slowdown on the first message, but on none of the subsequent? How do we go about avoiding this? Note: We operate on the microsecond scale.

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  • problems doing the Django tutorial on Dreamhost using Passengers

    - by Pietro Speroni
    I have looked and I could not find this question before, and it surprises me. I am reasonably proficient in Python, and I used Dreamhost for a number of years. Now I would like to learn Django. They are finally supporting it using Passenger. Which I do not know what is. Following the instructions on Dreamhost I installed Django. Then I started following the tutorial 01. This went well, except that I could not start the server (this in the tutorial) since the code was live on dreamhost. At the time this did not seem to make any difference. Then when I went on the second part of the tutorial I had to access the admin site. And it worked well going to myurl/admin/ , as it should. But here the problems started. According to the tutorial (here) I have to add a file in the poll application and then restart the server. But I never started the server in the first place, my code is running live on the web... but when I add a file the website the admin acts as if it does not see it. Probably dreamhost has started its own server, and I don't know how to restart it. But I assume this is going to be a common problem when you run django on dreamhost. Every time you add a file you will have to tell the server to consider it. So what should I do to let the server know about it? Thanks, Pietro

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  • problem writing xml to file with .net mvc - timeout?

    - by Mark
    Hey, so having an issue with writing out to an xml file. Works fine for single requests via the browser, but when I use something like Charles to perform 5-10 repeated requests concurrently several of them will fail. The trace simply shows a 500 error with no content inside, basically I think they start timing out waiting for write access or something... This method is inside my repository class, have also attempted to have repository instance as a singleton but doesn't appear to make any difference.. Any help would be much appreciated. Cheers public void Add(Request request) { try { XDocument requests; XmlReader xmlReader; using (xmlReader = XmlReader.Create(_requestsFilePath)) { requests = XDocument.Load(xmlReader); XElement xmlRequest = new XElement("request", new XElement("code", request.code), new XElement("date", request.date), new XElement("email", new XCData(request.email)), new XElement("name", new XCData(request.name)), new XElement("recieveOffers", request.recieveOffers) ); requests.Root.Element("requests").Add(xmlRequest); xmlReader.Close(); } requests.Save(_requestsFilePath); } catch (Exception ex) { HttpContext.Current.Trace.Warn("Error writing to file: "+ex); } }

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  • VB.net httpwebrequest For loop hangs every 10 or so iterations

    - by user574632
    Hello, I am trying to loop through an array and perform an httpwebrequest in each iteration. The code seems to work, however it pauses for a while (eg alot longer than the set timeout. Tried setting that to 100 to check and it still pauses) after every 10 or so iterations, then carries on working. Here is what i have so far: For i As Integer = 0 To numberOfProxies - 1 Try 'create request to a proxyJudge php page using proxy Dim request As HttpWebRequest = HttpWebRequest.Create("http://www.pr0.net/deny/azenv.php") request.Proxy = New Net.WebProxy(proxies(i)) 'select the current proxie from the proxies array request.Timeout = 10000 'set timeout Dim response As HttpWebResponse = request.GetResponse() Dim sr As StreamReader = New StreamReader(response.GetResponseStream()) Dim pageSourceCode As String = sr.ReadToEnd() 'check the downloaded source for certain phrases, each identifies a type of proxy 'HTTP_X_FORWARDED_FOR identifies a transparent proxy If pageSourceCode.Contains("HTTP_X_FORWARDED_FOR") Then 'delegate method for cross thread safe UpdateListbox(ListBox3, proxies(i)) ElseIf pageSourceCode.Contains("HTTP_VIA") Then UpdateListbox(ListBox2, proxies(i)) Else UpdateListbox(ListBox1, proxies(i)) End If Catch ex As Exception 'MessageBox.Show(ex.ToString) used in testing UpdateListbox(ListBox4, proxies(i)) End Try completedProxyCheck += 1 lblTotalProxiesChecked.CustomInvoke(Sub(l) l.Text = completedProxyCheck) Next I have searched all over this site and via google, and most responses to this type of question say the response must be closed. I have tried a using block, eg: Using response As HttpWebResponse = request.GetResponse() Using sr As StreamReader = New StreamReader(response.GetResponseStream()) Dim pageSourceCode As String = sr.ReadToEnd() 'check the downloaded source for certain phrases, each identifies a type of proxy 'HTTP_X_FORWARDED_FOR identifies a transparent proxy If pageSourceCode.Contains("HTTP_X_FORWARDED_FOR") Then 'delegate method for cross thread safe UpdateListbox(ListBox3, proxies(i)) ElseIf pageSourceCode.Contains("HTTP_VIA") Then UpdateListbox(ListBox2, proxies(i)) Else UpdateListbox(ListBox1, proxies(i)) End If End Using End Using And it makes no difference (though i may have implemented it wrong) As you can tell im very new to VB or any OOP so its probably a simple problem but i cant work it out. Any suggestions or just tips on how to diagnose these types of problems would be really appreciated.

