Question

在阅读了一些关于在python下创建文件的文本之后，我决定创建这个类，它在目录上创建一个新文件，如果文件已经存在，则在另一个目录上创建备份（如果它早于x小时））

我打开这个问题的主要原因是要知道这是否是使用try / except正确编写类的正确方法，因为实际上我对使用try / except的偏好有点困惑，如果/ elses

贝娄，工作范例：

import os
import datetime


class CreateXML():
    def __init__(self, path, filename):
        self.path = path
        self.bkp_path = "%s\\backup" % path
        self.filename = filename
        self.bkp_file = "%s.previous" % filename
        self.create_check = datetime.datetime.now()-datetime.timedelta(hours=-8)

    @staticmethod
    def create_dir(path):
        try:
            os.makedirs(path)
            return True
        except:
            return False

    @staticmethod
    def file_check(file):
        try:
            open(file)
            return True
        except:
            return False

    def create_file(self, target_dir, target_file):
        try:
            target = "%s\\%s" % (target_dir, target_file)
            open(target, 'w')
        except:
            return False

    def start_creation(self):
        try:
            # Check if file exists
            if self.file_check("%s\\%s" % (self.path, self.filename)):
                self.create_dir(self.bkp_path)
                creation = os.path.getmtime("%s\\%s" % (self.path, self.filename))
                fcdata = datetime.datetime.fromtimestamp(creation)
                # File exists and its older than 8 hours
                if fcdata < self.create_check:
                    bkp_file_path = "%s\\%s " % (self.bkp_path, self.bkp_file)
                    new_file_path = "%s\\%s " % (self.path, self.filename)
                    # If backup file exists, erase current backup file
                    # Move existing file to backup and create new file.
                    if self.file_check("%s\\%s" % (self.bkp_path, self.bkp_file)):
                        os.remove(bkp_file_path)
                        os.rename(new_file_path, bkp_file_path)
                        self.create_file(self.bkp_path, self.bkp_file)
                    #No backup file, create new one.
                    else:
                        self.create_file(self.bkp_path, self.bkp_file)
            else:
                # Fresh creation
                self.create_dir(self.path)
                self.create_file(self.path, self.filename)
        except OSError, e:
            print e
if __name__ == '__main__':
    path = 'c:\\tempdata'
    filename = 'somefile.txt'
    cx = CreateXML(path, filename)
    cx.start_creation()

所以，基本上真正的问题是：

- 通过上面的例子，try / except的用法是否正确？

- 使用try / except执行验证是否正确，以检查文件或目录是否已存在？而是使用像这样的简化版本：

import os
# Simple method of doing it
path = 'c:\\tempdata'
filename = 'somefile.txt'
bkp_path = 'c:\\tempdata\\backup'
bkp_file = 'somefile.txt.bkp'
new_file_path = "%s\\%s" % (path, filename)
bkp_file_path = "%s\\%s" % (bkp_path, bkp_file)

if not os.path.exists(path):
    print "create path"
    os.makedirs(bkp_path)
if not os.path.isfile(new_file_path):
    print "create new file"
    open(new_file_path, 'w')
else:
    print"file exists, moving to backup folder"
    #check if backup file exists
    if not os.path.isfile(bkp_file_path):
        print "New backup file created"
        open(bkp_file_path, 'w')
    else:
        print "backup exists, removing backup, backup the current, and creating newfile"
        os.remove(bkp_file_path)
        os.rename(new_file_path, bkp_file_path)
        open(bkp_file_path, 'w')

- 如果try / except的用法是正确的，那么如果有可能写一个简短的版本，它会建议写一个大类来创建一个文件吗？

请不要关闭这个步骤，因为我真的很困惑“最正确的pythonic方式”。

提前致谢。

用于文件创建和目录验证的类

0 个答案: