A) How could you modify Shelve with a technique discussed in class so that you can create Shelve instances that contain // Tools, Dishes or any other kind of object? // B) Create a function that takes in two shelves

A “shelf” is a dictionary-like object. A shelf is an arbitrary Python objects, that is; anything that the pickle module can handle. This includes recursive data types and objects containing lots of shared sub-objects. It must be noted that the keys are ordinary strings.

(A). modification to Shelve can be done by following this instructions;

(1). Do not redefine built-in functions,(2). grab shelved item, mutate item, write mutated item back to shelf.

The number (2) instructions is during iteration over shelved items.

(B). CREATING FUNCTIONS THAT TAKES IN TWO SHELVES;

import shelve

d = shelve.open(filename) # open -- file may get suffix added by low-level

# library

d[key] = data # store data at key (overwrites old data if

# using an existing key)

data = d[key] # retrieve a COPY of data at key (raise KeyError if no

# such key)

del d[key] # delete data stored at key (raises KeyError

# if no such key)

flag = key in d # true if the key exists

klist = list(d.keys()) # a list of all existing keys (slow!)

# or, d=shelve.open(filename,writeback=True) would let you just code

# d['xx'].append(5) and have it work as expected, BUT it would also

# consume more memory and make the d.close() operation slower.

d.close() # close it