<snip>
>
> http://code.google.com/p/psutil
>
I looked at the website and it looks like a cool module. Some of it appeared to
be *nix only, but I'll have to dig into it more.
But it's also just like you said: how far should one go with micromanaging
things? Maybe some things are the caller's responsibility.
> If you're also supporting the iterator protocol with the __iter__
> method, then I think a helper _items(start, stop, step) generator
> function would be a good idea.
>
> Here's an updated example (not tested however; it's just a suggestion):
>
>
> import operator
>
> def _items(self, start=0, stop=None, step=1):
> if stop is None:
> stop = self.nCases
>
> for i in range(start, stop, step):
> retcode1 = self.iomodule.SeekNextCase(self.fh, ctypes.c_long(i))
> self.caseBuffer, self.caseBufferPtr = self.getCaseBuffer()
> retcode2 = self.iomodule.WholeCaseIn(self.fh, self.caseBufferPtr)
> record = struct.unpack(self.structFmt, self.caseBuffer.raw)
> if any([retcode1, retcode2]):
> raise RuntimeError("Error retrieving record %d [%s,
> %s]" %
> (i, retcodes[retcode1], retcodes[retcode2]))
> yield record
>
>
> def __iter__(self):
> return self._items()
>
>
> def __getitem__(self, key):
>
> is_slice = isinstance(key, slice)
>
> if is_slice:
> start, stop, step = key.indices(self.nCases)
> else:
> key = operator.index(key)
> start = key + self.nCases if key < 0 else key
> if not 0 <= start < self.nCases:
> raise IndexError
> stop = start + 1
> step = 1
>
> records = self._items(start, stop, step)
> if is_slice:
> return list(records)
> return next(records)
>
>
Awesome, thank you so much. This has been very inspiring! When this is working,
I'm thinking about also implementing an Ellipsis (just because it's possible
;-), so I can cut out certain parts of the data using a numpy array. Another
idea would be to also use __getitem__ as a dictionary. So when the data
contains an id (let's say ssn), r = Reader(key="ssn"); r.data["87654321"]
returns the corresponding (first available) record. But although this is cool
from an educational perspective, I do wonder whether, from a design
perspective, it's a good idea to make __getitem__ this fully packed.
<snip>
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