struct foo and function foo !?

[Razvan]

Hi !



Today I saw some code like this:

struct foo {
foo(foo* s2){
cout << "foo::foo";
}
};

foo* foo(foo *s2)
{
cout << "foo::(foo* )";
return s2;
}

The name of the struct is 'foo' and the name of the
function is 'foo' also ! Why they are not conflicting ? The name of
types and the names of functions (and varialbles) are kept in separate
places ? Is this standard behaviour ?



Regards,
Razvan

[Razvan]

Re: struct foo and function foo !?

Tough question ?!!
Maybe somebody can pinpoint me to the right direction.

Razvan



mihai11@mailcit y.com (Razvan) wrote in message news:<15f19d61. 0406260828.7cc5 5@posting.googl e.com>...[color=blue]
> Hi !
>
>
>
> Today I saw some code like this:
>
> struct foo {
> foo(foo* s2){
> cout << "foo::foo";
> }
> };
>
> foo* foo(foo *s2)
> {
> cout << "foo::(foo* )";
> return s2;
> }
>
> The name of the struct is 'foo' and the name of the
> function is 'foo' also ! Why they are not conflicting ? The name of
> types and the names of functions (and varialbles) are kept in separate
> places ? Is this standard behaviour ?
>
>
>
> Regards,
> Razvan[/color]

[Prateek R Karandikar]

Re: struct foo and function foo !?

> > Today I saw some code like this:[color=blue][color=green]
> >
> > struct foo {
> > foo(foo* s2){
> > cout << "foo::foo";
> > }
> > };
> >
> > foo* foo(foo *s2)
> > {
> > cout << "foo::(foo* )";
> > return s2;
> > }
> >
> > The name of the struct is 'foo' and the name of the
> > function is 'foo' also ! Why they are not conflicting ? The name of
> > types and the names of functions (and varialbles) are kept in separate
> > places ? Is this standard behaviour ?[/color][/color]

Yes, unfotunately this is Standard behaviour. A struct and a function
in the same scope can have the same name. It is one of the unwanted
leftovers of the C language. In C, foo wouldn't be a type, struct foo
would be a type, so there was no ambiguity. In C++ now foo itself is a
type, but the committee chose not to break C compatibility in this
case. However it is best to avoid this "feature". A good compiler
should give a warning.

-- --
Abstraction is selective ignorance.
-Andrew Koenig
-- --

[Denis Remezov]

Re: struct foo and function foo !?

Prateek R Karandikar wrote:[color=blue]
>[color=green][color=darkred]
> > > Today I saw some code like this:
> > >
> > > struct foo {
> > > foo(foo* s2){
> > > cout << "foo::foo";
> > > }
> > > };
> > >
> > > foo* foo(foo *s2)
> > > {
> > > cout << "foo::(foo* )";
> > > return s2;
> > > }
> > >
> > > The name of the struct is 'foo' and the name of the
> > > function is 'foo' also ! Why they are not conflicting ? The name of
> > > types and the names of functions (and varialbles) are kept in separate
> > > places ? Is this standard behaviour ?[/color][/color]
>
> Yes, unfotunately this is Standard behaviour. A struct and a function
> in the same scope can have the same name. It is one of the unwanted
> leftovers of the C language. In C, foo wouldn't be a type, struct foo
> would be a type, so there was no ambiguity. In C++ now foo itself is a
> type, but the committee chose not to break C compatibility in this
> case. However it is best to avoid this "feature". A good compiler
> should give a warning.
>[/color]

Just to add, a function declaration or definition will hide the name
of a class /in the same scope/ (now you would need to say "struct foo"
in order to get down to the name of the /struct/ foo).

An interesting part is the function declarator itself:
foo* foo(foo* s2)
Here, foo* is still considered a pointer to struct foo since
the declaration of function foo is not yet complete. If I were
not able to change the names, I would use "struct foo" here too;
otherwise, a forward declaration of function foo would cause a
compilation error in the definition.

