Develop Reference

Python deleting a class object in run time

This is my code for reference:
class Manager(Employee):
def __init__(self, first, last, position, salary):
super().__init__(first, last, position)
self.salary = salary
def getinfo(self):
return self.first, self.last, self.position, self.salary
def give_raise(self, employee):
if type(employee) == type(Teller_1):
employee.hourly = int(employee.hourly * 1.10)
else:
employee.salary = int(employee.salary * 1.10)
def fire_employee(self, employee):
if type(employee.first) == type(Branch_manager) or type(employee) == type(Bank_executive):
print ("you cannot fire someone in an equal or higher position")
else:
print ("you have successfully fired " + str(employee.first) + " " + str(employee.last))
del employee
print (Analyst_1)
Analyst_1 = SalaryEmployee('Bob', 'Dun', 'Account Analyst', 40000)
When I put in this code:
Branch_manager.fire_employee(Analyst_1)
I want it to remove the object "Analyst_1". However, all it is doing is removing the reference variable "employee" and not the object itself.
How can I remove the actual object itself and not just the reference variable?

You can delete a name using the del keyword or the delattr built-in function, but you can't delete an object. (Objects don't get deleted, they get garbage collected when no names refer to them anymore.)
If your method looks like:
def fire_employee(employee):
...
and you call it like
fire_employee(Analyst_1)
then the object that the name Analyst_1 refers to will be the same object that the name employee refers to. So even if you delete one of those names, the object itself will still exist as long as the other name still references it.
You can delete the name from the global namespace, if you know what namespace it is and what name it is:
def fire_employee(employee_name):
module_object = sys.modules[__name__]
delattr(module_object, employee_name)
which you would call like this instead:
# Note that we pass a *string*, "Analyst_1", and not the *object*.
fire_employee('Analyst_1')
But if you're going to go that route, you'd be better off keeping the employee name to object mapping in its own data structure, likely a dict object as was already suggested.

How to use a method object (which is in the class) outside the class?

I have a method object with assigned value from user's input inside a class. The problem is i can't use the method object maxcount_inventory = int(input("How many Inventories: ")) outside the class. The error says "method' object cannot be interpreted as an integer"
class CLASS_INVENTORY:
maxcount_inventory = int(input("How many Inventories: "))
inventory_name = []
def __init__(Function_Inventory):
for count_inventory in range(Function_Inventory.maxcount_inventory):
add_inventory = str(input("Enter Inventory #%d: " % (count_inventory+1)))
Function_Inventory.inventory_name.append(add_inventory)
def Return_Inventory(Function_Inventory):
return Function_Inventory.inventory_name
def Return_Maxcount(Function_Inventory):
return maxcount_inventory
maxcount_inventory = CLASS_INVENTORY().Return_Maxcount
Another extra question if I may, how can i access items in the list per index outside the class? I have the code below, but I think it's not working. Haven't found out yet due to my error above.
for count_inventory in range(maxcount_inventory):
class_inv = CLASS_INVENTORY().Return_Inventory[count_inventory]
print(class_inv)
skip()
Here is my full code: https://pastebin.com/crnayXYy

Here you go I've refactored your code.
As #Daniel Roseman mentioned you should be using self rather than Function_Inventory, so I changed that. I also changed the return value of Return_Maxcount to provide a list as you requested.
class CLASS_INVENTORY:
maxcount_inventory = int(input("How many Inventories: "))
inventory_name = []
def __init__(self):
for count_inventory in range(self.maxcount_inventory):
add_inventory = str(input("Enter Inventory #%d: " % (count_inventory+1)))
self.inventory_name.append(add_inventory)
def Return_Inventory(self):
for item in self.inventory_name:
print(item)
def Return_Maxcount(self):
return self.inventory_name
maxcount_inventory = CLASS_INVENTORY()
inventory_list = maxcount_inventory.Return_Maxcount()
maxcount_inventory.Return_Inventory()
You can change the print statement at the bottom and set that equal to a variable to access it outside of the class itself.

In your code just change this:
maxcount_inventory = CLASS_INVENTORY().Return_Maxcount
to this:
maxcount_inventory = CLASS_INVENTORY().Return_Maxcount()
also change the variables in your class to have the self. prefix before them
like self.maxcount_inventory
the reason is you want to call your method , otherwise it will try getting a variable not the method.
you also want to change all your arguments in your functions inside of the class to self

Python: Append to list owned by an instance stored in shelved dictionary

So I'm writing a script to keep track of my correspondence.
It takes the name of someone who emailed me, looks for its associated 'Friend object' in a shelved dictionary of Friend instances (or creates itself a new instance and stores it in the dictionary), then appends the current time to that instance's list of timestamps.
So for example, if the script runs with 'John Citizen' as the input, it finds the key 'John Citizen' in the dictionary, gets the instance associated with that key, goes to that instance's list and appends to that list a timestamp.
This is all working as I want it to, except for the appending.
Here's the friend object:
class Friend():
def __init__(self, name):
self.name = name
self.timestamps = []
def add_timestamp(self, timestamp):
self.timestamps.append(timestamp)
Here's the global function that processes the input into a name string. (The input comes from AppleScript and is always in this format:
Input: "First [Middles] Last <emailaddress#email.com>"
def process_arguments():
parser = argparse.ArgumentParser()
parser.add_argument("sender", help="The output from AppleScript")
args = parser.parse_args()
full_name = args.sender
## gets just the name
words = full_name.split(' ')
words.pop()
full_name = ' '.join(words)
## takes away all the non alpha characters, newlines etc.
alpha_characters = []
for character in full_name:
if character.isalpha() or character == " ":
alpha_characters.append(character)
full_name = ''.join(alpha_characters)
return full_name
And then here's the script handling that full_name string.
## Get the timestamp and name
now = datetime.datetime.now()
full_name = process_arguments()
## open the shelf to store and access all the friend information
shelf = shelve.open('/Users/Perrin/Library/Scripts/friend_shelf.db')
if full_name in shelf:
shelf[full_name].add_timestamp(now)
shelf.close
else:
shelf[full_name] = Friend(full_name)
shelf.close
I've tried to debug it and full_name in shelf evaluates to True and the problem is still happening.
I just can't seem to get that self.timestamps list to populate. I would really appreciate any help!

You need to extract, mutate and store the object back in the shelf to persist it.
e.g
# extract
this_friend = shelf[full_name]
# mutate
this_friend.add_timestamp(now)
# re-add
shelf[full_name] = this_friend
shelf.close()
You can see an example of this in the python docs.
The other option is pass the writeback parameter as True to shelve.open and it will allow you to write to the keys directly.

#paulrooney answered this.
Objects in the shelf need to be removed from the shelf, assigned to a name, mutated (to add time stamp), then put back in the shelf. This code works fine.
shelf = shelve.open('/Users/Perrin/Library/Scripts/friend_shelf.db')
if full_name in shelf:
this_friend = shelf[full_name]
this_friend.add_timestamp(now)
shelf[full_name] = this_friend
print shelf[full_name].timestamps
shelf.close
else:
shelf[full_name] = Friend(full_name)
this_friend = shelf[full_name]
this_friend.add_timestamp(now)
shelf[full_name] = this_friend
shelf.close

