Just a quick update: Andy Lester read the original Combining ack-grep and xargs post and was so kind to point out a much better way to ignore unwanted files while searching i.e.
$ ack-grep --python --ignore-dir=tests/ -C 3 -w 'Message\('
as opposed to
$ find . -name \*.py | grep -v tests/ | xargs ack-grep -C 3 -w 'Message\('
Recently I started playing with Groovy, a dynamic language that — according to the first chapter of the Groovy in Action book — is Python-inspired.
One of the reasons why I find Groovy attractive is that it can be compiled to Java byte code (despite being a dynamic language) i.e. you gain access to all the Java libraries and the capability to deploy on the Java platform without actually having to write Java code.
Groovy is even supported by the Spring Framework. So, if you’re “forced” to work in a Java project in order to make a living but would rather be using a dynamic language then Groovy is definitely worth a look.
Some time ago I wrote a small tool (using Python) that manages my audiocasts. Based on the RSS feeds I am interested in it synchronises
It is also cognizant of the date of an audiocast and will only consider MP3 files that were published on a particular channel N days ago.
I thought building a similar tool in Groovy would be a nice exercise and a good way to get to know the language.
I started playing with the code that parses the RSS (XML) files first and was pleasantly surprised how quickly I was able to get my hands on the data required.
For an example of how an RSS file looks like see e.g. the MacBreak’s weekly RSS file. In essence the top level tag is <channel> with a number of embedded <item> tags. Each item is an audiocast and the data I needed for my purpose is as follows:
<title> tag)<pubDate> tag)<link> tag)Depending on the publisher the format of the RSS file may vary slightly. The publication date is e.g. sometimes buried in a <dc:date> tag (where dc is an XML name space pointing to http://purl.org/dc/elements/1.1/).
Likewise, the MP3 file URL is sometimes not contained in a <link> tag but in the url attribute of the <enclosure> tag.
The RSS files on my system are here:
1 bbox33:audiocasts $ pwd 2 /Users/mhr/dl/audio/audiocasts 3 bbox33:audiocasts $ find . -type f -name \\*.rss 4 ./metadata/Cc_zwei.rss 5 ./metadata/Elrep.rss 6 ./metadata/Security_now_.rss 7 ./metadata/Technometria.rss 8 ./metadata/This_week_in_tech.rss 9 ./metadata/Windows_weekly.rss
The Groovy code that finds the RSS files listed above and parses them is as follows:
1 def audioDir = new File("/Users/mhr/dl/audio/audiocasts") 2 3 // initialise RSS files list 4 files = [] 5 // find RSS files underneath 'audioDir' 6 audioDir.eachFileRecurse { if (it =~ /.*\.(xml|rss)$/) { files << it } } 7 8 println("\\\n-------- RSS files --------") 9 println files.join('\\\n') 10 11 // iterate over RSS files found 12 for (rssf in files) { 13 println("\\\n-------- $rssf --------") 14 // parse the RSS file 15 def d = new XmlSlurper().parse(rssf) 16 d.declareNamespace(dc:"http://purl.org/dc/elements/1.1/") 17 18 // iterate over item tags in RSS file (take only the first two) 19 d.channel.item[0..1].each { 20 println "==> ${it.title}" 21 if (it.pubDate.toString().trim()) { 22 println "pubDate: ${it.pubDate}" 23 } else { 24 println "dc:date: ${it.'dc:date'}" 25 } 26 if (it.link.toString().trim()) { 27 println "link: ${it.link}" 28 } else { 29 println "url: ${it.enclosure.@url}" 30 } 31 } 32 }
