Hi all!

Does D sport inner classes / structs in any form?

For some reason, I assumed it did and have got into some trouble! Either way I have at least one bug to report. If it is intended to have some support for these could someone explain what ways members of the outer class can be accessed?

From,

Rupert

"Rupert Millard" <rupertamillard@hotmail.dot.com> wrote in message news:bgnto9$qnv$2@digitaldaemon.com...
> Hi all!
>
> Does D sport inner classes / structs in any form?
>
> For some reason, I assumed it did and have got into some trouble! Either
way
> I have at least one bug to report. If it is intended to have some support for these could someone explain what ways members of the outer class can
be
> accessed?

D supports nested classes, where the scopes are nested. It does not support java-style 'inner' classes. If you've found a bug, please post it here!

Walter,

I doubt this code should be allowed to compile as a struct is nested within a class, however it does compile and it produces this output on my machine when executed:

in main():
x: 69

in B.displayX():
x: 4202672

I believe this behaviour is a bug.

As I was not able to find any help in the manual, could you explain exactly what kind of nesting is allowed and what it permits you to do? Specifically what does nested scopes mean?

Also, I understand that there is some ambiguity in the term 'inner classes' in JAVA. Could somebody clarify exactly what it means?

Please excuse my ignorance, I am an entirely self-taught programmer doing it as a hobby.

Thanks,

From,

Rupert


"Walter" <walter@digitalmars.com> wrote in message news:bgorth$1pmc$2@digitaldaemon.com...
>
> "Rupert Millard" <rupertamillard@hotmail.dot.com> wrote in message news:bgnto9$qnv$2@digitaldaemon.com...
> > Hi all!
> >
> > Does D sport inner classes / structs in any form?
> >
> > For some reason, I assumed it did and have got into some trouble! Either
> way
> > I have at least one bug to report. If it is intended to have some
support
> > for these could someone explain what ways members of the outer class can
> be
> > accessed?
>
> D supports nested classes, where the scopes are nested. It does not
support
> java-style 'inner' classes. If you've found a bug, please post it here!

Hi Rupert,

for the Java-style inner class explanation you can read the next link: http://java.sun.com/docs/books/tutorial/java/javaOO/innerclasses.html Hope you'll find that is brief and clear.

About the "bug" you arose I think that is not a bug at all. Pay attention to explanation about nested function that described either on the page 100 of the D spec in pdf pormat or go to the http://www.digitalmars.com/d/function.html

When you declare (and define) a nested class in another one you just declare the scope of that class, not a variable or some kind of instance that is connected to concrete instance ot outer class. So an inner class can't receive a value of non-static member of outer one, have no access to its frame.

Hope I've succeeded to explain the "bug" behavior.
Thanks!

