How to Improve This Program, Add Comments, etc.?

Question

Do you have any suggestions to improve or extend this script? Any ideas for removing or adding comments/docstrings?

import dbm
import subprocess
import time
subprocess.call("clear")
try:
 # Tries to import cPickle, a faster implementation of pickle.
 import cPickle as pickle
except ImportError:
 import pickle
class PickleDB:
 def open_db(self):
 """Gets and opens the database"""
 self.db_name = input("Enter a database name\n")
 # Makes sure the database name is compatible
 db_parts = self.db_name.split(".")
 self.db_name = db_parts[0]
 self.db = dbm.open(self.db_name, "n")
 def get_data(self):
 """Gets data to write into the database"""
 subprocess.call("clear")
 self.raw_data = input("Enter your raw data\n")
 # Pickles data
 self.pickled_data = pickle.dumps(self.raw_data)
 def write_to_db(self):
 """Writes data into database"""
 # Logs time
 self.start = time.time()
 # Creates keys
 self.db["raw"] = self.raw_data
 self.db["pickled"] = self.pickled_data
 def close_db(self):
 """Closes database"""
 self.db.close()
 # Logs end time
 self.end = time.time()
 def info(self):
 """Prints out info about the database"""
 subprocess.call("clear")
 print("Load data from database using dbm")
 print("Keys: raw\tpickled")
 # Prints total time
 print("Speed:", self.end - self.start, "seconds")
# Function calls
pickled_db = PickleDB()
pickled_db.open_db()
pickled_db.get_data()
pickled_db.write_to_db()
pickled_db.close_db()
pickled_db.info()

Answer 1

import dbm
import subprocess
import time
subprocess.call("clear")

This isn't cross-platform. Sadly, there isn't really a cross-platform alternative

try:
 # Tries to import cPickle, a faster implementation of pickle.
 import cPickle as pickle
except ImportError:
 import pickle
class PickleDB:
 def open_db(self):
 """Gets and opens the database"""
 self.db_name = input("Enter a database name\n")

You really shouldn't call input inside of a work class. The code responsible for User I/O should be separate from that doing any actual work.

 # Makes sure the database name is compatible
 db_parts = self.db_name.split(".")
 self.db_name = db_parts[0]

Ok, why are you ignoring part of the name if its not good? Shouldn't you complain to the user and ask for a new name? Also, I'd avoid assigning to self.db_name only the replace it again a bit later. Since you don't use it outside this function, I'd probably just have a local variable

 self.db = dbm.open(self.db_name, "n")
 def get_data(self):
 """Gets data to write into the database"""
 subprocess.call("clear")
 self.raw_data = input("Enter your raw data\n")
 # Pickles data

This comment is a little obvious, I'd delete it

 self.pickled_data = pickle.dumps(self.raw_data)

I'd expect a function that gets data to return it to the caller. Generally, functions that drop state onto the class is a sign of poor design. Methods should usually communicate by parameters and return values not object storage.

 def write_to_db(self):
 """Writes data into database"""
 # Logs time
 self.start = time.time()

Collecting timing information isn't something that's usually part of the actual class doing the work. Usually you'd time the class from the outside.

 # Creates keys
 self.db["raw"] = self.raw_data
 self.db["pickled"] = self.pickled_data
 def close_db(self):
 """Closes database"""
 self.db.close()
 # Logs end time
 self.end = time.time()
 def info(self):
 """Prints out info about the database"""
 subprocess.call("clear")
 print("Load data from database using dbm")
 print("Keys: raw\tpickled")
 # Prints total time
 print("Speed:", self.end - self.start, "seconds")

As noted, output and timing is usually something you want to do outside of the work class itself.

# Function calls
pickled_db = PickleDB()
pickled_db.open_db()
pickled_db.get_data()
pickled_db.write_to_db()
pickled_db.close_db()
pickled_db.info()

Here's the overall thing about your code. You are using a class as a group of functions and treating the object storage like a place to put global variables. You aren't making effective use of the class. In this case, you'd be better off to use a collection of functions than a class.

Answer 2

I think Winston Ewert summed up quite well what is wrong with the code. You should replace all that is after the line # Function calls by

if __name__ == "__main__":
 pickle_db = PickleDB(input("Enter a database name\n"))
 pickle_db.write(input("Enter your raw data\n"))
 pickle_db.close()
 print("Speed:{0} seconds".format(pickle_db.get_total_time())

and build your class from that snippet of code (put the open function in the init, for example)