About the series: perlancar's 2014 Advent Calendar: Introduction to a selection of 24 modules which I published in 2014. Table of contents.
Any Unix user probably knows about the uniq command, most often used in combination with sort. For example, to get distinct lines from a file:
% sort somefile.txt | uniq
sort is usually needed because uniq can only skip non-unique adjacent lines. In other words, it does not keep a memory of past lines. This probably has to do with most traditional Unix utilities created in a decade where memory was very scarce (think of an age where the saying "640K ought to be enough for everybody" was considered a truism).
If you want to print distinct lines from a file but keeping the original order, it is surprisingly cumbersome to do using standard Unix utilities. That's why I wrote nauniq (distributed in App-nauniq). With this utility, you can simply do:
In many contexts, programs need to identify
non-overlapping pieces of a text.
One very direct way to do this
is to use a pair of delimiters.
One delimiter of the pair marks the start
and the other marks the end.
Delimiters can take many forms:
Quote marks, parentheses, curly braces, square brackets,
XML tags, and HTML tags
are all delimiters in this sense.
Mismatching delimiters is easy to do.
Traditional parsers are often poor at reporting these errors:
hopeless after the first mismatch,
and for that matter none too precise about the first one.
This post outlines a scaleable method for the accurate
reporting of mismatched delimiters.
I will illustrate the method with a simple
but useable tool --
a utility which reports mismatched brackets.
I took some time today to prepare a number of pull requests by MOREGAN for release, and the tarball for 1.219_001 is now on CPAN. Please test it and let me know if you run into problems with your module. Most of the changes simply improve parsing, but the ->prototype changes might break things if you relied on the previously broken behavior.
If no problems crop up, this will be released as 1.220 on tuesday, 2014-11-11.
I am not picky about which way it is sent to me, but feedback is best provided here: Github Issue #92
The changes in this release are:
Summary:
incompatible behavior fixes on PPI::Statement::Sub->prototype
About the series: perlancar's 2014 Advent Calendar: Introduction to a selection of 24 modules which I published in 2014. Table of contents.
jpath (from App-jpath distribution) is a simple command-line interface wrapper for JSON::Path written by TOBYINK. With the provided jpath utility you can quickly select and transform some branch/node of a data structure. As a bonus, jpath also accepts/outputs Perl and YAML in addition to JSON.
A quick primer on JSON Path: $. to get everything as is, $.keyname to get hash value by key, $.[12] to get array element by index, $.[1,2,3] to get several elements (union), $.[*] to get all array elements, ?(...) to apply a filter (the Perl variant has some syntax modification for the filter). There are a few other constructs provided, please see the linked JSON Path page.
I was looking through the code of the Rakudo implementation of Perl6 where I noticed that it defines pi as my constant pi = 3.14159_26535_89793_238e0; ( with an alias my constant π := pi; )
I immediately remembered that for a subset of fractional numbers Perl6 has a type that stores them without the loss of precision that generally accompanies floating point math. That type is of course the Rat (and FatRat) type. So of course I type pi.Rat into the REPL, it then prints 3.141593 which is obviously nowhere near as precise as the result of just typing pi into the REPL 3.14159265358979.
I wanted to see the numerator and denominator values that Perl chose to use so I typed pi.Rat.perl and got <355/113>, which is nowhere near as precise as the Rat type is capable of handling. That was just the entrance to the rabbit hole.
I am in the process of authoring a talk for Sydney PM as an intro to HTML::FormFu (via Catalyst). The draft of which follows, to which I would welcome feedback and suggestions.
HTML::FormFu
Efficient web forms.
So you can leave at 5pm each day.
Web frameworks like Catalyst, Mojolicious & Dancer take care of repetitive things in web app development such as:
Connecting your code to an environment (mod_perl1/2, cgi, fast_cgi, nginx_perl etc. ok * Plack does a lot of this)
Mapping uri requests to code
Authentication
Authorization
Sessions
Connecting to databases & ORM's
Serialization/Deserialization (JSON, XML etc)
Templating (built on TT, Alloy etc)
Logging/Debugging levels
SiteMaps, Caching, Browser detection
Code Bootstrappers
Whats missing is form generation and validation.
It's very rare not to have form's in any software - business applications have lots of them.
They are very boring and repetitive, prone to mistakes and bugs as a result.
Data types are frequenly the same things: names, addresses, emails, phone numbers, etc.
01:41 < zzzzzzzzzz> Is there no site that gives a current status of Perl6 work
that a non-guru could follow?
01:42 < zzzzzzzzzz> Most of the hits under
https://duckduckgo.com/?q=current+state+of+Perl6 are ca.
