Overloading

Hi,

Why can I not overload on just the return type?

Say for example.

public int blah(int x)
{
}

and

public double blah(int x)
{
}
Why not, seems quite straight forward to me, why is this a limitation on C#?

[Jan Tielens]

This is not a limitation of C#, it's not possible in VB.NET too, so I think
it's a IL/CLR limitation. In my opinion it wouldn't make sense to overload a
method only by it's return type. For example, lets say you have an
overloaded method TestMe that returns either a string value or a long value:

string s = TestMe(); ///This is quite straight-forward
object o = TestMe(); ///Would be a problem.
--
Greetz

Jan Tielens
_______________ _______________ __
Read my weblog: http://weblogs.asp.net/jan

<di********@dis cussion.microso ft.com> wrote in message
news:O0******** ******@TK2MSFTN GP09.phx.gbl...

Hi,

Why can I not overload on just the return type?

Say for example.

public int blah(int x)
{
}

and

public double blah(int x)
{
}
Why not, seems quite straight forward to me, why is this a limitation on C#?

[Jon Skeet [C# MVP]]

<di********@dis cussion.microso ft.com> wrote:

Why can I not overload on just the return type?

Say for example.

public int blah(int x)
{
}

and

public double blah(int x)
{
}
Why not, seems quite straight forward to me, why is this a limitation on C#?

Which version would get called here:

blah(5);

?

Or how about:

Console.WriteLi ne (blah(5));

?

Basically, it introduces an awful lot of ambiguity - and ends up with
an expression without a specific type, which doesn't occur anywhere
else in the language.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet
If replying to the group, please do not mail me too

[Krishnan]

Good Q in fact.
Lemme take a shot at it:
As I understand, while a function *prototype* describes the return type and
parameters, a function signature *does not include* return types. And
functiona overloading *defines* only functions of different signatures can
be overloaded.
Please correct me if am wrong here.

TIA
Krishnan
<di********@dis cussion.microso ft.com> wrote in message
news:O0******** ******@TK2MSFTN GP09.phx.gbl...

Hi,

Why can I not overload on just the return type?

Say for example.

public int blah(int x)
{
}

and

public double blah(int x)
{
}
Why not, seems quite straight forward to me, why is this a limitation on C#?

[Willy Denoyette [MVP]]

No, threre's no such restriction at the IL level, but other managed MSFT
languages choose not to support it.

Willy.

"Jan Tielens" <ja*@no.spam.pl ease.leadit.be> wrote in message
news:ul******** ******@TK2MSFTN GP11.phx.gbl...

This is not a limitation of C#, it's not possible in VB.NET too, so I think it's a IL/CLR limitation. In my opinion it wouldn't make sense to overload a method only by it's return type. For example, lets say you have an
overloaded method TestMe that returns either a string value or a long value:
string s = TestMe(); ///This is quite straight-forward
object o = TestMe(); ///Would be a problem.
--
Greetz

Jan Tielens
_______________ _______________ __
Read my weblog: http://weblogs.asp.net/jan

<di********@dis cussion.microso ft.com> wrote in message
news:O0******** ******@TK2MSFTN GP09.phx.gbl...

Hi,

Why can I not overload on just the return type?

Say for example.

public int blah(int x)
{
}

and

public double blah(int x)
{
}
Why not, seems quite straight forward to me, why is this a limitation on

C#?

[andrew lowe]

<di********@dis cussion.microso ft.com> wrote in message
news:O0******** ******@TK2MSFTN GP09.phx.gbl...

Hi,

Why can I not overload on just the return type?

I believe Eiffel supports this

[Willy Denoyette [MVP]]

True, and ILASM also, here's a sample (compile with ilasm).