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  • SQL Design: representing a default value with overrides?

    - by Mark Harrison
    I need a sparse table which contains a set of "override" values for another table. I also need to specify the default value for the items overridden. For example, if the default value is 17, then foo,bar,baz will have the values 17,21,17: table "things" table "xvalue" name stuff name xval ---- ----- ---- ---- foo ... bar 21 bar ... baz ... If I don't care about a FK from xvalue.name - things.name, I could simply put a "DEFAULT" name: table "xvalue" name xval ---- ---- DEFAULT 17 bar 21 But I like having a FK. I could have a separate default table, but it seems odd to have 2x the number of tables. table "xvalue_default" xval ---- 17 table "xvalue" name xval ---- ---- bar 21 I could have a "defaults table" tablename attributename defaultvalue xvalue xval 17 but then I run into type issues on defaultvalue. My operations guys prefer as compact a representation as possible, so they can most easily see the "diff" or deviations from the default. What's the best way to represent this, including the default value? This will be for Oracle 10.2 if that makes a difference.

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  • Screen capture doesn't work on MFC application in Vista

    - by David Thornley
    We've got some in-house applications built in MFC, with OpenGL drawing routines. They all use the same code to draw on the screen and either print the screen or save it to a JPEG file. Everything's been working fine in Windows XP, and I need to find a way to make them work on Vista. In three of our applications, everything works. In the remaining one, I can get the window border, title bar, menus, and task bar, but the interior never shows up. As I said, these applications use the exact same code to write to the screen and capture the window image, and the only difference I see that looks like it might be relevant is that the problem application uses the MFC multiple document interface, while the ones that work use the single document interface. Either the answer isn't on the net, or I'm worse at Googling than I thought. I asked on the MSDN forums, and the only practical suggestion I got was to use GDI+ rather than GDI, and that did nothing different. I have tried different things with every part of the code that captures and prints or save, given a pointer to the window, so apparently it's a matter of the window itself. I haven't rebuilt the offending application using SDI yet, and I really don't have any other ideas. Has anybody seen anything like this?

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  • SDL with OpenGL (freeglut) crashes on call to glutBitmapCharacter

    - by stett
    I have a program using OpenGL through freeglut under SDL. The SDL/OpenGL initialization is as follows: // Initialize SDL SDL_Init(SDL_INIT_VIDEO); // Create the SDL window SDL_SetVideoMode(SCREEN_W, SCREEN_H, SCREEN_DEPTH, SDL_OPENGL); // Initialize OpenGL glClearColor(BG_COLOR_R, BG_COLOR_G, BG_COLOR_B, 1.f); glViewport(0, 0, SCREEN_W, SCREEN_H); glMatrixMode(GL_PROJECTION); glLoadIdentity(); glOrtho(0.0f, SCREEN_W, SCREEN_H, 0.0f, -1.0f, 1.0f); glEnable(GL_TEXTURE_2D); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); I've been using glBegin() ... glEnd() blocks without any trouble to draw primitives. However, in this program when I call any glutBitmapX function, the program simply exits without an error status. The code I'm using to draw text is: glColor3f(1.f, 1.f, 1.f); glRasterPos2f(x, y); glutStrokeString(GLUT_BITMAP_8_BY_13, (const unsigned char*)"test string"); In previous similar programs I've used glutBitmapCharacter and glutStrokeString to draw text and it's seemed to work. The only difference being that I'm using freeglut with SDL now instead of just GLUT as I did in previous programs. Is there some fundamental problem with my setup that I'm not seeing, or is there a better way of drawing text?

