What are the commands that are used to copy an object in Python?
The command that is used to copy an object in python includes:
- copy.copy() function: This makes a copy of the file from source to destination. It returns a shallow copy of the parameter that is passed.
- copy.deepcopy(): This also creates a copy of the object from source to destination. It returns a deep copy of the parameter that is passed to the function.
The dictionary consists of all the objects and the copy() method which is used as:
newdict = olddict.copy()
The assignment statement doesn’t copy any object but it creates a binding between the target and the object that is used for the mutable items. Copy is required to keep a copy of it using the modules that is provided to give generic and shallow operations.
What is the difference between deep and shallow copy?
- Shallow copy is used when a new instance type gets created and it keeps the values that are copied in the new instance. Whereas, deep copy is used to store the values that are already copied.
- Shallow copy is used to copy the reference pointers just like it copies the values. These references point to the original objects and the changes made in any member of the class will also affect the original copy of it. Whereas, deep copy doesn’t copy the reference pointers to the objects. Deep copy makes the reference to an object and the new object that is pointed by some other object gets stored. The changes made in the original copy won’t affect any other copy that uses the object.
- Shallow copy allows faster execution of the program and it depends on the size of the data that is used. Whereas, deep copy makes it slower due to making certain copies for each object that is been called.
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.
How can the ternary operators be used in python?
The ternary operator is the operator that is used to show the conditional statements. This consists of the true or false values with a statement that has to be evaluated for it. The operator will be given as:
[on_true] if [expression] else [on_false]
x, y = 25, 50
big = x if x < y else y
This is the lowest priority operator that is used in making a decision that is based on the values of true or false. The expression gets evaluated like if x<y else y, in this case if x<y is true then the value is returned as big=x and if it is incorrect then big=y will be sent as a result.
How the string does get converted to a number?
- To convert the string into a number the built-in functions are used like int() constructor. It is a data type that is used like int (‘1’) ==1.
- float() is also used to show the number in the format as float(‘1’)=1.
- The number by default are interpreted as decimal and if it is represented by int(‘0x1’) then it gives an error as ValueError. In this the int(string,base) function takes the parameter to convert string to number in this the process will be like int(‘0x1’,16)==16. If the base parameter is defined as 0 then it is indicated by an octal and 0x indicates it as hexadecimal number.
- There is function eval() that can be used to convert string into number but it is a bit slower and present many security risks like __import__('os').system("rm -rf$HOME") - use of this will delete the home directory of the system.
What is the function of negative index?
The sequences in python are indexed and it consists of the positive as well as negative numbers. The numbers that are positive uses ‘0’ as first index and ‘1’ as the second index and the process goes on like that. The index for the negative number starts from ‘-1’ that represents the last index in the sequence and ‘-2’ as the penultimate index and the sequence carries forward like the positive number. The negative index is used to remove any new-line spaces from the string and allow the string to except the last character that is given as S[:-1]. The negative index is also used to show the index to represent the string in correct order.
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 isinstance(obj,cls)
isinstance(obj, (class1, class2, ...)) is used to check 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 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.
Explain delegation in Python
Delegation is an object oriented technique (also called a design pattern). Let's say you have an object x and want to change the behaviour of just one of its methods. You can create a new class that provides a new implementation of the method you're interested in changing and delegates all other methods to the corresponding method of x. 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 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.
What is the function of “self”?
“Self” is a variable that represents the instance of the object to itself. In most of the object oriented programming language, this is passed to the methods as a hidden parameters that is defined by an object. But, in python, it is declared and passed explicitly. It is the first argument that gets created in the instance of the class A and the parameters to the methods are passed automatically. It refers to separate instance of the variable for individual objects. This is the first argument used in the class instance and the “self” method is defined explicitly to all the methods that are used and present. The variables are referred as “self.xxx”.
How is “self” explicitly defined in a method?
“Self” is a reference variable and an instance attribute that is used instead of the local variable inside the class. The function or the variable of the self like self.x or self.meth() can be used in case the class is not known. There are no variables declared as local. It doesn’t have any syntax and it allow the reference to be passed explicity or call the method for the class that is in use. The use of writebaseclass.methodname(self, <argument list>) shows that the method of _init_() can be extended to the base class methods. This also solves the problem that is syntactic by using the assignment and the local variables. This tells a way to the interpreter the values that are to be used for the instance variables and local variables. The use of explicit self.var solves the problem mentioned above.
What is the process of compilation and linking in python?
The compiling and linking allows the new extensions to be compiled properly without any error and the linking can be done only when it passes the compiled procedure. If the dynamic loading is used then it depends on the style that is being provided with the system. The python interpreter can be used to provide the dynamic loading of the configuration setup files.
The steps required are as follows:
- Create a file with any name and in any languages supported by the compiler of your system. For example comp.c
- Place this file in the Modules/ directory of the distribution which is getting used.
- Add a line in the file Setup.local present in the Modules/ directory.
- Run the file using spam comp.o
- After successful run of this rebuild the interpreter by using the make command on the top-level directory.
- If the file is changed then run rebuildMakefile by using the command as ‘make Makefile’.
What is the procedure to extract values from the object used in python?
To extract the value it requires the object type to be defined and the values are fetched according to the object type.
The values are extracted as:
- If the object is a tuple then PyTuple_Size() method is used that returns the length of the values and the method PyTuple_GetItem() returns the data item stored at a specific index.
- If the object is a list then PyListSize() and PyList_GetItem() perform the same function as they are for tuple.
- Strings use PyString_Size() to return the length of the value and PyString_AsString() returns the pointer to its value.
- To check the type of the object and the extracted values, methods like PyString_Check(), PyTuple_Check(), PyList_Check(), etc are used.