In article <bgqm0m$g2h$1@digitaldaemon.com>, Rupert Millard says...
>
>Walter,
>
>I doubt this code should be allowed to compile as a struct is nested within a class, however it does compile and it produces this output on my machine when executed:
>
>in main():
>x: 69
>
>in B.displayX():
>x: 4202672
>
>I believe this behaviour is a bug.
>
>As I was not able to find any help in the manual, could you explain exactly what kind of nesting is allowed and what it permits you to do? Specifically what does nested scopes mean?
>
>Also, I understand that there is some ambiguity in the term 'inner classes' in JAVA. Could somebody clarify exactly what it means?
>
>Please excuse my ignorance, I am an entirely self-taught programmer doing it as a hobby.
>
>Thanks,
>
>From,
>
>Rupert
>
>
>"Walter" <walter@digitalmars.com> wrote in message news:bgorth$1pmc$2@digitaldaemon.com...
>>
>> "Rupert Millard" <rupertamillard@hotmail.dot.com> wrote in message news:bgnto9$qnv$2@digitaldaemon.com...
>> > Hi all!
>> >
>> > Does D sport inner classes / structs in any form?
>> >
>> > For some reason, I assumed it did and have got into some trouble! Either
>> way
>> > I have at least one bug to report. If it is intended to have some
>support
>> > for these could someone explain what ways members of the outer class can
>> be
>> > accessed?
>>
>> D supports nested classes, where the scopes are nested. It does not
>support
>> java-style 'inner' classes. If you've found a bug, please post it here!
>
>
>
>begin 666 bug.d
>M+R\@0E5'.@T*+R\@;F5S=&5D(&-L87-S97,@9&]N)W0@8V]R<F5C=&QY(&%C
>M8V5S<R!M96UB97)S(&]F(&]U=&5R(&-L87-S#0HO+R!#3U!-4$E,15(Z#0HO
>M+R!$:6=I=&%L($UA<G,@1"!#;VUP:6QE<B!"971A('8P+C8X#0H-"FEM<&]R
>M="!C+G-T9&EO.PT*#0IC;&%S<R!!('L-"@EI;G0@>#L-"@T*"71H:7,H:6YT
>M('@R*0T*"7L-"@D)>#UX,CL-"@E]#0H)#0H)<')I=F%T92!S=')U8W0@0B![
>M#0H)"0T*"0EV;VED(&1I<W!L87E8("@I#0H)"7L-"@D)"7!R:6YT9B@B:6X@
>M0BYD:7-P;&%Y6"@I.EQN(@T*"0D)(" @(" @(")X.B E=5QN(BP@>"D[#0H)
>M"7T-"@E]#0H-"@EP<FEV871E('9O:60@9&ES<&QA>5@H*0T*"7L-"@D)0B!B
>M.PT*"0D-"@D)8BYD:7-P;&%Y6"@I.PT*"7T-"GT-"@T*:6YT(&UA:6X@*&-H
>M87);75M=(&%R9W,I#0I[#0H)02!A(#T@;F5W($$H-CDI.PT*"0T*"7!R:6YT
>M9B@B:6X@;6%I;B@I.EQN(@T*"2 @(" @(" B>#H@)74@7&Y<;B(L(&$N>"D[
>E#0H)#0H)82YD:7-P;&%Y6"@I.PT*"0T*"7)E='5R;B P.PT*?0``
>`
>end
>

Gennadi,

Thanks for the link.

I don't see the relevance of nested functions to the problem in question, however the manual says "Nested functions have access to the variables and other symbols defined by the lexically enclosing function." If one were to infer anything about nested classes from this, wouldn't it be that a nested class could access the members of the enclosing class?

If what you go on to say is the case then shouldn't the compiler generate an error (as it would do if B were a class instead of a struct) rather than compiling the code?

