有没有办法在不影响代码的情况下缩进 Python

Question

我正在尝试在 Maya 中编写一个用户界面，它变得令人难以置信地混淆了多个级别的父级并且没有缩进。基本代码（没有任何功能）目前大约有 400 行，需要一段时间才能找到我需要的部分。

例如，下面这段代码没有注释：

#Earlier user interface

py.rowColumnLayout( numberOfColumns = 5 )
py.text( label="", width = 1 )
py.text( label="Column 1", enable = False, width = 250 )
py.text( label="", width = 1 )
py.text( label="Column 2" enable = False, width = 250 )
py.text( label="", width = 1 )

py.text( label="" )
py.rowColumnLayout( numberOfColumns = 4 )
py.text( label="   Input data:", align="left" )
py.text( label="" )
py.text( label="" )
py.text( label="" )
py.textField( text = "Text here" )
py.text( label="" )
py.text( label="" )
py.text( label="" )
py.setParent( ".." )

py.text( label="" )
py.rowColumnLayout( numberOfColumns = 4 )
py.rowColumnLayout( numberOfColumns = 5 )
py.radioButton( label = "Read file from path", width = 100 )
py.text( label="" )
py.button( label = "Browse" )
py.text( label="" )
py.button( label = "Validate" )
py.setParent( ".." )
py.text( label="" )
py.text( label="" )
py.text( label="" )
py.setParent( ".." )
py.setParent( ".." )

但是，这是缩进后的样子

py.rowColumnLayout( numberOfColumns = 5 )
    py.text( label="", width = 1 )
    py.text( label="Column 1", enable = False, width = 250 )
    py.text( label="", width = 1 )
    py.text( label="Column 2" enable = False, width = 250 )
    py.text( label="", width = 1 )

    py.text( label="" )
    py.rowColumnLayout( numberOfColumns = 4 )
        py.text( label="   Input data:", align="left" )
        py.text( label="" )
        py.text( label="" )
        py.text( label="" )
        py.textField( text = "Text here" )
        py.text( label="" )
        py.text( label="" )
        py.text( label="" )
        py.setParent( ".." )

    py.text( label="" )
    py.rowColumnLayout( numberOfColumns = 4 )
        py.rowColumnLayout( numberOfColumns = 5 )
            py.radioButton( label = "Read file from path", width = 100 )
            py.text( label="" )
            py.button( label = "Browse" )
            py.text( label="" )
            py.button( label = "Validate" )
            py.setParent( ".." )
        py.text( label="" )
        py.text( label="" )
        py.text( label="" )
        py.setParent( ".." )
    py.setParent( ".." )

有没有什么办法可以让我用缩进来编写它，但让它在执行时忽略它们？我看到这个问题问你是否可以写 python 没有缩进，但我有点需要相反的东西。

注意：某些 py.* 函数的输出值也需要分配给变量，只是尚未分配给变量，因为布局需要先排序。

Answer 1

创建另一个程序来解析和执行您的 script.py:

parse.py

text = open('script.py').readlines()
text = [i.strip() for i in text]

edit = open('new.py', 'w')
for line in text:
    edit.write(line + '\n')
edit.close()

execfile('new.py')

此文件创建了一个修改后的 new.py，它将被执行。

Answer 2

您可以在执行代码行之前对其进行预处理，如图所示：

mycode = """\
    print "something"
        print "something else"
      print 42
    """

exec('\n'.join(line.lstrip() for line in mycode.splitlines()))

输出：

something
something else
42

甚至可以做成"one-liner":

exec('\n'.join(line.lstrip() for line in """\
    print "something"
        print "something else"
      print 42
    """.splitlines()))

您可以通过这种方式将代码保存在一个单独的文件中（这将使您的编辑器能够对其进行语法分析）：

文件mycode.py:

print "something"
    print "something else"
  var = 42

独立文件版本：

with open('mycode.py') as code:
    exec(''.join(line.lstrip() for line in code))
print 'var:', var

输出：

something
something else
var: 42

警告：我应该指出，这些都删除了每行的 all 缩进，这会弄乱任何多行 Python 代码（比如 if/else) 遇到——这可能会限制它的用处，具体取决于你在做什么。

Answer 3

我能想到两种可能性，允许您直接编写代码而不必从文本中解析它（语法着色完整，没有临时文件）。

第一个是在每行的开头加上一个老生常谈的前缀，就像上面建议的 if True: 或者，等效地，可能是这样的：

# ...

if 'level 1':  a = py.text( label="" )
if 'level 2':      b = py.rowColumnLayout( numberOfColumns = 4 )
if 'level 3':          c = py.rowColumnLayout( numberOfColumns = 5 )
if 'level 4':              d = py.radioButton( label = "Read file from path", width = 100 )

