Python：如何测试潜在的变量名是否在名称空间中？

Question

如何测试潜在变量名列表中的哪些元素位于命名空间中？我应该把它们初始化为“无”吗？或者它们是更好的方法吗？你知道吗

# Potential list. Won't work, will give NameError if one of them is not in the namespace
all_vars = [rds.rclass, \
           rds.rlevel, \
           rds.seg \] # the list is actually much longer

#Could do:
all_vars =[]
try:
   all_vars.append(rds.rclass)
except NameError:
   pass
....

#or as initially said:
rds.rclass = rds.rlevel = ... = None

还有别的（更好的）办法吗？你知道吗

Answer 1

很可怕，但这应该管用：

all_vars = locals().get('all_vars', [])