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Python: Adding objects to a list using Classes

I am new to Classes and hope someone can help me out. I am writing av program where a user can add cars to an existing list of cars. The code I have so far is below. I am probably doing several mistakes here, but the error message I get now is "NameError: name 'car' is not defined". I think I am using the Car Class / Vehicle Class wrong. Anybody got any ideas how I can get on track with this?
class Vehicle:
def __init__(self, Make, Model, Year, Mileage, Price):
self.Makename = Make
self.Modelname = Model
self.Yearr = Year
self.Mileagenw = Mileage
self.Pricenw = Price
def getValus(self):
return self.Makename + " " + self.Modelname+ " " + self.Yearr+" " + self.Mileagenw+" " + self.Pricenw
def Display(self):
print("Invetory Unit: Car \n Make: "+ self.Makename + "\n Model: " + self.Modelname+ "\n Year " + self.Yearr+"\n Miles " + self.Mileagenw+" \n Price :" + self.Pricenw)
class Car(Vehicle):
def __init__(self, Make, Model,Year,Mileage,Price,numofdoors):
Vehicle.__init__(self,Make, Model,Year,Mileage,Price)
self.numofdoorsnw = numofdoors
def GetCar(self):
return self.getValus() + ", " + self.numofdoorsnw
def Display(self):
print("Invetory Unit: Car \n Make: "+ self.Makename + "\n Model: " + self.Modelname+ "\n Year " + self.Yearr+"\n Miles " + self.Mileagenw+" \n Price :" + self.Pricenw+" \n Number of doors :" + self.numofdoorsnw)
def main():
vehicles_list = []
vehicles_list += [Car("Tesla", "S", "2020", "170000", "33000.0", "4")]
vehicles_list += [Car("Tesla", "X", "2021", "180000", "23000.0", "4")]
newCar = "Y"
while newCar == "Y":
print('Input car data')
Make = input('Merke: ')
Model = input('Model: ')
Year = input('Year: ')
Milage = input('Milage: ')
Price = input('Price: ')
numofdoors = input('Number of Doors: ')
vehicles_list += [Car(Make, Model, Year, Milage, Price, numofdoors)]
newCar = input('Add another car? (Y/N) ')
print(car.getValus())
main()

