from collections import namedtuple
Param = namedtuple("Param", "name default doc")
ReqParam = namedtuple("ReqParam", "name doc")
Getter = namedtuple("Getter", "name initial doc")
PROPERTY_TEMPLATE = """\
@property
def {name}(self):
"{doc}"
if not hasattr(self, "_{name}"):
self._{name} = {initial}
return self._{name}"""
def dataclass(typename, doc, params, properties, verbose=False):
"Return a new class around the params and properties."
namespace = {}
# handle class docstring
if not doc:
doc = ""
docstring = doc.splitlines()
if not docstring:
docstring = ['""']
elif len(docstring) > 1:
docstring.insert(0, '"""')
docstring.append('"""')
docstring.extend(line for line in doc.splitlines)
else:
docstring = ['"{}"'.format(docstring[0])]
# handle __init__ and params
params_constant = []
__init__ = []
if params:
params_constant = ["PARAMS = ("]
doc = []
assignment = []
for param in params:
params_constant.append(" {}{},".format(
param.__class__.__name__,
param.__getnewargs__(),
))
namespace[param.__class__.__name__] = param.__class__
default = ""
if hasattr(param, "default"):
default = param.default
if hasattr(default, "__name__"):
namespace[default.__name__] = default
default = default.__name__
default = "={}".format(default)
__init__.append(" {}{},".format(param.name, default))
if param.doc:
doc.append(" {} - {}".format(param.name, param.doc))
assignment.append("self.{} = {}".format(param.name, param.name))
__init__.append("):")
params_constant.append(" )")
if doc:
__init__.append('"""')
__init__.append("Parameters:")
__init__.extend(doc)
__init__.append("")
__init__.append('"""')
__init__.append("")
__init__.extend(assignment)
__init__ = [" "+line for line in __init__]
__init__.insert(0, "def __init__(self,")
# handle properties
properties_constant = []
props = []
for prop in properties:
properties_constant.append(" {}{},".format(
prop.__class__.__name__,
prop.__getnewargs__(),
))
namespace[prop.__class__.__name__] = prop.__class__
initial = prop.initial
if hasattr(initial, "__name__"):
namespace[initial.__name__] = initial
initial = initial.__name__
prop = PROPERTY_TEMPLATE.format(
name=prop.name,
initial=initial,
doc=prop.doc,
)
props.extend(prop.splitlines())
props.append("")
if properties_constant:
properties_constant.insert(0, "PROPERTIES = (")
properties_constant.append(" )")
# put it all together
template = ["class {}(object):".format(typename)]
template.extend(" "+line for line in docstring)
template.extend(" "+line for line in params_constant)
template.extend(" "+line for line in properties_constant)
template.append("")
template.extend(" "+line for line in __init__)
template.append("")
template.extend(" "+line for line in props)
template.append("")
template = "\n".join(template)
if verbose:
print(template)
try:
exec(template, namespace)
#except SyntaxError, e:
except SyntaxError as e:
raise SyntaxError(e.msg + ':\n' + template)
return namespace[typename]
def data(cls):
"A class decorator for the dataclass function."
return dataclass(cls.__name__, cls.__doc__, cls.PARAMS, cls.PROPERTIES)
