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  • Tweak Conky Layout via a script

    - by begtognen
    I'm using a script in Conky in order to display my new gmail on my desktop. It works beautifully, but is kind of ugly, and I'm not sure how to fix it. What I've currently got looks like this: And what I'd like is this: Any ideas for how to make that happen are much appreciated. Here's the script I'm currently using (I think I've snipped out the correct part, if I haven't please let me know.) #!/usr/bin/perl use Switch; use Text::Wrap; my $what=$ARGV[0]; $user="username"; #username for gmail account $pass="password"; #password for gmail account $file="/tmp/gmail.html"; #temporary file to store gmail #wrap format for subject $Text::Wrap::columns=65; #Number of columns to wrap subject at $initial_tab=""; #Tab for first line of subject $subsequent_tab="\t"; #tab for wrapped lines $quote="\""; #put quotes around subject #limit the number of emails to be displayed $emails=-1; #if -1 display all emails &passwd; #give password the proper url character encoding switch($what){ #determine what the user wants case "n" {&gmail; print "$new\n";} #print number of new emails case "s" { #print $from and $subj for new email &gmail; if ($new0){ my $size=@from; if ($emails!=-1 && $size$emails){$size=$emails;} #limit number of emails displayed for(my $i=0; $i$emails){print "$emails out of $size new emails displayed\n";} } } case "e" { #print number of new emails, $from, and $subj &gmail; if($new==0){print "You have no new emails.\n";} else{ print "You have $new new email(s).\n"; my $size=@from; if ($emails!=-1 && $size$emails){$size=$emails;} #limit number of emails displayed for(my $i=0; $i$emails){print "$emails out of $size new emails displayed\n";} } } else { print "Usage Error: gmail.pl \n"; print "\tn displays number of new emails\n"; print "\ts displays from line and subject line for each new email.\n"; print "\te displays the number of new emails and from line plus \n"; print "\t\tsubject line for each new email.\n"; } #didn't give proper option } sub gmail{ if(!(-e $file)){ #create file if it does not exists `touch $file`; } #get new emails `wget -O - https://$user:$pass\@mail.google.com/mail/feed/atom --no-check-certificate $file`; open(IN, $file); #open $file my $i=0; #initialize count $new=0; #initialize new emails to 0 my $flag=0; while(){ #cycle through $file if(//){$flag=1;} elsif(/(\d+)/){$new=$1;} #grab number of new emails elsif($flag==1){ if(/.+/){push(@subj, &msg);} #grab new email titles elsif(/(.+)/){push(@from, $1); $flag=0;} #grab new email from lines } } close(IN); #close $file } sub passwd{ #change to url escape codes in password #URL ESCAPE CODES $_=$pass; s/\%/\%25/g; s/\#/\%23/g; s/\$/\%24/g; s/\&/\%26/g; s/\//\%2F/g; s/\:/\%3A/g; s/\;/\%3B/g; s/\/\%3E/g; s/\?/\%3F/g; s/\@/\%40/g; s/\[/\%5B/g; s/\\/\%5C/g; s/\]/\%5D/g; s/\^/\%5E/g; s/\`/\%60/g; s/\{/\%7B/g; s/\|/\%7C/g; s/\}/\%7D/g; s/\~/\%7E/g; $pass=$_; } sub msg{ #THE HTML CODED CHARACTER SET [ISO-8859-1] chomp; s/(.+)/$1/; #get just the subject #now replace any special characters s/\&\#33\;/!/g; #Exclamation mark s/\&\#34\;/"/g; s/\"\;/"/g; #Quotation mark s/\&\#35\;/#/g; #Number sign s/\&\#36\;/\$/g; #Dollar sign s/\&\#37\;/%/g; #Percent sign s/\&\#38\;/&/g; s/\&\;/&/g; #Ampersand s/\&\#39\;/'/g; #Apostrophe s/\&\#40\;/(/g; #Left parenthesis s/\&\#41\;/)/g; #Right parenthesis s/\&\#42\;/*/g; #Asterisk s/\&\#43\;/+/g; #Plus sign s/\&\#44\;/,/g; #Comma s/\&\#45\;/-/g; #Hyphen s/\&\#46\;/./g; #Period (fullstop) s/\&\#47\;/\//g; #Solidus (slash) s/\&\#58\;/:/g; #Colon s/\&\#59\;/\;/g; #Semi-colon s/\&\#60\;//g; s/\>\;//g; #Greater than s/\&\#63\;/\?/g; #Question mark s/\&\#64\;/\@/g; #Commercial at s/\&\#91\;/\[/g; #Left square bracket s/\&\#92\;/\\/g; #Reverse solidus (backslash) s/\&\#93\;/\]/g; #Right square bracket s/\&\#94\;/\^/g; #Caret s/\&\#95\;/_/g; #Horizontal bar (underscore) s/\&\#96\;/\`/g; #Acute accent s/\&\#123\;/\{/g; #Left curly brace s/\&\#124\;/|/g; #Vertical bar s/\&\#125\;/\}/g; #Right curly brace s/\&\#126\;/~/g; #Tilde s/\&\#161\;/¡/g; #Inverted exclamation s/\&\#162\;/¢/g; #Cent sign s/\&\#163\;/£/g; #Pound sterling s/\&\#164\;/¤/g; #General currency sign s/\&\#165\;/¥/g; #Yen sign s/\&\#166\;/¦/g; #Broken vertical bar s/\&\#167\;/§/g; #Section sign s/\&\#168\;/¨/g; #Umlaut (dieresis) s/\&\#169\;/©/g; s/\©\;/©/g; #Copyright s/\&\#170\;/ª/g; #Feminine ordinal s/\&\#171\;/«/g; #Left angle quote, guillemotleft s/\&\#172\;/¬/g; #Not sign s/\&\#174\;/®/g; #Registered trademark s/\&\#175\;/¯/g; #Macron accent s/\&\#176\;/°/g; #Degree sign s/\&\#177\;/±/g; #Plus or minus s/\&\#178\;/²/g; #Superscript two s/\&\#179\;/³/g; #Superscript three s/\&\#180\;/´/g; #Acute accent s/\&\#181\;/µ/g; #Micro sign s/\&\#182\;/¶/g; #Paragraph sign s/\&\#183\;/·/g; #Middle dot s/\&\#184\;/¸/g; #Cedilla s/\&\#185\;/¹/g; #Superscript one s/\&\#186\;/º/g; #Masculine ordinal s/\&\#187\;/»/g; #Right angle quote, guillemotright s/\&\#188\;/¼/g; s/\¼\;/¼/g; # Fraction one-fourth s/\&\#189\;/½/g; s/\½\;/½/g; # Fraction one-half s/\&\#190\;/¾/g; s/\¾\;/¾/g; # Fraction three-fourths s/\&\#191\;/¿/g; #Inverted question mark s/\&\#192\;/À/g; #Capital A, grave accent s/\&\#193\;/Á/g; #Capital A, acute accent s/\&\#194\;/Â/g; #Capital A, circumflex accent s/\&\#195\;/Ã/g; #Capital A, tilde s/\&\#196\;/Ä/g; #Capital A, dieresis or umlaut mark s/\&\#197\;/Å/g; #Capital A, ring s/\&\#198\;/Æ/g; #Capital AE dipthong (ligature) s/\&\#199\;/Ç/g; #Capital C, cedilla s/\&\#200\;/È/g; #Capital E, grave accent s/\&\#201\;/É/g; #Capital E, acute accent s/\&\#202\;/Ê/g; #Capital E, circumflex accent s/\&\#203\;/Ë/g; #Capital E, dieresis or umlaut mark s/\&\#204\;/Ì/g; #Capital I, grave accent s/\&\#205\;/Í/g; #Capital I, acute accent s/\&\#206\;/Î/g; #Capital I, circumflex accent s/\&\#207\;/Ï/g; #Capital I, dieresis or umlaut mark s/\&\#208\;/Ð/g; #Capital Eth, Icelandic s/\&\#209\;/Ñ/g; #Capital N, tilde s/\&\#210\;/Ò/g; #Capital O, grave accent s/\&\#211\;/Ó/g; #Capital O, acute accent s/\&\#212\;/Ô/g; #Capital O, circumflex accent s/\&\#213\;/Õ/g; #Capital O, tilde s/\&\#214\;/Ö/g; #Capital O, dieresis or umlaut mark s/\&\#215\;/×/g; #Multiply sign s/\&\#216\;/Ø/g; #Capital O, slash s/\&\#217\;/Ù/g; #Capital U, grave accent s/\&\#218\;/Ú/g; #Capital U, acute accent s/\&\#219\;/Û/g; #Capital U, circumflex accent s/\&\#220\;/Ü/g; #Capital U, dieresis or umlaut mark s/\&\#221\;/Ý/g; #Capital Y, acute accent s/\&\#222\;/Þ/g; #Capital THORN, Icelandic s/\&\#223\;/ß/g; #Small sharp s, German (sz ligature) s/\&\#224\;/à/g; #Small a, grave accent s/\&\#225\;/á/g; #Small a, acute accent s/\&\#226\;/â/g; #Small a, circumflex accent s/\&\#227\;/ã/g; #Small a, tilde s/\&\#228\;/ä/g; #Small a, dieresis or umlaut mark s/\&\#229\;/å/g; #Small a, ring s/\&\#230\;/æ/g; #Small ae dipthong (ligature) s/\&\#231\;/ç/g; #Small c, cedilla s/\&\#232\;/è/g; #Small e, grave accent s/\&\#233\;/é/g; #Small e, acute accent s/\&\#234\;/ê/g; #Small e, circumflex accent s/\&\#235\;/ë/g; #Small e, dieresis or umlaut mark s/\&\#236\;/ì/g; #Small i, grave accent s/\&\#237\;/í/g; #Small i, acute accent s/\&\#238\;/î/g; #Small i, circumflex accent s/\&\#239\;/ï/g; #Small i, dieresis or umlaut mark s/\&\#240\;/ð/g; #Small eth, Icelandic s/\&\#241\;/ñ/g; #Small n, tilde s/\&\#242\;/ò/g; #Small o, grave accent s/\&\#243\;/ó/g; #Small o, acute accent s/\&\#244\;/ô/g; #Small o, circumflex accent s/\&\#245\;/õ/g; #Small o, tilde s/\&\#246\;/ö/g; #Small o, dieresis or umlaut mark s/\&\#247\;/÷/g; #Division sign s/\&\#248\;/ø/g; #Small o, slash s/\&\#249\;/ù/g; #Small u, grave accent s/\&\#250\;/ú/g; #Small u, acute accent s/\&\#251\;/û/g; #Small u, circumflex accent s/\&\#252\;/ü/g; #Small u, dieresis or umlaut mark s/\&\#253\;/ý/g; #Small y, acute accent s/\&\#254\;/þ/g; #Small thorn, Icelandic s/\&\#255\;/ÿ/g; #Small y, dieresis or umlaut mark s/^\s+//; return $_; }

