decimal.py 文件源码

def create_decimal_from_float(self, f):
        """Creates a new Decimal instance from a float but rounding using self
        as the context.

        >>> context = Context(prec=5, rounding=ROUND_DOWN)
        >>> context.create_decimal_from_float(3.1415926535897932)
        Decimal('3.1415')
        >>> context = Context(prec=5, traps=[Inexact])
        >>> context.create_decimal_from_float(3.1415926535897932)
        Traceback (most recent call last):
            ...
        decimal.Inexact: None

        """
        d = Decimal.from_float(f)       # An exact conversion
        return d._fix(self)             # Apply the context rounding

    # Methods