The Design

This week, Michael came up with the idea to write a blog about my work. Please start reading it from the beginning. The Blog should contain the progress of my work. It is also meant to simplify the communication with new contributors, me and interested experts.

We put much effort on improving the design and we made great progress. Currently, the design is the follwing (I hope, we can keep that).

citable.py
Contains all the meta-class-magic: CitationBase provides some basic functions, LoadableCitation can load the bib-file using pybtex, if the citation is needed. Then, it will change the class (!) of the element to Citation, which can print the citation using pybtex. We get a cache for free.
The class Citable: all classes representing cit-able elements in sage (citables.py) inherit from this class. They all have the (meta-)class LoadableCitation, when they are created. They can specify a type (default: software) and a filename to the bib-file (if it differs from the class' name).

citables.py

from citable import Citable

class singular(Citable):
    pass

class magma(Citable):
    pass

class slimgb(singular)
    pass

Note, that the code only holds the dependencies of citations, the rest is done automatically. (There are more examples below.)

citation.pyx
A cython-file containing the "ugly stuff". You can decorate your own function with @use_citation(citable). If the function is called, the citation will be added to the set of used citations. You can also manually add to this set by calling used_citations(citable). If you want to get all the used citations, simply call: print used_citations and it will give you back all you need (for this sage-session).
You can also refer to all formats supported by pybtex (bibtex, bibtexml, bibyaml, latex, html, plaintext) by calling used_citations.print_all(format).

>>> @use_citation(citables.magma)
... def simple_func():
...     pass
>>> print used_citations
None
>>> simple_func()
>>> print used_citations
@article{
    MR1484478,
    author = "Bosma, Wieb and Cannon, John and Playoust, Catherine",
    volume = "24",
    doi = "10.1006/jsco.1996.0125",
    title = "The {M}agma algebra system. {I}. {T}he user language",
    url = "http://dx.doi.org/10.1006/jsco.1996.0125",
    journal = "J. Symbolic Comput.",
    issn = "0747-7171",
    mrclass = "68Q40",
    number = "3-4",
    note = "Computational algebra and number theory (London, 1993)",
    mrnumber = "MR1484478",
    year = "1997",
    pages = "235--265",
    fjournal = "Journal of Symbolic Computation"
}
>>> print used_citations.print_all("latex")
\begin{thebibliography}{8}

\bibitem[1]{MR1484478}
Wieb Bosma, John Cannon, and Catherine Playoust.
\newblock The {M}agma algebra system. {I}. {T}he user language.
\newblock \emph{J. Symbolic Comput.}, 24:235--265, 1997.

\end{thebibliography}

Dependencies of citations are also possible.

>>> used_citations.forget()
>>> used_citations(citables.slimgb)
>>> used_citations.format = "latex"
>>> print used_citations
\begin{thebibliography}{8}

\bibitem[1]{DGPS}
W.~Decker, G.-M. Greuel, G.~Pfister, and H.~Sch\"{o}nemann.
\newblock {\sc Singular} {3-1-3} --- {A} computer algebra system for polynomial computations.
\newblock 2011, http://www.singular.uni-kl.de.

\bibitem[2]{slimgbrevista}
Michael Brickenstein.
\newblock Slimgb: {G}r{\"o}bner bases with slim polynomials.
\newblock \emph{Revista Matemática Complutense}, 23, issue 2:453--466, 2010.

\end{thebibliography}

There is a logging feature, which I'm not happy about yet. Furthermore, the documentation needs huge improvements.

It is very interesting to see, how the low-level stuff like cython-optimization, calling directly into Sets and Tuples, works so well together with high-level magic like metaclasses, changing a class' (meta-)class.