本文介绍了Python 条件赋值运算符的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着跟版网的小编来一起学习吧！
问题描述
Does a Python equivalent to the Ruby ||= operator ("set the variable if the variable is not set") exist?
Example in Ruby :
variable_not_set ||= 'bla bla'
variable_not_set == 'bla bla'
variable_set = 'pi pi'
variable_set ||= 'bla bla'
variable_set == 'pi pi'
解决方案
No, the replacement is:
try:
v
except NameError:
v = 'bla bla'
However, wanting to use this construct is a sign of overly complicated code flow. Usually, you'd do the following:
try:
v = complicated()
except ComplicatedError: # complicated failed
v = 'fallback value'
and never be unsure whether v is set or not. If it's one of many options that can either be set or not, use a dictionary and its get method which allows a default value.
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