搁置代码给出KeyError [英] Shelve Code gives KeyError

问题描述

我想从这里使用以下代码: 如何将所有变量保存在当前的python会话?

I wanted to use the following code from here: How can I save all the variables in the current python session?

import shelve

T='Hiya'
val=[1,2,3]

filename='/tmp/shelve.out'
my_shelf = shelve.open(filename,'n') # 'n' for new

for key in dir():
    try:
        my_shelf[key] = globals()[key]
    except TypeError:
        #
        # __builtins__, my_shelf, and imported modules can not be shelved.
        #
        print('ERROR shelving: {0}'.format(key))
my_shelf.close()

但是会出现以下错误:

Traceback (most recent call last):
  File "./bingo.py", line 204, in <module>
    menu()
  File "./bingo.py", line 67, in menu
    my_shelf[key] = globals()[key]
KeyError: 'filename'

你能帮我吗?

谢谢！

推荐答案

从您的追溯中，您似乎正在尝试从函数内部运行该代码.

From your traceback, it appears you are trying to run that code from inside a function.

但是 dir 在当前本地中查找名称范围.因此，如果在函数内部定义了filename，它将位于 locals() 而不是 globals() .

But dir looks up names in the current local scope. So if filename is defined inside the function, it will be in locals() rather than globals().

您可能想要更多类似这样的东西:

You probably want something more like this:

import shelve

T = 'Hiya'
val = [1, 2, 3]

def save_variables(globals_=None):
    if globals_ is None:
        globals_ = globals()
    filename = '/tmp/shelve.out'
    my_shelf = shelve.open(filename, 'n')
    for key, value in globals_.items():
        if not key.startswith('__'):
            try:
                my_shelf[key] = value
            except Exception:
                print('ERROR shelving: "%s"' % key)
            else:
                print('shelved: "%s"' % key)
    my_shelf.close()

save_variables()

请注意，当从内函数调用globals()时，它将从定义的模块中返回变量，而不是从的模块中返回变量叫做.

Note that when globals() is called from within the function, it returns the variables from the module where the function is defined, not from where it's called.

因此，如果导入了save_variables函数，并且您希望从 current 模块中获取变量，请执行以下操作:

So if the save_variables function is imported, and you want the variables from the current module, then do:

save_variables(globals())

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