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  • Node.js vs PHP processing speed

    - by Cody Craven
    I've been looking into node.js recently and wanted to see a true comparison of processing speed for PHP vs Node.js. In most of the comparisons I had seen, Node trounced Apache/PHP set ups handily. However all of the tests were small 'hello worlds' that would not accurately reflect any webpage's markup. So I decided to create a basic HTML page with 10,000 hello world paragraph elements. In these tests Node with Cluster was beaten to a pulp by PHP on Nginx utilizing PHP-FPM. So I'm curious if I am misusing Node somehow or if Node is really just this bad at processing power. Note that my results were equivalent outputting "Hello world\n" with text/plain as the HTML, but I only included the HTML as it's closer to the use case I was investigating. My testing box: Core i7-2600 Intel CPU (has 8 threads with 4 cores) 8GB DDR3 RAM Fedora 16 64bit Node.js v0.6.13 Nginx v1.0.13 PHP v5.3.10 (with PHP-FPM) My test scripts: Node.js script var cluster = require('cluster'); var http = require('http'); var numCPUs = require('os').cpus().length; if (cluster.isMaster) { // Fork workers. for (var i = 0; i < numCPUs; i++) { cluster.fork(); } cluster.on('death', function (worker) { console.log('worker ' + worker.pid + ' died'); }); } else { // Worker processes have an HTTP server. http.Server(function (req, res) { res.writeHead(200, {'Content-Type': 'text/html'}); res.write('<html>\n<head>\n<title>Speed test</title>\n</head>\n<body>\n'); for (var i = 0; i < 10000; i++) { res.write('<p>Hello world</p>\n'); } res.end('</body>\n</html>'); }).listen(80); } This script is adapted from Node.js' documentation at http://nodejs.org/docs/latest/api/cluster.html PHP script <?php echo "<html>\n<head>\n<title>Speed test</title>\n</head>\n<body>\n"; for ($i = 0; $i < 10000; $i++) { echo "<p>Hello world</p>\n"; } echo "</body>\n</html>"; My results Node.js $ ab -n 500 -c 20 http://speedtest.dev/ This is ApacheBench, Version 2.3 <$Revision: 655654 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking speedtest.dev (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Finished 500 requests Server Software: Server Hostname: speedtest.dev Server Port: 80 Document Path: / Document Length: 190070 bytes Concurrency Level: 20 Time taken for tests: 14.603 seconds Complete requests: 500 Failed requests: 0 Write errors: 0 Total transferred: 95066500 bytes HTML transferred: 95035000 bytes Requests per second: 34.24 [#/sec] (mean) Time per request: 584.123 [ms] (mean) Time per request: 29.206 [ms] (mean, across all concurrent requests) Transfer rate: 6357.45 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 0 0.2 0 2 Processing: 94 547 405.4 424 2516 Waiting: 0 331 399.3 216 2284 Total: 95 547 405.4 424 2516 Percentage of the requests served within a certain time (ms) 50% 424 66% 607 75% 733 80% 813 90% 1084 95% 1325 98% 1843 99% 2062 100% 2516 (longest request) PHP/Nginx $ ab -n 500 -c 20 http://speedtest.dev/test.php This is ApacheBench, Version 2.3 <$Revision: 655654 $> Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/ Licensed to The Apache Software Foundation, http://www.apache.org/ Benchmarking speedtest.dev (be patient) Completed 100 requests Completed 200 requests Completed 300 requests Completed 400 requests Completed 500 requests Finished 500 requests Server Software: nginx/1.0.13 Server Hostname: speedtest.dev Server Port: 80 Document Path: /test.php Document Length: 190070 bytes Concurrency Level: 20 Time taken for tests: 0.130 seconds Complete requests: 500 Failed requests: 0 Write errors: 0 Total transferred: 95109000 bytes HTML transferred: 95035000 bytes Requests per second: 3849.11 [#/sec] (mean) Time per request: 5.196 [ms] (mean) Time per request: 0.260 [ms] (mean, across all concurrent requests) Transfer rate: 715010.65 [Kbytes/sec] received Connection Times (ms) min mean[+/-sd] median max Connect: 0 0 0.2 0 1 Processing: 3 5 0.7 5 7 Waiting: 1 4 0.7 4 7 Total: 3 5 0.7 5 7 Percentage of the requests served within a certain time (ms) 50% 5 66% 5 75% 5 80% 6 90% 6 95% 6 98% 6 99% 6 100% 7 (longest request) Additional details Again what I'm looking for is to find out if I'm doing something wrong with Node.js or if it is really just that slow compared to PHP on Nginx with FPM. I certainly think Node has a real niche that it could fit well, however with these test results (which I really hope I made a mistake with - as I like the idea of Node) lead me to believe that it is a horrible choice for even a modest processing load when compared to PHP (let alone JVM or various other fast solutions). As a final note, I also tried running an Apache Bench test against node with $ ab -n 20 -c 20 http://speedtest.dev/ and consistently received a total test time of greater than 0.900 seconds.

