I’m currently trying to teach Unladen to recompile functions. This turned out to be more complicated than I anticipated.

There is one especially obscure ‘bug’. Enabling recompilation makes the subprocess module tests hang, but only if it is executed after the pickle tests. The hanging test tries to start a none-existent program around 2000 times. The subprocess module forks and tries to exec the command in the child process. If an exception occurs, it is pickled and send back to the parent via pipes.

Executing the pickle tests makes two functions considered hot and some command in the child process triggers a recompilation of these two functions.

Apparently the invocation of the JIT leads to a lot of memory being duplicated, which slows down the child process considerably.  Ugh.

Eagerly I updated from the release PPA, but what did I know back than. First thing I noticed was the half done translation. German technical terms just suck.

More importantly they broke the zeroconf module. As most of my hg pulls are within my network, this is pretty serious for me. A fix is already committed, but not yet released. So back to 1.1.2 for me, as I like my VCS stable.

The result was a nice little program which can compile simple functional programs into python bytecode!

The only thing you need is the ply parser generator. To compile a function just use:

import topcompiler

@topcompile.compile
def func(x, y):
    """let i = x*x in y*i"""
    pass # Compiles the docstring into a function

func(2, 3) == 12

Update:

TOPCompiler now also understands recursive definitions!

@topcompiler.compile
def fac(x):
    """
    let rec fac = fun i ->
    if i > 1 then
        fac (i-1)*i
    else
        1
    in fac x
    """
    pass

There is a working quicksort in tests.py.

Check out the code at http://bitbucket.org/ebo/pyvm!

@expose()
def xmlrpc(self, *args, **kw):
    return forward(XMLRPCServiceController())

class ValidateMixin(object):
    def validate(self, params, state=None):
        """A pass-thru to the widget's validate function."""
        return self.__widget__.validate(params, state)

It can be used with any Formbase class. Just inherit from ValidateMixin first:

class PostEditForm(ValidateMixin, EditableForm):
    pass

This works until a new version of Sprox is released and should continue to do so afterwards, even if it can be removed than.

So I wrote a quick extension myself: hggnome-keyring

It uses the usual yadda yadda for installing (see mercurial docs). Only drawback: Access to the keyring is determined by executable name, so any python programm is allowed to access those keys

There are two first in this post:

1. I used bitbucket.org to host the repo. It’s quite nice and very free.
2. This post is relayed to my twitter account.

repair.4geeks.de

Wie jeder der sich irgendwie mit Computern beschäftigt, habe auch ich meinen Ruf weg. Das hat zur Folge, dass ich genötigt werden Computer von Freunden und Bekannten zu reparieren. Irgendwann kam mir der Gedanke, meine Erlebnisse in wiederverwertbare Form zu gießen. Erste Versuche mit Pyke waren zwar vielversprechend, leider war die Bibliothek nicht komplett kompatibel mit meinem Ansatz: Erstens kann man Regeln nur aus Dateien lesen und zweitens hatte ich Zweifel daran, dass ich einen Zustand ordentlich serialisieren kann wärend eine Frage beantwortet wird.

Kurzerhand habe ich mir meine eigene Inference Engine geschrieben. Dazu noch ein paar Regeln einfügen und fertig war RepairExpert.

Ich hoffe, im Laufe der Zeit noch mehr Probleme und Lösungen einzufügen, aber leider muss das erstmal vor meiner Diplomarbeit zurückstehen.

To save you searching for yourself:

options = {'form_name' : {'attrs' : {'value':'your_value'}}}

Later in the template to show your form:

${tmpl_context.form(child_args=options)}

It’s written in Python (first big plus) and for the amount of code it’s really awesome. It features distributed source control, fast commits and a really nice web interface. There is also a Tortoise-’Version’ for it (unlike git).

Only big negative point: Its hard to control who pushes to a central repository. Of course thats a bit hard in a distributed rcs, but there is no way to include which http or ssh user pushed the changes.

But I’m still looking for solutions

Lets first have a look in the swig documentation:

SWIG provides full support for function pointers provided that the callback functions are defined in C and not in the target language.

That’s unfortunate. Further research revealed that there is indeed a (rather hackish) way to manage that.

First we define a function for setting the a callback:

void setCallback(PyObject* obj) ;

Now SWIG expects a wrapped PyObject-object, which we don’t have. That behavior can be overwritten be defining a custom typemap. The easiest possible solution would be:

%typemap(in) PyObject* {
$1 = $input;
}

All you have to do now is to check the object in your previously defined function and grab a reference to it. Read the Python documentation on how to do that.

Overall rating: Working, but not very portable.