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- Propertied(object)
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- BasicProperty
- object
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- MethodStore
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- MethodStoreProperty(MethodStore, BasicProperty)
class BasicProperty(Propertied) |
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The base class for all of our enhanced property classes
A BasicProperty has two distinct levels of accessor-methods:
The first level, comprised of the following methods (these
were renamed in version 0.5 to match the standard descriptor
API):
__get__(self, client, klass)
__set__(self, client, value)
__delete__(self, client)
allows you to override the entire get/set/delete process
in your subclass. Overriding these methods allows you to
short-circuit around bounds checking and coercion. You
become responsible for implementing everything.
The second level, comprised of the following methods:
_getValue(self, client)
_setValue(self, client, value)
_delValue(self, client)
allows you to override only the storage/retrieval process
in your subclass without affecting the bounds checking or
coercion functions of the property. See: the MethodStore
mix-in for an example of overriding just these methods.
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- Method resolution order:
- BasicProperty
- Propertied
- object
Methods defined here:
- __delete__(self, client)
- Delete the current value of the property for the client
At the moment, this method does nothing beyond calling
_delValue( client ), as there does not appear to be
any common feature required from __delete__. The method is
here primarily to maintain the consistency of the interface
and allow for applications to override _delValue without
worrying about losing future features added to __delete__.
- __get__(self, client, klass=None)
- Retrieve the current value of the property for the client
This function provides the machinery for default value and
default function support. If the _getValue method raises
a KeyError or AttributeError, this method will attempt to
find a default value for the property using self.getDefault
- __init__(self, name, documentation='', **namedarguments)
- Create a new basic property object
name -- name of the property, used for storage and reporting
documentation -- appears in automated documentation systems
baseType -- an object representing the base-type of the
property's values. May include the following values:
coerce( value ) -- coerce value to acceptable type
check( value ) -- check that given value is acceptable,
return false if it is not.
factories( ) -- return a list of factory functions/classes
for creating new instances of the class
dataType -- string specifying a data-type key for the
values. This specifier is entirely local to the
properties system, with no neccessary relation to
class or type names. With that said, generally the
values are the dotted-name of the class/type allowed
for the property.
Note: This can be a dotted name with the trailing
items specifying more specific data types, so, for
instance, str.long will use the "long string" editor if
it's registered, or the "string" editor if not.
if coerce is not present, the class should have an initialiser
that allows passing a single value as the value to coerce.
if check is not present, check will be done as
isinstance( value, baseType).
if factories is not present, factories will be assumed to be
the baseType itself.
defaultValue -- static value to be used as default, if not
specified, not provided
defaultFunction -- function with signature function( property,
client ) which returns a dynamic default value
setDefaultOnGet -- if true (default), then retrieving a
default value causes the value to be explicitly set as the
current value
friendlyName -- user-friendly name for use in UIs and the like,
defaults to the current value of name
trueProperty -- if true, this property really does describe a
property, that is, a descriptor for an attribute which is
accessed using object.x notation.
if false, this property is used to interact with the
property system, but is not actually a property of an
object (for instance when the object is an old-style class
which cannot support properties, you can define virtual
properties for use with the class) The property system
can examine the value of trueProperty to determine whether
to use setattr(object,name,value) or call
property.__set__(object, value) to use the property.
Notes:
You can specify _any_ name=value set to store a value, so,
for instance, you could specify __get__ to override the
__get__ method, or similarly _getValue or getDefault.
Sub-classes may (and do) define extra name=value pairs to
support extended functionality. You will need to look at
the sub-class's documentation for details on other
significant attribute names.
- __repr__(self)
- Get a representation of this property object
- __set__(self, client, value)
- Set the current value of the property for the client
This function provides the machinery for coercion and
bounds checking. Before calling the _setValue method,
__set__ calls coerce( client, value ), with the return
value from the coercion becoming the value to be set.
Coercion may raise TypeError or ValueError exceptions,
and the application should be ready to catch these errors.
Once coercion is finished, __set__ calls
check( client, value ) to allow each boundary
condition to check the current value. The boundary
conditions may raise BoundaryErrors (with the particular
error classes generally being sub-classes of ValueError
or TypeError).
- __str__ = __repr__(self)
- check(self, client, value)
- Use our basetype to check the coerced value's type
- coerce(self, client, value)
- Attempt to convert the given value to an appropriate data type
Tries to use the baseType's coerce function,
failing that, calls the base type with the
value as the first positional parameter.
