Why graphical libraries as dependencies to console client?

[Behinder (behinder)]

I wanted to install again PianoBar which is CLI client for Pandora Music. But I got such dependency info before install:

Xft2 XviD cairo ffmpeg fontconfig freetype fribidi gd2 gdk-pixbuf2 giflib gobject-introspection graphite2 graphviz gts harfbuzz jasper jbigkit jpeg json-c lame lcms2 libLASi libao libass libbluray libcroco libgcrypt libmodplug libnetpbm libogg libopus libpiano libpixman libpng librsvg libsdl2 libtheora libvorbis libvpx openjpeg ossp-uuid pango perl5.26 py27-beaker py27-funcsigs py27-mako py27-markupsafe py27-setuptools shared-mime-info soxr speex tiff urw-fonts vala webp x264 x265 xorg-libX11 xorg-libXau xorg-libXaw xorg-libXdmcp xorg-libXext xorg-libXmu xorg-libXt xorg-libice xorg-libpthread-stubs xorg-libsm xorg-libxcb xorg-xcb-proto xorg-xcb-util xorg-xorgproto xpm xrender

what the hell PERL is doing in app that essentialy streaming audio? I can understand all the codecs library, but why Xorg-libX11? Terminal is terminal there is nothing to to with Windows! Could someone contact developer and ask about explanations? Overall it looks very cluttered.

[ryandesign (Ryan Carsten Schmidt)]

I understand your frustration and your initial impression that a simple command-line program like pianobar shouldn't have this many dependencies, or dependencies on software that performs functions that don't appear to be required.

Pianobar's direct library dependencies (see port deps pianobar) are curl, ffmpeg, libao, libgcrypt, and json-c (and libpiano, pianobar's own library)—pianobar uses functions from those libraries directly—but each of those has additional dependencies, and so on.

There are different ways one can approach installing a program like pianobar. If you care only about pianobar, then you would probably install the minimum of dependencies needed to run pianobar, and where those dependencies have optional features, you would enable only those features that pianobar would use.

That's not the approach MacPorts takes, because we have to care about all of the software we offer, not just pianobar. And where a program or library offers optional features, we err on the side of enabling more features, even if not all users or programs or libraries will need them, for the benefit of those that do.

For example, curl has optional support for internationalized domain names. Pianobar doesn't need this, but a user using curl might, so we enable IDN support; this causes a few additional libraries to be installed.

As another example, ffmpeg is an audio/video conversion and download library, which pianobar uses to get the audio data from Pandora. Pianobar doesn't need ffmpeg's video conversion functionality, but a user or another port the user installs might, so we enable it, hence the video codecs and their dependencies. ffmpeg also has support for SVG files, which we enable, via a dependency on librsvg. librsvg has many dependencies of its own, including on the pango text library and the cairo graphics library, both of which have optional X11 support which we enable by default, hence the X11 dependencies. cairo depends on fontconfig, which depends on ossp-uuid, which has optional perl bindings which we enable by default, hence the dependency on perl.

I hope this clarifies why the dependencies are there. The upshot is that even if you don't need all of this functionality for pianobar, it's there if you should need it for other ports you install. I see that curl and its dependencies weren't in your list of dependencies above, presumably because they were already installed for you when you previously requested them or another port that uses them, so you can see that the more ports you install and manage with MacPorts, the more they can share their dependencies.

A couple days ago I installed pianobar onto a computer with a fresh MacPorts installation and no ports installed. Despite the number of dependencies, it only took a few minutes, since we offer precompiled binaries for a large number of our ports. So hopefully installing all these dependencies will not be too inconvenient.

In some cases, we offer variants for enabling or disabling functionality. Using port variants ossp-uuid you can see that it has a "perl5_26" variant which is on by default; you can disable it with sudo port install ossp-uuid -perl5_26 to avoid the perl dependency. fontconfig doesn't need ossp-uuid's perl bindings, but other ports might, so doing this would break those other ports, were you to install them. And perl is a very popular scripting language, which many ports use either in their build systems or at runtime, so you will most likely encounter other situations where MacPorts will install perl for you; the same can be said for python.

For ports that have optional X11 functionality, we usually put it in a variant called "x11" and enable it by default. Many of these ports have an alternative variant "quartz" for using macOS-native graphics instead of X11. If you wish to use this, you can add +quartz and -x11 to /opt/local/etc/macports/variants.conf but if you do this it is recommended that you uninstall all ports and then reinstall the ones you want, so that all ports get built with this choice.

Note that we only build binaries of each port for its default set of variants, so even though disabling a variant might remove some dependencies, it might take longer to build the port from source than it would have to download the binaries. Also, building a port from source could also pull in additional build dependencies. So if your goal in changing a port's variants is to shorten installation time, it might not actually do that.

If you have other questions about how MacPorts works or why it does what it does, the macports-users mailing list is a better place to ask those questions. The Trac issue tracker is for bug reports and feature requests.