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dyndesign-0.9.7
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مشاهده بیشترتوضیحات
Toolset for Dynamic Design Patterns in Python.
| ویژگی | مقدار |
|---|---|
| سیستم عامل | - |
| نام فایل | dyndesign-0.9.7 |
| نام | dyndesign |
| نسخه کتابخانه | 0.9.7 |
| نگهدارنده | ['Patrizio Gelosi'] |
| ایمیل نگهدارنده | ['patrizio.gelosi@amarulasolutions.com'] |
| نویسنده | Patrizio Gelosi |
| ایمیل نویسنده | patrizio.gelosi@amarulasolutions.com |
| آدرس صفحه اصلی | https://github.com/amarula/dyndesign |
| آدرس اینترنتی | https://pypi.org/project/dyndesign/ |
| مجوز | MIT |
DynDesign
=========
|Build Status| |PyPi Version Status| |Python Version Status| |License|
A set of tools for Dynamic Design Patterns in Python.
Install
-------
Dyndesign is on the Python Package Index (PyPI):
::
pip install dyndesign
Overview
--------
Merge two or more classes:
.. code:: python
from dyndesign import mergeclasses
MergedClass = mergeclasses(Base, Ext1, Ext2, ...)
Decorate a method with one or more instance methods loaded at runtime:
.. code:: python
from dyndesign import decoratewith
@decoratewith("decorator_1", "component.decorator_2", ...)
def decorated_method(self, ...):
...
Safely invoke functions or methods from a ``safezone`` context manager:
.. code:: python
from dyndesign import safezone
with safezone():
...
function_possibly_non_existent()
...
Create and destroy Singleton classes:
.. code:: python
from dyndesign import SingletonMeta
class Singleton(metaclass=SingletonMeta):
...
singleton_instance = Singleton(...)
same_singleton_instance = Singleton()
Singleton().destroy_singleton()
new_singleton_instance = Singleton(...)
Import classes dynamically using the path:
.. code:: python
from dyndesign import importclass
ImportedClass = importclass("directory.module.class_name")
Merging Classes
---------------
Dyndesign provides API ``mergeclasses`` to merge two or more classes as if they
were dictionaries, so that the merged class has the attributes and methods of
the base class and of the extension classes. If two or more classes have the
same attributes/methods, the attributes/methods from the rightmost classes (in
the order in which the classes are passed to ``mergeclasses``) overload the
ones from the leftmost classes, similarly to what happens when merging
dictionaries.
.. code:: python
from dyndesign import mergeclasses
class Base:
def __init__(self, init_value):
self.param = init_value
def m1(self):
print(f"Method `m1` of class `Base`, and {self.param=}")
def m2(self):
print(f"Method `m2` of class `Base`")
class Ext:
def m1(self):
print(f"Method `m1` of class `Ext`, and {self.param=}")
MergedClass = mergeclasses(Base, Ext)
merged_instance = MergedClass("INITIAL VALUE")
merged_instance.m1()
merged_instance.m2()
# Method `m1` of class `Ext`, and self.param='INITIAL VALUE'
# Method `m2` of class `Base`
When a merged class is instantiated with arguments, the constructor of each
merging class is invoked, since constructors are excluded from being overloaded.
Also, arguments passed to each constructor are adaptively filtered based on the
constructor signature so that each constructor takes just the arguments it
requires, and no exception is raised for exceeding arguments passed:
.. code:: python
class A:
def __init__(self):
print("No argument passed to class `A`")
class B:
def __init__(self, a):
print(f"Argument {a=} passed to class `B`")
class C:
def __init__(self, a, b, kw1=None):
print(f"Argument {a=}, {b=} and {kw1=} passed to class `C`")
class D:
def __init__(self, kw2=None):
print(f"Argument {kw2=} passed to class `D`")
MergedClass = mergeclasses(A, B, C, D)
MergedClass("Alpha", "Beta", kw1="kwarg #1", kw2="kwarg #2")
# No argument passed to class `A`
# Argument a='Alpha' passed to class `B`
# Argument a='Alpha', b='Beta' and kw1='kwarg #1' passed to class `C`
# Argument kw2='kwarg #2' passed to class `D`
On the other hand, if any required positional argument is missing, an exception
is raised. If `MergedClass` of the above example is initialized with no
parameters, and exception is raised when the constructor of class `B` is called:
.. code:: python
...