- getBaseType(self)
- Get our base-type object or None if not set
- getDataType(self)
- Get our data-type string
- getDefault(self, client)
- Get the default value of this property for the given client
This simply calls the Default object registered as self.default,
which, depending on whether defaultValue or defaultFunction was
specified during initialisation, will return a value or the
result of a function call. If neither was specified, an
AttributeError will be raised.
- getFactories(self)
- Attempt to determine the factory callables for this property
- getState(self, client)
- Helper for client.__getstate__, gets storable value for this property
- setState(self, client, value)
- Helper for client.__setstate__, sets storable value
Data and other attributes defined here:
- baseType = None
- setDefaultOnGet = 1
- trueProperty = 1
Methods inherited from Propertied:
- clone(self, **newValues)
- Clone this object, with optional new property values
This method calls the __init__ method of your class with
the current property values of your class. Providing newValues
(a dictionary) overrides property settings with new values.
- getCloneProperties(self)
- Get properties dictionary (key:value) for use in cloning of the instance
By default you get getProperties()' values, with an
attempt made to use the property's name, then the property's
direct "__get__" method.
- toString(self, indentation='', alreadyDone=None, indentString=' ')
- Get a nicely formatted representation of this object
This version assumes that getProperties returns
the list of properties which should be presented,
it recursively calls it's children with greater
indents to get their representations.
indentation -- current string indentation level
alreadyDone -- set of object ids which are already finished
XXX Needs a far better API, likely a stand-alone class
without the automatic inheritance problems here :(
Class methods inherited from Propertied:
- getProperties(cls) from type
- Get the BasicProperty properties for a particular object's class
Data and other attributes inherited from Propertied:
- __dict__ = <dictproxy object at 0x01FE0B30>
- dictionary for instance variables (if defined)
- __weakref__ = <attribute '__weakref__' of 'Propertied' objects>
- list of weak references to the object (if defined)
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class MethodStore(object) |
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Mix-in class calling object methods for low-level storage/retrieval
This mix-in class provides three attributes, setMethod, getMethod
and delMethod. You use the class by setting these attributes to
the name of methods on your client with the following signatures:
getMethod( )
setMethod( value )
delMethod( )
You can set these attributes either by defining class-attributes
to override the MethodStore class attributes, or by passing the named
arguments "getMethod", "setMethod", "delMethod" to the property's
__init__ method. Note: these attributes are always strings, do not
use function or instance method objects!
If you have failed to provide one of the attributes, or have provided
a null value (""), a NotImplementedError will be raised when you
attempt to store/retrieve the value using that attribute.
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Data and other attributes defined here:
- __dict__ = <dictproxy object at 0x01FE0BF0>
- dictionary for instance variables (if defined)
- __weakref__ = <attribute '__weakref__' of 'MethodStore' objects>
- list of weak references to the object (if defined)
- delMethod = ''
- getMethod = ''
- setMethod = ''
- trueProperty = 0
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class MethodStoreProperty(MethodStore, BasicProperty) |
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Class providing default MethodStore + BasicProperty operation
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- Method resolution order:
- MethodStoreProperty
- MethodStore
- BasicProperty
- Propertied
- object
Data and other attributes inherited from MethodStore:
- __dict__ = <dictproxy object at 0x01FE0DD0>
- dictionary for instance variables (if defined)
- __weakref__ = <attribute '__weakref__' of 'MethodStore' objects>
- list of weak references to the object (if defined)
- delMethod = ''
- getMethod = ''
- setMethod = ''
- trueProperty = 0
Methods inherited from BasicProperty:
- __delete__(self, client)
- Delete the current value of the property for the client
At the moment, this method does nothing beyond calling
_delValue( client ), as there does not appear to be
any common feature required from __delete__. The method is
here primarily to maintain the consistency of the interface
and allow for applications to override _delValue without
worrying about losing future features added to __delete__.
