mirrors/cpython
1
0
Fork 0
mirror of https://github.com/python/cpython.git synced 2025-08-04 00:48:58 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 8

Improve Context construction and representation:

Browse source 
* Rename "trap_enablers" to just "traps".
* Simplify names of "settraps" and "setflags" to just "traps" and "flags".
* Show "capitals" in the context representation
* Simplify the Context constructor to match its repr form so that only
  the set flags and traps need to be listed.
* Representation can now be run through eval().

Improve the error message when the Decimal constructor is given a float.

The test suite no longer needs a duplicate reset_flags method.
This commit is contained in:
Raymond Hettinger 2004-07-10 14:14:37 +00:00
parent d9dfe0213f
commit bf4406971c
3 changed files with 54 additions and 58 deletions
Download patch file Download diff file Expand all files Collapse all files

54
Lib/decimal.py
View file

@ -70,7 +70,7 @@ NaN
-Infinity
>>> print dig / 0
Infinity
>>> getcontext().trap_enablers[DivisionByZero] = 1
>>> getcontext().traps[DivisionByZero] = 1
>>> print dig / 0
Traceback (most recent call last):
...
@ -78,12 +78,12 @@ Traceback (most recent call last):
...
DivisionByZero: x / 0
>>> c = Context()
>>> c.trap_enablers[InvalidOperation] = 0
>>> c.traps[InvalidOperation] = 0
>>> print c.flags[InvalidOperation]
0
>>> c.divide(Decimal(0), Decimal(0))
Decimal("NaN")
>>> c.trap_enablers[InvalidOperation] = 1
>>> c.traps[InvalidOperation] = 1
>>> print c.flags[InvalidOperation]
1
>>> c.flags[InvalidOperation] = 0
@ -98,7 +98,7 @@ InvalidOperation: 0 / 0
>>> print c.flags[InvalidOperation]
1
>>> c.flags[InvalidOperation] = 0
>>> c.trap_enablers[InvalidOperation] = 0
>>> c.traps[InvalidOperation] = 0
>>> print c.divide(Decimal(0), Decimal(0))
NaN
>>> print c.flags[InvalidOperation]
@ -495,7 +495,11 @@ class Decimal(object):
self._int = value._int
return
raise TypeError("Can't convert %r" % value)
if isinstance(value, float):
raise TypeError("Cannot convert float to Decimal. " +
"First convert the float to a string")
raise TypeError("Cannot convert %r" % value)
def _convert_other(self, other):
"""Convert other to Decimal.
@ -2096,7 +2100,7 @@ class Context(object):
prec - precision (for use in rounding, division, square roots..)
rounding - rounding type. (how you round)
_rounding_decision - ALWAYS_ROUND, NEVER_ROUND -- do you round?
trap_enablers - If trap_enablers[exception] = 1, then the exception is
traps - If traps[exception] = 1, then the exception is
raised when it is caused. Otherwise, a value is
substituted in.
flags - When an exception is caused, flags[exception] is incremented.
@ -2110,13 +2114,15 @@ class Context(object):
"""
def __init__(self, prec=None, rounding=None,
trap_enablers=None, flags=None,
traps=None, flags=[],
_rounding_decision=None,
Emin=None, Emax=None,
capitals=None, _clamp=0,
_ignored_flags=[]):
if flags is None:
flags = dict.fromkeys(Signals, 0)
if not isinstance(flags, dict):
flags = dict([(s,s in flags) for s in Signals])
if traps is not None and not isinstance(traps, dict):
traps = dict([(s,s in traps) for s in Signals])
for name, val in locals().items():
if val is None:
setattr(self, name, copy.copy(getattr(DefaultContext, name)))
@ -2125,11 +2131,11 @@ class Context(object):
del self.self
def __repr__(self):
"""Show the current context in readable form, not in a form for eval()."""
"""Show the current context."""
s = []
s.append('Context(prec=%(prec)d, rounding=%(rounding)s, Emin=%(Emin)d, Emax=%(Emax)d' % vars(self))
s.append('setflags=%r' % [f.__name__ for f, v in self.flags.items() if v])
s.append('settraps=%r' % [t.__name__ for t, v in self.trap_enablers.items() if v])
s.append('Context(prec=%(prec)d, rounding=%(rounding)s, Emin=%(Emin)d, Emax=%(Emax)d, capitals=%(capitals)d' % vars(self))
s.append('flags=[' + ', '.join([f.__name__ for f, v in self.flags.items() if v]) + ']')
s.append('traps=[' + ', '.join([t.__name__ for t, v in self.traps.items() if v]) + ']')
return ', '.join(s) + ')'
def clear_flags(self):
@ -2139,7 +2145,7 @@ class Context(object):
def copy(self):
"""Returns a copy from self."""
nc = Context(self.prec, self.rounding, self.trap_enablers, self.flags,
nc = Context(self.prec, self.rounding, self.traps, self.flags,
self._rounding_decision, self.Emin, self.Emax,
self.capitals, self._clamp, self._ignored_flags)
return nc
@ -2159,7 +2165,7 @@ class Context(object):
return error().handle(self, *args)
self.flags[error] += 1
if not self.trap_enablers[error]:
if not self.traps[error]:
#The errors define how to handle themselves.
return condition().handle(self, *args)
@ -2946,13 +2952,10 @@ def _isnan(num):
# The default context prototype used by Context()
# Is mutable, so than new contexts can have different default values
_default_traps = dict.fromkeys(Signals, 0)
_default_traps.update({DivisionByZero:1, Overflow:1, InvalidOperation:1})
DefaultContext = Context(
prec=28, rounding=ROUND_HALF_EVEN,
trap_enablers=_default_traps,
flags=None,
traps=[DivisionByZero, Overflow, InvalidOperation],
flags=[],
_rounding_decision=ALWAYS_ROUND,
Emax=DEFAULT_MAX_EXPONENT,
Emin=DEFAULT_MIN_EXPONENT,
@ -2964,20 +2967,17 @@ DefaultContext = Context(
# contexts and be able to reproduce results from other implementations
# of the spec.
_basic_traps = dict.fromkeys(Signals, 1)
_basic_traps.update({Inexact:0, Rounded:0, Subnormal:0})
BasicContext = Context(
prec=9, rounding=ROUND_HALF_UP,
trap_enablers=_basic_traps,
flags=None,
traps=[DivisionByZero, Overflow, InvalidOperation, Clamped, Underflow],
flags=[],
_rounding_decision=ALWAYS_ROUND,
)
ExtendedContext = Context(
prec=9, rounding=ROUND_HALF_EVEN,
trap_enablers=dict.fromkeys(Signals, 0),
flags=None,
traps=[],
flags=[],
_rounding_decision=ALWAYS_ROUND,
)