[Python-Dev] Christmas Wishlist (original) (raw)

Phillip J. Eby pje at telecommunity.com
Mon Dec 15 14:32:27 EST 2003

At 02:26 PM 12/15/03 -0500, Raymond Hettinger wrote:

> On Sun, Dec 14, 2003 at 04:31:09PM -0500, Raymond Hettinger wrote: > > I. eval() to accept custom mapping arguments for globals and locals. > > This makes it possible to write a smart getitem method for > > applications like spreadsheets or case-insensitive evaluation. > > http://mail.python.org/pipermail/python-dev/2002-October/029770.html > [and the rest of that thread]

[Jeff Epler] > A 3% slowdown in the common case was considered too big to allow a > feature like this to be included. The slowdown might be smaller if > the builtin module wasn't allowed to be anything but a dict instance, or > might disappear if there were two versions of ceval.c were included, and > one used PyObject APIs and the other used PyDict APIs (as long as only > one was fighting for space in the cpu cache, main memory, etc) Ordinarily, I would say that 3% is a reasonable price to pay for this functionality but there is that pesky pie throwing event coming up.

There is a workaround for this in CPython, which used to be used by Zope, and which I have used on occasion: scan the code object for LOAD_NAME opcodes, and note what names are used by the code block. Then, look up those names in your non-dictionary dictionary, and copy them into a real dictionary.

So, it's got to be something pretty specialized to really need PyObject_* APIs instead of PyDict_* APIs in CPython at present. Why penalize everything for such an specialized need?

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