Class does not seem to be Global in python

I setup a class and it accepts and prints out the variables fine in one if statement.
class npc: #class for creating mooks
def __init__(self, name):
self.name = name
def npc_iq (self,iq):
self.iq = []
def npc_pp (self,pp):
self.pp = []
def npc_melee (self, melee):
self.melee = []
def npc_ct (self, ct):
self.ct = []
It works fine in this if statement
if menu_option == 1:
print "Choose melees for npc"
init_bonus = random.randint(0,2)
char_PP = random.randint(7,15)
char_iq = random.randint(7,15)
npc_Melees = int(raw_input(prompt))
combat_time = math.floor((round_attacks - init_bonus - math.floor(char_PP/2) - math.floor(char_iq/2)) / npc_Melees)
#function for calculating sequence number
print "combat time is"
print combat_time
mook = "mook%s" % counter # adds different mook names to program
mook = npc(mook)
mook.iq = (char_iq)
mook.pp = (char_PP)
mook.melee = (npc_Melees)
mook.ct = (combat_time)
counter += 1
But on this statement it will print out the name in the class but not ct.
elif menu_option ==4:
print "Printing out all mooks"
print
printcount = counter -1
while printcount != 0:
mookprint = "mook%s" % printcount
mookprint = npc(mookprint)
print mookprint.name
print mookprint.ct
print
printcount -= 1

Why would a mookprint have any idea what value ct should be? The constructor for npc initialises a new instance of npc, with the name given as a parameter, but ct is left empty.
When you create an NPC in menu option 1, you do not create a global instance of npc. If you want to refer to a previously created instance of npc, you will need to find some way of storing them. Dictionaries may be a good solution for you. A dictionary is an object that holds mappings between keys and values. If you know the key, then you can find the assosicated value. In this case you would make name the key and the value the npc instances.
eg.
npcsDict = dict()
if menu_option == 1:
# code for intialising a new instance of npc
...
# most, if not all of the initialisation code should be moved to the
# __init__ method for npc
# now store the newly created mook
npcsDict[mook.name] = mook
elif menu_option == 4:
print "Printing out all mooks"
print
for mookName in npcsDict:
print npcsDict[mookName].name
print npcsDict[mookName].ct
print

i dont really understand your problem.
your working example:
mook = npc(mook)
mook.iq = (char_iq)
mook.pp = (char_PP)
mook.melee = (npc_Melees)
mook.ct = (combat_time)
mook.ct is value of (combat_time)
your failing example:
mookprint = npc(mookprint)
print mookprint.name
print mookprint.ct
mookprint.ct's value is nothing because it is never set.

The elif will only be executed if the if has not, so if the elif block runs, ct was never set

I don't think you're understanding how four lines work:
mookprint = "mook%s" % printcount
mookprint = npc(mookprint)
print mookprint.name
print mookprint.ct
Every time this block of code is run, the following things are happending:
You're assigning a string of the form "mook" to the variable mookprint
You're creating a new instance of the npc class. You should note that all of the instances you're creating will be separate from eachother. This new instance will have an attribute with the name that was previously held in the variable mookprint and this instance of npc will be assigned to mookprint.
You're printing the name attribute of the instance of the npc class that you created in the previous step. This works because when this instance was created, the __init__ method of your class was called with the argument name being set to "mook1" or whatever was stored in mookprint at the time.
You're printing the ct attribute of the instance of the npc class that you just created. Since you never set the ct attribute to anything, this will not work how you expected.
If you want to count the number of instances of your npc class, you'll need to create a class attribute. This is a variable whose value is common across all instances of a class. To do so, you'll need to modify your class definition to add an item to this attribute every time you make a new instance of the class. It will look something like this:
class npc: #class for creating mooks
ct = []
def __init__(self, name):
self.name = name
self.ct.append(name)
def get_ct(self):
return len(self.ct)
With the above, the variable ct will be a list that is common to all instances of npc and will grow every time a new npc is created. Then the method get_ct will count how long this list is.
Then you'll need to modify the four lines I mentioned to look like:
mookprint = "mook%s" % printcount
mookprint = npc(mookprint)
print mookprint.name
print mookprint.get_ct()
I think the code above shows how to change your code to work more how you expected it to work. However, it should be noted that you rarely want to create classes where each instance depends on information about the other instances. It is usually a better design to do something like Dunes suggested, storing the instances in a dictionary, or some other data structure, and keeping track of them that way.

In python. How do I have a user change a dictionary value, when that dictionary is in a class?