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  • PASS: Bylaw Change 2013

    - by Bill Graziano
    PASS launched a Global Growth Initiative in the Summer of 2011 with the appointment of three international Board advisors.  Since then we’ve thought and talked extensively about how we make PASS more relevant to our members outside the US and Canada.  We’ve collected much of that discussion in our Global Growth site.  You can find vision documents, plans, governance proposals, feedback sites, and transcripts of Twitter chats and town hall meetings.  We also address these plans at the Board Q&A during the 2012 Summit. One of the biggest changes coming out of this process is around how we elect Board members.  And that requires a change to the bylaws.  We published the proposed bylaw changes as a red-lined document so you can clearly see the changes.  Our goal in these bylaw changes was to address the changes required by the global growth initiatives, conduct a legal review of the document and address other minor issues in the document.  There are numerous small wording changes throughout the document.  For example, we replaced every reference of “The Corporation” with the word “PASS” so it now reads “PASS is organized…”. Board Composition The biggest change in these bylaw changes is how the Board is composed and elected.  This discussion starts in section VI.2.  This section now says that some elected directors will come from geographic regions.  I think this is the best way to make sure we give all of our members a voice in the leadership of the organization.  The key parts of this section are: The remaining Directors (i.e. the non-Officer Directors and non-Vendor Appointed Directors) shall be elected by the voting membership (“Elected Directors”). Elected Directors shall include representatives of defined PASS regions (“Regions”) as set forth below (“Regional Directors”) and at minimum one (1) additional Director-at-Large whose selection is not limited by region. Regional Directors shall include, but are not limited to, two (2) seats for the Region covering Canada and the United States of America. Additional Regions for the purpose of electing additional Regional Directors and additional Director-at-Large seats for the purpose of expanding the Board shall be defined by a majority vote of the current Board of Directors and must be established prior to the public call for nominations in the general election. Previously defined Regions and seats approved by the Board of Directors shall remain in effect and can only be modified by a 2/3 majority vote by the then current Board of Directors. Currently PASS has six At-Large Directors elected by the members.  These changes allow for a Regional Director position that is elected by the members but must come from a particular region.  It also stipulates that there must always be at least one Director-at-Large who can come from any region. We also understand that PASS is currently a very US-centric organization.  Our Summit is held in America, roughly half our chapters are in the US and Canada and most of the Board members over the last ten years have come from America.  We wanted to reflect that by making sure that our US and Canadian volunteers would continue to play a significant role by ensuring that two Regional seats are reserved specifically for Canada and the US. Other than that, the bylaws don’t create any specific regional seats.  These rules allow us to create Regional Director seats but don’t require it.  We haven’t fully discussed what the criteria will be in order for a region to have a seat designated for it or how many regions there will be.  In our discussions we’ve broadly discussed regions for United States and Canada Europe, Middle East, and Africa (EMEA) Australia, New Zealand and Asia (also known as Asia Pacific or APAC) Mexico, South America, and Central America (LATAM) As you can see, our thinking is that there will be a few large regions.  I’ve also considered a non-North America region that we can gradually split into the regions above as our membership grows in those areas.  The regions will be defined by a policy document that will be published prior to the elections. I’m hoping that over the next year we can begin to publish more of what we do as Board-approved policy documents. While the bylaws only require a single non-region specific At-large Director, I would expect we would always have two.  That way we can have one in each election.  I think it’s important that we always have one seat open that anyone who is eligible to run for the Board can contest.  The Board is required to have any regions defined prior to the start of the election process. Board Elections – Regional Seats We spent a lot of time discussing how the elections would work for these Regional Director seats.  Ultimately we decided that the simplest solution is that every PASS member should vote for every open seat.  Section VIII.3 reads: Candidates who are eligible (i.e. eligible to serve in such capacity subject to the criteria set forth herein or adopted by the Board of Directors) shall be designated to fill open Board seats in the following order of priority on the basis of total votes received: (i) full term Regional Director seats, (ii) full term Director-at-Large seats, (iii) not full term (vacated) Regional Director seats, (iv) not full term (vacated) Director-at-Large seats. For the purposes of clarity, because of eligibility requirements, it is contemplated that the candidates designated to the open Board seats may not receive more votes than certain other candidates who are not selected to the Board. We debated whether to have multiple ballots or one single ballot.  Multiple ballot elections get complicated quickly.  Let’s say we have a ballot for US/Canada and one for Region 2.  After that we’d need a mechanism to merge those two together and come up with the winner of the at-large seat or have another election for the at-large position.  We think the best way to do this is a single ballot and putting the highest vote getters into the most restrictive seats.  Let’s look at an example: There are seats open for Region 1, Region 2 and at-large.  The election results are as follows: Candidate A (eligible for Region 1) – 550 votes Candidate B (eligible for Region 1) – 525 votes Candidate C (eligible for Region 1) – 475 votes Candidate D (eligible for Region 2) – 125 votes Candidate E (eligible for Region 2) – 75 votes In this case, Candidate A is the winner for Region 1 and is assigned that seat.  Candidate D is the winner for Region 2 and is assigned that seat.  The at-large seat is filled by the high remaining vote getter which is Candidate B. The key point to understand is that we may have a situation where a person with a lower vote total is elected to a regional seat and a person with a higher vote total is excluded.  This will be true whether we had multiple ballots or a single ballot.  Board Elections – Vacant Seats The other change to the election process is for vacant Board seats.  The actual changes are sprinkled throughout the document. Previously we didn’t have a mechanism that allowed for an election of a Board seat that we knew would be vacant in the future.  The most common case is when a Board members moves to an Officer role in the middle of their term.  One of the key changes is to allow the number of votes members have to match the number of open seats.  This allows each voter to express their preference on all open seats.  This only applies when we know about the opening prior to the call for nominations.  This all means that if there’s a seat will be open at the start of the next Board term, and we know about it prior to the call for nominations, we can include that seat in the elections.  Ultimately, the aim is to have PASS members decide who sits on the Board in as many situations as possible. We discussed the option of changing the bylaws to just take next highest vote-getter in all other cases.  I think that’s wrong for the following reasons: All voters aren’t able to express an opinion on all candidates.  If there are five people running for three seats, you can only vote for three.  You have no way to express your preference between #4 and #5. Different candidates may have different information about the number of seats available.  A person may learn that a Board member plans to resign at the end of the year prior to that information being made public. They may understand that the top four vote getters will end up on the Board while the rest of the members believe there are only three openings.  This may affect someone’s decision to run.  I don’t think this creates a transparent, fair election. Board members may use their knowledge of the election results to decide whether to remain on the Board or not.  Admittedly this one is unlikely but I don’t want to create a situation where this accusation can be leveled. I think the majority of vacancies in the future will be handled through elections.  The bylaw section quoted above also indicates that partial term vacancies will be filled after the full term seats are filled. Removing Directors Section VI.7 on removing directors has always had a clause that allowed members to remove an elected director.  We also had a clause that allowed appointed directors to be removed.  We added a clause that allows the Board to remove for cause any director with a 2/3 majority vote.  The updated text reads: Any Director may be removed for cause by a 2/3 majority vote of the Board of Directors whenever in its judgment the best interests of PASS would be served thereby. Notwithstanding the foregoing, the authority of any Director to act as in an official capacity as a Director or Officer of PASS may be suspended by the Board of Directors for cause. Cause for suspension or removal of a Director shall include but not be limited to failure to meet any Board-approved performance expectations or the presence of a reason for suspension or dismissal as listed in Addendum B of these Bylaws. The first paragraph is updated and the second and third are unchanged (except cleaning up language).  If you scroll down and look at Addendum B of these bylaws you find the following: Cause for suspension or dismissal of a member of the Board of Directors may include: Inability to attend Board meetings on a regular basis. Inability or unwillingness to act in a capacity designated by the Board of Directors. Failure to fulfill the responsibilities of the office. Inability to represent the Region elected to represent Failure to act in a manner consistent with PASS's Bylaws and/or policies. Misrepresentation of responsibility and/or authority. Misrepresentation of PASS. Unresolved conflict of interests with Board responsibilities. Breach of confidentiality. The bold line about your inability to represent your region is what we added to the bylaws in this revision.  We also added a clause to section VII.3 allowing the Board to remove an officer.  That clause is much less restrictive.  It doesn’t require cause and only requires a simple majority. The Board of Directors may remove any Officer whenever in their judgment the best interests of PASS shall be served by such removal. Other There are numerous other small changes throughout the document. Proxy voting.  The laws around how members and Board members proxy votes are specific in Illinois law.  PASS is an Illinois corporation and is subject to Illinois laws.  We changed section IV.5 to come into compliance with those laws.  Specifically this says you can only vote through a proxy if you have a written proxy through your authorized attorney.  English language proficiency.  As we increase our global footprint we come across more members that aren’t native English speakers.  The business of PASS is conducted in English and it’s important that our Board members speak English.  If we get big enough to afford translators, we may be able to relax this but right now we need English language skills for effective Board members. Committees.  The language around committees in section IX is old and dated.  Our lawyers advised us to clean it up.  This section specifically applies to any committees that the Board may form outside of portfolios.  We removed the term limits, quorum and vacancies clause.  We don’t currently have any committees that this would apply to.  The Nominating Committee is covered elsewhere in the bylaws. Electronic Votes.  The change allows the Board to vote via email but the results must be unanimous.  This is to conform with Illinois state law. Immediate Past President.  There was no mechanism to fill the IPP role if an outgoing President chose not to participate.  We changed section VII.8 to allow the Board to invite any previous President to fill the role by majority vote. Nominations Committee.  We’ve opened the language to allow for the transparent election of the Nominations Committee as outlined by the 2011 Election Review Committee. Revocation of Charters. The language surrounding the revocation of charters for local groups was flagged by the lawyers. We have allowed for the local user group to make all necessary payment before considering returning of items to PASS if required. Bylaw notification. We’ve spent countless meetings working on these bylaws with the intent to not open them again any time in the near future. Should the bylaws be opened again, we have included a clause ensuring that the PASS membership is involved. I’m proud that the Board has remained committed to transparency and accountability to members. This clause will require that same level of commitment in the future even when all the current Board members have rolled off. I think that covers everything.  I’d encourage you to look through the red-line document and see the changes.  It’s helpful to look at the language that’s being removed and the language that’s being added.  I’m happy to answer any questions here or you can email them to [email protected].

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  • External USB attached drive works in Windows XP but not in Windows 7. How to fix?

