-----Original Message----- From: Boost [mailto:boost-bounces@lists.boost.org] On Behalf Of John Maddock Sent: 31 May 2014 12:56 To: boost@lists.boost.org Subject: [boost] [multiprecision] General/design query about which conversions should be implicit/explicit
Folks,
I have an open bug report https://svn.boost.org/trac/boost/ticket/10082 that requests that conversions from floating point to rational multiprecision-types be made implicit (currently they're explicit).
Now on the one hand the bug report is correct: these are non-lossy conversions, so there's no harm in them being implicit. However, it still sort of feels wrong to me, the only arguments against I can come up with are:
1) An implicit conversion lets you assign values such as 0.1 to a rational (which actually leads to 3602879701896397/36028797018963968 not 1/10), where as making the conversion explicit at least forces you to use a cast (or an explicit construction).
Killer argument against implicit. But I can see that a not-at-all-dumb user might prefer otherwise, so as a compromise could allowing implicit be MACRO controlled? (We hit this sort of problem back with using NTL, and patched it to permit implicit conversions so I can understand both views). Paul --- Paul A. Bristow Prizet Farmhouse Kendal UK LA8 8AB +44 01539 561830