PYTHON索引器错误：元组索引超出范围

Question

非常感谢您对这个问题的反馈

import subprocess

def main():
'''
Here's where the whole thing starts.
'''
#Edit this constant to change the file name in the git log command.
FILE_NAME = 'file1.xml'

#Do the git describe command to get the tag names.
gitDescribe = 'git describe --tags `git rev-list --tags --max-count=2`'
print ('Invoking: {0}'.format(gitDescribe))
p1 = subprocess.Popen(gitDescribe, shell=True, stdout=subprocess.PIPE)
output = p1.stdout.read()

#Get the first 2 tags from the output.
parsedOutput = output.split('\n')
tag1 = parsedOutput[0]
tag2 = parsedOutput[1]

print('First revision: {0}'.format(tag1))
print('Second revision: {1}'.format(tag2))
#Do the git log command for the revision comparison.
gitLog = 'git log {0}..{1} --pretty=format:"%an %h %ad %d %s" --date=short --topo-order --no-merges {2}'.format(tag1, tag2, FILE_NAME)
print('Invoking: {0}'.format(gitLog))
p2 = subprocess.Popen(gitLog, shell=True, stdout=subprocess.PIPE)
output = p2.stdout.read()
print(output)

if __name__ == "__main__":
    main()

。。。

bash-3.2$ python pygit5.py 
Invoking: git describe --tags `git rev-list --tags --max-count=2`

First revision: 14.5.5.1
Traceback (most recent call last):
File "pygit5.py", line 31, in <module>
main()
File "pygit5.py", line 22, in main
print('Second revision: {1}'.format(tag2))
IndexError: tuple index out of range

Answer 1

在使用现有格式时，请记住，在大多数编程语言中，计数从零开始。因此，由于tag2只携带一个值，因此以下行：

print('Second revision: {1}'.format(tag2))

应该是：

print('Second revision: {0}'.format(tag2))

如果使用Python2.7+，对于简单脚本，也可以将其保留为空：

print('Second revision: {}'.format(tag2))

或者以任何顺序为它们提供命名变量：

print('Second revision: {revisiontag}'.format(revisiontag=tag2))

Answer 2

tag2只是一个值，比如tag1，所以不能引用项[1]。毫无疑问你是说

print('Second revision: {0}'.format(tag2))