why function overloading needed in Object oriented programming

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Hi All,

This is Sachin, a newbie in oop, asking a very foolish question but need an explaination to avoid big confusion.

Why function overloading needed in Object oriented programming?

Posted 10-Apr-11 21:02pm

Coder Block

Updated 10-Apr-11 22:14pm

Dalek Dave

v2

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Dalek Dave 11-Apr-11 4:15am

Edited for spelling and grammar.

4 solutions

Solution 4

To make life easier for us all.

If I construct a generic email method, I will construct it with a number of overloads:

public static void Email(string body)
public static void Email(string body,
                         params MailAttachment[] attachments)
public static void Email(string to, string body)
public static void Email(string to,
                         string body,
                         params MailAttachment[] attachments)
public static void Email(string to,
                         string body,
                         string subject)
public static void Email(string to,
                         string body,
                         string subject,
                         params MailAttachment[] attachments)
public static void Email(string to,
                         string body,
                         string subject,
                         string fromAddress)
public static void Email(string to,
                         string body,
                         string subject,
                         string fromAddress,
                         params MailAttachment[] attachments)
public static void Email(string to,
                         string body,
                         string subject,
                         string fromAddress,
                         string fromDisplay,
                         params MailAttachment[] attachments)
public static void Email(string to,
                         string body,
                         string subject,
                         string fromAddress,
                         string fromDisplay,
                         string credentialUser,
                         string credentialPassword,
                         params MailAttachment[] attachments)

And these will all eventually call the final one, which will do the actual job. All the others just "fill in the blanks" with appropriate defaults, or prepare suitable parameters.

In the old days, I would have had to construct nine different routines, all with different names such as "EmailToBodySubjectFromaddressWithAttachments", and then try desperately to remember which had which parameters, or how to construct the relevant defaults. This way, I have to remember one name: "Email" and the system will help me fill in the blanks.

Much easier for me, and a whole lot more reliable to boot!

Posted 10-Apr-11 21:13pm

OriginalGriff

Comments

Sergey Alexandrovich Kryukov 11-Apr-11 3:15am

I know your style of answering this question. Well, a 5, but...
It should be noted that this has nothing to do with OOP.
See my Answer.
--SA

Philippe Mori 6-Feb-15 12:22pm

In practice, you would never provide that much overload... You would provide those that often used and the generic one. By the way, how would you use the one that does not have "to".

OriginalGriff 6-Feb-15 13:58pm

Default version to send direct to "webmaster at mydomain" etc.

Solution 1

Function overloading allows you to create different methods with the same name.
So basically, I can call the same method and based on my requirement (and implementation) the right method is automatically called.

For e.g. I can have two overloaded methods GetName(string firstname) and GetName(string firstname, string lastname). Based on whether I call the first GetName or the second one, I could get back only first name or first name and lastname concatenated together.

Posted 10-Apr-11 21:08pm

Abhinav S

Updated 10-Apr-11 21:09pm

v2

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Sergey Alexandrovich Kryukov 11-Apr-11 3:12am

We've been answering at the same time. My 5 for yours.
It must be just a big OP's confusion.
Please see my answer as well.
--SA

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-04-10T21:11:00

Solution 2

It is not needed — not at all. Function overloading is only for convenience, just to allow same name for actually different methods. Compiler can tell one method from another just by looking at the parameters of the call, where possible.

Formally, I answered this question fully. However…

What is used on OOP is overriding. This is a central point of OOP. You cannot explain it without understanding the main idea of OOP. See any manual of the topic — this is a bit beyond the format of CodeProject. It this is just a school test or interview question, experts usually don't answer such Questions.

—SA

Posted 10-Apr-11 21:11pm

Sergey Alexandrovich Kryukov

Updated 10-Apr-11 21:17pm

v3

Comments

Abhinav S 11-Apr-11 3:15am

5. Another approach to answer OP's question.

Sergey Alexandrovich Kryukov 11-Apr-11 3:16am

Thank you, Abhinav. Well, not a really different approach.
The key here is: overloading has nothing to do with OOP.
--SA

CPallini 11-Apr-11 3:23am

Well done, my 5. I like expecially the: "Is is not needed - not at all" sentence.

Sergey Alexandrovich Kryukov 11-Apr-11 3:56am

Thank you very much.
--SA

[no name] 11-Apr-11 3:45am

Nice one.

Sergey Alexandrovich Kryukov 11-Apr-11 3:56am

Thank you, Santosh.
--SA

Coder Block 11-Apr-11 3:50am

Thanks --SA.

Sergey Alexandrovich Kryukov 11-Apr-11 3:57am

You're welcome.
Thank you for accepting this Answer.
Good luck.
--SA

Niklas L 11-Apr-11 4:31am

Good answer! Overloading and overriding is too often confused seeing the questions asked here.

Sergey Alexandrovich Kryukov 11-Apr-11 4:35am

Thank you, Niklas.

You're right. The term "overriding" is perfectly adequate.
The invention of the term "overloading" was poorely idiotic (and now it's maybe too late). There is nothing "loaded" to be "overloaded". What's good, there is not such key word. This term is a source of confusion.

--SA

Niklas L 11-Apr-11 4:43am

As with all aspects of programming, good naming is essential for learning, readability, maintainability, etc. Unfortunately, this one cannot easily be re-factored.

