在Python中引用实例属性的快捷方式

Question

I have a Python class that contains many variables, along the lines of:

class file:
    def __init__(self, name)
        self.name = name
        self.size = None
        self.num_lines = None
        self.directory = None

• Note that this is just an example - my real class has very descriptive (and therefore long) names and many more members

After I create an instance, I have to assign values to those variables:

f = file("abc.txt")
f.size = get_file_info(f.name)
f.num_lines = count_lines(f.name)
f.directory = get_dir(f.name)
f.new_name = root + f.directory + f.name + f.size

What I'd really like is the syntactic sugar of a using keyword:

f = file("abc.txt")
using f:
    size = get_file_info(name)
    num_lines = count_lines(name)
    directory = get_dir(name)
    new_name = root + directory + name + size

That is, I want to provide a new context in which variables will be searched for first, before Python does all the rest of its searches.

Is there anything like this? If not, it seems like a useful addition to the language.

Edit: Per the answers, I deliberately don't want to do this inside the init function. For personal reasons. Not really - it just doesn't make sense in my use case

Answer 1

All the code you want to put in a using block should be handled by your class's __init__ method.

class File:
    def __init__(self, name)
        self.name = name
        self.size = get_file_info(name)
        self.num_lines = count_lines(name)
        self.directory = get_dir(name)
        self.new_name = os.path.join(root, self.directory, self.name, self.fize)

f = File("abc.txt")

Some of the functions you imply ( get_file_info , etc.) may be more suited to being methods of the File class, rather than standalone functions that take a file name as an argument.

Answer 2

There is no support in the language for this. You can only create variable namespaces by functions and modules. Not even with classes (that's why, even inside a class, you have to use self to refer to its attributes)