[英]How can i improve the readablility of nested if and for statements
I have got a very nasty piece of code i would like to refactor but i've because its getting totaly unreadable.我有一段非常讨厌的代码,我想重构,但我已经这样做了,因为它变得完全不可读。
for region in feed['config']['regions']:
if region['region'] == region_name:
for instance_type in region['instanceTypes']:
if instance_type['type'] == instance_type_name:
for instance_size in instance_type['sizes']:
if instance_size['size'] == instance_size_name:
for platform in instance_size['valueColumns']:
if platform['name'] == platform_name:
prices = platform['prices']
assert prices.keys() == ['USD']
return decimal.Decimal(prices['USD'])
assert False, "Failed to determine price for instance with region=%r, type=%r, size=%r, platform=%r" % \
(region_name, instance_type_name, instance_size_name, platform_name)
I've tought about using functions with each loop or if statement but that will give me a load of functions.我一直在努力在每个循环或 if 语句中使用函数,但这会给我一大堆函数。 Are there beter solutions?
有更好的解决方案吗?
try:
region = [r for r in feed['config']['regions'] if region['region'] == region_name][0]
instance_type = [t for t in region['instanceTypes'] if i['type'] == instance_type_name][0]
# ...
return decimal.Decimal(prices['USD'])
except IndexError:
raise Exception("Failed to determine price for instance with region=%r, type=%r, size=%r, platform=%r" %
(region_name, instance_type_name, instance_size_name, platform_name))
or one step farther:或更进一步:
def filter_by_key(key, value, objects):
return [o for o in objects if region[key] == value][0]
try:
region = filter_by_key('region', region_name, feed['config']['regions'])
instance_type = filter_by_key('type', instace_type_name, region['instanceTypes'])
# ...
return decimal.Decimal(prices['USD'])
except IndexError:
raise Exception("Failed to determine price for instance with region=%r, type=%r, size=%r, platform=%r" %
(region_name, instance_type_name, instance_size_name, platform_name))
If you wanted to keep it in a loop you could use continue
to save indents:如果你想让它保持循环,你可以使用
continue
来保存缩进:
for region in feed['config']['regions']:
if region['region'] != region_name: continue
for instance_type in region['instanceTypes']:
if instance_type['type'] != instance_type_name: continue
for instance_size in instance_type['sizes']:
if instance_size['size'] != instance_size_name: continue
for platform in instance_size['valueColumns']:
if platform['name'] != platform_name: continue
prices = platform['prices']
assert prices.keys() == ['USD']
return decimal.Decimal(prices['USD'])
assert False, "Failed to determine price for instance with region=%r, type=%r, size=%r, platform=%r" % \
(region_name, instance_type_name, instance_size_name, platform_name)
Or with list comprehensions:或者使用列表理解:
regions = (r for r in feed['config']['regions'] if r['region'] == region_name)
instance_types = (i for i in r['instanceTypes'] for r in regions if i['type'] == instance_type_name)
instance_sizes = (i for i in t['sizes'] for t in instance_types if i['size'] == instance_size_name)
platforms = (p for p in s['valueColumns'] for s in instance_sizes if p['name'] == platform_name)
for platform in platforms:
prices = platform['prices']
assert prices.keys() == ['USD']
return decimal.Decimal(prices['USD'])
assert False, "Failed to determine price for instance with region=%r, type=%r, size=%r, platform=%r" % \
(region_name, instance_type_name, instance_size_name, platform_name)
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.