So I had a similar question that was answered in another thread.
How do I update a dictionary value having the user choose the key to update and then the new value, in Python?
Basically, how did one get a nested dictionary value changed via raw_input. I used the solution and it worked well, but I wanted to write the program using classes. So I made a class with a method for editing the dictionary using essentially the same code, however when i try run it in the class method it gives me a "key error" now.
So in the main function this works the solution in the above linked question works great. But in a class method:
class team: # create a class where each team will be an instance
def __init__(self, name):
self.name = name #name of team will be passed from main
self.list_of_players = [] # create a list of the players
self.position1 = {} # create a dictionary for each of the positions on that team
self.position2 = {}
self.roster = [self.position1, self.position2]
def addplayer(self, player_name): # the name of the player is passed to this method from main
print 'add stats' # fill out the appropriate stats through raw_input
stat1 = raw_input('stat1: ')
stat2 = raw_input('stat2: ')
pos = raw_input('POS: ')
vars()[player_name] = {'stat1' : stat1, 'stat2' : stat2, 'POS' : pos} #create a dictionary
# for the player where all his stats are kept
player = {player_name : vars()[player_name]} # create a dictionary that will show the
# player's name as a string and his stats which are held in the dictionary named after him
self.list_of_players.append(player) # append the new player to the list of players
if pos == 'p1': # add the player and his stats to the appropriate position on the team
self.position1[player_name] = player
elif pos == 'p2':
self.position2[player_name] = player
else:
pass
def editplayer(self, player_name): # player's name is passed to the edit function from main
print self.list_of_players # player's name shows up in the list of players for the team
edit_stat = raw_input('which stat? ') # choose which stat(key) to edit via raw input
new_value = raw_input('new value: ') # choose the new value to apply to the chosen key
vars()[player_name][edit_stat] = new_value # here is where it gives a key error! this worked
#in fact even trying to call and print the players name gives the key error.
#player = vars()[player_name]
#print player
def main(): # the main function
loop1 = 0 # creating a loop so one can come back and edit the teams after creating them
list_of_teams = [] # initializing list of teams
while loop1 < 1:
print list_of_teams # show the user what teams are available to choose from
team_option = raw_input('new team or old: ') # create a new team or work with an old one
if team_option == 'new':
team_name = raw_input('team name? ') # get the team name from raw_input
vars()[team_name] = team(team_name) #create an instance of this team name
list_of_teams.append(team_name) # add the team to the list
else:
team_name = raw_input('which team? ') # choose which existing team to work with
player_choice = raw_input('new player or old? ') # choose to create or edit existing player
player_name = raw_input('player_name? ') # choose which player from raw_input
if player_choice == 'new':
vars()[team_name].addplayer(player_name) # give player_name to addplayer method
print vars()[team_name].list_of_players # shows the new player in the appropriate
# instance's roster. This method seems to be working fine
else:
vars()[team_name].editplayer(player_name) # gives the player's name to the editplayer
# method for the appropriate instance. But the player name just raises a key error in
# edit player method. I am baffled.
print vars()[team_name].list_of_players
if __name__ == '__main__':
main()
When it was all one long function this worked but looked like a disaster. Trying to learn better OOP practices but I can't figure out how to call up that dictionary with by the player's name to change the value. I've spent the past few days reviewing tutorials and questions on classes and dictionaries, but clearly I am misunderstanding something about how variables are passed from function to methods.
The fact that it wont even assign the dictionary vars()[player_name] to a var to be printed out means its not recognizing it as the dictionary that was created in the addplayer methond I think. But the fact that it still lists that dictionary in the list of players means it is existing in that instance. So why isn't it recognizing it when i try to address it in the editplayer method? And how do i call up the embeded dictionary created in one method, to change a value in that dictionary in the second method?
Karl pointed out good points that need clarifying: Here's what the attribues I want are.
self.name- i want an instance for each team created
self.list of players - each team should have its own list of players which are dictionaries holding that persons stats. so team1 should have its own list. team2 a different list etc
self.position1/2 - the players on each team would be filed in their various position dictionaries. so Player joe montana's dictionary of statistics would be found in that team's Quarterbacks dictionary
self.roster - should be that team's roster grouped by positions. So a call to print team1.roster should print those players grouped by positions