    - by irrational John
    Earlier this week I purchased this "N52300 EZQuest Pro" external hard drive enclosure from here. I can connect the enclosure using USB 2.0 and access the files in both NTFS partitions on the MBR partitioned drive when I use either Windows XP (SP3) or Mac OS X 10.6. So it works as expected in XP & Snow Leopard. However, the enclosure does not work in Windows 7 (Home Premium) either 64-bit or 32-bit or in Ubuntu 10.04 (kernel 2.6.32-23-generic). I'm thinking this must be a Windows 7 driver problem because the enclosure works in XP & Snow Leopard. I do know that no special drivers are required to use this enclosure. It is supported using the USB mass storage drivers included with XP and OS X. It should also work fine using the mass storage support in Windows 7, no? FWIW, I have also tried using 32-bit Windows 7 on both my desktop, a Gigabyte GA-965P-DS3 with a Pentium Dual-Core E6500 @ 2.93GHz, and on my early 2008 MacBook. I see the same failure in both cases that I see with 64-bit Windows 7. So it doesn't appear to be specific to one hardware platform. I'm hoping someone out there can help me either get the enclosure to work in Windows 7 or convince me that the enclosure hardware is bad and should be RMAed. At the moment though an RMA seems pointless since this appears to be a (Windows 7) device driver problem. I have tried to track down any updates to the mass storage drivers included with Windows 7 but have so far come up empty. Heck, I can't even figure out how to place a bug report with Microsoft since apparently the grace period for Windows 7 email support is only a few months. I came across a link to some USB troubleshooting steps in another question. I haven't had a chance to look over the suggestions on that site or try them yet. Maybe tomorrow if I have time ... ;-) I'll finish up with some more details about the problem. When I connect the enclosure using USB to Windows 7 at first it appears everything worked. Windows detects the drive and installs a driver for it. Looking in Device Manager there is an entry under the Hard Drives section with the title, Hitachi HDT721010SLA360 USB Device. When you open Windows Disk Management the first time after the enclosure has been attached the drive appears as "Not initialize" and I'm prompted to initialize it. This is bogus. After all, the drive worked fine in XP so I know it has already been initialized, partitioned, and formatted. So of course I never try to initialize it "again". (It's a 1 GB drive and I don't want to lose the data on it). Except for this first time, the drive never shows up in Disk Management again unless I uninstall the Hitachi HDT721010SLA360 USB Device entry under Hard Drives, unplug, and then replug the enclosure. If I do that then the process in the previous paragraph repeats. In Ubuntu the enclosure never shows up at all at the file system level. Below are an excerpt from kern.log and an excerpt from the result of lsusb -v after attaching the enclosure. It appears that Ubuntu at first recongnizes the enclosure and is attempting to attach it, but encounters errors which prevent it from doing so. Unfortunately, I don't know whether any of this info is useful or not. excerpt from kern.log [ 2684.240015] usb 1-2: new high speed USB device using ehci_hcd and address 22 [ 2684.393618] usb 1-2: configuration #1 chosen from 1 choice [ 2684.395399] scsi17 : SCSI emulation for USB Mass Storage devices [ 2684.395570] usb-storage: device found at 22 [ 2684.395572] usb-storage: waiting for device to settle before scanning [ 2689.390412] usb-storage: device scan complete [ 2689.390894] scsi 17:0:0:0: Direct-Access Hitachi HDT721010SLA360 ST6O PQ: 0 ANSI: 4 [ 2689.392237] sd 17:0:0:0: Attached scsi generic sg7 type 0 [ 2689.395269] sd 17:0:0:0: [sde] 1953525168 512-byte logical blocks: (1.00 TB/931 GiB) [ 2689.395632] sd 17:0:0:0: [sde] Write Protect is off [ 2689.395636] sd 17:0:0:0: [sde] Mode Sense: 11 00 00 00 [ 2689.395639] sd 17:0:0:0: [sde] Assuming drive cache: write through [ 2689.412003] sd 17:0:0:0: [sde] Assuming drive cache: write through [ 2689.412009] sde: sde1 sde2 [ 2689.455759] sd 17:0:0:0: [sde] Assuming drive cache: write through [ 2689.455765] sd 17:0:0:0: [sde] Attached SCSI disk [ 2692.620017] usb 1-2: reset high speed USB device using ehci_hcd and address 22 [ 2707.740014] usb 1-2: device descriptor read/64, error -110 [ 2722.970103] usb 1-2: device descriptor read/64, error -110 [ 2723.200027] usb 1-2: reset high speed USB device using ehci_hcd and address 22 [ 2738.320019] usb 1-2: device descriptor read/64, error -110 [ 2753.550024] usb 1-2: device descriptor read/64, error -110 [ 2753.780020] usb 1-2: reset high speed USB device using ehci_hcd and address 22 [ 2758.810147] usb 1-2: device descriptor read/8, error -110 [ 2763.940142] usb 1-2: device descriptor read/8, error -110 [ 2764.170014] usb 1-2: reset high speed USB device using ehci_hcd and address 22 [ 2769.200141] usb 1-2: device descriptor read/8, error -110 [ 2774.330137] usb 1-2: device descriptor read/8, error -110 [ 2774.440069] usb 1-2: USB disconnect, address 22 [ 2774.440503] sd 17:0:0:0: Device offlined - not ready after error recovery [ 2774.590023] usb 1-2: new high speed USB device using ehci_hcd and address 23 [ 2789.710020] usb 1-2: device descriptor read/64, error -110 [ 2804.940020] usb 1-2: device descriptor read/64, error -110 [ 2805.170026] usb 1-2: new high speed USB device using ehci_hcd and address 24 [ 2820.290019] usb 1-2: device descriptor read/64, error -110 [ 2835.520027] usb 1-2: device descriptor read/64, error -110 [ 2835.750018] usb 1-2: new high speed USB device using ehci_hcd and address 25 [ 2840.780085] usb 1-2: device descriptor read/8, error -110 [ 2845.910079] usb 1-2: device descriptor read/8, error -110 [ 2846.140023] usb 1-2: new high speed USB device using ehci_hcd and address 26 [ 2851.170112] usb 1-2: device descriptor read/8, error -110 [ 2856.300077] usb 1-2: device descriptor read/8, error -110 [ 2856.410027] hub 1-0:1.0: unable to enumerate USB device on port 2 [ 2856.730033] usb 3-2: new full speed USB device using uhci_hcd and address 11 [ 2871.850017] usb 3-2: device descriptor read/64, error -110 [ 2887.080014] usb 3-2: device descriptor read/64, error -110 [ 2887.310011] usb 3-2: new full speed USB device using uhci_hcd and address 12 [ 2902.430021] usb 3-2: device descriptor read/64, error -110 [ 2917.660013] usb 3-2: device descriptor read/64, error -110 [ 2917.890016] usb 3-2: new full speed USB device using uhci_hcd and address 13 [ 2922.911623] usb 3-2: device descriptor read/8, error -110 [ 2928.051753] usb 3-2: device descriptor read/8, error -110 [ 2928.280013] usb 3-2: new full speed USB device using uhci_hcd and address 14 [ 2933.301876] usb 3-2: device descriptor read/8, error -110 [ 2938.431993] usb 3-2: device descriptor read/8, error -110 [ 2938.540073] hub 3-0:1.0: unable to enumerate USB device on port 2 excerpt from lsusb -v Bus 001 Device 017: ID 0dc4:0000 Macpower Peripherals, Ltd Device Descriptor: bLength 18 bDescriptorType 1 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 idVendor 0x0dc4 Macpower Peripherals, Ltd idProduct 0x0000 bcdDevice 0.01 iManufacturer 1 EZ QUEST iProduct 2 USB Mass Storage iSerial 3 220417 bNumConfigurations 1 Configuration Descriptor: bLength 9 bDescriptorType 2 wTotalLength 32 bNumInterfaces 1 bConfigurationValue 1 iConfiguration 5 Config0 bmAttributes 0xc0 Self Powered MaxPower 0mA Interface Descriptor: bLength 9 bDescriptorType 4 bInterfaceNumber 0 bAlternateSetting 0 bNumEndpoints 2 bInterfaceClass 8 Mass Storage bInterfaceSubClass 6 SCSI bInterfaceProtocol 80 Bulk (Zip) iInterface 4 Interface0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x01 EP 1 OUT bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Endpoint Descriptor: bLength 7 bDescriptorType 5 bEndpointAddress 0x81 EP 1 IN bmAttributes 2 Transfer Type Bulk Synch Type None Usage Type Data wMaxPacketSize 0x0200 1x 512 bytes bInterval 0 Device Qualifier (for other device speed): bLength 10 bDescriptorType 6 bcdUSB 2.00 bDeviceClass 0 (Defined at Interface level) bDeviceSubClass 0 bDeviceProtocol 0 bMaxPacketSize0 64 bNumConfigurations 1 Device Status: 0x0001 Self Powered Update: Results using Firewire to connect. Today I recieved a 1394b 9 pin to 1394a 6 pin cable which allowed me to connect the "EZQuest Pro" via Firewire. Everything works. When I use Firewire I can connect whether I'm using Windows 7 or Ubuntu 10.04. I even tried booting my Gigabyte desktop as an OS X 10.6.3 Hackintosh and it worked there as well. (Though if I recall correctly, it also worked when using USB 2.0 and booting OS X on the desktop. Certainly it works with USB 2.0 and my MacBook.) I believe the firmware on the device is at the latest level available, v1.07. I base this on the excerpt below from the OS X System Profiler which shows Firmware Revision: 0x107. Bottom line: It's nice that the enclosure is actually usable when I connect with Firewire. But I am still searching for an answer as to why it does not work correctly when using USB 2.0 in Windows 7 (and Ubuntu ... but really Windows 7 is my biggest concern). OXFORD IDE Device 1: Manufacturer: EZ QUEST Model: 0x0 GUID: 0x1D202E0220417 Maximum Speed: Up to 800 Mb/sec Connection Speed: Up to 400 Mb/sec Sub-units: OXFORD IDE Device 1 Unit: Unit Software Version: 0x10483 Unit Spec ID: 0x609E Firmware Revision: 0x107 Product Revision Level: ST6O Sub-units: OXFORD IDE Device 1 SBP-LUN: Capacity: 1 TB (1,000,204,886,016 bytes) Removable Media: Yes BSD Name: disk3 Partition Map Type: MBR (Master Boot Record) S.M.A.R.T. status: Not Supported

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  • Does anyone really understand how HFSC scheduling in Linux/BSD works?