class Vehicle:
def __init__(self, Make, Model, Year, Mileage, Price):
# are you making names unique here? if so, they are in a different namespace so don't have to be different
self.Makename = Make
self.Modelname = Model
self.Yearr = Year
self.Mileagenw = Mileage
self.Pricenw = Price
def getValus(self):
return self.Makename + " " + self.Modelname+ " " + self.Yearr+" " + self.Mileagenw+" " + self.Pricenw
def Display(self):
print("Invetory Unit: Car \n Make: "+ self.Makename + "\n Model: " + self.Modelname+ "\n Year " + self.Yearr+"\n Miles " + self.Mileagenw+" \n Price :" + self.Pricenw)
class Car(Vehicle):
def __init__(self, Make, Model,Year,Mileage,Price,numofdoors):
Vehicle.__init__(self,Make, Model,Year,Mileage,Price)
self.numofdoorsnw = numofdoors
def GetCar(self):
return self.getValus() + ", " + self.numofdoorsnw
def Display(self):
print("Invetory Unit: Car \n Make: "+ self.Makename + "\n Model: " + self.Modelname+ "\n Year " + self.Yearr+"\n Miles " + self.Mileagenw+" \n Price :" + self.Pricenw+" \n Number of doors :" + self.numofdoorsnw)
def main():
# adding unnamed instances of the class Car to a list. Each Car object is an element of the list
vehicles_list = []
vehicles_list += [Car("Tesla", "S", "2020", "170000", "33000.0", "4")]
vehicles_list += [Car("Tesla", "X", "2021", "180000", "23000.0", "4")]
newCar = "Y"
while newCar == "Y":
print('Input car data')
Make = input('Merke: ')
Model = input('Model: ')
Year = input('Year: ')
Milage = input('Milage: ')
Price = input('Price: ')
numofdoors = input('Number of Doors: ')
vehicles_list += [Car(Make, Model, Year, Milage, Price, numofdoors)]
newCar = input('Add another car? (Y/N) ')
print(car.getValus()) # car is undefined. print the vehicles_list instead, it contains all Car objects you have made.
main()
Improved version:
class Vehicle:
def __init__(self, make, model, year, mileage, price):
self.make = make
self.model = model
self.year = year
self.mileage = mileage
self.price = price
def getValues(self):
return self.make + " " + self.model + " " + self.year + " " + self.mileage + " " + self.price
def Display(self):
print("Invetory Unit: Car \n Make: " + self.make + "\n Model: " + self.model + "\n Year " + self.year + "\n Miles " + self.mileage + " \n Price :" + self.price)
class Car(Vehicle):
def __init__(self, Make, Model,Year,Mileage,Price,num_doors):
Vehicle.__init__(self,Make, Model,Year,Mileage,Price)
self.num_doors = num_doors
def GetCar(self):
return self.getValues() + ", " + self.num_doors
def Display(self):
print("Invetory Unit: Car \n Make: "+ self.make + "\n Model: " + self.model+ "\n Year " + self.year + "\n Miles " + self.mileage +" \n Price :" + self.price + " \n Number of doors :" + self.num_doors)
def main():
vehicles_list = []
vehicles_list.append(Car("Tesla", "S", "2020", "170000", "33000.0", "4"))
vehicles_list.append(Car("Tesla", "X", "2021", "180000", "23000.0", "4"))
newCar = "Y"
while newCar == "Y":
print('Input car data')
Make = input('Make: ')
Model = input('Model: ')
Year = input('Year: ')
Milage = input('Milage: ')
Price = input('Price: ')
numofdoors = input('Number of Doors: ')
vehicles_list.append(Car(Make, Model, Year, Milage, Price, numofdoors))
newCar = input('Add another car? (Y/N) ')
for car in vehicles_list:
print(car.GetCar())
main()
result:
Input car data
Make: VW
Model: Golf
Year: 2020
Milage: 10000
Price: 20000
Number of Doors: 5
Add another car? (Y/N) n
Tesla S 2020 170000 33000.0, 4
Tesla X 2021 180000 23000.0, 4
VW Golf 2020 10000 20000, 5
On the point about class namespaces, there is a great talk from Raymond Hettinger explaining those : https://www.youtube.com/watch?v=8moWQ1561FY

On print(car.getValus()), you want to get values from an object of class Car called car but you never defined this object. You probably want to modify your main in the following way
def main():
vehicles_list = []
vehicles_list += [Car("Tesla", "S", "2020", "170000", "33000.0", "4")]
vehicles_list += [Car("Tesla", "X", "2021", "180000", "23000.0", "4")]
newCar = "Y"
while newCar == "Y":
print('Input car data')
Make = input('Merke: ')
Model = input('Model: ')
Year = input('Year: ')
Milage = input('Milage: ')
Price = input('Price: ')
numofdoors = input('Number of Doors: ')
input_car = Car(Make, Model, Year, Milage, Price, numofdoors)
vehicles_list += [input_car]
newCar = input('Add another car? (Y/N) ')
for car in veichles_list:
print(car.getValus())

Pass variables to another module which contains classes

I have a module with a Class
class Record(object):
Name = ''
Gender = ''
Age = ''
Line = 'Bob=Male=40'
M = Line.split('=')
exec(M[0] + ' = ' + 'Record()')
exec(M[0] + '.' + 'Name' + ' = ' + "'" + M[0] + "'")
exec(M[0] + '.' + 'Gender' + ' = ' + "'" + M[1] + "'")
exec(M[0] + '.' + 'Age' + ' = ' + "'" + M[2] + "'")
I am trying to import the above module but to pass it the "Line" variable.
How could I do that ?