1) vars() is a dictionary of local variables within a function.
When you are in a method in Python, the contents of the object that you called the method on are not local variables. That's why you have to have a self parameter.
If you want to look up the players by name, then do that. Don't have a list of players, but instead a dict of players.
2) vars() is something you should almost never be using. It is used so that you can pretend that a string is a variable name. You do not need to do this for anything that you're doing here. In fact, you do not need a variable at all in most of the places where you're using one. You have more to learn about than just OO here.
Consider this part for example:
vars()[team_name] = team(team_name)
list_of_teams.append(team_name)
Instead of trying to remember the team by name in vars(), again, look up the teams by name. Have a dict of teams instead of a list. To get the names of teams, you can just print the keys of the dictionary.
Simple is better than complicated. Creating variables on the fly is complicated. Using dictionaries is simple.
I hate spoon-feeding this much code, but it seems like the only way to get the idea(s - I didn't really say everything above) across this time:
# Just like we want a class to represent teams, since those are "a thing" in our
# program, we want one for each player as well.
class player(object):
__slots__ = ['name', 'stats', 'pos']
def __init__(self, name, stats, pos):
self.name = name
self.stats = stats
self.pos = pos
# Asking the user for information to create an object is not the responsibility of
# that class. We should use external functions for this.
def create_player(name):
print 'add stats' # fill out the appropriate stats through raw_input
stat1 = raw_input('stat1: ')
stat2 = raw_input('stat2: ')
pos = raw_input('POS: ')
# Now we create and return the 'player' object.
return player(name, {'stat1': stat1, 'stat2': stat2}, pos)
class team(object):
__slots__ = ['name_to_player', 'position_to_player']
def __init__(self):
# We don't make any lists, just dicts, because we want to use them primarily
# for lookup. Notice how I've named the attributes. In particular, I **don't**
# talk about type names. That's just an implementation detail. What we care about
# is how they work: you put a name in, get a player out.
self.name_to_player = {}
self.position_to_player = {}
# Again, we don't ask the questions here; this just actually adds the player.
def add_player(self, player):
self.name_to_player[player.name] = player
self.position_to_player[player.pos] = player
# Again, we don't ask the questions here; this just does the actual edit.
def edit_player(self, name, stat, new_value):
self.name_to_player[name].stats[stat] = new_value
def main(): # the main function
teams = {} # dict from team name to team object.
while True:
print teams.keys()
# Your human interface was needlessly awkward here; you know from the supplied name
# whether it's a new team or an old one, because it will or won't be in your
# existing set of teams. Similarly for players.
team_name = raw_input('team name? ')
if team_name not in teams.keys():
teams[team_name] = team() # create a new team
else: # edit an existing one
team = teams[team_name]
player_name = raw_input('player name? ')
if player_name in team.name_to_player.keys(): # edit an existing player
stat = raw_input("stat? ")
value = raw_input("value? ")
team.edit_player(player_name, stat, value)
else: # add a new player
team.add_player(create_player(player_name))
if __name__ == '__main__':
main()
This still isn't doing everything "right", but it should give you more than enough to think about for now.

First of all, the traceback that accompanies the Key error, will tell you which line in your program triggered it, and if it is not obvious from reviewing the code, then inserting a print statement before that line should make it obvious.
Second, you are using user input as a key. User input is not reliable. You WILL have key errors all the time so your code should be dealing with that, either by using try: except: to catch the exception, or by checking every time using if key in mydict: before actually using the key to lookup the dictionary.
Third, what you are doing with vars() is very, very weird. If your app uses a global variable, then it should know the name and have no need to refer to vars. Have you forgotten to declare a global variable in some method?
def method(self,name):
global bigdict
bigdict[name] = "set at least one time"