    - by Mecki
    I read the original SIGCOMM '97 PostScript paper about HFSC, it is very technically, but I understand the basic concept. Instead of giving a linear service curve (as with pretty much every other scheduling algorithm), you can specify a convex or concave service curve and thus it is possible to decouple bandwidth and delay. However, even though this paper mentions to kind of scheduling algorithms being used (real-time and link-share), it always only mentions ONE curve per scheduling class (the decoupling is done by specifying this curve, only one curve is needed for that). Now HFSC has been implemented for BSD (OpenBSD, FreeBSD, etc.) using the ALTQ scheduling framework and it has been implemented Linux using the TC scheduling framework (part of iproute2). Both implementations added two additional service curves, that were NOT in the original paper! A real-time service curve and an upper-limit service curve. Again, please note that the original paper mentions two scheduling algorithms (real-time and link-share), but in that paper both work with one single service curve. There never have been two independent service curves for either one as you currently find in BSD and Linux. Even worse, some version of ALTQ seems to add an additional queue priority to HSFC (there is no such thing as priority in the original paper either). I found several BSD HowTo's mentioning this priority setting (even though the man page of the latest ALTQ release knows no such parameter for HSFC, so officially it does not even exist). This all makes the HFSC scheduling even more complex than the algorithm described in the original paper and there are tons of tutorials on the Internet that often contradict each other, one claiming the opposite of the other one. This is probably the main reason why nobody really seems to understand how HFSC scheduling really works. Before I can ask my questions, we need a sample setup of some kind. I'll use a very simple one as seen in the image below: Here are some questions I cannot answer because the tutorials contradict each other: What for do I need a real-time curve at all? Assuming A1, A2, B1, B2 are all 128 kbit/s link-share (no real-time curve for either one), then each of those will get 128 kbit/s if the root has 512 kbit/s to distribute (and A and B are both 256 kbit/s of course), right? Why would I additionally give A1 and B1 a real-time curve with 128 kbit/s? What would this be good for? To give those two a higher priority? According to original paper I can give them a higher priority by using a curve, that's what HFSC is all about after all. By giving both classes a curve of [256kbit/s 20ms 128kbit/s] both have twice the priority than A2 and B2 automatically (still only getting 128 kbit/s on average) Does the real-time bandwidth count towards the link-share bandwidth? E.g. if A1 and B1 both only have 64kbit/s real-time and 64kbit/s link-share bandwidth, does that mean once they are served 64kbit/s via real-time, their link-share requirement is satisfied as well (they might get excess bandwidth, but lets ignore that for a second) or does that mean they get another 64 kbit/s via link-share? So does each class has a bandwidth "requirement" of real-time plus link-share? Or does a class only have a higher requirement than the real-time curve if the link-share curve is higher than the real-time curve (current link-share requirement equals specified link-share requirement minus real-time bandwidth already provided to this class)? Is upper limit curve applied to real-time as well, only to link-share, or maybe to both? Some tutorials say one way, some say the other way. Some even claim upper-limit is the maximum for real-time bandwidth + link-share bandwidth? What is the truth? Assuming A2 and B2 are both 128 kbit/s, does it make any difference if A1 and B1 are 128 kbit/s link-share only, or 64 kbit/s real-time and 128 kbit/s link-share, and if so, what difference? If I use the seperate real-time curve to increase priorities of classes, why would I need "curves" at all? Why is not real-time a flat value and link-share also a flat value? Why are both curves? The need for curves is clear in the original paper, because there is only one attribute of that kind per class. But now, having three attributes (real-time, link-share, and upper-limit) what for do I still need curves on each one? Why would I want the curves shape (not average bandwidth, but their slopes) to be different for real-time and link-share traffic? According to the little documentation available, real-time curve values are totally ignored for inner classes (class A and B), they are only applied to leaf classes (A1, A2, B1, B2). If that is true, why does the ALTQ HFSC sample configuration (search for 3.3 Sample configuration) set real-time curves on inner classes and claims that those set the guaranteed rate of those inner classes? Isn't that completely pointless? (note: pshare sets the link-share curve in ALTQ and grate the real-time curve; you can see this in the paragraph above the sample configuration). Some tutorials say the sum of all real-time curves may not be higher than 80% of the line speed, others say it must not be higher than 70% of the line speed. Which one is right or are they maybe both wrong? One tutorial said you shall forget all the theory. No matter how things really work (schedulers and bandwidth distribution), imagine the three curves according to the following "simplified mind model": real-time is the guaranteed bandwidth that this class will always get. link-share is the bandwidth that this class wants to become fully satisfied, but satisfaction cannot be guaranteed. In case there is excess bandwidth, the class might even get offered more bandwidth than necessary to become satisfied, but it may never use more than upper-limit says. For all this to work, the sum of all real-time bandwidths may not be above xx% of the line speed (see question above, the percentage varies). Question: Is this more or less accurate or a total misunderstanding of HSFC? And if assumption above is really accurate, where is prioritization in that model? E.g. every class might have a real-time bandwidth (guaranteed), a link-share bandwidth (not guaranteed) and an maybe an upper-limit, but still some classes have higher priority needs than other classes. In that case I must still prioritize somehow, even among real-time traffic of those classes. Would I prioritize by the slope of the curves? And if so, which curve? The real-time curve? The link-share curve? The upper-limit curve? All of them? Would I give all of them the same slope or each a different one and how to find out the right slope? I still haven't lost hope that there exists at least a hand full of people in this world that really understood HFSC and are able to answer all these questions accurately. And doing so without contradicting each other in the answers would be really nice ;-)

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  • Does anyone really understand how HFSC scheduling in Linux/BSD works?

    - by Mecki
    I read the original SIGCOMM '97 PostScript paper about HFSC, it is very technically, but I understand the basic concept. Instead of giving a linear service curve (as with pretty much every other scheduling algorithm), you can specify a convex or concave service curve and thus it is possible to decouple bandwidth and delay. However, even though this paper mentions to kind of scheduling algorithms being used (real-time and link-share), it always only mentions ONE curve per scheduling class (the decoupling is done by specifying this curve, only one curve is needed for that). Now HFSC has been implemented for BSD (OpenBSD, FreeBSD, etc.) using the ALTQ scheduling framework and it has been implemented Linux using the TC scheduling framework (part of iproute2). Both implementations added two additional service curves, that were NOT in the original paper! A real-time service curve and an upper-limit service curve. Again, please note that the original paper mentions two scheduling algorithms (real-time and link-share), but in that paper both work with one single service curve. There never have been two independent service curves for either one as you currently find in BSD and Linux. Even worse, some version of ALTQ seems to add an additional queue priority to HSFC (there is no such thing as priority in the original paper either). I found several BSD HowTo's mentioning this priority setting (even though the man page of the latest ALTQ release knows no such parameter for HSFC, so officially it does not even exist). This all makes the HFSC scheduling even more complex than the algorithm described in the original paper and there are tons of tutorials on the Internet that often contradict each other, one claiming the opposite of the other one. This is probably the main reason why nobody really seems to understand how HFSC scheduling really works. Before I can ask my questions, we need a sample setup of some kind. I'll use a very simple one as seen in the image below: Here are some questions I cannot answer because the tutorials contradict each other: What for do I need a real-time curve at all? Assuming A1, A2, B1, B2 are all 128 kbit/s link-share (no real-time curve for either one), then each of those will get 128 kbit/s if the root has 512 kbit/s to distribute (and A and B are both 256 kbit/s of course), right? Why would I additionally give A1 and B1 a real-time curve with 128 kbit/s? What would this be good for? To give those two a higher priority? According to original paper I can give them a higher priority by using a curve, that's what HFSC is all about after all. By giving both classes a curve of [256kbit/s 20ms 128kbit/s] both have twice the priority than A2 and B2 automatically (still only getting 128 kbit/s on average) Does the real-time bandwidth count towards the link-share bandwidth? E.g. if A1 and B1 both only have 64kbit/s real-time and 64kbit/s link-share bandwidth, does that mean once they are served 64kbit/s via real-time, their link-share requirement is satisfied as well (they might get excess bandwidth, but lets ignore that for a second) or does that mean they get another 64 kbit/s via link-share? So does each class has a bandwidth "requirement" of real-time plus link-share? Or does a class only have a higher requirement than the real-time curve if the link-share curve is higher than the real-time curve (current link-share requirement equals specified link-share requirement minus real-time bandwidth already provided to this class)? Is upper limit curve applied to real-time as well, only to link-share, or maybe to both? Some tutorials say one way, some say the other way. Some even claim upper-limit is the maximum for real-time bandwidth + link-share bandwidth? What is the truth? Assuming A2 and B2 are both 128 kbit/s, does it make any difference if A1 and B1 are 128 kbit/s link-share only, or 64 kbit/s real-time and 128 kbit/s link-share, and if so, what difference? If I use the seperate real-time curve to increase priorities of classes, why would I need "curves" at all? Why is not real-time a flat value and link-share also a flat value? Why are both curves? The need for curves is clear in the original paper, because there is only one attribute of that kind per class. But now, having three attributes (real-time, link-share, and upper-limit) what for do I still need curves on each one? Why would I want the curves shape (not average bandwidth, but their slopes) to be different for real-time and link-share traffic? According to the little documentation available, real-time curve values are totally ignored for inner classes (class A and B), they are only applied to leaf classes (A1, A2, B1, B2). If that is true, why does the ALTQ HFSC sample configuration (search for 3.3 Sample configuration) set real-time curves on inner classes and claims that those set the guaranteed rate of those inner classes? Isn't that completely pointless? (note: pshare sets the link-share curve in ALTQ and grate the real-time curve; you can see this in the paragraph above the sample configuration). Some tutorials say the sum of all real-time curves may not be higher than 80% of the line speed, others say it must not be higher than 70% of the line speed. Which one is right or are they maybe both wrong? One tutorial said you shall forget all the theory. No matter how things really work (schedulers and bandwidth distribution), imagine the three curves according to the following "simplified mind model": real-time is the guaranteed bandwidth that this class will always get. link-share is the bandwidth that this class wants to become fully satisfied, but satisfaction cannot be guaranteed. In case there is excess bandwidth, the class might even get offered more bandwidth than necessary to become satisfied, but it may never use more than upper-limit says. For all this to work, the sum of all real-time bandwidths may not be above xx% of the line speed (see question above, the percentage varies). Question: Is this more or less accurate or a total misunderstanding of HSFC? And if assumption above is really accurate, where is prioritization in that model? E.g. every class might have a real-time bandwidth (guaranteed), a link-share bandwidth (not guaranteed) and an maybe an upper-limit, but still some classes have higher priority needs than other classes. In that case I must still prioritize somehow, even among real-time traffic of those classes. Would I prioritize by the slope of the curves? And if so, which curve? The real-time curve? The link-share curve? The upper-limit curve? All of them? Would I give all of them the same slope or each a different one and how to find out the right slope? I still haven't lost hope that there exists at least a hand full of people in this world that really understood HFSC and are able to answer all these questions accurately. And doing so without contradicting each other in the answers would be really nice ;-)