..assembly extern mscorlib
{
.publickeytoken = (B7 7A 5C 56 19 34 E0 89 )
.ver 1:0:5000:0
}

..assembly invaril
{
.hash algorithm 0x00008004
.ver 0:0:0:1
}

..class private Invariant
{
.method public specialname
instance void .ctor()
{
ret
}

.method public instance int32 Foo()
{
.locals init (int32 local0)
ldc.i4.1
ret //return 1
}

.method public instance int64 Foo()
{
.locals init (int64 local0)
ldc.i4.2
conv.i8
ret // return 2
}
}

..method public static void Execute()
{
.entrypoint
.locals init (class Invariant local0)
newobj instance void Invariant::.cto r()
stloc.0
ldloc.0
//Call int32::Foo()
callvirt instance int32 Invariant::Foo( )
call void [mscorlib]System.Console: :WriteLine(int3 2)
ldloc.0
// Call int64::Foo()
callvirt instance int64 Invariant::Foo( )
call void [mscorlib]System.Console: :WriteLine(int6 4)
ret
}
Willy.

"andrew lowe" <andrew dot lowe at geac dot com> wrote in message
news:uU******** ******@tk2msftn gp13.phx.gbl...

<di********@dis cussion.microso ft.com> wrote in message
news:O0******** ******@TK2MSFTN GP09.phx.gbl...

Hi,

Why can I not overload on just the return type?

I believe Eiffel supports this

[Alvin Bruney]

It SHOULD be supported as its technically a DIFFERENT function signiture.

I think its stupid not to support this. Is there any valid reason why this
is not implemented?

I cant think of one.

"Willy Denoyette [MVP]" <wi************ *@pandora.be> wrote in message
news:ub******** ******@TK2MSFTN GP11.phx.gbl...

True, and ILASM also, here's a sample (compile with ilasm).

.assembly extern mscorlib
{
.publickeytoken = (B7 7A 5C 56 19 34 E0 89 )
.ver 1:0:5000:0
}

.assembly invaril
{
.hash algorithm 0x00008004
.ver 0:0:0:1
}

.class private Invariant
{
.method public specialname
instance void .ctor()
{
ret
}

.method public instance int32 Foo()
{
.locals init (int32 local0)
ldc.i4.1
ret //return 1
}

.method public instance int64 Foo()
{
.locals init (int64 local0)
ldc.i4.2
conv.i8
ret // return 2
}
}

.method public static void Execute()
{
.entrypoint
.locals init (class Invariant local0)
newobj instance void Invariant::.cto r()
stloc.0
ldloc.0
//Call int32::Foo()
callvirt instance int32 Invariant::Foo( )
call void [mscorlib]System.Console: :WriteLine(int3 2)
ldloc.0
// Call int64::Foo()
callvirt instance int64 Invariant::Foo( )
call void [mscorlib]System.Console: :WriteLine(int6 4)
ret
}
Willy.

"andrew lowe" <andrew dot lowe at geac dot com> wrote in message
news:uU******** ******@tk2msftn gp13.phx.gbl...

<di********@dis cussion.microso ft.com> wrote in message
news:O0******** ******@TK2MSFTN GP09.phx.gbl...

Hi,

Why can I not overload on just the return type?

I believe Eiffel supports this

[Daniel O'Connell]

"Alvin Bruney" <alvin.bruney@. telia..com.> wrote in message
news:O6******** ******@TK2MSFTN GP11.phx.gbl...

It SHOULD be supported as its technically a DIFFERENT function signiture.

I think its stupid not to support this. Is there any valid reason why this
is not implemented?

I cant think of one.

Its pretty simple, it heavily complicates the language for very little
benifit. I don't care to have to specify return type on every call, doubt
you would either. Even with defaults it is a messy situation.
Do you have a suggestion as to how to implement it without causing a major
complexity increase?
"Willy Denoyette [MVP]" <wi************ *@pandora.be> wrote in message
news:ub******** ******@TK2MSFTN GP11.phx.gbl...

True, and ILASM also, here's a sample (compile with ilasm).

