How to implement range checking with guts.

range_check.py

from pyrocko.guts import Float, Object, ValidationError, List


def float_or_none(x):
    if x is None:
        return None
    else:
        return float(x)


class FloatWithRange(Float):

    class __T(Float.T):
        def __init__(
                self, ge=None, le=None, gt=None, lt=None, *args, **kwargs):

            Float.T.__init__(self, *args, **kwargs)

            self.ge = float_or_none(ge)
            self.le = float_or_none(le)
            self.gt = float_or_none(gt)
            self.lt = float_or_none(lt)

        def validate_extra(self, val):
            if self.ge is not None and val < self.ge:
                raise ValidationError(
                    'must be greater than or equal to %g (value: %g)' % (
                        self.ge, val))

            if self.le is not None and val > self.le:
                raise ValidationError(
                    'must be less than or equal to %g (value: %g)' % (
                        self.le, val))

            if self.gt is not None and val <= self.gt:
                raise ValidationError(
                    'must be greater than %g (value: %g)' % (
                        self.gt, val))

            if self.lt is not None and val >= self.lt:
                raise ValidationError(
                    'must be less than %g (value: %g)' % (
                        self.lt, val))

            return Float.T.validate_extra(self, val)


class Test(Object):
    a = FloatWithRange.T(ge=0., le=10.)
    l = List.T(FloatWithRange.T(gt=0.))


t = Test(a=1., l=[2., 0., 2.])

try:
    t.validate()
    assert False

except ValidationError as e:
    print e

t = Test(a=0.)
t.validate()

t = Test(a=-12.)
try:
    t.validate()
    assert False

except ValidationError as e:
    print e