Here’s the output generated by the code above:
1 bbox33:groovy $ groovy xml.groovy 2 3 -------- RSS files -------- 4 /Users/mhr/dl/audio/audiocasts/metadata/Cc_zwei.rss 5 /Users/mhr/dl/audio/audiocasts/metadata/Elrep.rss 6 /Users/mhr/dl/audio/audiocasts/metadata/Security_now_.rss 7 /Users/mhr/dl/audio/audiocasts/metadata/Technometria.rss 8 /Users/mhr/dl/audio/audiocasts/metadata/This_week_in_tech.rss 9 /Users/mhr/dl/audio/audiocasts/metadata/Windows_weekly.rss 10 11 -------- /Users/mhr/dl/audio/audiocasts/metadata/Cc_zwei.rss -------- 12 ==> CC2 - 62. Folge 13 pubDate: Mon, 13 Aug 2007 20:00:00 +0200 +0200 14 url: http://www.media01-live.de/CC-Zwei-62.mp3 15 ==> CC2 - 61. Folge 16 pubDate: Mon, 06 Aug 2007 20:00:00 +0200 +0200 17 url: http://www.media01-live.de/CC-Zwei-61.mp3 18 19 -------- /Users/mhr/dl/audio/audiocasts/metadata/Elrep.rss -------- 20 ==> 36: Lutz Schmitt ^_ber Machinima 21 dc:date: 2007-08-05T21:30:00+01:00 22 link: http://www.elektrischer-reporter.de/index.php/site/film/48/ 23 ==> 35: Peter Schaar ^_ber Vorratsdatenspeicherung und Online-Durchsuchungen 24 dc:date: 2007-07-22T21:30:00+01:00 25 link: http://www.elektrischer-reporter.de/index.php/site/film/47/ 26 27 -------- /Users/mhr/dl/audio/audiocasts/metadata/Security_now_.rss -------- 28 ==> Security Now 104: SteveOs Questions, Your Answers 22 - sponsored by Astaro Corp. 29 pubDate: Thu, 09 Aug 2007 08:22:49 -0700 30 link: http://www.podtrac.com/pts/redirect.mp3/aolradio.podcast.aol.com/sn/SN-104.mp3 31 ==> Security Now 103: Paypal Security Key - sponsored by Astaro Corp. 32 pubDate: Thu, 02 Aug 2007 15:17:58 -0700 33 link: http://www.podtrac.com/pts/redirect.mp3/aolradio.podcast.aol.com/sn/SN-103.mp3 34 35 -------- /Users/mhr/dl/audio/audiocasts/metadata/Technometria.rss -------- 36 ==> Scott Lemon, Ben Galbraith - Technometria 37 pubDate: Tue, 14 Aug 2007 00:00:00 CDT 38 link: http://www.itconversations.com/shows/detail1892.html 39 ==> Drew Major - Technometria 40 pubDate: Tue, 7 Aug 2007 00:00:00 CDT 41 link: http://www.itconversations.com/shows/detail1886.html 42 43 -------- /Users/mhr/dl/audio/audiocasts/metadata/This_week_in_tech.rss -------- 44 ==> TWiT 109: The Numinous From The Quotidian 45 pubDate: Sun, 12 Aug 2007 22:39:47 -0700 46 link: http://www.podtrac.com/pts/redirect.mp3/aolradio.podcast.aol.com/twit/TWiT0109H.mp3 47 ==> TWiT 108: The Crash of 2007 48 pubDate: Sun, 05 Aug 2007 20:48:59 -0700 49 link: http://www.podtrac.com/pts/redirect.mp3/aolradio.podcast.aol.com/twit/TWiT0108H.mp3 50 51 -------- /Users/mhr/dl/audio/audiocasts/metadata/Windows_weekly.rss -------- 52 ==> Windows Weekly 32: Neener Neener Neener 53 pubDate: Fri, 27 Jul 2007 18:49:31 -0700 54 link: http://www.podtrac.com/pts/redirect.mp3/twit.cachefly.net/WW-032.mp3 55 ==> Windows Weekly 31: Computing In The Clouds 56 pubDate: Fri, 20 Jul 2007 08:57:52 -0700 57 link: http://www.podtrac.com/pts/redirect.mp3/twit.cachefly.net/WW-031.mp3
I have not written any substantial code in Groovy yet but my first impressions of the language are favourable. Groovy should be an interesting addition to your arsenal (particularly if you know the Java libraries fairly well).