# ...

如果您不使用计算结果为 False 的字符串（如 ''），您可以将这些字符串用作注释，以帮助您记住您正在构建的 GUI 的哪一部分在任何给定的行上（当然，用适当数量的空格填充以确保事情仍然排成一行）。

第二个想法是创建一个包含可调用对象及其参数的容器列表，根据需要格式化该列表，并在最后执行每个容器：

objects = {}
commands = [

    # ...

    dict( name = 'spam', func = py.text, label="" ),
    dict( name = 'ham', func = py.rowColumnLayout, numberOfColumns = 4 ),
        dict( name = 'eggs', func = py.rowColumnLayout, numberOfColumns = 5 ),
            dict( name = 'beans', func = py.radioButton, label = "Read file from path", width = 100 ),

    # ...
]

for d in commands:
    objects[ d.pop( 'name' ) ] = d.pop( 'func' )( **d )

Answer 4

使用声明式方法：

interface = [
  [py.rowColumnLayout, [], dict(numberOfColumns=5)],
     [py.text, [], dict(label="", width=1)],
     [py.text, [], dict(label="Column 1", enable=False, width=250)],
     ...
     [py.setParent, [".."], {}],
]    

for callable, args, kwargs in interface:
    callable(*args, **kwargs)

() 或 [] 内的缩进无关紧要，因此您可以随意组织行。

Answer 5

这是像我们这样的技术艺术家在 Maya 中构建 UI 时每天都会遇到的一个很好的用例。

基于 PyMEL UI:

这是内置于 PyMEL 中的。您不必创建上下文管理器。布局命令本身就是上下文管理器。您只需在每个布局命令调用之前添加一个 with 关键字，如下所示：

# Do this when using PyMEL for your UI code
import pymel.core as pm

# ...

with pm.rowColumnLayout( numberOfColumns = 5 ):
    pm.text( label="", width = 1 )
    pm.text( label="Column 1", enable = False, width = 250 )
    pm.text( label="", width = 1 )
    pm.text( label="Column 2", enable = False, width = 250 )
    pm.text( label="", width = 1 )

    pm.text( label="" )

    with pm.rowColumnLayout( numberOfColumns = 4 ):
        pm.text( label="   Input data:", align="left" )
        pm.text( label="" )
        pm.text( label="" )
        pm.text( label="" )
        pm.textField( text = "Text here" )
        pm.text( label="" )
        pm.text( label="" )
        pm.text( label="" )        

    pm.text( label="" )
    with pm.rowColumnLayout( numberOfColumns = 4 ):
        with pm.rowColumnLayout( numberOfColumns = 5 ):
            pm.radioButton( label = "Read file from path", width = 100 )
            pm.text( label="" )
            pm.button( label = "Browse" )
            pm.text( label="" )
            pm.button( label = "Validate" )

        pm.text( label="" )
        pm.text( label="" )
        pm.text( label="" )

基于maya.cmds UI:

一个快速的解决方案是制作一个虚拟上下文管理器。你可以这样做

# Do this when using Maya's cmds for your UI code
import maya.cmds as cmds

# ...

from contextlib import contextmanager
@contextmanager
def neat_indent():
    # OPTIONAL: This is also an opportunity to do something before the block of code runs!
    try:
        # During this is where your indented block will execute
        # Leave it empty
        yield
    finally:
        # OPTIONAL: This is where you can write code that executes AFTER your indented block executes.
        pass

这样您的代码就不必更改太多。只需在每个预期缩进的开头添加带有 with 关键字的上下文管理器函数！

cmds.rowColumnLayout( numberOfColumns = 5 )
with neat_indent():
    cmds.text( label="", width = 1 )
    cmds.text( label="Column 1", enable = False, width = 250 )
    cmds.text( label="", width = 1 )
    cmds.text( label="Column 2", enable = False, width = 250 )
    cmds.text( label="", width = 1 )

    cmds.text( label="" )

    cmds.rowColumnLayout( numberOfColumns = 4 )
    with neat_indent():
        cmds.text( label="   Input data:", align="left" )
        cmds.text( label="" )
        cmds.text( label="" )
        cmds.text( label="" )
        cmds.textField( text = "Text here" )
        cmds.text( label="" )
        cmds.text( label="" )
        cmds.text( label="" )
        cmds.setParent( ".." )

    cmds.text( label="" )
    cmds.rowColumnLayout( numberOfColumns = 4 )
    with neat_indent():
        cmds.rowColumnLayout( numberOfColumns = 5 )
        with neat_indent():
            cmds.radioButton( label = "Read file from path", width = 100 )
            cmds.text( label="" )
            cmds.button( label = "Browse" )
            cmds.text( label="" )
            cmds.button( label = "Validate" )
            cmds.setParent( ".." )
        cmds.text( label="" )
        cmds.text( label="" )
        cmds.text( label="" )
        cmds.setParent( ".." )
    cmds.setParent( ".." )

