Martin.Drautzburg at web.de
Sun Feb 7 11:13:41 CET 2010
Steven D'Aprano wrote:
> If you want iterator operations "similar to itertools", why does this
> mean you need to replace anything? Just create your own iterators.
> Or use pre-processing and post-processing to get what you want.
> Can you show an example of what you would like to happen?
my classes repesent musical objects. The fundamental paradigm I want to
apply is that of a Sequence, i.e. the most abstract aspect of music is
that "things" occur in a certain order.
Then I have a TimedSequence class, which is a Sequences whose elements
have a "time" attribute. I now want to be able to append such Sequences
s1 = TimedSequence (time=1,'a') # one-element Sequence
s2 = TimedSequence (time=2,'b')
y = s1*2 + s2
Naively appending those sequences would give me
but this is not what I want. Time needs to progress if I append a
sequence to another. So what I really want is something like
This implies that time is shifted to the next integer, but this is not
always the case. I need to know about some kind of "alignment". In
music this translates to "let a sequence start at the beginning of a
bar", or half bar or quarter note or whatever.
So I want to write
y = s1*2 + s2(align=10)
which should iterate as
I have no difficulty passing "align" to the object (using __call__) and
use it while I furnish my own __iter__() method. However I don't quite
see how I can do this with bare itertools, though I may be wrong here.
Bare in mind that it is not only about somehow getting the job done. The
beauty of the resulting syntax is also important.
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