Adding this one line should do the job
# in main script
from lib import file_name
file_name.Line = Line #Assuming line is declared already
you need not declare Line in your module

You create objects by calling a class. You don't need to use exec to do that
#record.py
class Record:
def __init__(self, name, gender, age):
self.Name = name
self.Gender = gender
self.Age = age
def __str__(self):
return ' '.join((self.Name, self.Gender, self.Age))
Person = Record("Bob", "Male", "30")
# workspace.py
import record
print(record.Person)
Person2 = record.Record("Alice", "F", "30")
print(Person2)
Outputs:
Bob M 30
Alice F 30
In python you probably would get away with this
name = "Bob"
gend = "M"
age = '30'
exec(f'{name} = record.Record("{name}", "{gend}", "{age}")')
print(Bob)
# Bob M 30
But I would not advise that

How to access local variables within a class

I am working on an assignment and am trying to access a local variable within a function that is in a class. Does anyone know how I can print a local variable from a function in a class? We are not allowed to print anything within our functions in the classes so I am wondering how I can do this.
def driver():
q = my_queue.Queue_()
for line in df:
if 'received' in line:
q.enqueue(line)
print("Adding job " + q.new_item.job_ID + " to the queue with the timestamp: " + q.new_item.time_stamp + ".")
print("The prority of the job is: " + q.new_item.job_priority)
print("The job type is: " + q.new_item.job_type)
if 'respond' in line:
q.dequeue()
print("Completed job " + q.current.job_ID + " in " + str(int(q.time_elapsed)) + " seconds.")
if 'active' in line:
q.active_jobs()
print("Total number of jobs: " + str(len(q.active_jobs.temp)))
print("Average priority: " + str(q.active_jobs.average))
I am trying to print the last two lines but that is where the error is occurring.
The error I am getting is: AttributeError: 'function' object has no attribute 'temp'.
This is the function within the class:
def active_jobs(self):
if self.head == None:
pass
# print("No Jobs Available. ")
else:
current = self.head
self.temp = []
while current:
self.temp.append(current.get_data())
current = current.get_next()
return self.temp
# print("Total number of jobs: " + str(len(self.temp)))
self.priority = []
for i in range(len(self.temp)):
self.priority.append(self.temp[i][2])
x = [int(i) for i in self.priority]
self.average = sum(x) / len(x)
return self.average

active_jobs creates the temp instance attribute. Assuming the instance is q; access that attribute with q.temp.

How can I write this to a file

class PersonalInfo:
def set_titles(self, title):
self.__titles = title
def set_names(self, name):
self.__names = name
def set_addresses(self, add):
self.__addresses = add
def set_ages(self, age):
self.__ages = age
def set_numbers(self, number):
self.__numbers = number
# Accessor methods
def get_titles(self):
return self.__titles
def get_names(self):
return self.__names
def get_addresses(self):
return self.__addresses
def get_ages(self):
return self.__ages
def get_numbers(self):
return self.__numbers
def main():
# references PersonalInfo object
info = PersonalInfo()
# stores values in the object
info.set_titles(input("Enter Mr, Mrs, Miss:"))
info.set_names(input("Enter full name:"))
info.set_addresses(input("Enter address:"))
info.set_ages(input("Enter age:"))
info.set_numbers(input("Enter number:"))
#displays values stored in object's fields
print("Name: " + info.get_titles() + " " + info.get_names() + "\n"
+"Address: " + info.get_addresses() + "\n"
+ "Birth: " + info.get_ages() + "\n"
+ "Number: " + info.get_numbers() + "\n")
main()
main()
I want this to be printed out 2 times since I have 2 users who will answer the questions, but I can't seem to understand how to save the input answers in a text file. Can someone please give me an example??:)
I'm such a noob at this

