[Python-3000] PEP 3138- String representation in Python 3000 (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Sun May 18 09:30:38 CEST 2008

Selecting an encoding is the kind of thing that will often come from the application's environment, or user preferences or configuration options, rather than being hardcoded at development time.

And that's the main difference why having encode/decode is a good idea, and having transform/untransform is a bad idea.

Encoding names are in configuration data all the time, or even in the actual data (e.g. in MIME); they rarely are in configuration.

You typically don't read the name of transformations from a configuration file. And even if they are in configuration, you typically have a fixed set of options, rather than an extensible one.

With a flat, string-based codec namespace, those things are trivial to look up. Having to mess around with import just to support a "choose compression method" configuration option would be fairly annoying.

I wouldn't mess with import:

import gzip, bz2 compressors = {"gzip":gzip.StreamCompressor, "bzip2":bz2.BZ2Compressor} decompressors={"gzip":gzip.StreamDecompressor, "bzip2":bz2.BZ2Decompressor}

It's not that people invent new compression methods every day.

OTOH, these things have often more complex parameters than just a name; e.g. the compressors also take a compression level. In these cases, using

output_to = compressorsname

could work fine (as both might happen to support the compresslevel keyword argument).

The case for the special namespace is much stronger for the actual unicode encodings, but it still has at least some force for the bytes->bytes and str->str transforms.

Not to me, no.

Regards, Martin

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