Alternatives to long if statement

问题

I currently have a long if statement, which looks ugly, and I'm fairly certain isn't proper. It looks something like this.

if self.folderactive.isChecked:
    folders.createDir('Desktop')
elif not self.folderactive.isChecked:
    folders.deleteDir('Desktop')

if self.folderactive_2.isChecked:
    folders.createDir('Documents')
elif not self.folderactive_2.isChecked:
    folders.deleteDir('Documents')

if self.folderactive_3.isChecked:
    folders.createDir('Downloads')
elif not self.folderactive_3.isChecked:
    folders.deleteDir('Downloads')

if self.folderactive_4.isChecked:
    folders.createDir('Music')
elif not self.folderactive_4.isChecked:
    folders.deleteDir('Music')

if self.folderactive_5.isChecked:
    folders.createDir('Pictures')
elif not self.folderactive_5.isChecked:
    folders.deleteDir('Pictures')

if self.folderactive_6.isChecked:
    folders.createDir('Public')
elif not self.folderactive_6.isChecked:
    folders.deleteDir('Public')

if self.folderactive_7.isChecked:
    folders.createDir('Templates')
elif not self.folderactive_7.isChecked:
    folders.deleteDir('Templates')

if self.folderactive_8.isChecked:
    folders.createDir('Videos')
elif not self.folderactive_8.isChecked:
    folders.deleteDir('Videos')

How would I go about simplifying this long list of conditionals?

回答1:

First, all elif ... clause can be written as else:.

Multiple if .. else .. can be expressed as for loop:

checkbox_directory_pairs = [
    (self.folderactive, 'Desktop'),
    (self.folderactive_2, 'Documents'),
    (self.folderactive_3, 'Downloads'),
    ...
]

for checkbox, directory in checkbox_directory_pairs:
    if checkbox.isChecked:
        folders.createDir(directory)
    else:
        folders.deleteDir(directory)

回答2:

First of all, you can simplify a statement like this:

if self.folderactive.isChecked:
    folders.createDir('Desktop')
elif not self.folderactive.isChecked:
    folders.deleteDir('Desktop')

if self.folderactive.isChecked:
    folders.createDir('Desktop')
else:
    folders.deleteDir('Desktop')

回答3:

You should use associative arrays: checkbox number as index, folder name as value.

来源：https://stackoverflow.com/questions/20455147/alternatives-to-long-if-statement

标签

python-2.7

if-statement

conditional