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<h1><a href=".">meandering<img src="./theme/images/logo.png"/>journey</a></h1>
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title="Permalink to The pyKonsole distraction">The pyKonsole distraction</a></h2>
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Published on <abbr class="published" title="2010-11-08T22:24:00"> Mon 08 November 2010 </abbr> under
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<p>I use KDE 4. One of my workspaces is configured with a "dashboard" activity, displaying all the usual monitoring widgets (CPU, RAM, network, temperatures). When my notebook starts acting slow, I hop over to the dashboard to check out my CPU load. If it's high I whip out Konsole and launch <strong>htop</strong> to find the culprit. It has occurred to me that it would really be nice if I could see the CPU hog right away.</p>
<p>I realized there must be a process-monitor plasmoid out there but a Konsole widget seemed so much more flexible. Plasmacon seemed to fit the bill and I had it on the desktop in next to no time. It turned out, however, that it has no facility to launch a command at start-up. I figured it should be easy to extend the widget as it's written in Python. Checking the documentation for Konsole's KPart turned up two promising methods: <strong>sendInput()</strong> and <strong>startProgram()</strong>. Neither of them worked.</p>
<p>I inserted some trace code into Plasmacon's init method and it turned out that the object Plasmacon creates is just a plain <strong>KParts::ReadOnlyPart</strong>. Browsing PyKDE documentation brought the answer: PyKDE doesn't include a binding for kdebase-apps. The upshot is that you can create a <strong>Konsole::Part</strong> instance from Python but you can't access its full API.</p>
<p>Things didn't look so trivial anymore but I decided to have a go at creating the necessary bindings. PyKDE uses a generator called SIP (<strong>apt-get install python-sip</strong> in Debian) to create Python modules from C++ headers and deceptively simple spec files. I tried to write a SIP spec for Konsole starting from <strong>Konsole::Part</strong>'s header file and various <strong>.sip</strong> files I dug up. I have to say SIP provides rather modest feedback. I ended up stuck with a terse "syntax error" message providing no detail at all.</p>
<p>I noticed a little comment in one of the <strong>.sip</strong> files, saying "Generated by twine". Googling for twine proved to be quite a challenge; this is really obscure code used primarily by PyKDE creators and few others. There is no website nor documentation. Another comment in a <strong>.sip</strong> file provided the decisive clue: a mention of "twine2". It brought me to <a href="http://gitorious.org/twine2">http://gitorious.org/twine2</a> where the tool currently seems to live. And yes, it's a generator of input for a generator. Go figure...</p>
<p>Writing a twine2 script seemed quite daunting but I came up with an entirely different approach: what if I could talk to the Konsole via DBus? I quickly discovered <strong>qdbusviewer</strong> and clicked around to see what I could do. Unfortunately, while the <strong>org.kde.plasma-desktop</strong> service does expose a <strong>/Konsole</strong> object, it doesn't provide its Sessions. Some could be found under <strong>org.kde.konsole</strong> but they included strictly sessions in proper Konsole windows; the one in the Plasma widget didn't show up in the list. I had to go back to twine2.</p>
<p>Except I didn't. The ability to delve into the guts of open source software is one of its most useful aspects but there is a limit to how far down the rabbit hole one can reasonably afford to go. I've reached that limit and had to accept that, for the foreseeable future, I will simply not have a process monitor on my dashboard. Worse things have happened.</p>
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