oliphant at ee.byu.edu
Fri Apr 1 01:30:38 EST 2005
For the most part, it seems the array protocol is easy to agree on. The
one difficulty is typestr.
For what it's worth, here are my opinions on what has been said
regarding the typestr.
* Endian-ness should be included in the typestr --- it is how the data
is viewed and an intrinsic part of the type as much as int, or float.
* I like the fact that struct character codes are documented, but it is
hard to remember. The simpler division into basic types and byte-widths
that the numarray record module uses is easier to remember.
* I'm mixed on whether or not support for describing complex data types
should be used or if their description as a record is good enough. On
the one hand we think of complex numbers as additional types, but on the
other hand, in terms of machine layout they really are just two floats,
so perhaps it is better to look at them that way in a protocol whose
purpose is just describing how to interpret a block of memory.
Especially since complex numbers could conceivably be built on top of
any of the other types. In addition, it is conceivable that a rational
array might be supported by some array object in the future and that
would most easily be handled by a record array where the names were now
something like ("numer", "denom") . The typestr argument should just
help us specify what is in the memory chunk at each array element (how
should it be described).
* I'm wondering about including multiple types in the typestr. On the
one hand we could describe complicated structures by packing all the
information into the typestr. On the other hand, it may be better if
we just use 'V8' to describe an 8-byte memory buffer with an additional
attribute that contains both the names and the typestr:
__array_recinfo__ = (('real','f4'),('imag','f4'))
or for a "rational type"
__array_recinfo__ = (('numer','i4'),('denom','i4'))
so that the detail of the typecode for a "record" type is handled by
another special method using tuples. On this level, we could add the
possibility of specifying a shape for a small array inside (just like
the record array of numarray does).
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