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  • Compare images after canny edge detection in OpenCV (C++)

    - by typoknig
    Hi all, I am working on an OpenCV project and I need to compare some images after canny has been applied to both of them. Before the canny was applied I had the gray scale images populating a histogram and then I compared the histograms, but when canny is added to the images the histogram does not populate. I have read that a canny image can populate a histogram, but have not found a way to make it happen. I do not necessairly need to keep using the histograms, I just want to know the best way to compare two canny images. SSCCE below for you to chew on. I have poached and patched about 75% of this code from books and various sites on the internet, so props to those guys... // SLC (Histogram).cpp : Defines the entry point for the console application. #include "stdafx.h" #include <cxcore.h> #include <cv.h> #include <cvaux.h> #include <highgui.h> #include <stdio.h> #include <sstream> #include <iostream> using namespace std; IplImage* image1= 0; IplImage* imgHistogram1 = 0; IplImage* gray1= 0; CvHistogram* hist1; int main(){ CvCapture* capture = cvCaptureFromCAM(0); if(!cvQueryFrame(capture)){ cout<<"Video capture failed, please check the camera."<<endl; } else{ cout<<"Video camera capture successful!"<<endl; }; CvSize sz = cvGetSize(cvQueryFrame(capture)); IplImage* image = cvCreateImage(sz, 8, 3); IplImage* imgHistogram = 0; IplImage* gray = 0; CvHistogram* hist; cvNamedWindow("Image Source",1); cvNamedWindow("gray", 1); cvNamedWindow("Histogram",1); cvNamedWindow("BG", 1); cvNamedWindow("FG", 1); cvNamedWindow("Canny",1); cvNamedWindow("Canny1", 1); image1 = cvLoadImage("image bin/use this image.jpg");// an image has to load here or the program will not run //size of the histogram -1D histogram int bins1 = 256; int hsize1[] = {bins1}; //max and min value of the histogram float max_value1 = 0, min_value1 = 0; //value and normalized value float value1; int normalized1; //ranges - grayscale 0 to 256 float xranges1[] = { 0, 256 }; float* ranges1[] = { xranges1 }; //create an 8 bit single channel image to hold a //grayscale version of the original picture gray1 = cvCreateImage( cvGetSize(image1), 8, 1 ); cvCvtColor( image1, gray1, CV_BGR2GRAY ); IplImage* canny1 = cvCreateImage(cvGetSize(gray1), 8, 1 ); cvCanny( gray1, canny1, 55, 175, 3 ); //Create 3 windows to show the results cvNamedWindow("original1",1); cvNamedWindow("gray1",1); cvNamedWindow("histogram1",1); //planes to obtain the histogram, in this case just one IplImage* planes1[] = { canny1 }; //get the histogram and some info about it hist1 = cvCreateHist( 1, hsize1, CV_HIST_ARRAY, ranges1,1); cvCalcHist( planes1, hist1, 0, NULL); cvGetMinMaxHistValue( hist1, &min_value1, &max_value1); printf("min: %f, max: %f\n", min_value1, max_value1); //create an 8 bits single channel image to hold the histogram //paint it white imgHistogram1 = cvCreateImage(cvSize(bins1, 50),8,1); cvRectangle(imgHistogram1, cvPoint(0,0), cvPoint(256,50), CV_RGB(255,255,255),-1); //draw the histogram :P for(int i=0; i < bins1; i++){ value1 = cvQueryHistValue_1D( hist1, i); normalized1 = cvRound(value1*50/max_value1); cvLine(imgHistogram1,cvPoint(i,50), cvPoint(i,50-normalized1), CV_RGB(0,0,0)); } //show the image results cvShowImage( "original1", image1 ); cvShowImage( "gray1", gray1 ); cvShowImage( "histogram1", imgHistogram1 ); cvShowImage( "Canny1", canny1); CvBGStatModel* bg_model = cvCreateFGDStatModel( image ); for(;;){ image = cvQueryFrame(capture); cvUpdateBGStatModel( image, bg_model ); //Size of the histogram -1D histogram int bins = 256; int hsize[] = {bins}; //Max and min value of the histogram float max_value = 0, min_value = 0; //Value and normalized value float value; int normalized; //Ranges - grayscale 0 to 256 float xranges[] = {0, 256}; float* ranges[] = {xranges}; //Create an 8 bit single channel image to hold a grayscale version of the original picture gray = cvCreateImage(cvGetSize(image), 8, 1); cvCvtColor(image, gray, CV_BGR2GRAY); IplImage* canny = cvCreateImage(cvGetSize(gray), 8, 1 ); cvCanny( gray, canny, 55, 175, 3 );//55, 175, 3 with direct light //Planes to obtain the histogram, in this case just one IplImage* planes[] = {canny}; //Get the histogram and some info about it hist = cvCreateHist(1, hsize, CV_HIST_ARRAY, ranges,1); cvCalcHist(planes, hist, 0, NULL); cvGetMinMaxHistValue(hist, &min_value, &max_value); //printf("Minimum Histogram Value: %f, Maximum Histogram Value: %f\n", min_value, max_value); //Create an 8 bits single channel image to hold the histogram and paint it white imgHistogram = cvCreateImage(cvSize(bins, 50),8,3); cvRectangle(imgHistogram, cvPoint(0,0), cvPoint(256,50), CV_RGB(255,255,255),-1); //Draw the histogram for(int i=0; i < bins; i++){ value = cvQueryHistValue_1D(hist, i); normalized = cvRound(value*50/max_value); cvLine(imgHistogram,cvPoint(i,50), cvPoint(i,50-normalized), CV_RGB(0,0,0)); } double correlation = cvCompareHist (hist1, hist, CV_COMP_CORREL); double chisquare = cvCompareHist (hist1, hist, CV_COMP_CHISQR); double intersection = cvCompareHist (hist1, hist, CV_COMP_INTERSECT); double bhattacharyya = cvCompareHist (hist1, hist, CV_COMP_BHATTACHARYYA); double difference = (1 - correlation) + chisquare + (1 - intersection) + bhattacharyya; printf("correlation: %f\n", correlation); printf("chi-square: %f\n", chisquare); printf("intersection: %f\n", intersection); printf("bhattacharyya: %f\n", bhattacharyya); printf("difference: %f\n", difference); cvShowImage("Image Source", image); cvShowImage("gray", gray); cvShowImage("Histogram", imgHistogram); cvShowImage( "Canny", canny); cvShowImage("BG", bg_model->background); cvShowImage("FG", bg_model->foreground); //Page 19 paragraph 3 of "Learning OpenCV" tells us why we DO NOT use "cvReleaseImage(&image)" in this section cvReleaseImage(&imgHistogram); cvReleaseImage(&gray); cvReleaseHist(&hist); cvReleaseImage(&canny); char c = cvWaitKey(10); //if ASCII key 27 (esc) is pressed then loop breaks if(c==27) break; } cvReleaseBGStatModel( &bg_model ); cvReleaseImage(&image); cvReleaseCapture(&capture); cvDestroyAllWindows(); }

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  • Bindable richTextBox still hanging in memory {WPF, Caliburn.Micro}