2010 and even http://perl6.org/compilers/features is close
to two months old.
...
01:47 < zzzzzzzzzz> That's the impression I get but I have a hard
time getting much farther than that. For example, "what
exactly do I download to start learning, and why those bits
instead of other bits?"
...
01:52 < zzzzzzzzzz> Whichever. A site that took a snapshot of the state every
quarter or two would make it a lot easier for relative
noobs to get up to speed and start learning things.
This is a feeling I've shared for a while. Working out where Perl 6 is takes a bit of archeology, trying to figure out what the Compiler Feature matrix means.
Anyway, I've taken a stab at trying to create a very short, simple, regularly updated set of answers: http://perl6.guide/, hopefully accessible to Perl 5 developers and random other developers. It's on Github (there's a link in there), so if you think I've gotten something wrong, or want to update it, please send me a pull request.
This month has been quite a busy one for me, so I haven't had much chance to work on my (in-progress) book. However, I have had some time to start work on a short talk for London Perl Workshop 2014 which will cover some of the OO best practices followed in the book. (At the time of writing, I've not yet heard whether the talk has been accepted/scheduled.)
A week ago I mentioned that I've started to create a clone of search.cpan.org using the MetaCPAN API as back-end. I've also promised to record a series of screencasts explaining the process. Something, that can be very useful if you need to rewrite an application and you can't read the source-code.
My adventure in shell tab completion continues. (A bit of background: I got interested in tab completion around two years ago when I realized that it is a significant UX element, if not one of the most important ones, in a CLI environment. Since then I've created, among other things, acoupleof command-line frameworks that make it easy to do custom tab completion in Perl, as well as a bunch of modules in Complete::* namespace for generic completion which can be used in other environments like GUI and web).
This week, I added tab completion support to my frameworks for several other shells other than bash: tcsh, zsh, and fish. This blog is an observation of the different ways of doing programmable tab completion in those shells, especially from the viewpoint of a programmer who wants to do it using Perl (or other programming languages) instead of using built-in shell functions.
So myself and I think most of the Perl world missed an important date on October 12th
Well that day marked the first release of DBI to CPAN.
It is hard to judge how much an impact this hunk of code has had on dare I say it the world. IMHO it was the first killer app for the web and still with us today being actively developed and improved on and has kept its place just quietly sitting in the background doing its job.
If I sit back and think of 20 years ago I had just upgraded to a 12k modem from a 1.2k, browsed the internet, (If you could call it that) with text browser, Netscape was only release 1 day later, (By the way it too me 19+ hours to download it) a few week later one used something call web-crawler
Boilerplate is everything I hate about programming:
Doing the same thing more than once
Leaving clutter in every file
Making it harder to change things in the future
Eventually blindly copying without understanding (cargo-cult programming)
In an effort to reduce some of my boilerplate, I wrote
Import::Base a module to collect and
import useful bundles of modules, removing the need for long lists of use ...
lines everywhere.
Just finished up week #1 of the TPF Grant for Inline Modules with DAVIDO++. We've been having a blast, making great progress, all while trying to push the boundaries of open/public/televised/pair/perl programming!
Here's our weekly status report (using our new homemade blogging system (thinking about you, Tony Bowden!)): http://inline.ouistreet.com/
We'll be writing up a report each Saturday, just in time for Gabor's http://perlweekly.com/
Stop by #inline on irc.perl.org and say HAI, if you are so inclined.
I have started to write an open source clone of search.cpan.org. In case you are interested, see more details and links in that article. It is currently hosted here. The front-page is already there, but of course most of the parts don't work yet.
Unfortunately I have managed to release strawberry-perl-5.20.1.1-32bit.msi and strawberry-perl-5.20.1.1-64bit.msi files with wrong MSI signature. The installer will very likely complain about revoked certificate (although I do not know why my laptop have not complained when I tested these MSI).
I am sorry for any inconvenience this might caused you.
The trouble is that although I have sent scanned copy of my passport to Certum CA approx. a year ago they claim that they do not have it. Unfortunately the reminder they sent me was probably "swallowed" by cpan.org's spam filter and they simply revoked my certificate. I have submitted a new request for code signing certificate, unfortunately cpan.org's spam filter struck again and block an e-mail with verification URL I have to click on.
I am tired of dealing with Certum CA and I am fed up with cpan.org's spam filter, therefore I am considering to stop signing MSI packages.
It's been over a week now since the Austrian Perl Workshop of 2014. It took place in Salzburg for the second consecutive year. On Thursday, the day before the conference started, Mozart's home town greeted the attendants with glorious summer weather and amazing 26 degrees Celsius.