From,

Rupert

"Gennadi Pais" <Gennadi_member@pathlink.com> wrote in message news:bgqq03$jgj$1@digitaldaemon.com...
> Hi Rupert,
>
> for the Java-style inner class explanation you can read the next link: http://java.sun.com/docs/books/tutorial/java/javaOO/innerclasses.html Hope you'll find that is brief and clear.
>
> About the "bug" you arose I think that is not a bug at all. Pay attention
to
> explanation about nested function that described either on the page 100 of
the D
> spec in pdf pormat or go to the http://www.digitalmars.com/d/function.html
>
> When you declare (and define) a nested class in another one you just
declare the
> scope of that class, not a variable or some kind of instance that is
connected
> to concrete instance ot outer class. So an inner class can't receive a
value of
> non-static member of outer one, have no access to its frame.
>
> Hope I've succeeded to explain the "bug" behavior.
> Thanks!
>
> In article <bgqm0m$g2h$1@digitaldaemon.com>, Rupert Millard says...
> >
> >Walter,
> >
> >I doubt this code should be allowed to compile as a struct is nested
within
> >a class, however it does compile and it produces this output on my
machine
> >when executed:
> >
> >in main():
> >x: 69
> >
> >in B.displayX():
> >x: 4202672
> >
> >I believe this behaviour is a bug.
> >
> >As I was not able to find any help in the manual, could you explain
exactly
> >what kind of nesting is allowed and what it permits you to do?
Specifically
> >what does nested scopes mean?
> >
> >Also, I understand that there is some ambiguity in the term 'inner
classes'
> >in JAVA. Could somebody clarify exactly what it means?
> >
> >Please excuse my ignorance, I am an entirely self-taught programmer doing
it
> >as a hobby.
> >
> >Thanks,
> >
> >From,
> >
> >Rupert
> >
> >
> >"Walter" <walter@digitalmars.com> wrote in message news:bgorth$1pmc$2@digitaldaemon.com...
> >>
> >> "Rupert Millard" <rupertamillard@hotmail.dot.com> wrote in message news:bgnto9$qnv$2@digitaldaemon.com...
> >> > Hi all!
> >> >
> >> > Does D sport inner classes / structs in any form?
> >> >
> >> > For some reason, I assumed it did and have got into some trouble!
Either
> >> way
> >> > I have at least one bug to report. If it is intended to have some
> >support
> >> > for these could someone explain what ways members of the outer class
can
> >> be
> >> > accessed?
> >>
> >> D supports nested classes, where the scopes are nested. It does not
> >support
> >> java-style 'inner' classes. If you've found a bug, please post it here!
> >
> >
> >
> >begin 666 bug.d
> >M+R\@0E5'.@T*+R\@;F5S=&5D(&-L87-S97,@9&]N)W0@8V]R<F5C=&QY(&%C
> >M8V5S<R!M96UB97)S(&]F(&]U=&5R(&-L87-S#0HO+R!#3U!-4$E,15(Z#0HO
> >M+R!$:6=I=&%L($UA<G,@1"!#;VUP:6QE<B!"971A('8P+C8X#0H-"FEM<&]R
> >M="!C+G-T9&EO.PT*#0IC;&%S<R!!('L-"@EI;G0@>#L-"@T*"71H:7,H:6YT
> >M('@R*0T*"7L-"@D)>#UX,CL-"@E]#0H)#0H)<')I=F%T92!S=')U8W0@0B![
> >M#0H)"0T*"0EV;VED(&1I<W!L87E8("@I#0H)"7L-"@D)"7!R:6YT9B@B:6X@
> >M0BYD:7-P;&%Y6"@I.EQN(@T*"0D)(" @(" @(")X.B E=5QN(BP@>"D[#0H)
> >M"7T-"@E]#0H-"@EP<FEV871E('9O:60@9&ES<&QA>5@H*0T*"7L-"@D)0B!B
> >M.PT*"0D-"@D)8BYD:7-P;&%Y6"@I.PT*"7T-"GT-"@T*:6YT(&UA:6X@*&-H
> >M87);75M=(&%R9W,I#0I[#0H)02!A(#T@;F5W($$H-CDI.PT*"0T*"7!R:6YT
> >M9B@B:6X@;6%I;B@I.EQN(@T*"2 @(" @(" B>#H@)74@7&Y<;B(L(&$N>"D[
> >E#0H)#0H)82YD:7-P;&%Y6"@I.PT*"0T*"7)E='5R;B P.PT*?0``
> >`
> >end
> >
>
>

Rupert,

You could see the example of variable access from inner class in function (not
in outer class) in the D spec: "Member functions of nested classes and structs
do not have access to the stack variables of the enclosing function, but do have
access to the other symbols". So I think that is the same logical decision.
In the question of compilation error I agree with.

Thanks!

