Strange FUNCTOR inconsistency

[RCS]

I have this Functor:

typedef std::vector < std::string > String_vec;

typedef std::vector < String_vec > StrVec_vec;

class Compare : public std::unary_func tion<String_vec , void>
{
public:
StrVec_vec myData;
Compare(StrVec_ vec const& data) : myData(data) {}

void operator() (const String_vec& data) const
{
StrVec_vec datax = myData;
std::pair<StrVe c_vec::iterator , StrVec_vec::ite rator > range =
std::equal_rang e(datax.begin() , datax.myData.en d(), data,
DataCompare());
}
};

This one above compiles fine (Visual Studio 7.0), but the assignment of
myData to datax seems a waste, and I would rather have it this way:

.....

void operator() (const String_vec& data) const
{
std::pair<StrVe c_vec::iterator , StrVec_vec::ite rator > range =
std::equal_rang e(myData.begin( ), myData.myData.e nd(), data,
DataCompare()); // I access myData directly in the loop instead of first
assigning it to datax and then using datax in the loop
}

......

BUT this last variant does not compile ??????????????? ???? (Error message
"..... cannot convert parameter 1 from 'const std::vector<_Ty ,
_Ax>::const_ite rator' to 'std::vector<_T y, _Ax>::_Tptr .............")

Anyone got a clue why myData variable is OK as an assignment to a temporary,
and this temporary is OK in the loop, while myData is not OK in the loop?
This does not make sense to me!

RCS

[Alf P. Steinbach]

Re: Strange FUNCTOR inconsistency

On Mon, 8 Sep 2003 09:07:33 +0200, "RCS" <rcs333@online. no> wrote:
[color=blue]
>I have this Functor:
>
>typedef std::vector < std::string > String_vec;
>
>typedef std::vector < String_vec > StrVec_vec;
>
>class Compare : public std::unary_func tion<String_vec , void>
>{
>public:
> StrVec_vec myData;
> Compare(StrVec_ vec const& data) : myData(data) {}
>
>void operator() (const String_vec& data) const
> {
> StrVec_vec datax = myData;
> std::pair<StrVe c_vec::iterator , StrVec_vec::ite rator > range =
> std::equal_rang e(datax.begin() , datax.myData.en d(), data, DataCompare());[/color]

Here 'datax' is of type 'StrVec_vec'.

'StrVec_vec' does not have a member 'myData', as far as I can see.
[color=blue]
>}
>};
>
>This one above compiles fine (Visual Studio 7.0)[/color]

It should absolutely not compile, and in fact does not compile.


[color=blue]
>...
>This does not make sense to me![/color]

It simply does not make sense at all.

[RCS]

Re: Strange FUNCTOR inconsistency


"Alf P. Steinbach" <alfps@start.no > skrev i melding
news:3f5c2acb.3 57370078@News.C IS.DFN.DE...[color=blue]
> On Mon, 8 Sep 2003 09:07:33 +0200, "RCS" <rcs333@online. no> wrote:
>[color=green]
> >I have this Functor:
> >
> >typedef std::vector < std::string > String_vec;
> >
> >typedef std::vector < String_vec > StrVec_vec;
> >
> >class Compare : public std::unary_func tion<String_vec , void>
> >{
> >public:
> > StrVec_vec myData;
> > Compare(StrVec_ vec const& data) : myData(data) {}
> >
> >void operator() (const String_vec& data) const
> > {
> > StrVec_vec datax = myData;
> > std::pair<StrVe c_vec::iterator , StrVec_vec::ite rator > range =
> > std::equal_rang e(datax.begin() , datax.myData.en d(), data,[/color][/color]
DataCompare());[color=blue]
>
> Here 'datax' is of type 'StrVec_vec'.
>
> 'StrVec_vec' does not have a member 'myData', as far as I can see.
>[color=green]
> >}
> >};
> >
> >This one above compiles fine (Visual Studio 7.0)[/color]
>
> It should absolutely not compile, and in fact does not compile.[/color]

"It SHOULD not compile" is fine with me, but the fact is it DOES compile
(with my version of the compiler)...... .

Whatever, what IS interesting to know (for me) is why this SHOULD not
compile, and if anybody has got another way of accomplishing what I'm trying
to do, I would be very grateful!

RCS

[tom_usenet]

Re: Strange FUNCTOR inconsistency

On Mon, 8 Sep 2003 11:03:53 +0200, "RCS" <rcs333@online. no> wrote:
[color=blue]
>
>"Alf P. Steinbach" <alfps@start.no > skrev i melding
>news:3f5c2acb. 357370078@News. CIS.DFN.DE...[color=green]
>> On Mon, 8 Sep 2003 09:07:33 +0200, "RCS" <rcs333@online. no> wrote:
>>[color=darkred]
>> >I have this Functor:
>> >
>> >typedef std::vector < std::string > String_vec;
>> >
>> >typedef std::vector < String_vec > StrVec_vec;
>> >
>> >class Compare : public std::unary_func tion<String_vec , void>
>> >{
>> >public:
>> > StrVec_vec myData;
>> > Compare(StrVec_ vec const& data) : myData(data) {}
>> >
>> >void operator() (const String_vec& data) const
>> > {
>> > StrVec_vec datax = myData;
>> > std::pair<StrVe c_vec::iterator , StrVec_vec::ite rator > range =
>> > std::equal_rang e(datax.begin() , datax.myData.en d(), data,[/color][/color]
>DataCompare()) ;[color=green]
>>
>> Here 'datax' is of type 'StrVec_vec'.
>>
>> 'StrVec_vec' does not have a member 'myData', as far as I can see.
>>[color=darkred]
>> >}
>> >};
>> >
>> >This one above compiles fine (Visual Studio 7.0)[/color]
>>
>> It should absolutely not compile, and in fact does not compile.[/color]
>
>"It SHOULD not compile" is fine with me, but the fact is it DOES compile
>(with my version of the compiler)...... .
>
>Whatever, what IS interesting to know (for me) is why this SHOULD not
>compile, and if anybody has got another way of accomplishing what I'm trying
>to do, I would be very grateful![/color]

