[Python-Dev] Python for small platforms

[M.-A. Lemburg]

Jeff Collins wrote:
> 
> The approach I've taken for removing "features" (like float objects):
> 1)  removes the feature with WITHOUT_XXX #ifdef/#endif decorations,
>         where XXX denotes the removable feature (configurable in config.h)
> 2)  preserves the python API:  builtin functions, C API, PyArg_Parse,
>         print format specifiers, etc., raise MissingFeatureError if
>         attempts are made to use them.  Of course, the API associated
>         with the removed feature is no longer present.
> 3)  protects the reduced VM: all reads (via marshal, compile, etc.)
>         involving source/compiled python code will fail with
>         a MissingFeatureError if the reduced VM doesn't support it.
> 4)  does not yet support a MissingFeatureError in the tokenizer
>         if, say, 2.2 (for removed floats) is entered on the python
>         command line.  This instead results in a SyntaxError
>         indicating a problem with the decimal point.  It appears that
>         another error token would have to be added to support
>         this error.

Wouldn't it be simpler to replace the parts in question
with dummy replacements ? The dummies could then raise
appropriate exceptions as needed. This would work for 
float, complex and Unicode objects which all have a defined
API.

The advantage of this approach is that you don't need to maintain
separate patches for these parts (which is a pain) and that you
can provide drop-in archives which are easy to install: simply
unzip over the full source tree and recompile.

> Of course, I may have missed something, but if the above appears to be
> a reasonable approach, I can supply patches (at least for floats and
> complexes) for further discussion.  In the longer term, it would be
> helpful if developers would follow this (or a similar agreed upon
> approach) when adding new features.  This would reduce the burden of
> maintaining python for small embedded platforms.

-- 
Marc-Andre Lemburg
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