L10n of numbers (i.e. decimal point)

We need localized number format support in our application, in the
very least being able to parse the native decimal point for numeric
(Float and BigDecimal) fields.

I’ve been spending some time looking at various plugins that do
something with number L10n
but as far as I can tell most won’t do form IO.

Some probably can, i.e. Globalize, but I can’t make heads & tails of the

We already use gettext for translation, so a plugin which just does
the number work would be ideal.

I am prepared to roll my own, but would need a little help getting
started in that case.

“Look at the globalize source” isn’t specific enough - I’d need
something along the lines of: “for input, hook/override methods … of
modules/classes … , for output override the ror helpers”, or

Thanks in advance,