Denis

[Razvan]

Re: struct foo and function foo !?

kprateek88@yaho o.com (Prateek R Karandikar) wrote in message news:<607f883e. 0406271709.7c42 7a4a@posting.go ogle.com>...[color=blue][color=green][color=darkred]
> > > Today I saw some code like this:
> > >
> > > struct foo {
> > > foo(foo* s2){
> > > cout << "foo::foo";
> > > }
> > > };
> > >
> > > foo* foo(foo *s2)
> > > {
> > > cout << "foo::(foo* )";
> > > return s2;
> > > }
> > >
> > > The name of the struct is 'foo' and the name of the
> > > function is 'foo' also ! Why they are not conflicting ? The name of
> > > types and the names of functions (and varialbles) are kept in separate
> > > places ? Is this standard behaviour ?[/color][/color]
>
> Yes, unfotunately this is Standard behaviour. A struct and a function
> in the same scope can have the same name. It is one of the unwanted
> leftovers of the C language. In C, foo wouldn't be a type, struct foo
> would be a type, so there was no ambiguity. In C++ now foo itself is a
> type, but the committee chose not to break C compatibility in this
> case. However it is best to avoid this "feature". A good compiler
> should give a warning.[/color]

Why are you saying that the function 'foo' is a type ? That
makes no sense to me. What king of variables can you define with this
type ?!!



Regards,
Razvan

[Richard Herring]

Re: struct foo and function foo !?

In message <15f19d61.04062 80045.4783fcd0@ posting.google. com>, Razvan
<mihai11@mailci ty.com> writes[color=blue]
>kprateek88@yah oo.com (Prateek R Karandikar) wrote in message
>news:<607f883e .0406271709.7c4 27a4a@posting.g oogle.com>...[color=green][color=darkred]
>> > > Today I saw some code like this:
>> > >
>> > > struct foo {
>> > > foo(foo* s2){
>> > > cout << "foo::foo";
>> > > }
>> > > };
>> > >
>> > > foo* foo(foo *s2)
>> > > {
>> > > cout << "foo::(foo* )";
>> > > return s2;
>> > > }
>> > >
>> > > The name of the struct is 'foo' and the name of the
>> > > function is 'foo' also ! Why they are not conflicting ? The name of
>> > > types and the names of functions (and varialbles) are kept in separate
>> > > places ? Is this standard behaviour ?[/color]
>>
>> Yes, unfotunately this is Standard behaviour. A struct and a function
>> in the same scope can have the same name. It is one of the unwanted
>> leftovers of the C language. In C, foo wouldn't be a type, struct foo
>> would be a type, so there was no ambiguity. In C++ now foo itself is a
>> type, but the committee chose not to break C compatibility in this
>> case. However it is best to avoid this "feature". A good compiler
>> should give a warning.[/color]
>
> Why are you saying that the function 'foo' is a type ? That
>makes no sense to me. What king of variables can you define with this
>type ?!!
>[/color]
Variables of type "pointer to {function taking one argument of type foo*
and returning a foo*}".

--
Richard Herring

[John Harrison]

Re: struct foo and function foo !?


"Razvan" <mihai11@mailci ty.com> wrote in message
news:15f19d61.0 406280045.4783f cd0@posting.goo gle.com...[color=blue]
> kprateek88@yaho o.com (Prateek R Karandikar) wrote in message[/color]
news:<607f883e. 0406271709.7c42 7a4a@posting.go ogle.com>...[color=blue][color=green][color=darkred]
> > > > Today I saw some code like this:
> > > >
> > > > struct foo {
> > > > foo(foo* s2){
> > > > cout << "foo::foo";
> > > > }
> > > > };
> > > >
> > > > foo* foo(foo *s2)
> > > > {
> > > > cout << "foo::(foo* )";
> > > > return s2;
> > > > }
> > > >
> > > > The name of the struct is 'foo' and the name of the
> > > > function is 'foo' also ! Why they are not conflicting ? The name of
> > > > types and the names of functions (and varialbles) are kept in[/color][/color][/color]
separate[color=blue][color=green][color=darkred]
> > > > places ? Is this standard behaviour ?[/color]
> >
> > Yes, unfotunately this is Standard behaviour. A struct and a function
> > in the same scope can have the same name. It is one of the unwanted
> > leftovers of the C language. In C, foo wouldn't be a type, struct foo
> > would be a type, so there was no ambiguity. In C++ now foo itself is a
> > type, but the committee chose not to break C compatibility in this
> > case. However it is best to avoid this "feature". A good compiler
> > should give a warning.[/color]
>
> Why are you saying that the function 'foo' is a type ? That
> makes no sense to me. What king of variables can you define with this
> type ?!!
>[/color]

function foo is not a type, struct foo is a type.

john

[Razvan]

Re: struct foo and function foo !?

Hi !




int someFunc (int a)
{
return a + 2;
}



In order to declare a pointer to such a func you can use:

typedef int (*ptr_to_func) (int);

This is how you define a type of pointer to some function. Then you
can write:


ptr_to_func pFunc = someFunc;

int rr = 10;
cout << pFunc(rr) << endl;


"someFunc" is not a type therefore you cannot use it like the type
ptr_to_func is used.




Regards,
Razvan