    - by Paul
    Hi, I use in WFP Caliburn.Micro Framework. I need bindable richTextbox for Document property. I found many ways how do it bindable richTextBox. But I have one problem. From parent window I open child window. Child window consist bindable richTextBox user control. After I close child window and use memory profiler view class with bindabelrichTextBox control and view model class is still hanging in memory. - this cause memory leaks. If I use richTextBox from .NET Framework or richTextBox from Extended WPF Toolkit it doesn’t cause this memory leak problem. I can’t identified problem in bindable richTextBox class. Here is ist class for bindable richTextBox: Base class can be from .NET or Extended toolkit. /// <summary> /// Represents a bindable rich editing control which operates on System.Windows.Documents.FlowDocument /// objects. /// </summary> public class BindableRichTextBox : RichTextBox { /// <summary> /// Identifies the <see cref="Document"/> dependency property. /// </summary> public static readonly DependencyProperty DocumentProperty = DependencyProperty.Register("Document", typeof(FlowDocument), typeof(BindableRichTextBox)); /// <summary> /// Initializes a new instance of the <see cref="BindableRichTextBox"/> class. /// </summary> public BindableRichTextBox() : base() { } /// <summary> /// Initializes a new instance of the <see cref="BindableRichTextBox"/> class. /// </summary> /// <param title="document">A <see cref="T:System.Windows.Documents.FlowDocument"></see> to be added as the initial contents of the new <see cref="T:System.Windows.Controls.BindableRichTextBox"></see>.</param> public BindableRichTextBox(FlowDocument document) : base(document) { } /// <summary> /// Raises the <see cref="E:System.Windows.FrameworkElement.Initialized"></see> event. This method is invoked whenever <see cref="P:System.Windows.FrameworkElement.IsInitialized"></see> is set to true internally. /// </summary> /// <param title="e">The <see cref="T:System.Windows.RoutedEventArgs"></see> that contains the event data.</param> protected override void OnInitialized(EventArgs e) { // Hook up to get notified when DocumentProperty changes. DependencyPropertyDescriptor descriptor = DependencyPropertyDescriptor.FromProperty(DocumentProperty, typeof(BindableRichTextBox)); descriptor.AddValueChanged(this, delegate { // If the underlying value of the dependency property changes, // update the underlying document, also. base.Document = (FlowDocument)GetValue(DocumentProperty); }); // By default, we support updates to the source when focus is lost (or, if the LostFocus // trigger is specified explicity. We don't support the PropertyChanged trigger right now. this.LostFocus += new RoutedEventHandler(BindableRichTextBox_LostFocus); base.OnInitialized(e); } /// <summary> /// Handles the LostFocus event of the BindableRichTextBox control. /// </summary> /// <param title="sender">The source of the event.</param> /// <param title="e">The <see cref="System.Windows.RoutedEventArgs"/> instance containing the event data.</param> void BindableRichTextBox_LostFocus(object sender, RoutedEventArgs e) { // If we have a binding that is set for LostFocus or Default (which we are specifying as default) // then update the source. Binding binding = BindingOperations.GetBinding(this, DocumentProperty); if (binding.UpdateSourceTrigger == UpdateSourceTrigger.Default || binding.UpdateSourceTrigger == UpdateSourceTrigger.LostFocus) { BindingOperations.GetBindingExpression(this, DocumentProperty).UpdateSource(); } } /// <summary> /// Gets or sets the <see cref="T:System.Windows.Documents.FlowDocument"></see> that represents the contents of the <see cref="T:System.Windows.Controls.BindableRichTextBox"></see>. /// </summary> /// <value></value> /// <returns>A <see cref="T:System.Windows.Documents.FlowDocument"></see> object that represents the contents of the <see cref="T:System.Windows.Controls.BindableRichTextBox"></see>.By default, this property is set to an empty <see cref="T:System.Windows.Documents.FlowDocument"></see>. Specifically, the empty <see cref="T:System.Windows.Documents.FlowDocument"></see> contains a single <see cref="T:System.Windows.Documents.Paragraph"></see>, which contains a single <see cref="T:System.Windows.Documents.Run"></see> which contains no text.</returns> /// <exception cref="T:System.ArgumentException">Raised if an attempt is made to set this property to a <see cref="T:System.Windows.Documents.FlowDocument"></see> that represents the contents of another <see cref="T:System.Windows.Controls.RichTextBox"></see>.</exception> /// <exception cref="T:System.ArgumentNullException">Raised if an attempt is made to set this property to null.</exception> /// <exception cref="T:System.InvalidOperationException">Raised if this property is set while a change block has been activated.</exception> public new FlowDocument Document { get { return (FlowDocument)GetValue(DocumentProperty); } set { SetValue(DocumentProperty, value); } } } Thank fro help and advice. Qucik example: Child window with .NET richTextBox <Window x:Class="WpfApplication2.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Window1" Height="300" Width="300"> <Grid> <RichTextBox Background="Green" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" FontSize="13" Margin="4,4,4,4" Grid.Row="0"/> </Grid> </Window> This window I open from parent window: var w = new Window1(); w.Show(); Then close this window, check with memory profiler and it memory doesn’t exist any object of window1 - richTextBox. It’s Ok. But then I try bindable richTextBox: Child window 2: <Window x:Class="WpfApplication2.Window2" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:Controls="clr-namespace:WpfApplication2.Controls" Title="Window2" Height="300" Width="300"> <Grid> <Controls:BindableRichTextBox Background="Red" VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Auto" FontSize="13" Margin="4,4,4,4" Grid.Row="0" /> </Grid> </Window> Open child window 2, close this child window and in memory are still alive object of this child window also bindable richTextBox object.

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  • Problems with sticky footer html css

    - by CJava
    I'm having trouble making a sticky footer, whatever I do the code completely messes up and re-arranged positioning of other elements. I'm using multiple div elements. I have tried pretty much most tutorials on stickying footers online like http://www.cssstickyfooter.com/using-sticky-footer-code.html Help would be much appreciated. Thanks a lot! html: <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta name="generator" content="HTML Tidy for Linux (vers 25 March 2009), see www.w3.org"> <title>Southend-on-Sea Independant Tourist Guide</title> <!--Attached CSS to keep constant throughout site--> <link rel="stylesheet" type="text/css" href="style.css"> <meta http-equiv="content-type" content="text/html; charset=utf-8"> <meta name="description" content="An independant tourist guide on Southend-on-Sea"> <meta name="keywords" content="southend, southend-on-sea, tourist guide, tourist, independant"> <meta name="author" content="Callum Stevens"> <link rel="shortcut icon" type="image/x-icon" href="/favicon.ico"><!--[if !IE 7]> <style type="text/css"> #wrap {display:table;height:100%} </style> <![endif]--> <link rel="stylesheet" type="text/css" href="style.css"> <link rel="stylesheet" type="text/css" href="navigation.css"> </head> <body> <div id="container"> <div id="content"> <div id="header"> <table width="200" border="0" align="center" cellpadding="0" cellspacing="0"> <tr> <td><img src="southendpiersept2006edit.jpg" width="700" height="389" alt="southend pier site logo"></td> </tr> </table> </div> <div id="navigation"> <ul> <li class="home"><a href="index.htm">Home</a></li> <li class="places"><a href="places.htm">Places to go</a></li> <li class="things"><a href="things.htm">Things to do</a></li> <li class="where"><a href="where.htm">Where to stay</a></li> <li class="getting"><a href="getting.htm">Getting&lt; here/a&gt;</a></li> <li class="about"><a href="getting.htm"></a><a href="getting.htm"></a><a href="about.htm">About the town</a></li> <li class="contact"><a href="contact.htm">Contact us</a></li> </ul> <table width="700" border="0" align="center" cellpadding="0" cellspacing="0"> <tr> <td></td> </tr> </table> </div> <br> <br> <h1>Southend-On-Sea</h1> <br> <h2>Welcome to Southend-On-Sea Tourist Information Site. You're #1 stop for finding out about Southend!</h2> <br> <h3>This site aims to help you in getting here, finding accomodation, and letting you know whats going on.</h3> <p>paragraph</p> <p id="p2">paragraph2</p> </div> </div> <div id="footer"></div> </body> </html> style.css: html, body { margin: 0px; padding: 0px; text-align:center } body{ background: url(bg.jpg) repeat-x;} #content { text-align:center width:67%; } h2 { text-transform: capitalize;} navigation.css #navigation ul { width: 700px; height: 50px; position: absolute; /** Places image at the top of the page **/ top: 389px; /** Determines the height from the top of the page **/ left: 15.3%; /** Determines the width from the left of the page **/ background: url(menu.jpg) no-repeat 0 0; list-style: none; margin: 0; padding: 0; } #navigation li { display: inline; } #navigation li a:link, #navigation li a:visited { border: none; width: 100px; height: 50px; display: block; position: absolute; top: 0; text-indent: -7000px; outline: none; } #navigation li.home a:link, #navigation li.home a:visited { left: 0; } #navigation li.places a:link, #navigation li.places a:visited { left: 100px } #navigation li.things a:link, #navigation li.things a:visited { left: 200px } #navigation li.where a:link, #navigation li.where a:visited { left: 300px } #navigation li.getting a:link, #navigation li.getting a:visited { left: 400px } #navigation li.about a:link, #navigation li.about a:visited { left: 500px } #navigation li.contact a:link, #navigation li.contact a:visited { left: 600px } #navigation li.home a:hover { background: url(menu.jpg) no-repeat 0 -50px; } #navigation li.places a:hover { background: url(menu.jpg) no-repeat -100px -50px; } #navigation li.things a:hover { background: url(menu.jpg) no-repeat -200px -50px; } #navigation li.where a:hover { background: url(menu.jpg) no-repeat -300px -50px; } #navigation li.getting a:hover { background: url(menu.jpg) no-repeat -400px -50px; } #navigation li.about a:hover { background: url(menu.jpg) no-repeat -500px -50px; } #navigation li.contact a:hover { background: url(menu.jpg) no-repeat -600px -50px; }

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  • Followup: Python 2.6, 3 abstract base class misunderstanding