Change your main() to init(self): And call it twice if you need run it twice. You could write a method to output the data to a file instead of including it in init if you wanted to.
def __init__(self):
# stores values in the object
self.title = self.set_titles(input("Enter Mr, Mrs, Miss: "))
self.name = self.set_names(input("Enter full name: "))
self.age = self.set_ages(input("Enter age: "))
self.address = self.set_addresses(input("Enter address: "))
self.number = self.set_numbers(input("Enter number: "))
# displays values stored in object's fields
print("Name: " + self.get_titles() + " " + self.get_names() + "\n"
+"Address: " + self.get_addresses() + "\n"
+ "Birth: " + self.get_ages() + "\n"
+ "Number: " + self.get_numbers() + "\n")
# Appends data to file
outfile = open('data_from_user.txt','a')
outfile.write("Name: " + self.get_titles() + " " + self.get_names() + "\n")
outfile.write("Address: " + self.get_addresses() + "\n")
outfile.write("Birth: " + self.get_ages() + "\n")
outfile.write("Number: " + self.get_numbers() + "\n")
outfile.close()
person_1 = PersonalInfo()
person_2 = PersonalInfo()

# storing data inside string
string = 'NAME: {} \n Address: {} \n Birth: {} \n Number: {} \n'.format(info.get_titles(),info.get_names(),
info.get_addresses(),info.get_ages(),info.get_numbers())
# printing 2 times
print(string,string,sep='\n')
# writing in a file
x = open('filename','a')
x.write(string)
x.close()

Dynamically create a Python function with positional or key-word args, not from a string

Over at this question there are some neat tricks for generating functions on the fly in Python.
In my use case, however, I need to make sure the generated function has a particular name and particularly-named arguments as well. I'll give an example.
Suppose I want to parse a Yaml file that has a format like this:
Root:
my_idea:
type: conditional
conditionals:
- foo
- bar
query: >
SELECT * FROM some_table
This needs to be interpreted as: create a function for me called "my_idea" which has arguments named "foo" and "bar" (in that order).
When the function is called, use some existing tool to connect to a database and prepare the query element from the Yaml file. Then add a WHERE clause based on the conditional names matching the values passed in to the function for that argument.
So, after this happens, a user should be able to call:
my_idea(10, 20)
and it would be equivalent to executing the query
SELECT * FROM some_table WHERE foo = 10 AND bar = 20
If I used def to make the function, it might be something like this:
def my_idea(arg1, arg2):
query = (query_retrieved_from_file +
" WHERE {}={} AND {}={}".format(arg1_name_from_file,
arg1,
arg2_name_from_file,
arg2))
connection = ExistingLibraryConnectionMaker()
return connection.execute(query).fetchall()
This is a really simplified example -- I'm not endorsing the specifics of this little function, just trying to illustrate the idea.
The question is: how to create this on-the-fly, where the name of the function and the name of the positional arguments are extracted from a text file?
In the other question, there is some example code:
import types
def create_function(name, args):
def y(): pass
y_code = types.CodeType(args,
y.func_code.co_nlocals,
y.func_code.co_stacksize,
y.func_code.co_flags,
y.func_code.co_code,
y.func_code.co_consts,
y.func_code.co_names,
y.func_code.co_varnames,
y.func_code.co_filename,
name,
y.func_code.co_firstlineno,
y.func_code.co_lnotab)
return types.FunctionType(y_code, y.func_globals, name)
but it's not clear how to have the positional args reflect what I want them to semantically reflect.
The other solution I found was like this:
import types
import sys,imp
code = """def f(a,b,c):
print a+b+c, "really WoW"
"""
module = imp.new_module('myfunctions')
exec code in module.__dict__
module.f('W', 'o', 'W')
Output:
WoW really WoW
This is much closer, but requires all of the code to be embedded in a string format. I'm looking to build up a function programmatically, and across a reasonably large set of options, so handling them all deep in strings is not doable.

