Python内置（3）exec&eval、globals&locals、input&print、5个基本类型、object

x = [1, 2]
print(x)

>>> code = '''
... x = [1, 2]
... print(x)
... '''
>>> exec(code)

>>> x = 5
>>> exec('print(x)')
5

>>> import ast
>>> code = '''
... x = [1, 2]
... print(x)
... '''
>>> tree = ast.parse(code)
>>> print(ast.dump(tree, indent=2))

Module(
  body=[
    Assign(
      targets=[
        Name(id='x', ctx=Store())],
      value=List(
        elts=[
          Constant(value=1),
          Constant(value=2)],
        ctx=Load())),
    Expr(
      value=Call(
        func=Name(id='print', ctx=Load()),
        args=[
          Name(id='x', ctx=Load())],
        keywords=[]))],
  type_ignores=[])

>>> import ast
>>> code = '''
... x = [1, 2]
... print(x)
... '''
>>> tree = ast.parse(code)
>>> code_obj = compile(tree, 'myfile.py', 'exec')
>>> exec(code_obj)
[1, 2]

>>> code_obj.co_code
b'd\x00d\x01g\x02Z\x00e\x01e\x00\x83\x01\x01\x00d\x02S\x00'
>>> code_obj.co_filename
'myfile.py'
>>> code_obj.co_names
('x', 'print')
>>> code_obj.co_consts
(1, 2, None)

>>> import dis
>>> dis.dis('''
... x = [1, 2]
... print(x)
... ''')

>>> result = eval('1 + 1')
>>> result
2

>>> expr = ast.parse('1 + 1', mode='eval')
>>> code_obj = compile(expr, '<code>', 'eval')
>>> eval(code_obj)
2

def double(number):
    return number * 2

>>> value = 5
>>> def double(number):
...     return number * 2
...
>>> double(value)
10
>>> locals()
{'__name__': '__main__', '__doc__': None, '__package__': None,
'__loader__': <class '_frozen_importlib.BuiltinImporter'>, '__spec__': None,
'__annotations__': {}, '__builtins__': <module 'builtins' (built-in)>,
'value': 5, 'double': <function double at 0x7f971d292af0>}

magic_number = 42

def function():
    x = 10
    y = 20
    print(locals())
    print(globals())

print(*values, sep=' ', end='\n', file=sys.stdout, flush=False)

print(1,2,3,4, sep='\n')

>>> for i in range(10):
...     print(i, end='')

with open('myfile.txt', 'w') as f:
    print('Hello!', file=f)

>>> import sys
>>> print('Hello!')
Hello!
>>> 'Hello!\n'.encode()  # Produces bytes
b'Hello!\n'
>>> char_count = sys.stdout.buffer.write('Hello!\n'.encode())
Hello!
>>> char_count  # write() returns the number of bytes written to console
7

>>> import sys
>>> '🐍'.encode()
b'\xf0\x9f\x90\x8d'   # utf-8 encoded string of the snake emoji
>>> _ = sys.stdout.buffer.write(b'\xf0\x9f\x90\x8d')
🐍

>>> x = 5
>>> y = 5.0
>>> z = 5.0+0.0j
>>> type(x), type(y), type(z)
(<class 'int'>, <class 'float'>, <class 'complex'>)
>>> x == y == z  # All the same value
True
>>> y
5.0
>>> float(x)    # float(x) produces the same result as y
5.0
>>> z
(5+0j)
>>> complex(x)  # complex(x) produces the same result as z
(5+0j)

>>> int.mro()
[<class 'int'>, <class 'object'>]
>>> float.mro()
[<class 'float'>, <class 'object'>]
>>> complex.mro()
[<class 'complex'>, <class 'object'>]
>>> str.mro()
[<class 'str'>, <class 'object'>]
>>> bool.mro()
[<class 'bool'>, <class 'int'>, <class 'object'>]  # Look!

>>> import json
>>> data = {'a': 1, 'b': {'c': 2}}
>>> print(json.dumps(data))
{"a": 1, "b": {"c": 2}}
>>> print(json.dumps(data, indent=4))
{
    "a": 1,
    "b": {
        "c": 2
    }
}
>>> print(json.dumps(data, indent=True))
{
 "a": 1,
 "b": {
  "c": 2
 }
}

>>> dir(object)
['__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__',
'__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__',
'__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__',
'__setattr__', '__sizeof__', '__str__', '__subclasshook__']

>>> object()  # This creates an object with no properties
<object object at 0x7f47aecaf210>  # defined in __repr__()
>>> class dummy(object):
...     pass
>>> x = dummy()
>>> x
<__main__.dummy object at 0x7f47aec510a0>  # functionality inherited from object
>>> hash(object())
8746615746334
>>> hash(x)
8746615722250
>>> x.__hash__()  # is the same as hash(x)
8746615722250