In article <bgqsqc$lvm$1@digitaldaemon.com>, Rupert Millard says...
>
>Gennadi,
>
>Thanks for the link.
>
>I don't see the relevance of nested functions to the problem in question, however the manual says "Nested functions have access to the variables and other symbols defined by the lexically enclosing function." If one were to infer anything about nested classes from this, wouldn't it be that a nested class could access the members of the enclosing class?
>
>If what you go on to say is the case then shouldn't the compiler generate an error (as it would do if B were a class instead of a struct) rather than compiling the code?
>
>From,
>
>Rupert
>
>"Gennadi Pais" <Gennadi_member@pathlink.com> wrote in message news:bgqq03$jgj$1@digitaldaemon.com...
>> Hi Rupert,
>>
>> for the Java-style inner class explanation you can read the next link: http://java.sun.com/docs/books/tutorial/java/javaOO/innerclasses.html Hope you'll find that is brief and clear.
>>
>> About the "bug" you arose I think that is not a bug at all. Pay attention
>to
>> explanation about nested function that described either on the page 100 of
>the D
>> spec in pdf pormat or go to the http://www.digitalmars.com/d/function.html
>>
>> When you declare (and define) a nested class in another one you just
>declare the
>> scope of that class, not a variable or some kind of instance that is
>connected
>> to concrete instance ot outer class. So an inner class can't receive a
>value of
>> non-static member of outer one, have no access to its frame.
>>
>> Hope I've succeeded to explain the "bug" behavior.
>> Thanks!
>>
>> In article <bgqm0m$g2h$1@digitaldaemon.com>, Rupert Millard says...
>> >
>> >Walter,
>> >
>> >I doubt this code should be allowed to compile as a struct is nested
>within
>> >a class, however it does compile and it produces this output on my
>machine
>> >when executed:
>> >
>> >in main():
>> >x: 69
>> >
>> >in B.displayX():
>> >x: 4202672
>> >
>> >I believe this behaviour is a bug.
>> >
>> >As I was not able to find any help in the manual, could you explain
>exactly
>> >what kind of nesting is allowed and what it permits you to do?
>Specifically
>> >what does nested scopes mean?
>> >
>> >Also, I understand that there is some ambiguity in the term 'inner
>classes'
>> >in JAVA. Could somebody clarify exactly what it means?
>> >
>> >Please excuse my ignorance, I am an entirely self-taught programmer doing
>it
>> >as a hobby.
>> >
>> >Thanks,
>> >
>> >From,
>> >
>> >Rupert
>> >
>> >
>> >"Walter" <walter@digitalmars.com> wrote in message news:bgorth$1pmc$2@digitaldaemon.com...
>> >>
>> >> "Rupert Millard" <rupertamillard@hotmail.dot.com> wrote in message news:bgnto9$qnv$2@digitaldaemon.com...
>> >> > Hi all!
>> >> >
>> >> > Does D sport inner classes / structs in any form?
>> >> >
>> >> > For some reason, I assumed it did and have got into some trouble!
>Either
>> >> way
>> >> > I have at least one bug to report. If it is intended to have some
>> >support
>> >> > for these could someone explain what ways members of the outer class
>can
>> >> be
>> >> > accessed?
>> >>
>> >> D supports nested classes, where the scopes are nested. It does not
>> >support
>> >> java-style 'inner' classes. If you've found a bug, please post it here!
>> >
>> >
>> >
>> >begin 666 bug.d
>> >M+R\@0E5'.@T*+R\@;F5S=&5D(&-L87-S97,@9&]N)W0@8V]R<F5C=&QY(&%C
>> >M8V5S<R!M96UB97)S(&]F(&]U=&5R(&-L87-S#0HO+R!#3U!-4$E,15(Z#0HO
>> >M+R!$:6=I=&%L($UA<G,@1"!#;VUP:6QE<B!"971A('8P+C8X#0H-"FEM<&]R
>> >M="!C+G-T9&EO.PT*#0IC;&%S<R!!('L-"@EI;G0@>#L-"@T*"71H:7,H:6YT
>> >M('@R*0T*"7L-"@D)>#UX,CL-"@E]#0H)#0H)<')I=F%T92!S=')U8W0@0B![
>> >M#0H)"0T*"0EV;VED(&1I<W!L87E8("@I#0H)"7L-"@D)"7!R:6YT9B@B:6X@
>> >M0BYD:7-P;&%Y6"@I.EQN(@T*"0D)(" @(" @(")X.B E=5QN(BP@>"D[#0H)
>> >M"7T-"@E]#0H-"@EP<FEV871E('9O:60@9&ES<&QA>5@H*0T*"7L-"@D)0B!B
>> >M.PT*"0D-"@D)8BYD:7-P;&%Y6"@I.PT*"7T-"GT-"@T*:6YT(&UA:6X@*&-H
>> >M87);75M=(&%R9W,I#0I[#0H)02!A(#T@;F5W($$H-CDI.PT*"0T*"7!R:6YT
>> >M9B@B:6X@;6%I;B@I.EQN(@T*"2 @(" @(" B>#H@)74@7&Y<;B(L(&$N>"D[
>> >E#0H)#0H)82YD:7-P;&%Y6"@I.PT*"0T*"7)E='5R;B P.PT*?0``
>> >`
>> >end
>> >
>>
>>
>
>

Gennadi,

Well spotted! Thanks very much for all your help.