Sergey Alexandrovich Kryukov 11-Apr-11 4:52am

Why? Again, the term "overload" never appears in code itself. (but good term "override" does appear). So, situation is not so bad. The only problem is informal communication.
--SA

Niklas L 11-Apr-11 5:01am

It would probably be easier to change the name if it did appear in code. Its hard to tag a commonly used term deprecated.

Sergey Alexandrovich Kryukov 11-Apr-11 5:07am

I'm not sure. The name would be the keyword, which are hard to change because of backup compatibility. There are many stupid or sloppy terms.

For example, I used to read a very self-describing term "incorrect dependency on the order or execution" but now everyone calls it "race condition". As a result, huge number of developers mix up "race condition" with "deadlock" and other unrelated concepts.

If I invent of dig out a better term I tend to force it. Some limited improvement is possible :-)

--SA

Niklas L 11-Apr-11 5:31am

You can make a keyword deprecated and still allow using it for backward compatibility.
But I wish you all the best in your quest for a better 'override' term :)

Sergey Alexandrovich Kryukov 11-Apr-11 14:01pm

If works with API, not with key word, which would create a new incompatible version of the language. Do you see the difference. I personally would prefer new version of language to avoid sloppiness but million of hamsters wine badly in some cases...
--SA

Niklas L 11-Apr-11 14:28pm

API or keyword, there's only a time-to-market difference. You could one day decide that the use of for-loops should be avoided, in favor of while-loops. Every new compiler would issue a warning on for-loop use. Not as easy as pushing new API sources I admit, but not unrealistic.
You might argue that these changes never comes to those who doesn't upgrade to the latest compiler, but that also holds for those not upgrading to latest API version. There really isn't a big difference, other than time-to-market.
(This comment is for API vs keyword only.)

Sergey Alexandrovich Kryukov 11-Apr-11 14:30pm

I understand. This is a good note. We're on a highly hypothetical matters. There is not such keywords as "overload" anyway... :-) I think you already understand each other well enough...
--SA

Guyverthree 11-Apr-11 8:52am

I disagree that overloading was purely idiotic, you load a functions with parameters, and in it's first instance (very old I might add) overloading was used to increase the variables which were passed to a function, hence the terms overloading.

But I agree that the terms are mixed on occasion. And need to be understood completely.

Sergey Alexandrovich Kryukov 11-Apr-11 14:06pm

What are your talking about?! I say about the word "overloading", not overloading itself.
Your argument is breaking through the open door. Nobody question the use of overloading, the term is bad.
--SA

Guyverthree 14-Apr-11 4:25am

Sorry I miss read the wording of your post of poorly as purely.

I apologize.

Sergey Alexandrovich Kryukov 14-Apr-11 13:04pm

No problem. I guess we finalized this part of discussion.
--SA

Stefan_Lang 11-Apr-11 4:38am

Good answer mostly, but I disagree on one thing:

Overloading is needed in OOP, otherwise you couldn't define constructors! (apart from the default constructor, obviously). Of course, you could overcome this by adding Create() methods, but that would require two function calls to properly construct an object rather than just one, and that also recursively applies to base classes. It would be inefficient and error prone to do this; I'd call that more than an inconvenience.

[edit]
This comment is specific to C++, and was meant as such.

Strictly speaking, you can write OOP programs in any language; and as a consequence, any particular language feature isn't *needed* for OOP. However, many concepts that are part of the OOP paradigm cannot be easily verified in a general purpose language without taking advantage of certain language features.

In C++, the ability to overload constructors is one of these features which helps describe the properties of an object in terms of the class attributes and methods and their declarations only. Templates are another.

In other languages, other features may be required to properly encode OOP properties, and overloading may not be neccesary.
[/edit]

Niklas L 11-Apr-11 4:50am

I see that as a convenience for the programmer, not a necessity for OOP as a concept.

Sergey Alexandrovich Kryukov 11-Apr-11 4:56am

I agree, this is not really a necessity.
Nevertheless Stephan's note is useful in context of C++, C++/CLI, C#, etc.
--SA

Sergey Alexandrovich Kryukov 11-Apr-11 4:54am

Stefan, I understand you point, but your topic of discussion is too narrow. This is C++ specific. In some other languages constructors are not named as the class. (Surprise?) So, you want to discuss OOP as such, this is a side dish. Your note is useful nevertheless.
Thank you.
--SA

Stefan_Lang 11-Apr-11 4:58am

Ah, my bad. I've seen it filed under C++ questions and didn't think to check that it wasn't actually language dependend.

Sergey Alexandrovich Kryukov 11-Apr-11 5:08am

That's not really bad, just less fundamental aspect. It was good to note though.
Thank you.
--SA

santosh dhanawade · Accepted Answer · 2011-04-10T21:11:00

Hey dear first try google for this then asked question
Google[^]

but let me explain some logic and some interesting concept,
A Function overloading means same function with different parameter list like,
following

add(int k,int j)  //for adding two integer

add(float k,float j)//for adding two floats

Now in java take example,

int indexOf(String str) //take one parameter
int indexOf(int ch, int startIndex) //overloaded with two parameter

now if there no function overloading then for same task there two saparates functions.
Like there goes increase for different purpose so
To reduce the increase order of function for same task a operator overloading introduced,
same with constructor overloading

why function overloading needed in Object oriented programming

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