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  • Problem with setVisible (true)

    - by Jessy
    The two examples shown below are same. Both are supposed to produce same result e.g. generate the coordinates of images displayed on JPanel. Example 1, works perfectly (print the coordinates of images), however example 2 returning 0 for the coordinate. I was wondering why because, I have put the setvisible (true) after adding the panel, in both examples. The only difference is that example 1 used extends JPanel and example 2 extends JFrame EXAMPLE 1: public class Grid extends JPanel{ public static void main(String[] args){ JFrame jf=new JFrame(); jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); final Grid grid = new Grid(); jf.add(grid); jf.pack(); Component[] components = grid.getComponents(); for (Component component : components) { System.out.println("Coordinate: "+ component.getBounds()); } jf.setVisible(true); } } EXAMPLE 2: public class Grid extends JFrame { public Grid () { setLayout(new GridBagLayout()); GridBagLayout m = new GridBagLayout(); Container c = getContentPane(); c.setLayout (m); GridBagConstraints con = new GridBagConstraints(); //construct the JPanel pDraw = new JPanel(); ... m.setConstraints(pDraw, con); pDraw.add (new GetCoordinate ()); // call new class to generate the coordinate c.add(pDraw); pack(); setVisible(true); } public static void main(String[] args) { new Grid(); } }

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  • Calculate differences between rows while grouping with SQL

    - by Guido
    I have a postgresql table containing movements of different items (models) between warehouses. For example, the following record means that 5 units of model 1 have been sent form warehouse 1 to 2: source target model units ------ ------ ----- ----- 1 2 1 5 I am trying to build a SQL query to obtain the difference between units sent and received, grouped by models. Again with an example: source target model units ------ ------ ----- ----- 1 2 1 5 -- 5 sent from 1 to 2 1 2 2 1 2 1 1 2 -- 2 sent from 2 to 1 2 1 1 1 -- 1 more sent from 2 to 1 The result should be: source target model diff ------ ------ ----- ---- 1 2 1 2 -- 5 sent minus 3 received 1 2 2 1 I wonder if this is possible with a single SQL query. Here is the table creation script and some data, just in case anyone wants to try it: CREATE TEMP TABLE movements ( source INTEGER, target INTEGER, model INTEGER, units INTEGER ); insert into movements values (1,2,1,5); insert into movements values (1,2,2,1); insert into movements values (2,1,1,2); insert into movements values (2,1,1,1);

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  • Is it safe to use random Unicode for complex delimiter sequences in strings?

    - by ccomet
    Question: In terms of program stability and ensuring that the system will actually operate, how safe is it to use chars like ¦, § or ‡ for complex delimiter sequences in strings? Can I reliable believe that I won't run into any issues in a program reading these incorrectly? I am working in a system, using C# code, in which I have to store a fairly complex set of information within a single string. The readability of this string is only necessary on the computer side, end-users should only ever see the information after it has been parsed by the appropriate methods. Because some of the data in these strings will be collections of variable size, I use different delimiters to identify what parts of the string correspond to a certain tier of organization. There are enough cases that the standard sets of ;, |, and similar ilk have been exhausted. I considered two-char delimiters, like ;# or ;|, but I felt that it would be very inefficient. There probably isn't that large of a performance difference in storing with one char versus two chars, but when I have the option of picking the smaller option, it just feels wrong to pick the larger one. So finally, I considered using the set of characters like the double dagger and section. They only take up one char, and they are definitely not going to show up in the actual text that I'll be storing, so they won't be confused for anything. But character encoding is finicky. While the visibility to the end user is meaningless (since they, in fact, won't see it), I became recently concerned about how the programs in the system will read it. The string is stored in one database, while a separate program is responsible for both encoding and decoding the string into different object types for the rest of the application to work with. And if something is expected to be written one way, is possibly written another, then maybe the whole system will fail and I can't really let that happen. So is it safe to use these kind of chars for background delimiters?

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  • How much effort do you have to put in to get gains from using SSE?

    - by John
    Case One Say you have a little class: class Point3D { private: float x,y,z; public: operator+=() ...etc }; Point3D &Point3D::operator+=(Point3D &other) { this->x += other.x; this->y += other.y; this->z += other.z; } A naive use of SSE would simply replace these function bodies with using a few intrinsics. But would we expect this to make much difference? MMX used to involve costly state cahnges IIRC, does SSE or are they just like other instructions? And even if there's no direct "use SSE" overhead, would moving the values into SSE registers and back out again really make it any faster? Case Two Instead, you're working with a less OO-based code base. Rather than an array/vector of Point3D objects, you simply have a big array of floats: float coordinateData[NUM_POINTS*3]; void add(int i,int j) //yes it's unsafe, no overlap check... example only { for (int x=0;x<3;++x) { coordinateData[i*3+x] += coordinateData[j*3+x]; } } What about use of SSE here? Any better? In conclusion Is trying to optimise single vector operations using SSE actually worthwhile, or is it really only valuable when doing bulk operations?

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