lcpan tips 023: What’s new (including whatsnew)

About this series: A collection of short blog posts about lcpan tips/recipes. Some posts will also end up in the upcoming App::lcpan::Manual::Cookbook POD to be included in the App::lcpan distribution. First article is here. See the whole series.

About lcpan: an application to download and index a mini CPAN mirror on your local filesystem, so in effect you will have something like your own CPAN with a command-line tool (or perl API) to query and extract information from your mirror.

The previous tip was posted in January 2019. I thought I'd post a status update of what has been added to lcpan since then.

New subcommands

As usual, a bunch of subcommands have been added, most of them for convenience, can be composed from existing subcommands, and not that groundbreaking. For example, the extract-dist subcommands extracts a distro tarball. lcpan already has extract-mod, but sometimes we want to specify a distro name instead of a module. This could almost as easily be expressed using lcpan extract-mod and lcpan dist-mods:

% lcpan extract-dist libwww-perl

can also be written as:

% lcpan extract-mod `lcpan dist-mods libwww-perl | head -n1`

Or, the author, dist, module, release, script subcommands accompany the existing plural versions authors et al to retrieve only a single entity with an exact name search.

The following subcommands have also added: rdeps-scripts, dist-rdeps, heaviest-dists, most-depended-authors, most-mentioned-mods, most-mentioned-scripts, and whatsnew (more on this one below).

Recording of creation and last modification times

One of the most important new features is that lcpan now stores creation time and last modification time of most entities, like authors, modules, dependencies, as well as mentions. Everytime you update the index using lcpan update, when a database record is added or updated, the rec_ctime and rec_mtime columns are set respectively. This means you can query whether a distribution, or author, or dependency is new or recently added. Along with this, many subcommands now sport the filtering options like –added-since, –updated-since, –added-or-updated-since, or the more convenient options like –added-since-last-index-update or –update-since-last-n-index-updates.

For example, to see what modules are added in the last index update:

% lcpan mods -l --added-since-last-index-update

Or, to see what authors are added or updated after Jun 1, 2020 (assuming this year is 2020):

% lcpan authors -l --added-or-updated-since 'jun 1'

Of course, the creation and update times are based on the time you perform lcpan update, since PAUSE itself does not record creation/modification times on the CPAN index files. So if your local CPAN index is only created from scratch today, everything will be new.

Whatsnew

One new subcommand is particularly convenient: whatsnew. It will display modules, distributions, and authors that are recently added/updated, by default since the last index update. And if you specify the –my-author option, or put it in your lcpan.conf:

[subcommand=whatsnew]
my_author=PERLANCAR

then whatsnew will also display new reverse dependencies and new mentions to one of your modules. The output is in the form of Org document, which you can view as-is using a pager, or view using Emacs, directly from the command-line:

% lcpan whatsnew --pager
% lcpan whatsnew --view

There's a demo video for this.

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