LL Parser example, made for fun.
Generates
Generated Code:
def my_idea(arg0,arg1,atasdasd):
query = "SELECT * FROM some_table WHERE foo==arg0 AND bar>arg1"
connection = ExistingLibraryConnectionMaker()
return connection.execute(query).fetchall()
def lool(hihi,ahah):
query = "SELECT * FROM some_table WHERE foo<=hihi AND bar<ahah"
connection = ExistingLibraryConnectionMaker()
return connection.execute(query).fetchall()
###end
from
Root:
my_idea:
args :
-arg0
-arg1
-atasdasd
type: conditional
conditional:
-foo == arg0
-bar > arg1
query:
SELECT * FROM some_table
lool:
args :
-hihi
-ahah
type: conditional
conditional:
- foo <= hihi
- bar < ahah
query:
SELECT * FROM some_table
Can handle any number of functions.
Code:
from __future__ import print_function
import re
import traceback
import sys
glIndex = 0
code = ""
class Token(object):
def __init__(self, pattern, name, value=None, transform=None):
self.pattern = pattern
self.name = name
self.value = value
tokens = {
Token(r"(\()","lpar"),
Token(r"(\))","rpar"),
Token(r"(\d(?:\.\d*)?)","number"),
Token(r"(\+)", "plus"),
Token(r"(?!\-\-)(\-)","minus"),
Token(r"(?!\=\=)(\=)","egal"),
Token(r"(;)","colon"),
Token(r"([a-zA-Z][a-zA-Z0-9_]*)(?=[\s\:])","unique"),
Token(r"(\=)\=","=="),
Token(r"(\>\=)",">="),
Token(r"(\<\=)","<="),
Token(r"(?!\>\=)(\>)",">"),
Token(r"(?!\<\=)(\<)","<"),
Token(r"\:",":"),
Token(r"\*","*")}
def peekComp(l):
symbol = None
if peekMatch(l,">=") :
symbol = ">="
elif peekMatch(l,"<=") :
symbol = "<="
elif peekMatch(l,">") :
symbol = ">"
elif peekMatch(l,"<") :
symbol = "<"
elif peekMatch(l,"==") :
symbol = "=="
return symbol
def parseListItem(l):
match(l,"minus")
u = match(l,"unique")
return u
def parseTitle(l):
val = match(l,"unique")
match(l,":")
return val
def parseComp(l):
match(l,"minus")
lvar = match(l,"unique")
symbol = peekComp(l)
if symbol == None:
print("Homemaid SyntaxError: needed a comp symbol")
exit(1)
symbolS = match(l,symbol)
rvar = match(l,"unique")
return (lvar,symbolS,rvar)
def tokenize(s):
l=[]
i=0
while i < s.__len__():
if re.match(r"\s",s[i]):
i+=1
continue
foundAMatch = False
for t in tokens:
pat = "^(" + t.pattern + ").*"
#print("trying with pat :'"+pat+"';")
res = re.match(pat,s[i:])
if res != None:
print("Match: -what : '" + res.group(1) + "' -to-token-named :'" + t.name + "'; \t\tTotal text : '" + res.group(0) + "';" )
i += res.group(1).__len__()
foundAMatch = True
l.append(Token(t.pattern,t.name,res.group(1)))
break
if not foundAMatch:
print("Homemaid SyntaxError: No match for '" + s[i:] + "';")
quit()
return l
def syntaxError(l,fname):
global glIndex
print("Homemaid SyntaxError: '"+l[glIndex].name+"'")
print(fname)
quit()
def match(tokens, wanted):
global glIndex
if tokens[glIndex].name == wanted:
glIndex+=1
print("Matched '" + tokens[glIndex-1].value + "' as '" + wanted + "';")
return tokens[glIndex-1].value
else:
print("Homemaid Syntax Error : Match failed on token '" + tokens[glIndex].name + "' with wanted token '" + wanted + "' and text '" + tokens[glIndex].value + "';")
exit(1)
def peekMatch(token, wanted):
global glIndex