From,

Rupert

"Gennadi Pais" <Gennadi_member@pathlink.com> wrote in message news:bgqumc$nop$1@digitaldaemon.com...
> Rupert,
>
> You could see the example of variable access from inner class in function
(not
> in outer class) in the D spec: "Member functions of nested classes and
structs
> do not have access to the stack variables of the enclosing function, but
do have
> access to the other symbols". So I think that is the same logical
decision.
> In the question of compilation error I agree with.
>
> Thanks!
>
> In article <bgqsqc$lvm$1@digitaldaemon.com>, Rupert Millard says...
> >
> >Gennadi,
> >
> >Thanks for the link.
> >
> >I don't see the relevance of nested functions to the problem in question, however the manual says "Nested functions have access to the variables
and
> >other symbols defined by the lexically enclosing function." If one were
to
> >infer anything about nested classes from this, wouldn't it be that a
nested
> >class could access the members of the enclosing class?
> >
> >If what you go on to say is the case then shouldn't the compiler generate
an
> >error (as it would do if B were a class instead of a struct) rather than
> >compiling the code?
> >
> >From,
> >
> >Rupert
> >
> >"Gennadi Pais" <Gennadi_member@pathlink.com> wrote in message news:bgqq03$jgj$1@digitaldaemon.com...
> >> Hi Rupert,
> >>
> >> for the Java-style inner class explanation you can read the next link: http://java.sun.com/docs/books/tutorial/java/javaOO/innerclasses.html Hope you'll find that is brief and clear.
> >>
> >> About the "bug" you arose I think that is not a bug at all. Pay
attention
> >to
> >> explanation about nested function that described either on the page 100
of
> >the D
> >> spec in pdf pormat or go to the
http://www.digitalmars.com/d/function.html
> >>
> >> When you declare (and define) a nested class in another one you just
> >declare the
> >> scope of that class, not a variable or some kind of instance that is
> >connected
> >> to concrete instance ot outer class. So an inner class can't receive a
> >value of
> >> non-static member of outer one, have no access to its frame.
> >>
> >> Hope I've succeeded to explain the "bug" behavior.
> >> Thanks!
> >>
> >> In article <bgqm0m$g2h$1@digitaldaemon.com>, Rupert Millard says...
> >> >
> >> >Walter,
> >> >
> >> >I doubt this code should be allowed to compile as a struct is nested
> >within
> >> >a class, however it does compile and it produces this output on my
> >machine
> >> >when executed:
> >> >
> >> >in main():
> >> >x: 69
> >> >
> >> >in B.displayX():
> >> >x: 4202672
> >> >
> >> >I believe this behaviour is a bug.
> >> >
> >> >As I was not able to find any help in the manual, could you explain
> >exactly
> >> >what kind of nesting is allowed and what it permits you to do?
> >Specifically
> >> >what does nested scopes mean?
> >> >
> >> >Also, I understand that there is some ambiguity in the term 'inner
> >classes'
> >> >in JAVA. Could somebody clarify exactly what it means?
> >> >
> >> >Please excuse my ignorance, I am an entirely self-taught programmer
doing
> >it
> >> >as a hobby.
> >> >
> >> >Thanks,
> >> >
> >> >From,
> >> >
> >> >Rupert
> >> >
> >> >
> >> >"Walter" <walter@digitalmars.com> wrote in message news:bgorth$1pmc$2@digitaldaemon.com...
> >> >>
> >> >> "Rupert Millard" <rupertamillard@hotmail.dot.com> wrote in message news:bgnto9$qnv$2@digitaldaemon.com...
> >> >> > Hi all!
> >> >> >
> >> >> > Does D sport inner classes / structs in any form?
> >> >> >
> >> >> > For some reason, I assumed it did and have got into some trouble!
> >Either
> >> >> way
> >> >> > I have at least one bug to report. If it is intended to have some
> >> >support
> >> >> > for these could someone explain what ways members of the outer
class
> >can
> >> >> be
> >> >> > accessed?
> >> >>
> >> >> D supports nested classes, where the scopes are nested. It does not
> >> >support
> >> >> java-style 'inner' classes. If you've found a bug, please post it
here!
> >> >
> >> >
> >> >
> >> >begin 666 bug.d
> >> >M+R\@0E5'.@T*+R\@;F5S=&5D(&-L87-S97,@9&]N)W0@8V]R<F5C=&QY(&%C
> >> >M8V5S<R!M96UB97)S(&]F(&]U=&5R(&-L87-S#0HO+R!#3U!-4$E,15(Z#0HO
> >> >M+R!$:6=I=&%L($UA<G,@1"!#;VUP:6QE<B!"971A('8P+C8X#0H-"FEM<&]R
> >> >M="!C+G-T9&EO.PT*#0IC;&%S<R!!('L-"@EI;G0@>#L-"@T*"71H:7,H:6YT
> >> >M('@R*0T*"7L-"@D)>#UX,CL-"@E]#0H)#0H)<')I=F%T92!S=')U8W0@0B![
> >> >M#0H)"0T*"0EV;VED(&1I<W!L87E8("@I#0H)"7L-"@D)"7!R:6YT9B@B:6X@
> >> >M0BYD:7-P;&%Y6"@I.EQN(@T*"0D)(" @(" @(")X.B E=5QN(BP@>"D[#0H)
> >> >M"7T-"@E]#0H-"@EP<FEV871E('9O:60@9&ES<&QA>5@H*0T*"7L-"@D)0B!B
> >> >M.PT*"0D-"@D)8BYD:7-P;&%Y6"@I.PT*"7T-"GT-"@T*:6YT(&UA:6X@*&-H
> >> >M87);75M=(&%R9W,I#0I[#0H)02!A(#T@;F5W($$H-CDI.PT*"0T*"7!R:6YT
> >> >M9B@B:6X@;6%I;B@I.EQN(@T*"2 @(" @(" B>#H@)74@7&Y<;B(L(&$N>"D[
> >> >E#0H)#0H)82YD:7-P;&%Y6"@I.PT*"0T*"7)E='5R;B P.PT*?0``
> >> >`
> >> >end
> >> >
> >>
> >>
> >
> >
>
>