我们创建的上下文管理器 neat_indent() 还让您有机会编写封装缩进块的代码。这里的一个实际例子是，在每个缩进的末尾，你发现自己写着 py.setParent("..")。您可以将其放入上下文管理器的 finally 部分：

from contextlib import contextmanager
@contextmanager
def neat_indent(parent=None):
    # OPTIONAL: This is also an opportunity to do something before the block of code runs!
    try:
        # During this is where your indented block will execute
        # Leave it empty
        yield
    finally:
        # OPTIONAL: This is where you can write code that executes AFTER your indented block executes.
        if parent:
            cmds.setParent(parent)

您的代码现在会更有意义：

cmds.rowColumnLayout( numberOfColumns = 5 )
with neat_indent(".."):
    cmds.text( label="", width = 1 )
    cmds.text( label="Column 1", enable = False, width = 250 )
    cmds.text( label="", width = 1 )
    cmds.text( label="Column 2", enable = False, width = 250 )
    cmds.text( label="", width = 1 )

    cmds.text( label="" )

    cmds.rowColumnLayout( numberOfColumns = 4 )
    with neat_indent(".."):
        cmds.text( label="   Input data:", align="left" )
        cmds.text( label="" )
        cmds.text( label="" )
        cmds.text( label="" )
        cmds.textField( text = "Text here" )
        cmds.text( label="" )
        cmds.text( label="" )
        cmds.text( label="" )        

    cmds.text( label="" )
    cmds.rowColumnLayout( numberOfColumns = 4 )
    with neat_indent(".."):
        cmds.rowColumnLayout( numberOfColumns = 5 )
        with neat_indent(".."):
            cmds.radioButton( label = "Read file from path", width = 100 )
            cmds.text( label="" )
            cmds.button( label = "Browse" )
            cmds.text( label="" )
            cmds.button( label = "Validate" )

        cmds.text( label="" )
        cmds.text( label="" )
        cmds.text( label="" )

上下文管理器很强大。在这个 post 中，我使用了 contextlib 标准库模块中的 contextmanager 装饰器。您可以阅读有关此技术的信息 here. About with in general here。

此外，正是出于这个目的（目的之一），使 UI 在 Maya 中的开发更清洁和更 Pythonic @theodox 创建了 mGui 模块。看看吧。

Answer 6

@Kartik 的回答很好地涵盖了基础。我要指出的是，您可以通过允许上下文管理器在线声明布局（rowLayout、columnLayout 等）来进一步清理布局代码，这使它变得更加容易：

class uiCtx(object):
   '''
   quickie layouthelper: automatically setParents after a layout is finished
   '''
   def __init__(self, uiClass, *args, **kwargs):
        self.Control = uiClass(*args, **kwargs)

    def __enter__(self):
        return self

    def __exit__(self, tb, val, traceback):
        cmds.setParent("..")

    def __repr__(self):
        return self.Control

会在遇到时调用 maya.cmds 布局函数，然后在缩进块的末尾关闭父级，因此您可以像此代码段中一样进行布局调用

    with uiCtx(cmds.rowLayout, **layout_options) as widget:
        self.Toggle = cmds.checkBox('', v = self.Module.enabled, cc = self._state_changed)
        with uiCtx(cmds.columnLayout, w=self.COLUMNS[1], cal='left') as details:
            cmds.text(l = self.ModuleKey, fn = "boldLabelFont")
            cmds.text(l = self.Module.path, fn = "smallObliqueLabelFont")
        cmds.button("edit",  c=self._edit)
        cmds.button("show", c=self._show)
    return widget

将 __repr__ 添加到 uiCtx 后，您就可以像普通 Maya 布局命令那样将其视为返回字符串，因此在该示例中可以查询 'widget'通常的方式。

整个就是up on GitHub to see it in context. As Kartik also pointed out there's a more elaborate declarative UI option in the form of mGui，实际上是这样的：

with gui.Window('window', title = 'fred') as example_window:
    with BindingContext() as bind_ctx:
        with VerticalForm('main') as main:
            Text(None, label = "The following items don't have vertex colors")
            lists.VerticalList('lister' ).Collection < bind() < bound  
            with HorizontalStretchForm('buttons'):
                Button('refresh', l='Refresh')
                Button('close', l='Close')

# show the window
example_window.show()

还有一些 maya 布局相关信息 here

Answer 7

我已经用了很多年了，效果非常好：

if True:
    # Indented code.
    print("This entire code block is indented.")

有没有办法在不影响代码的情况下缩进 Python

Is there a way to indent Python without affecting the code

python

maya

pymel

基于 PyMEL UI:

基于maya.cmds UI: