def make_converter(proto):
"""Return a function that will convert its argument using <proto> as a
prototype. The <proto> is either a type or an instance of a Quantity
or a string that can be parsed as a Quantity.
"""
if proto in (int, float): # simple numerical type
def topod(other):
return proto(other)
return topod
if proto == str: # treat string special to instrument some error checking
def tostr(other):
other = str(other)
if other == "":
raise ValueError, "Empty string is an illegal value for str"
if other is None:
raise ValueError, "None is an illegal value for str"
return other
return tostr
if isquantity(proto):
return toquantity(proto)
# it better be of some type of self-converting prototype
def toobj(other):
ret = proto(other)
return ret
return toobj
def validate_input(proto, *args, **kwargs):
"""Validate the input <args> and <kwargs> against the prototypes in <proto>.
<proto> is a list of ("name",object) tuples.
<args> is a list of positional arguments assumed to follow the
ordering of <proto> but may be of shorter length.
<kwargs> is a dictionary of "name"/object pairs supplying any
remaining arguments.
Any unspecified arguments are given the default from <proto> and
no keys in <kwargs> may be given in addition to what are specified
in <args>.
A an ordered list of values are returned.
"""
# print 'VALIDATE INPUT', str(proto)
members = OrderedDict()
converters = dict()
for name, pval in proto:
c = make_converter(pval)
converters[name] = c
# print 'CONVERTER:',name,c,pval
# set default
if isquantity(pval):
members[name] = c(pval)
elif hasattr(pval, "default"):
# print 'SET DEFAULT:',name,pval.default
members[name] = pval.default()
else:
members[name] = None
# if isquantity(pval):
# pval = toquantity(pval)(pval)
# members[name] = pval
# converters[name] = make_converter(pval)
already = list()
for k, v in zip(members.keys(), args):
members[k] = converters[k](v)
# print 'ARGS:',k,v,members[k]
already.append(k)
for k, v in kwargs.items():
if k not in converters.keys():
raise ValueError, 'Object "%s" not in prototype' % (k,)
if k in already:
raise ValueError, "Keyword argument already supplied as positional: %s" % k
members[k] = converters[k](v)
# print 'KWDS:',k,v,members[k]
return members.values()