MergedClass()
# ...
# TypeError: B.__init__() missing 1 required positional argument: 'a'
So as to have constructor instances with missing positional arguments silently
skipped, `strict_merged_args` can be set to False in `mergeclasses`. In the
above example, constructors of class `B` and `C` are skipped:
.. code:: python
...
MergedClass = mergeclasses(A, B, C, D, strict_merged_args=False)
MergedClass()
# No argument passed to class `A`
# Argument kw2=None passed to class `D`
It is also possible to extend the same behavior of the constructor ``__init__``
(i.e., all the methods from all the merged classes are invoked rather than being
overloaded by the same name method from the rightmost class) to other methods. A
list of method names whose instances have to be all invoked can be specified in
the ``invoke_all`` argument of ``mergeclasses``. Adaptive filtering of the
arguments of the method instances is performed as well.
.. code:: python
class E:
def method(self):
print("No argument passed to `method` of class `E`")
class F:
def method(self, a):
print(f"Argument {a=} passed to `method` of class `F`")
MergedClass = mergeclasses(E, F, invoke_all=["method"])
MergedClass().method("Alpha")
# No argument passed to `method` of class `E`
# Argument a='Alpha' passed to `method` of class `F`
Dynamic Decorators
------------------
Meta decorator ``decoratewith`` decorates a class method with one or more
pipelined instance decorators (regardless whether they statically exist or not).
The syntax of the dynamic decorators aims to get rid of the boilerplate for
wrapping and returning the decorator code, leaving just the wrapper's code. For
example, dynamic decorators can be used to decorate a method from a base class
with a method from an extension class:
.. code:: python
from dyndesign import decoratewith
class Base:
@decoratewith("decorator")
def m(self):
print(f"Method `m` of class `Base`")
class Ext:
def decorator(self, func):
print("Beginning of method decoration from Ext.")
func(self)
print("End of method decoration from Ext.")
merged = mergeclasses(Base, Ext)()
merged.m()
# Beginning of method decoration from Ext.
# Method `m` of class `Base`
# End of method decoration from Ext.
If a decorator name is passed in the ``invoke_all`` argument of
``mergeclasses``, then multiple decorator instances with the same name from
different extension classes may be used in pipeline:
.. code:: python
class Ext2:
def decorator(self, func):
print("Beginning of method decoration from Ext2.")
func(self)
print("End of method decoration from Ext2.")
merged = mergeclasses(Base, Ext, Ext2, invoke_all=["decorator"])()
merged.m()
# Beginning of method decoration from Ext.
# Beginning of method decoration from Ext2.
# Method `m` of class `Base`
# End of method decoration from Ext2.
# End of method decoration from Ext.
Arguments of ``decoratewith`` are loaded at runtime as properties of the
variable 'self': a dynamic decorator can be, for example, a method of a
component class. In case of dynamic decoration from a sub-instance of 'self',
the instance object of the decorated method is passed to the decorator as the
argument ``decorated_self``. If a dynamic decorator is not found at runtime
(e.g., because it is a method of an optional class that has not been merged),
then the code execution proceeds normally, as shown below with the decorator
``non_existent_decorator``:
.. code:: python
class Base:
def __init__(self):
self.comp = Component()
@decoratewith("comp.decorator1", "comp.decorator2", "non_existent_decorator")
def m(self):
print("Method `m` of class `Base`")
class Component:
def __init__(self):
self.value = "Initial"
def decorator1(self, func, decorated_self):
print(f"Beginning of method decoration #1 ({self.value=})")
self.value = "Processed"
func(decorated_self)
print("End of method decoration #1")
def decorator2(self, func, decorated_self):
print(f"Beginning of method decoration #2 ({self.value=})")
func(decorated_self)
print("End of method decoration #2")
base = Base()
base.m()
# Beginning of method decoration #1 (self.value='Initial')
# Beginning of method decoration #2 (self.value='Processed')
# Method `m` of class `Base`
# End of method decoration #2
# End of method decoration #1
Safezone Context Manager
------------------------
Any function or method that may or may not exist at runtime (e.g., methods of
merged classes) can be invoked from Context Manager ``safezone`` in order to
