[9fans] source header question

[9fans] source header question

[EBo]

I noticed that some of the plan9port .h files have "extern C" C++ compiler
directives:

#if defined(__cplusplus)
extern "C" {
#endif
...

Is this actually necessary since I thought C++ was not supported in Plan
9, et al.

Just checking...

  EBo --

Re: [9fans] source header question

[Iruatã Souza]

On Fri, Aug 20, 2010 at 3:29 PM, EBo <ebo@sandien.com> wrote:
>
> I noticed that some of the plan9port .h files have "extern C" C++ compiler
> directives:
>
> #if defined(__cplusplus)
> extern "C" {
> #endif
> ...
>
> Is this actually necessary since I thought C++ was not supported in Plan
> 9, et al.
>
> Just checking...
>
>  EBo --
>
>
>

i guess you answered that yourself. does p9p run on Plan 9?

Re: [9fans] source header question

[EBo]

> i guess you answered that yourself. does p9p run on Plan 9?

There a plenty of programs which are made to run under both p9p and plan9.
So, no the question is still open, but I will rephrase it.

Should any program which can run under p9p and plan9 ever be compiled with
g++ or another c++ compilers?  Otherwise is it necessary to check for
__cplusplus?

   EBo --

Re: [9fans] source header question

[Devon H. O'Dell]

2010/8/20 EBo <ebo@sandien.com>:
>
>
>> i guess you answered that yourself. does p9p run on Plan 9?
>
> There a plenty of programs which are made to run under both p9p and plan9.
> So, no the question is still open, but I will rephrase it.
>
> Should any program which can run under p9p and plan9 ever be compiled with
> g++ or another c++ compilers?  Otherwise is it necessary to check for
> __cplusplus?

I think it may be for Sun compilers.

--dho

>   EBo --
>
>
>

Re: [9fans] source header question

[EBo]

>> Should any program which can run under p9p and plan9 ever be compiled
>> with
>> g++ or another c++ compilers?  Otherwise is it necessary to check for
>> __cplusplus?
> 
> I think it may be for Sun compilers.

Thanks Devon,

Is there anyone who can verify it?  I gave away my old Sun workstations a
few years ago and cannot test it...

My reason for asking is whether I should continue adding all that to my
projects if it is fact not necessary.

  EBo --

Re: [9fans] source header question

[Lyndon Nerenberg]

>> Should any program which can run under p9p and plan9 ever be compiled with
>> g++ or another c++ compilers?  Otherwise is it necessary to check for
>> __cplusplus?

C is a subset of C++, so a C++ program can validly include native C code.

Re: [9fans] source header question

[Devon H. O'Dell]

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I meant my understanding was that Sun's compiler is a C++ compiler. As
Lyndon points out, C is a subset. I may be wrong, but it can't possibly hurt
to leave it in. Any c++ compiler should be able to compile it.

On Aug 20, 2010 6:00 PM, "Lyndon Nerenberg" <lyndon@orthanc.ca> wrote:
>>> Should any program which can run under p9p and plan9 ever be compiled
with
>>> g++ or another c++ compilers? Otherwise is it necessary to check for
>>> __cplusplus?
>
> C is a subset of C++, so a C++ program can validly include native C code.
>

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Re: [9fans] source header question

[erik quanstrom]

On Fri Aug 20 17:59:16 EDT 2010, lyndon@orthanc.ca wrote:
> >> Should any program which can run under p9p and plan9 ever be compiled with
> >> g++ or another c++ compilers?  Otherwise is it necessary to check for
> >> __cplusplus?
>
> C is a subset of C++, so a C++ program can validly include native C code.

that's no longer correct.  c is not a subset of c++.
however, there is a subset of c++ and a subset of c that
can be compiled by either compiler.  trivially,
	int catch, delete, friend, new, operator,
		protected, public, template,
		this, throw, try, virtual;
works in c but not c++.

- erik

Re: [9fans] source header question

[Iruatã Souza]

On Fri, Aug 20, 2010 at 5:41 PM, EBo <ebo@sandien.com> wrote:
>
>
>> i guess you answered that yourself. does p9p run on Plan 9?
>
> There a plenty of programs which are made to run under both p9p and plan9.
> So, no the question is still open, but I will rephrase it.
>
> Should any program which can run under p9p and plan9 ever be compiled with
> g++ or another c++ compilers?  Otherwise is it necessary to check for
> __cplusplus?
>

what I meant was that p9p is used on unix-like systems.
with that in mind, what if i wanted to:

% cat a.cc
#include <iostream>
#undef _XOPEN_SOURCE
#define NOPLAN9DEFINES
#include <u.h>
#include <libc.h>
#include <draw.h>
#include <geometry.h>

int
main(void)
{
        Point3 x = {1,0,1}, y = {0,1,1}, z;
        z = add3(x,y);
        std::cout << z.x << std::endl;
        std::cout << z.y << std::endl;
        std::cout << z.z << std::endl;
        return 0;
}

% g++ -I$PLAN9/include -c a.cc && g++ -o a a.o $PLAN9/lib/libgeometry.a
% a
1
1
2

without the extern definitions?
sorry if i was harsh.

Re: [9fans] source header question

[EBo]

Iruatã,

Thanks for following up.  Your example demonstrates that it is possible,
and maybe even desirable, to work in this way.  So, I know to deal with it
appropriately.

Thanks again.

  EBo --


> % g++ -I$PLAN9/include -c a.cc && g++ -o a a.o $PLAN9/lib/libgeometry.a
> % a
> 1
> 1
> 2
> 
> without the extern definitions?
> sorry if i was harsh.

Re: [9fans] source header question

[Russ Cox]

> I noticed that some of the plan9port .h files have "extern C" C++ compiler
> directives:
>
> #if defined(__cplusplus)
> extern "C" {
> #endif
> ...
>
> Is this actually necessary since I thought C++ was not supported in Plan
> 9, et al.

They're for compiling mpm.

Russ