- __get__(self, client, klass=None)
- Retrieve the current value of the property for the client
This function provides the machinery for default value and
default function support. If the _getValue method raises
a KeyError or AttributeError, this method will attempt to
find a default value for the property using self.getDefault
- __init__(self, name, documentation='', **namedarguments)
- Create a new basic property object
name -- name of the property, used for storage and reporting
documentation -- appears in automated documentation systems
baseType -- an object representing the base-type of the
property's values. May include the following values:
coerce( value ) -- coerce value to acceptable type
check( value ) -- check that given value is acceptable,
return false if it is not.
factories( ) -- return a list of factory functions/classes
for creating new instances of the class
dataType -- string specifying a data-type key for the
values. This specifier is entirely local to the
properties system, with no neccessary relation to
class or type names. With that said, generally the
values are the dotted-name of the class/type allowed
for the property.
Note: This can be a dotted name with the trailing
items specifying more specific data types, so, for
instance, str.long will use the "long string" editor if
it's registered, or the "string" editor if not.
if coerce is not present, the class should have an initialiser
that allows passing a single value as the value to coerce.
if check is not present, check will be done as
isinstance( value, baseType).
if factories is not present, factories will be assumed to be
the baseType itself.
defaultValue -- static value to be used as default, if not
specified, not provided
defaultFunction -- function with signature function( property,
client ) which returns a dynamic default value
setDefaultOnGet -- if true (default), then retrieving a
default value causes the value to be explicitly set as the
current value
friendlyName -- user-friendly name for use in UIs and the like,
defaults to the current value of name
trueProperty -- if true, this property really does describe a
property, that is, a descriptor for an attribute which is
accessed using object.x notation.
if false, this property is used to interact with the
property system, but is not actually a property of an
object (for instance when the object is an old-style class
which cannot support properties, you can define virtual
properties for use with the class) The property system
can examine the value of trueProperty to determine whether
to use setattr(object,name,value) or call
property.__set__(object, value) to use the property.
Notes:
You can specify _any_ name=value set to store a value, so,
for instance, you could specify __get__ to override the
__get__ method, or similarly _getValue or getDefault.
Sub-classes may (and do) define extra name=value pairs to
support extended functionality. You will need to look at
the sub-class's documentation for details on other
significant attribute names.
- __repr__(self)
- Get a representation of this property object
- __set__(self, client, value)
- Set the current value of the property for the client
This function provides the machinery for coercion and
bounds checking. Before calling the _setValue method,
__set__ calls coerce( client, value ), with the return
value from the coercion becoming the value to be set.
Coercion may raise TypeError or ValueError exceptions,
and the application should be ready to catch these errors.
Once coercion is finished, __set__ calls
check( client, value ) to allow each boundary
condition to check the current value. The boundary
conditions may raise BoundaryErrors (with the particular
error classes generally being sub-classes of ValueError
or TypeError).
- __str__ = __repr__(self)
- Get a representation of this property object
- check(self, client, value)
- Use our basetype to check the coerced value's type
- coerce(self, client, value)
- Attempt to convert the given value to an appropriate data type
Tries to use the baseType's coerce function,
failing that, calls the base type with the
value as the first positional parameter.
- getBaseType(self)
- Get our base-type object or None if not set
- getDataType(self)
- Get our data-type string
- getDefault(self, client)
- Get the default value of this property for the given client
This simply calls the Default object registered as self.default,
which, depending on whether defaultValue or defaultFunction was
specified during initialisation, will return a value or the
result of a function call. If neither was specified, an
AttributeError will be raised.
- getFactories(self)
- Attempt to determine the factory callables for this property
- getState(self, client)
- Helper for client.__getstate__, gets storable value for this property
- setState(self, client, value)
- Helper for client.__setstate__, sets storable value
Data and other attributes inherited from BasicProperty:
- baseType = None
- setDefaultOnGet = 1
Methods inherited from Propertied:
- clone(self, **newValues)
- Clone this object, with optional new property values
This method calls the __init__ method of your class with
the current property values of your class. Providing newValues
(a dictionary) overrides property settings with new values.
- getCloneProperties(self)
- Get properties dictionary (key:value) for use in cloning of the instance
By default you get getProperties()' values, with an
attempt made to use the property's name, then the property's
direct "__get__" method.
- toString(self, indentation='', alreadyDone=None, indentString=' ')
- Get a nicely formatted representation of this object
This version assumes that getProperties returns
the list of properties which should be presented,
it recursively calls it's children with greater
indents to get their representations.
indentation -- current string indentation level
alreadyDone -- set of object ids which are already finished
XXX Needs a far better API, likely a stand-alone class
without the automatic inheritance problems here :(
Class methods inherited from Propertied:
- getProperties(cls) from type
- Get the BasicProperty properties for a particular object's class
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