.assembly extern mscorlib
{
.publickeytoken = (B7 7A 5C 56 19 34 E0 89 )
.ver 1:0:5000:0
}

.assembly invaril
{
.hash algorithm 0x00008004
.ver 0:0:0:1
}

.class private Invariant
{
.method public specialname
instance void .ctor()
{
ret
}

.method public instance int32 Foo()
{
.locals init (int32 local0)
ldc.i4.1
ret //return 1
}

.method public instance int64 Foo()
{
.locals init (int64 local0)
ldc.i4.2
conv.i8
ret // return 2
}
}

.method public static void Execute()
{
.entrypoint
.locals init (class Invariant local0)
newobj instance void Invariant::.cto r()
stloc.0
ldloc.0
//Call int32::Foo()
callvirt instance int32 Invariant::Foo( )
call void [mscorlib]System.Console: :WriteLine(int3 2)
ldloc.0
// Call int64::Foo()
callvirt instance int64 Invariant::Foo( )
call void [mscorlib]System.Console: :WriteLine(int6 4)
ret
}
Willy.

"andrew lowe" <andrew dot lowe at geac dot com> wrote in message
news:uU******** ******@tk2msftn gp13.phx.gbl...

<di********@dis cussion.microso ft.com> wrote in message
news:O0******** ******@TK2MSFTN GP09.phx.gbl...
> Hi,
>
> Why can I not overload on just the return type?

I believe Eiffel supports this

[Alvin Bruney]

You already do have to SPECIFY RETURN TYPES.

"Daniel O'Connell" <[e-mail]> wrote in message
news:Oa******** ******@TK2MSFTN GP10.phx.gbl...

"Alvin Bruney" <alvin.bruney@. telia..com.> wrote in message
news:O6******** ******@TK2MSFTN GP11.phx.gbl...

It SHOULD be supported as its technically a DIFFERENT function signiture.
I think its stupid not to support this. Is there any valid reason why this is not implemented?

I cant think of one.

Its pretty simple, it heavily complicates the language for very little
benifit. I don't care to have to specify return type on every call, doubt
you would either. Even with defaults it is a messy situation.
Do you have a suggestion as to how to implement it without causing a major
complexity increase?

"Willy Denoyette [MVP]" <wi************ *@pandora.be> wrote in message
news:ub******** ******@TK2MSFTN GP11.phx.gbl...

True, and ILASM also, here's a sample (compile with ilasm).

.assembly extern mscorlib
{
.publickeytoken = (B7 7A 5C 56 19 34 E0 89 )
.ver 1:0:5000:0
}

.assembly invaril
{
.hash algorithm 0x00008004
.ver 0:0:0:1
}

.class private Invariant
{
.method public specialname
instance void .ctor()
{
ret
}

.method public instance int32 Foo()
{
.locals init (int32 local0)
ldc.i4.1
ret //return 1
}

.method public instance int64 Foo()
{
.locals init (int64 local0)
ldc.i4.2
conv.i8
ret // return 2
}
}

.method public static void Execute()
{
.entrypoint
.locals init (class Invariant local0)
newobj instance void Invariant::.cto r()
stloc.0
ldloc.0
//Call int32::Foo()
callvirt instance int32 Invariant::Foo( )
call void [mscorlib]System.Console: :WriteLine(int3 2)
ldloc.0
// Call int64::Foo()
callvirt instance int64 Invariant::Foo( )
call void [mscorlib]System.Console: :WriteLine(int6 4)
ret
}
Willy.

"andrew lowe" <andrew dot lowe at geac dot com> wrote in message
news:uU******** ******@tk2msftn gp13.phx.gbl...
>
> <di********@dis cussion.microso ft.com> wrote in message
> news:O0******** ******@TK2MSFTN GP09.phx.gbl...
> > Hi,
> >
> > Why can I not overload on just the return type?
>
> I believe Eiffel supports this
>
>