    - by Aaron
    I asked a question at Python 2.6, 3 abstract base class misunderstanding. My problem was that python abstract base classes didn't work quite the way I expected them to. There was some discussion in the comments about why I would want to use ABCs at all, and Alex Martelli provided an excellent answer on why my use didn't work and how to accomplish what I wanted. Here I'd like to address why one might want to use ABCs, and show my test code implementation based on Alex's answer. tl;dr: Code after the 16th paragraph. In the discussion on the original post, statements were made along the lines that you don't need ABCs in Python, and that ABCs don't do anything and are therefore not real classes; they're merely interface definitions. An abstract base class is just a tool in your tool box. It's a design tool that's been around for many years, and a programming tool that is explicitly available in many programming languages. It can be implemented manually in languages that don't provide it. An ABC is always a real class, even when it doesn't do anything but define an interface, because specifying the interface is what an ABC does. If that was all an ABC could do, that would be enough reason to have it in your toolbox, but in Python and some other languages they can do more. The basic reason to use an ABC is when you have a number of classes that all do the same thing (have the same interface) but do it differently, and you want to guarantee that that complete interface is implemented in all objects. A user of your classes can rely on the interface being completely implemented in all classes. You can maintain this guarantee manually. Over time you may succeed. Or you might forget something. Before Python had ABCs you could guarantee it semi-manually, by throwing NotImplementedError in all the base class's interface methods; you must implement these methods in derived classes. This is only a partial solution, because you can still instantiate such a base class. A more complete solution is to use ABCs as provided in Python 2.6 and above. Template methods and other wrinkles and patterns are ideas whose implementation can be made easier with full-citizen ABCs. Another idea in the comments was that Python doesn't need ABCs (understood as a class that only defines an interface) because it has multiple inheritance. The implied reference there seems to be Java and its single inheritance. In Java you "get around" single inheritance by inheriting from one or more interfaces. Java uses the word "interface" in two ways. A "Java interface" is a class with method signatures but no implementations. The methods are the interface's "interface" in the more general, non-Java sense of the word. Yes, Python has multiple inheritance, so you don't need Java-like "interfaces" (ABCs) merely to provide sets of interface methods to a class. But that's not the only reason in software development to use ABCs. Most generally, you use an ABC to specify an interface (set of methods) that will likely be implemented differently in different derived classes, yet that all derived classes must have. Additionally, there may be no sensible default implementation for the base class to provide. Finally, even an ABC with almost no interface is still useful. We use something like it when we have multiple except clauses for a try. Many exceptions have exactly the same interface, with only two differences: the exception's string value, and the actual class of the exception. In many exception clauses we use nothing about the exception except its class to decide what to do; catching one type of exception we do one thing, and another except clause catching a different exception does another thing. According to the exception module's doc page, BaseException is not intended to be derived by any user defined exceptions. If ABCs had been a first class Python concept from the beginning, it's easy to imagine BaseException being specified as an ABC. But enough of that. Here's some 2.6 code that demonstrates how to use ABCs, and how to specify a list-like ABC. Examples are run in ipython, which I like much better than the python shell for day to day work; I only wish it was available for python3. Your basic 2.6 ABC: from abc import ABCMeta, abstractmethod class Super(): __metaclass__ = ABCMeta @abstractmethod def method1(self): pass Test it (in ipython, python shell would be similar): In [2]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods method1 Notice the end of the last line, where the TypeError exception tells us that method1 has not been implemented ("abstract methods method1"). That was the method designated as @abstractmethod in the preceding code. Create a subclass that inherits Super, implement method1 in the subclass and you're done. My problem, which caused me to ask the original question, was how to specify an ABC that itself defines a list interface. My naive solution was to make an ABC as above, and in the inheritance parentheses say (list). My assumption was that the class would still be abstract (can't instantiate it), and would be a list. That was wrong; inheriting from list made the class concrete, despite the abstract bits in the class definition. Alex suggested inheriting from collections.MutableSequence, which is abstract (and so doesn't make the class concrete) and list-like. I used collections.Sequence, which is also abstract but has a shorter interface and so was quicker to implement. First, Super derived from Sequence, with nothing extra: from abc import abstractmethod from collections import Sequence class Super(Sequence): pass Test it: In [6]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods __getitem__, __len__ We can't instantiate it. A list-like full-citizen ABC; yea! Again, notice in the last line that TypeError tells us why we can't instantiate it: __getitem__ and __len__ are abstract methods. They come from collections.Sequence. But, I want a bunch of subclasses that all act like immutable lists (which collections.Sequence essentially is), and that have their own implementations of my added interface methods. In particular, I don't want to implement my own list code, Python already did that for me. So first, let's implement the missing Sequence methods, in terms of Python's list type, so that all subclasses act as lists (Sequences). First let's see the signatures of the missing abstract methods: In [12]: help(Sequence.__getitem__) Help on method __getitem__ in module _abcoll: __getitem__(self, index) unbound _abcoll.Sequence method (END) In [14]: help(Sequence.__len__) Help on method __len__ in module _abcoll: __len__(self) unbound _abcoll.Sequence method (END) __getitem__ takes an index, and __len__ takes nothing. And the implementation (so far) is: from abc import abstractmethod from collections import Sequence class Super(Sequence): # Gives us a list member for ABC methods to use. def __init__(self): self._list = [] # Abstract method in Sequence, implemented in terms of list. def __getitem__(self, index): return self._list.__getitem__(index) # Abstract method in Sequence, implemented in terms of list. def __len__(self): return self._list.__len__() # Not required. Makes printing behave like a list. def __repr__(self): return self._list.__repr__() Test it: In [34]: a = Super() In [35]: a Out[35]: [] In [36]: print a [] In [37]: len(a) Out[37]: 0 In [38]: a[0] --------------------------------------------------------------------------- IndexError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() /home/aaron/projects/test/test.py in __getitem__(self, index) 10 # Abstract method in Sequence, implemented in terms of list. 11 def __getitem__(self, index): ---> 12 return self._list.__getitem__(index) 13 14 # Abstract method in Sequence, implemented in terms of list. IndexError: list index out of range Just like a list. It's not abstract (for the moment) because we implemented both of Sequence's abstract methods. Now I want to add my bit of interface, which will be abstract in Super and therefore required to implement in any subclasses. And we'll cut to the chase and add subclasses that inherit from our ABC Super. from abc import abstractmethod from collections import Sequence class Super(Sequence): # Gives us a list member for ABC methods to use. def __init__(self): self._list = [] # Abstract method in Sequence, implemented in terms of list. def __getitem__(self, index): return self._list.__getitem__(index) # Abstract method in Sequence, implemented in terms of list. def __len__(self): return self._list.__len__() # Not required. Makes printing behave like a list. def __repr__(self): return self._list.__repr__() @abstractmethod def method1(): pass class Sub0(Super): pass class Sub1(Super): def __init__(self): self._list = [1, 2, 3] def method1(self): return [x**2 for x in self._list] def method2(self): return [x/2.0 for x in self._list] class Sub2(Super): def __init__(self): self._list = [10, 20, 30, 40] def method1(self): return [x+2 for x in self._list] We've added a new abstract method to Super, method1. This makes Super abstract again. A new class Sub0 which inherits from Super but does not implement method1, so it's also an ABC. Two new classes Sub1 and Sub2, which both inherit from Super. They both implement method1 from Super, so they're not abstract. Both implementations of method1 are different. Sub1 and Sub2 also both initialize themselves differently; in real life they might initialize themselves wildly differently. So you have two subclasses which both "is a" Super (they both implement Super's required interface) although their implementations are different. Also remember that Super, although an ABC, provides four non-abstract methods. So Super provides two things to subclasses: an implementation of collections.Sequence, and an additional abstract interface (the one abstract method) that subclasses must implement. Also, class Sub1 implements an additional method, method2, which is not part of Super's interface. Sub1 "is a" Super, but it also has additional capabilities. Test it: In [52]: a = Super() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Super with abstract methods method1 In [53]: a = Sub0() --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: Can't instantiate abstract class Sub0 with abstract methods method1 In [54]: a = Sub1() In [55]: a Out[55]: [1, 2, 3] In [56]: b = Sub2() In [57]: b Out[57]: [10, 20, 30, 40] In [58]: print a, b [1, 2, 3] [10, 20, 30, 40] In [59]: a, b Out[59]: ([1, 2, 3], [10, 20, 30, 40]) In [60]: a.method1() Out[60]: [1, 4, 9] In [61]: b.method1() Out[61]: [12, 22, 32, 42] In [62]: a.method2() Out[62]: [0.5, 1.0, 1.5] [63]: a[:2] Out[63]: [1, 2] In [64]: a[0] = 5 --------------------------------------------------------------------------- TypeError Traceback (most recent call last) /home/aaron/projects/test/<ipython console> in <module>() TypeError: 'Sub1' object does not support item assignment Super and Sub0 are abstract and can't be instantiated (lines 52 and 53). Sub1 and Sub2 are concrete and have an immutable Sequence interface (54 through 59). Sub1 and Sub2 are instantiated differently, and their method1 implementations are different (60, 61). Sub1 includes an additional method2, beyond what's required by Super (62). Any concrete Super acts like a list/Sequence (63). A collections.Sequence is immutable (64). Finally, a wart: In [65]: a._list Out[65]: [1, 2, 3] In [66]: a._list = [] In [67]: a Out[67]: [] Super._list is spelled with a single underscore. Double underscore would have protected it from this last bit, but would have broken the implementation of methods in subclasses. Not sure why; I think because double underscore is private, and private means private. So ultimately this whole scheme relies on a gentleman's agreement not to reach in and muck with Super._list directly, as in line 65 above. Would love to know if there's a safer way to do that.

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