if glIndex < token.__len__() and token[glIndex].name == wanted:
print("Matched "+wanted)
return True
else:
return False
def parse(l):
#root
localCode = ""
rootName = parseTitle(l)
print("Root : " + rootName)
#parse funcitons
while peekMatch(l,"unique"):
localCode += parseFunction(l)
print("Done with the parsing.")
return localCode
def parseFunction(l):
print("CAME IN PARSE FUNCITON")
#function name
localCode = "\n\ndef " + parseTitle(l) +"(";
#args
args = set()
title = parseTitle(l)
if title!="args":
print("Homemaid Syntax Error : title should be 'args', was instead '" + title + "';")
exit(1)
while(peekMatch(l,"minus")):
lastArg = parseListItem(l)
args.add(lastArg)
localCode += lastArg
if peekMatch(l,"minus") :
localCode += ","
localCode += "):\n"
#type
if parseTitle(l)!="type":
print("Homemaid Syntax Error : title should be 'type'")
exit(1)
#query
##query name
queryTypeName = match(l, "unique")
##query args
queryTypeArgs = []
if parseTitle(l)!=queryTypeName:
print("Homemaid Syntax Error : title should be the same as the name of the query.")
exit(1)
while(peekMatch(l,"minus")):
queryTypeArgs.append(parseComp(l))
##query sql code
if parseTitle(l) != "query":
print("Homemaid Syntax Error : title should be 'query'.")
exit(1)
initialQuery = parseBasicSqlQuery(l)
if queryTypeName == "conditional" and queryTypeArgs.__len__() <= 0 :
print("Homemaid Syntax error : Conditional query needs at least one arg.")
exit(1)
##query codegen
localCode += "\tquery = \"" + initialQuery + " WHERE "
first = True
if queryTypeName == "conditional":
for lArg, cmpSign, rArg in queryTypeArgs:
if not first:
localCode += " AND "
if rArg in args:
first = False
localCode += lArg + cmpSign + rArg
else:
print("queryTypeArgs : " + str(queryTypeArgs))
print("Homemaid Logic Error: Query arg '" + rArg + "' is not in the funciton args " + str(args) + ".")
quit(1)
localCode += "\"\n\tconnection = ExistingLibraryConnectionMaker()\n\treturn connection.execute(query).fetchall()"
return localCode
def parseBasicSqlQuery(l):
selectS = match(l,"unique")
whatS = match(l,"*")
fromS = match(l,"unique")
tableNameS = match(l,"unique")
if selectS.upper() != "SELECT" or fromS.upper() != "FROM":
print("Homemaid Syntax error: bad basic sql.")
exit(0)
return selectS + " " + whatS + " " + fromS + " " + tableNameS
def parseVal(l):
if match(l, "lpar"):
parseVal(l)
match(l, "rpar")
elif peekMatch(l, "number") and (peekMatch(l, "plus") or peekMatch(l, "minus") or peekMatch(l, "equal")):
glIndex+=1
print("peekMatched!")
parseOp(l)
parseVal(l)
elif match(l, "number"):
pass
else:
syntaxError(l, "parseVal")
print("** Parsed val.")
def parseOp(l):
if match(l, "plus"):
pass
elif match(l, "minus"):
pass
elif match(l, "egal"):
pass
else:
syntaxError(l, "parseVal")
print("** Parsed op.")
if __name__ == "__main__":
with open("sqlGenTest.SQLGEN", "rw") as file:
print("File:\n'")
text = file.read()
print(text + "'\n")
tokens = tokenize(text)
names = map(lambda x: str("'" + x.name + "'" + " : " + "'" + x.value + "'"), tokens)
map(print,names)
code = parse(tokens)
print("")
print("###Generated Code:\n" + code)
print("###end")
print()