The command that is used to copy an object in python includes:
- copy.copy() function: This makes a copy of the file from source to destination. It returns a shallow copy of the parameter that is passed.
- copy.deepcopy(): This also creates a copy of the object from source to destination. It returns a deep copy of the parameter that is passed to the function.
The dictionary consists of all the objects and the copy() method which is used as:
newdict = olddict.copy()
The assignment statement doesn’t copy any object but it creates a binding between the target and the object that is used for the mutable items. Copy is required to keep a copy of it using the modules that is provided to give generic and shallow operations.
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What is the difference between deep and shallow copy?
- Shallow copy is used when a new instance type gets created and it keeps the values that are copied in the new instance. Whereas, deep copy is used to store the values that are already copied.
- Shallow copy is used to copy the reference pointers just like it copies the values. These references point to the original objects and the changes made in any member of the class will also affect the original copy of it. Whereas, deep copy doesn’t copy the reference pointers to the objects. Deep copy makes the reference to an object and the new object that is pointed by some other object gets stored. The changes made in the original copy won’t affect any other copy that uses the object.
- Shallow copy allows faster execution of the program and it depends on the size of the data that is used. Whereas, deep copy makes it slower due to making certain copies for each object that is been called.
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.
How can the ternary operators be used in python?
The ternary operator is the operator that is used to show the conditional statements. This consists of the true or false values with a statement that has to be evaluated for it. The operator will be given as:
[on_true] if [expression] else [on_false]
x, y = 25, 50
big = x if x < y else y
This is the lowest priority operator that is used in making a decision that is based on the values of true or false. The expression gets evaluated like if x<y else y, in this case if x<y is true then the value is returned as big=x and if it is incorrect then big=y will be sent as a result.
How the string does get converted to a number?
- To convert the string into a number the built-in functions are used like int() constructor. It is a data type that is used like int (‘1’) ==1.
- float() is also used to show the number in the format as float(‘1’)=1.
- The number by default are interpreted as decimal and if it is represented by int(‘0x1’) then it gives an error as ValueError. In this the int(string,base) function takes the parameter to convert string to number in this the process will be like int(‘0x1’,16)==16. If the base parameter is defined as 0 then it is indicated by an octal and 0x indicates it as hexadecimal number.
- There is function eval() that can be used to convert string into number but it is a bit slower and present many security risks like __import__('os').system("rm -rf$HOME") - use of this will delete the home directory of the system.
What is the function of negative index?
The sequences in python are indexed and it consists of the positive as well as negative numbers. The numbers that are positive uses ‘0’ as first index and ‘1’ as the second index and the process goes on like that. The index for the negative number starts from ‘-1’ that represents the last index in the sequence and ‘-2’ as the penultimate index and the sequence carries forward like the positive number. The negative index is used to remove any new-line spaces from the string and allow the string to except the last character that is given as S[:-1]. The negative index is also used to show the index to represent the string in correct order.
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 isinstance(obj,cls)
isinstance(obj, (class1, class2, ...)) is used to check 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 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.
Explain delegation in Python
Delegation is an object oriented technique (also called a design pattern). Let's say you have an object x and want to change the behaviour of just one of its methods. You can create a new class that provides a new implementation of the method you're interested in changing and delegates all other methods to the corresponding method of x. 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 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.
What is the function of “self”?
“Self” is a variable that represents the instance of the object to itself. In most of the object oriented programming language, this is passed to the methods as a hidden parameters that is defined by an object. But, in python, it is declared and passed explicitly. It is the first argument that gets created in the instance of the class A and the parameters to the methods are passed automatically. It refers to separate instance of the variable for individual objects. This is the first argument used in the class instance and the “self” method is defined explicitly to all the methods that are used and present. The variables are referred as “self.xxx”.
How is “self” explicitly defined in a method?
“Self” is a reference variable and an instance attribute that is used instead of the local variable inside the class. The function or the variable of the self like self.x or self.meth() can be used in case the class is not known. There are no variables declared as local. It doesn’t have any syntax and it allow the reference to be passed explicity or call the method for the class that is in use. The use of writebaseclass.methodname(self, <argument list>) shows that the method of _init_() can be extended to the base class methods. This also solves the problem that is syntactic by using the assignment and the local variables. This tells a way to the interpreter the values that are to be used for the instance variables and local variables. The use of explicit self.var solves the problem mentioned above.
What is the process of compilation and linking in python?
The compiling and linking allows the new extensions to be compiled properly without any error and the linking can be done only when it passes the compiled procedure. If the dynamic loading is used then it depends on the style that is being provided with the system. The python interpreter can be used to provide the dynamic loading of the configuration setup files.
The steps required are as follows:
- Create a file with any name and in any languages supported by the compiler of your system. For example comp.c
- Place this file in the Modules/ directory of the distribution which is getting used.
- Add a line in the file Setup.local present in the Modules/ directory.
- Run the file using spam comp.o
- After successful run of this rebuild the interpreter by using the make command on the top-level directory.
- If the file is changed then run rebuildMakefile by using the command as ‘make Makefile’.
What is the procedure to extract values from the object used in python?
To extract the value it requires the object type to be defined and the values are fetched according to the object type.
The values are extracted as:
- If the object is a tuple then PyTuple_Size() method is used that returns the length of the values and the method PyTuple_GetItem() returns the data item stored at a specific index.
- If the object is a list then PyListSize() and PyList_GetItem() perform the same function as they are for tuple.
- Strings use PyString_Size() to return the length of the value and PyString_AsString() returns the pointer to its value.
- To check the type of the object and the extracted values, methods like PyString_Check(), PyTuple_Check(), PyList_Check(), etc are used.
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