overload or inherit

[epanda]

Hi,

I would like to merge two class which have got 90% of same source
code. But I don't know what to do.

class A {

int putLightOn () {

switch(status)
{
case iAmOff :
print "I am off" ;
print "put me on!!!\n" ;
}
}

}


class B {

int putLightOn () {

switch(status)
{
case iAmOff :
print "I am off" ;
print "and I am a red light" ; <<<< the only difference
between A and B
print "put me on!!!\n" ;
}
}

}


I would like that B inherit from A but I don't know how re writing B's
putLightOn function

Can you help me?
Thanks

[Kevin Frey]

Re: overload or inherit

These kinds of questions are hard to give good answers to because the
classes don't convey any kind of real-world concept.

It is not a case of "overload" OR inherit - because usually (in a class
sense) you will perform overloading as a result of inheritance, to change
part of the derived class' behaviour.

In you are looking to deal with class A and class B in a polymorphic manner
(eg. class A is "Light" and class B is a specialised type of light, such as
"InfraredLight" ), then you will want to make certain methods virtual (the
ones which change between implementations , as opposed to the "common"
implementation.

If on the other hand you are just looking to use inheritance as a way to
"re-use" some of the implementation, but not necessarily in a polymorphic
manner, then just derive B from A and overload the methods that need to
change.

From my perspective, it looks like you are more looking to do the latter.

[epanda]

Re: overload or inherit

Ok thanks Kevin.

Kevin Frey a écrit :

These kinds of questions are hard to give good answers to because the
classes don't convey any kind of real-world concept.
>
It is not a case of "overload" OR inherit - because usually (in a class
sense) you will perform overloading as a result of inheritance, to change
part of the derived class' behaviour.
>
In you are looking to deal with class A and class B in a polymorphic manner
(eg. class A is "Light" and class B is a specialised type of light, such as
"InfraredLight" ), then you will want to make certain methods virtual (the
ones which change between implementations , as opposed to the "common"
implementation.
>
If on the other hand you are just looking to use inheritance as a way to
"re-use" some of the implementation, but not necessarily in a polymorphic
manner, then just derive B from A and overload the methods that need to
change.
>
From my perspective, it looks like you are more looking to do the latter.

[James Kanze]

Re: overload or inherit

On Aug 5, 10:31 pm, epanda <callingel...@h otmail.frwrote:

I would like to merge two class which have got 90% of same
source code. But I don't know what to do.

class A {
int putLightOn () {
switch(status)
{
case iAmOff :
print "I am off" ;
print "put me on!!!\n" ;
}
}
}

class B {
int putLightOn () {
switch(status)
{
case iAmOff :
print "I am off" ;
print "and I am a red light" ; <<<< the only difference
between A and B
print "put me on!!!\n" ;
}
}
}

I would like that B inherit from A but I don't know how re
writing B's putLightOn function

As Kevin said, it largely depends on whether you want the two
classes to behave polymorphically nor not. If so, look into the
Template Method pattern or the Strategy pattern. If not,
consider using variations on mixins.

--
James Kanze (GABI Software) email:james.kan ze@gmail.com
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