Creating a reliable sandboxed Python environment

[Stefan Behnel]

Chris Angelico schrieb am 29.05.2015 um 09:41:
> On Fri, May 29, 2015 at 4:18 PM, Stefan Behnel wrote:
>>> Lua's a much weaker language than Python is, though. Can it handle
>>> arbitrary-precision integers? Unicode? Dare I even ask,
>>> arbitrary-precision rationals (fractions.Fraction)?
>>
>> All of those and way more, as long as you use it embedded in Python.
> 
> Okay, so how would you go about using Lua-embedded-in-Python to
> manipulate Unicode text?

Lua only supports byte strings, so Lupa will encode and decode them for
you. If that's not enough, you'll have to work with Python Unicode string
objects through the language interface. (And I just noticed that the
handling can be improved here by overloading Lua operators with Python
operators - not currently implemented.)


> Looks to me as if Lua doesn't have integers at all

The standard number type in Lua is a C double float, i.e. the steady
integer range is somewhere within +/-2^53. That tends to be enough for a
*lot* of use cases. You could change that type in the Lua C code (e.g. to a
64 bit int), but that's usually a bad idea. The same comment as above
applies: if you need Python object features, use Python objects.

Embedding Lua in Python gives you access to all of Python's objects and
ecosystem. It may not always be as cool to use as from Python, but in that
case, why not code it in Python in the first place? You wouldn't use
Lua/Lupa to write whole applications, just the user defined parts of them.
The rest can happily remain in Python. And should, for your own sanity.

Stefan