The code you posted can't really compile. Are you sure you posted the
actual code? Anyway, I think this is what you are looking for:

void operator()(cons t String_vec& data) const
{
std::pair<StrVe c_vec::const_it erator, StrVec_vec::con st_iterator>
range = std::equal_rang e(myData.begin( ), myData.end(), data);
}

The problem was caused by the fact that in a const member function,
data members are const, and hence myData.begin() returns a
const_iterator.

Tom

[fabio]

Re: Strange FUNCTOR inconsistency

RCS wrote:
[color=blue]
>
> "Alf P. Steinbach" <alfps@start.no > skrev i melding
> news:3f5c2acb.3 57370078@News.C IS.DFN.DE...[color=green]
>> On Mon, 8 Sep 2003 09:07:33 +0200, "RCS" <rcs333@online. no> wrote:
>>[color=darkred]
>> >I have this Functor:
>> >
>> >typedef std::vector < std::string > String_vec;
>> >
>> >typedef std::vector < String_vec > StrVec_vec;
>> >
>> >class Compare : public std::unary_func tion<String_vec , void>
>> >{
>> >public:
>> > StrVec_vec myData;
>> > Compare(StrVec_ vec const& data) : myData(data) {}
>> >
>> >void operator() (const String_vec& data) const
>> > {
>> > StrVec_vec datax = myData;
>> > std::pair<StrVe c_vec::iterator , StrVec_vec::ite rator > range =
>> > std::equal_rang e(datax.begin() , datax.myData.en d(), data,[/color][/color]
> DataCompare());[color=green]
>>
>> Here 'datax' is of type 'StrVec_vec'.
>>
>> 'StrVec_vec' does not have a member 'myData', as far as I can see.
>>[color=darkred]
>> >}
>> >};
>> >
>> >This one above compiles fine (Visual Studio 7.0)[/color]
>>
>> It should absolutely not compile, and in fact does not compile.[/color]
>
> "It SHOULD not compile" is fine with me, but the fact is it DOES compile
> (with my version of the compiler)...... .
>
> Whatever, what IS interesting to know (for me) is why this SHOULD not
> compile, and if anybody has got another way of accomplishing what I'm
> trying to do, I would be very grateful!
>
> RCS[/color]

could you explain us what would you like doing?

[RCS]

Re: Strange FUNCTOR inconsistency

That was the missing piece!

Thanks a lot!

RCS

"tom_usenet " <tom_usenet@hot mail.com> skrev i melding
news:3f5c78ce.2 47772375@news.e asynet.co.uk...[color=blue]
> On Mon, 8 Sep 2003 11:03:53 +0200, "RCS" <rcs333@online. no> wrote:
>[color=green]
> >
> >"Alf P. Steinbach" <alfps@start.no > skrev i melding
> >news:3f5c2acb. 357370078@News. CIS.DFN.DE...[color=darkred]
> >> On Mon, 8 Sep 2003 09:07:33 +0200, "RCS" <rcs333@online. no> wrote:
> >>
> >> >I have this Functor:
> >> >
> >> >typedef std::vector < std::string > String_vec;
> >> >
> >> >typedef std::vector < String_vec > StrVec_vec;
> >> >
> >> >class Compare : public std::unary_func tion<String_vec , void>
> >> >{
> >> >public:
> >> > StrVec_vec myData;
> >> > Compare(StrVec_ vec const& data) : myData(data) {}
> >> >
> >> >void operator() (const String_vec& data) const
> >> > {
> >> > StrVec_vec datax = myData;
> >> > std::pair<StrVe c_vec::iterator , StrVec_vec::ite rator > range =
> >> > std::equal_rang e(datax.begin() , datax.myData.en d(), data,[/color]
> >DataCompare()) ;[color=darkred]
> >>
> >> Here 'datax' is of type 'StrVec_vec'.
> >>
> >> 'StrVec_vec' does not have a member 'myData', as far as I can see.
> >>
> >> >}
> >> >};
> >> >
> >> >This one above compiles fine (Visual Studio 7.0)
> >>
> >> It should absolutely not compile, and in fact does not compile.[/color]
> >
> >"It SHOULD not compile" is fine with me, but the fact is it DOES compile
> >(with my version of the compiler)...... .
> >
> >Whatever, what IS interesting to know (for me) is why this SHOULD not
> >compile, and if anybody has got another way of accomplishing what I'm[/color][/color]
trying[color=blue][color=green]
> >to do, I would be very grateful![/color]
>
> The code you posted can't really compile. Are you sure you posted the
> actual code? Anyway, I think this is what you are looking for:
>
> void operator()(cons t String_vec& data) const
> {
> std::pair<StrVe c_vec::const_it erator, StrVec_vec::con st_iterator>
> range = std::equal_rang e(myData.begin( ), myData.end(), data);
> }
>
> The problem was caused by the fact that in a const member function,
> data members are const, and hence myData.begin() returns a
> const_iterator.
>
> Tom[/color]