Hướng dẫn wrapper class python - lớp bao bọc trăn

Cải thiện bài viết

Lưu bài viết

Cải thiện bài viết

Lưu bài viết

Đọc is a way to specify management code for functions and classes. Decorators themselves take the form of callable objects that process other callable objects. A Class Decorator is similar to function decorators, but they are run at the end of a class statement to rebind a class name to a callable [e.g functions]. As such, they can be used to either manage classes just after they are created or insert a layer of wrapper logic to manage instances when they are later created. Class decorator can be used to manage class object directly, instead of instance calls – to increase/modify a class with new methods. Class decorators are strongly related to function decorators, in fact, they use nearly the same syntax and very similar coding pattern but somewhere logic differs.

Bàn luận For more information, refer to Decorators in Python

Trang trí là một cách để chỉ định mã quản lý cho các chức năng và lớp học. Bản thân các nhà trang trí ở dạng các đối tượng có thể gọi được xử lý các đối tượng có thể gọi khác. Một người trang trí lớp tương tự như các nhà trang trí chức năng, nhưng chúng được chạy ở cuối một câu lệnh lớp để viết lại một tên lớp thành một có thể gọi được [ví dụ: các chức năng]. Do đó, chúng có thể được sử dụng để quản lý các lớp ngay sau khi chúng được tạo hoặc chèn một lớp logic bao bọc để quản lý các phiên bản khi chúng được tạo sau đó. Trình trang trí lớp có thể được sử dụng để quản lý trực tiếp đối tượng lớp, thay vì các cuộc gọi ví dụ - để tăng/sửa đổi một lớp bằng các phương thức mới. Các nhà trang trí lớp có liên quan mạnh mẽ đến các bộ trang trí chức năng, trên thực tế, họ sử dụng gần như cùng một cú pháp và mẫu mã hóa rất giống nhau nhưng ở đâu đó logic khác nhau.
Syntactically, class decorators appear just before class statements.

@decorator
class Class_Name:       
      ...

inst = Class_Name[50]

This piece of code is equivalent to

class Class_Name:
      ...

Class_Name = decorator[Class_Name]
inst = Class_Name[50];

Lưu ý: Để biết thêm thông tin, hãy tham khảo các nhà trang trí trong Python

Example:

Cú pháp: Cú pháp, trang trí lớp xuất hiện ngay trước các tuyên bố của lớp.

Hãy để hiểu về cú pháp và cách thức hoạt động của nó với một ví dụ:

def scope_test[]:
    def do_local[]:
        spam = "local spam"

    def do_nonlocal[]:
        nonlocal spam
        spam = "nonlocal spam"

    def do_global[]:
        global spam
        spam = "global spam"

    spam = "test spam"
    do_local[]
    print["After local assignment:", spam]
    do_nonlocal[]
    print["After nonlocal assignment:", spam]
    do_global[]
    print["After global assignment:", spam]

scope_test[]
print["In global scope:", spam]

def scope_test[]:
    def do_local[]:
        spam = "local spam"

    def do_nonlocal[]:
        nonlocal spam
        spam = "nonlocal spam"

    def do_global[]:
        global spam
        spam = "global spam"

    spam = "test spam"
    do_local[]
    print["After local assignment:", spam]
    do_nonlocal[]
    print["After nonlocal assignment:", spam]
    do_global[]
    print["After global assignment:", spam]

scope_test[]
print["In global scope:", spam]

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

def scope_test[]:
    def do_local[]:
        spam = "local spam"

    def do_nonlocal[]:
        nonlocal spam
        spam = "nonlocal spam"

    def do_global[]:
        global spam
        spam = "global spam"

    spam = "test spam"
    do_local[]
    print["After local assignment:", spam]
    do_nonlocal[]
    print["After nonlocal assignment:", spam]
    do_global[]
    print["After global assignment:", spam]

scope_test[]
print["In global scope:", spam]

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

class ClassName:
    
    .
    .
    .
    

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

class ClassName:
    
    .
    .
    .
    

class ClassName:
    
    .
    .
    .
    

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

class ClassName:
    
    .
    .
    .
    

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

def scope_test[]:
    def do_local[]:
        spam = "local spam"

    def do_nonlocal[]:
        nonlocal spam
        spam = "nonlocal spam"

    def do_global[]:
        global spam
        spam = "global spam"

    spam = "test spam"
    do_local[]
    print["After local assignment:", spam]
    do_nonlocal[]
    print["After nonlocal assignment:", spam]
    do_global[]
    print["After global assignment:", spam]

scope_test[]
print["In global scope:", spam]

class ClassName:
    
    .
    .
    .
    

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

class MyClass:
    """A simple example class"""
    i = 12345

    def f[self]:
        return 'hello world'

class ClassName:
    
    .
    .
    .
    

class MyClass:
    """A simple example class"""
    i = 12345

    def f[self]:
        return 'hello world'

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

class MyClass:
    """A simple example class"""
    i = 12345

    def f[self]:
        return 'hello world'

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

class MyClass:
    """A simple example class"""
    i = 12345

    def f[self]:
        return 'hello world'

class MyClass:
    """A simple example class"""
    i = 12345

    def f[self]:
        return 'hello world'

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

def __init__[self]:
    self.data = []

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

def scope_test[]:
    def do_local[]:
        spam = "local spam"

    def do_nonlocal[]:
        nonlocal spam
        spam = "nonlocal spam"

    def do_global[]:
        global spam
        spam = "global spam"

    spam = "test spam"
    do_local[]
    print["After local assignment:", spam]
    do_nonlocal[]
    print["After nonlocal assignment:", spam]
    do_global[]
    print["After global assignment:", spam]

scope_test[]
print["In global scope:", spam]

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

def __init__[self]:
    self.data = []

>>> class Complex:
...     def __init__[self, realpart, imagpart]:
...         self.r = realpart
...         self.i = imagpart
...
>>> x = Complex[3.0, -4.5]
>>> x.r, x.i
[3.0, -4.5]

>>> class Complex:
...     def __init__[self, realpart, imagpart]:
...         self.r = realpart
...         self.i = imagpart
...
>>> x = Complex[3.0, -4.5]
>>> x.r, x.i
[3.0, -4.5]

OUTPUT:

Geeks

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

After local assignment: test spam
After nonlocal assignment: nonlocal spam
After global assignment: nonlocal spam
In global scope: global spam

def __init__[self]:
    self.data = []

class ClassName:
    
    .
    .
    .
    

>>> class Complex:
...     def __init__[self, realpart, imagpart]:
...         self.r = realpart
...         self.i = imagpart
...
>>> x = Complex[3.0, -4.5]
>>> x.r, x.i
[3.0, -4.5]

>>> class Complex:
...     def __init__[self, realpart, imagpart]:
...         self.r = realpart
...         self.i = imagpart
...
>>> x = Complex[3.0, -4.5]
>>> x.r, x.i
[3.0, -4.5]

class ClassName:
    
    .
    .
    .
    

>>> class Complex:
...     def __init__[self, realpart, imagpart]:
...         self.r = realpart
...         self.i = imagpart
...
>>> x = Complex[3.0, -4.5]
>>> x.r, x.i
[3.0, -4.5]

>>> class Complex:
...     def __init__[self, realpart, imagpart]:
...         self.r = realpart
...         self.i = imagpart
...
>>> x = Complex[3.0, -4.5]
>>> x.r, x.i
[3.0, -4.5]

>>> class Complex:
...     def __init__[self, realpart, imagpart]:
...         self.r = realpart
...         self.i = imagpart
...
>>> x = Complex[3.0, -4.5]
>>> x.r, x.i
[3.0, -4.5]