INTERVIEW QUESTIONS

What are the ways to write a function using call by reference?

Arguments in python are passed as an assignment. This assignment creates an object that has no relationship between an argument name in source and target. The procedure to write the function using call by reference includes:
The tuple result can be returned to the object which called it. The example below shows it:

def function(a, b):
a = 'value'
b = b + 1
# a and b are local variables that are used to assign the new objects
return a, b
# This is the function that is used to return the value stored in b

- The use of global variables allows the function to be called as reference but this is not the safe method to call any function. 
- The use of mutable (they are the classes that consists of changeable objects) objects are used to pass the function by reference.

def function(a):
a[0] = 'string'
a[1] = a[1] + 1
# The ‘a’ array give reference to the mutable list and it changes the changes that are shared
args = ['string', 10]
func1(args)
print args[0], args[1]
#This prints the value stored in the array of ‘a’

Write a program to find out the name of an object in python.

The object doesn’t have any name and there is no way the can be found out for objects. The assignment is used to bind a name to the value that includes the name of the object that has to be bound by a value. If the value is callable then the statements are made true and then the program followed can be used to find the reference name of an object.

class try:
pass
B = A
a = B()
b = a
print b
<__main__.try instance at 0x16D07CC>
print b

The class consists of name and the names are invoked by using the the variable B that creates an instance for the class try. The method is to find out from all the namespaces that the object exists and then print the name of the object.

Write a program to check whether the object is of a class or its subclass.

There is a method which is built-in to show the instances of an object that consists of many classes by providing a tuple in a table instead of individual classes. The method is given as isinstance(obj,cls) and in more details given as:

isinstance(obj, (class1, class2, ...)) that is used to check about the object’s presence in one of the classes. The built in types can also have many formats of the same function like isinstance(obj, str) or isinstance(obj, (int, long, float, complex)). 

It is not preferred to use the class instead user-defined classes are made that allow easy object-oriented style to define the behavior of the object’s class. These perform different thing that is based on the class. The function differs from one class to another class. 
To find out the object of the particular class the following program is used:

def search(obj):
if isinstance(obj, box):
# This is the code that is given for the box and write the program in the object
elif isinstance(obj, Document):
# This is the code that searches the document and writes the values in it
elif
obj.search()
#This is the function used to search the object’s class.

Why does delegation performed in Python?

Delegation is a technique that is used in object oriented programming. This is used to show the object and the behavior of the methods that are used. The class can be created to provide an implementation of the method that allows the method to be referenced. The delegate is having the parameter and the return value in an object. It also allows the methods to be passed as parameters and allow the defining of the callback methods that can be grouped together in multiple methods. These methods can be called from a single event. The example shows a class that captures the behavior of the file and converts data from lower to uppercase.

class upcase:
def __init__(self, out):
self._out = out
def write(self, s):
self._outfile.write(s.upper())
def __getattr__(self, name):
return getattr(self._out, name)

The write() method that is used in the upcase class converts the string to the uppercase before calling another method. The delegation is being given using the self.__outfile object.

Write a program to read and write the binary data using python?

The module that is used to write and read the binary data is known as struct. This module allows the functionality and with it many functionalities to be used that consists of the string class. This class contains the binary data that is in the form of numbers that gets converted in python objects for use and vice versa. The program can read or write the binary data is:

import struct
f = open(file-name, "rb")
# This Open() method allows the file to get opened in binary mode to make it portable for # use.
s = f.read(8)
x, y, z = struct.unpack(">hhl", s)

The ‘>” is used to show the format string that allows the string to be converted in big-endian data form. For homogenous list of data the array module can be used that will allow the data to be kept more organized fashion.

How does global value mutation used for thread-safety?

The global interpreter lock is used to allow the running of the thread one at a time. This is internal to the program only and used to distribute the functionality along all the virtual machines that are used. Python allows the switching between the threads to be performed by using the byte code instructions that are used to provide platform-independence. The sys.setcheckinterval() method is used that allow the switching to occur during the implementation of the program and the instruction. This provides the understanding in the field of accounting to use the byte code implementation that makes it portable to use. The atomicity can be provided such that the shared variables can be given as built-in data types.

Write a program to read and write the binary data using python?
The module that is used to write and read the binary data is known as struct. This module allows the functionality and with it many functionalities to be used that consists of the string class. This class contains the binary data that is in the form of numbers that gets converted in python objects for use and vice versa. The program can read or write the binary data is:

import struct
f = open(file-name, "rb")
# This Open() method allows the file to get opened in binary mode to make it portable for # use.
s = f.read(8)
x, y, z = struct.unpack(">hhl", s)

The ‘>” is used to show the format string that allows the string to be converted in big-endian data form. For homogenous list of data the array module can be used that will allow the data to be kept more organized fashion.

What are the different ways to generate random numbers?

Random module is the standard module that is used to generate the random number. 
The method is defined as:

import random
random.random()

The statement random.random() method return the floating point number that is in the range of [0, 1). The function generates the random float numbers. The methods that are used with the random class are the bound methods of the hidden instances. The instances of the Random can be done to show the multi-threading programs that creates different instance of individual threads. The other random generators that are used in this are:
- randrange(a, b): it chooses an integer and define the range in-between [a, b). It returns the elements by selecting it randomly from the range that is specified. It doesn’t build a range object. 
- uniform(a, b): it chooses a floating point number that is defined in the range of [a,b).Iyt returns the floating point number
- normalvariate(mean, sdev): it is used for the normal distribution where the mu is a mean and the sdev is a sigma that is used for standard deviation. 
- The Random class that is used and instantiated creates an independent multiple random number generators.