[英]What is the correct way of duplicating base class '__init__' signature in Python?
[英]correct way to extend __init__ in python 3 from parent class
一般问题 :什么是最简单/“最pythonic”的方式初始化子类与其父类完全相同,但添加单个属性?
我的具体问题:我想扩展一个( Urwid ) Edit
对象以包含一个附加属性my_attribute
; 我已将原始签名复制到__init__
和super().__init__
,但签名中有一些未定义的参数/常量( LEFT
, SPACE
),我不明白它们是如何在父类中设置的。 下面是我的(破碎)类定义和父init方法:
class MyEdit(urwid.Edit):
def __init__(self, my_attribute, caption="", edit_text="", multiline=False, align=LEFT, wrap=SPACE, allow_tab=False, edit_pos=None, layout=None, mask=None):
super().__init__(caption="", edit_text="", multiline=False, align=LEFT, wrap=SPACE, allow_tab=False, edit_pos=None, layout=None, mask=None)
self.my_attribute = []
# super().__super.__init__("", align, wrap, layout)
def my_method(self):
#some code that modifies my_attribute
return self.my_attribute
class Edit(Text):
"""
Text editing widget implements cursor movement, text insertion and
deletion. A caption may prefix the editing area. Uses text class
for text layout.
Users of this class to listen for ``"change"`` events
sent when the value of edit_text changes. See :func:``connect_signal``.
"""
# (this variable is picked up by the MetaSignals metaclass)
signals = ["change"]
def valid_char(self, ch):
"""
Filter for text that may be entered into this widget by the user
:param ch: character to be inserted
:type ch: bytes or unicode
This implementation returns True for all printable characters.
"""
return is_wide_char(ch,0) or (len(ch)==1 and ord(ch) >= 32)
def selectable(self): return True
def __init__(self, caption="", edit_text="", multiline=False,
align=LEFT, wrap=SPACE, allow_tab=False,
edit_pos=None, layout=None, mask=None):
"""
:param caption: markup for caption preceeding edit_text, see
:class:`Text` for description of text markup.
:type caption: text markup
:param edit_text: initial text for editing, type (bytes or unicode)
must match the text in the caption
:type edit_text: bytes or unicode
:param multiline: True: 'enter' inserts newline False: return it
:type multiline: bool
:param align: typically 'left', 'center' or 'right'
:type align: text alignment mode
:param wrap: typically 'space', 'any' or 'clip'
:type wrap: text wrapping mode
:param allow_tab: True: 'tab' inserts 1-8 spaces False: return it
:type allow_tab: bool
:param edit_pos: initial position for cursor, None:end of edit_text
:type edit_pos: int
:param layout: defaults to a shared :class:`StandardTextLayout` instance
:type layout: text layout instance
:param mask: hide text entered with this character, None:disable mask
:type mask: bytes or unicode
>>> Edit()
<Edit selectable flow widget '' edit_pos=0>
>>> Edit("Y/n? ", "yes")
<Edit selectable flow widget 'yes' caption='Y/n? ' edit_pos=3>
>>> Edit("Name ", "Smith", edit_pos=1)
<Edit selectable flow widget 'Smith' caption='Name ' edit_pos=1>
>>> Edit("", "3.14", align='right')
<Edit selectable flow widget '3.14' align='right' edit_pos=4>
"""
self.__super.__init__("", align, wrap, layout)
self.multiline = multiline
self.allow_tab = allow_tab
self._edit_pos = 0
self.set_caption(caption)
self.set_edit_text(edit_text)
if edit_pos is None:
edit_pos = len(edit_text)
self.set_edit_pos(edit_pos)
self.set_mask(mask)
self._shift_view_to_cursor = False
你不要使用这些变量,所以只是盲目地通过它们。
class MyEdit(urwid.Edit):
def __init__(self, my_attribute, *args, **kw):
super().__init__(*args, **kw)
self.my_attribute = []
def my_method(self):
#some code that modifies my_attribute
return self.my_attribute
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