As a former Java guy, I would personally RATHER have inner classes than nested classes. As far as I can tell, nested classes only limit the SCOPE of the class, which can occasionally be somewhat useful. But inner classes allow the inner class to talk to the outer class, which can OFTEN be REALLY useful.

I'd love to see inner classes in D.

--Benji Smith

I've so often wished I could do that.

I'd like to see some kind of inner class support as well.

Sean

"BenjiSmith" <BenjiSmith_member@pathlink.com> wrote in message news:bgr1m8$qmc$1@digitaldaemon.com...
> As a former Java guy, I would personally RATHER have inner classes than
nested
> classes. As far as I can tell, nested classes only limit the SCOPE of the
class,
> which can occasionally be somewhat useful. But inner classes allow the
inner
> class to talk to the outer class, which can OFTEN be REALLY useful.
>
> I'd love to see inner classes in D.
>
> --Benji Smith

Can we not have both?

I've found nested classes very useful in C++, essential in many ways to enforce design decisions and control users of one's classes.

I've found inner classes very useful in Java (along with those groovy
anonymous gizmos)

Let's have both in D!

"Sean L. Palmer" <palmer.sean@verizon.net> wrote in message news:bgrcff$1563$1@digitaldaemon.com...
> I've so often wished I could do that.
>
> I'd like to see some kind of inner class support as well.
>
> Sean
>
> "BenjiSmith" <BenjiSmith_member@pathlink.com> wrote in message news:bgr1m8$qmc$1@digitaldaemon.com...
> > As a former Java guy, I would personally RATHER have inner classes than
> nested
> > classes. As far as I can tell, nested classes only limit the SCOPE of
the
> class,
> > which can occasionally be somewhat useful. But inner classes allow the
> inner
> > class to talk to the outer class, which can OFTEN be REALLY useful.
> >
> > I'd love to see inner classes in D.
> >
> > --Benji Smith
>
>