suppress the possible exceptions raised if the function or method is not found
at runtime. Optionally, a fallback function/method can be also passed. If no
function name(s) is passed as argument of ``safezone``, then each function in
the safe zone's code is protected; if any function name(s) is passed, the
protection is restricted to the functions having that/those name(s). For
example, ``safezone`` can be used to safely call functions that may or may not
exist at runtime:
.. code:: python
from dyndesign import safezone
def fallback():
print("Fallback function")
def function_a():
print("Function `a`")
with safezone(fallback=fallback):
function_a()
non_existent_function()
# Function `a`
# Fallback function
A further example shows that ``safezone`` can be used to safely invoke methods
of classes that may or may not be merged with other classes:
.. code:: python
class Base:
def fallback(self):
print("Fallback method")
def m(self, class_desc):
print(f"Method `m` of {class_desc}")
with safezone("optional_method", fallback=self.fallback):
self.optional_method()
class ExtOptional:
def optional_method(self):
print("Optional method from class `ExtOptional`")
merged = mergeclasses(Base, ExtOptional)()
merged.m("merged class")
base = Base()
base.m("class `Base` standalone")
# Method `m` of merged class
# Optional method from class `ExtOptional`
# Method `m` of class `Base` standalone
# Fallback method
Invoking methods safely
-----------------------
As alternative to ``safezone`` context manager, ``safeinvoke`` can be used to
safely invoke methods that may or may not exist at runtime. To this end, method
``m`` of class ``Base`` of the example above can be replaced as follows:
.. code:: python
from dyndesign import safeinvoke
...
def m(self, class_desc):
print(f"Method `m` of {class_desc}")
safeinvoke("optional_method", self, fallback=self.fallback)
Singleton classes
-----------------
Singleton classes can be swiftly created and destroyed with
``destroy_singleton``:
.. code:: python
from dyndesign import SingletonMeta
class Singleton(metaclass=SingletonMeta):
def __init__(self, instance_id = None):
if instance_id:
self.instance_id = instance_id
print(f"Created a {instance_id} instance of `Singleton`")
def where_points(self, object_name):
print(f"Object `{object_name}` points to the {self.instance_id} instance")
s_A = Singleton("first")
s_A.where_points("s_A")
s_B = Singleton()
s_B.where_points("s_B")
Singleton().destroy_singleton()
s_C = Singleton("second")
s_C.where_points("s_C")
# Created a first instance of `Singleton`
# Object `s_A` points to the first instance
# Object `s_B` points to the first instance
# Created a second instance of `Singleton`
# Object `s_C` points to the second instance
The class method ``destroy`` of SingletonMeta can be invoked to destroy all the
Singleton classes at once. As a further alternative to the instance call
``destroy_singleton``, the names of the Singleton classes to destroy can be
passed to the class method ``destroy``:
.. code:: python
Singleton().destroy_singleton() # Destroy only `Singleton`
SingletonMeta.destroy() # Destroy all the singleton classes
SingletonMeta.destroy('Singleton1', 'Singleton2', 'Singleton3') # Destroy selectively
Importing classes dynamically
-----------------------------
Classes can be imported dynamically using the package/class names or the path in
dot-notation as shown below:
.. code:: python
from dyndesign import importclass
ClassA = importclass('package_A', 'ClassA')
ClassB = importclass('directory_B.package_B.ClassB')
Running tests
--------------
To run the tests using your default python:
::
pip install -U pytest
python3 -m pytest test
.. |Build Status| image:: https://github.com/amarula/dyndesign/actions/workflows/python-app.yml/badge.svg
:target: https://github.com/amarula/dyndesign/actions
.. |Python Version Status| image:: https://img.shields.io/badge/python-3.8_3.9_3.10_3.11-blue.svg
:target: https://github.com/amarula/dyndesign/actions
.. |PyPi Version Status| image:: https://badge.fury.io/py/dyndesign.svg
:target: https://badge.fury.io/py/dyndesign
.. |License| image:: https://img.shields.io/badge/License-MIT-yellow.svg
:target: https://opensource.org/licenses/MIT
زبان مورد نیاز
| مقدار | نام |
|---|---|
| >=3.8,<4.0 | Python |
نحوه نصب
نصب پکیج whl dyndesign-0.9.7:
pip install dyndesign-0.9.7.whl
نصب پکیج tar.gz dyndesign-0.9.7:
pip install dyndesign-0.9.7.tar.gz