W liście z pią, 13-08-2004, godz. 17:26 +0200, Tels napisał:
> > Is there a relatively easy way to handle various BigInt representations
> > as well?
>
> "use Math::BigInt;" and "use Math::BigFloat;" (as well as "use Math::BigInt
> lib => 'GMP';").
This is from the point of view of a Perl user. But I'm making a bridge
between my pet language Kogut and Perl, and I don't think that I should
impose using a particular bigint library, especially if it makes all
Perl arithmetic slower.
This bridge is harder than the Kogut<->Python bridge I made earlier.
For Python I could convert various simple types automatically in both
directions (numbers, strings, booleans), despite differences in Unicode
handling between languages.
For Perl I can convert numbers and strings when passing from Kogut to
Perl, but not in the other direction, for two reasons:
- It's impossible to distinguish whether a Perl code meant a number 5 or
a string "5".
- Perl Strings are mutable, so converting them by value would lose their
identity in cases it's important.
Not only that, but a Perl subroutine can be called in scalar, list,
or void context. This implies it can't be directly wrapped in a Kogut
function which is just applied to arguments, because there is no place
to pass the context. So I have separate functions for invoking Perl
subroutines, depending on what is expected from them:
CallPerlVoid
CallPerlScalar
CallPerlList
CallPerlNumber \
CallPerlInt \
CallPerlFloat \ convenience wrappers over CallPerlScalar
CallPerlString /
CallPerlBool /
CallPerlUnwrap /
and analogously for methods. Arguments of various common types are
converted automatically, but the result must be converted explicitly.
I must rename these functions to something shorter...
The case I asked about is needed for CallPerlNumber, or generally for
converting a Perl scalar to a Kogut number if we don't know what kind of
number to expect.
Dually, when exposing a Kogut function to Perl, its arguments are not
converted automatically - they are just wrapped Perl scalars - but the
result can be converted, thanks to a richer type system on this side.
A Kogut list is converted to a list of results, and other types are
converted to single Perl scalars.
--
__("< Marcin Kowalczyk
\__/ [EMAIL PROTECTED]
^^ http://qrnik.knm.org.pl/~qrczak/
