python - 如何创建多对多关系变量并提高代码可用性？

Question

我正在尝试创建一个通用实用程序，用于从源到目标的文件传输。参数分为 dir 和 filename，这是 os.path.dirname(some_file) 和 os.path 的结果.basename(some_file) 分别。如果不指定，目标文件名默认与源文件名相同。

我创建了一个脚本，至少可以完美地满足我的第一个项目中的特定要求。但正如您所注意到的，get_src_des 方法非常重复，我想提高代码的可重用性，摆脱令人讨厌的 if...elif...声明。有人有更好的想法重写这个方法吗？

class FileTransfer:

    def __init__(self, ftp_dir, local_dir, ftp_filename=None, local_filename=None):
        self.ftp_dir = ftp_dir
        self.ftp_filename = ftp_filename
        self.local_dir = local_dir
        self.local_filename = local_filename

        self.ftp_dict = self.get_group(ftp_dir, ftp_filename)
        self.local_dict = self.get_group(local_dir, local_filename)

    @staticmethod
    def get_group(dir, filename):
        group = {
            "dir": dir,
            "filename": filename,
        }
        return group

    def get_src_des(self, src):
        if src == "ftp":
            dict_src = self.ftp_dict
            dict_des = self.local_dict
        elif src == "local":
            dict_src = self.local_dict
            dict_des = self.ftp_dict
        else:
            dict_src = None
            dict_des = None

        return dict_src, dict_des

    # other methods, such as download_from_src_to_des, upload_from_src_to_des, ...

Answer 1

是的。这是字典的经典用例。

您可以按如下方式重写代码:

class FileTransfer:

    def __init__(self, ftp_dir, local_dir, ftp_filename=None, local_filename=None):
        self.ftp_dir = ftp_dir
        self.ftp_filename = ftp_filename
        self.local_dir = local_dir
        self.local_filename = local_filename

        self.ftp_dict = self.get_group(ftp_dir, ftp_filename)
        self.local_dict = self.get_group(local_dir, local_filename)
        self.param_dict = {
            'ftp':(self.ftp_dict,self.local_dict),
            'local' : (self.local_dict,self.ftp_dict)
        }

    @staticmethod
    def get_group(dir, filename):
        group = {
            "dir": dir,
            "filename": filename,
        }
        return group

    def get_src_des(self, src):
        if src in param_dict:
           return param_dict[src]

        else:
          return (None,None)

下次，您只需在 param_dict 中添加另一个条目，而不是添加另一个 elif 语句