Re: Idiosyncratic python

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From	Ian Kelly <ian.g.kelly@gmail.com>
Date	Thu, 24 Sep 2015 12:19:33 -0600
Subject	Re: Idiosyncratic python
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On Thu, Sep 24, 2015 at 12:04 PM, jmp <jeanmichel@sequans.com> wrote:
> I'm not an expert but I think this "return by value thing" is only for C++.
> In vintage C, you can only return something that fits within a register.

If that was true at one time, it was before ANSI C.

$ cat test.c
#include <assert.h>

struct foo {
  int a;
  long b;
  float c;
  double d;
};

struct foo get_foo() {
  struct foo value;
  value.a = 12;
  value.b = 92L;
  value.c = 4.5f;
  value.d = -21.5;
  return value;
}

int main() {
  struct foo value = get_foo();
  assert(value.a == 12);
  assert(value.b == 92L);
  assert(value.c == 4.5f);
  assert(value.d == -21.5);
  return 0;
}
$ gcc -Wall -O0 -std=c89 test.c
$ ./a.out
$

There is a danger however in that it's only a shallow copy. If any
struct members are pointers, then the pointer value will be copied,
not the thing pointed to.

Thread

Idiosyncratic python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-09-24 16:02 +1000
  Re: Idiosyncratic python Paul Rubin <no.email@nospam.invalid> - 2015-09-23 23:16 -0700
    Re: Idiosyncratic python Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-09-24 16:35 +1000
      Re: Idiosyncratic python Ben Finney <ben+python@benfinney.id.au> - 2015-09-24 16:54 +1000
        Re: Idiosyncratic python Steven D'Aprano <steve@pearwood.info> - 2015-09-25 11:08 +1000
      Re: Idiosyncratic python Terry Reedy <tjreedy@udel.edu> - 2015-09-24 02:54 -0400
  Re: Idiosyncratic python wxjmfauth@gmail.com - 2015-09-24 00:06 -0700
    Re: Idiosyncratic python Laurent Pointal <laurent.pointal@free.fr> - 2015-09-24 19:50 +0200
      Re: Idiosyncratic python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-24 21:05 +0100
  Re: Idiosyncratic python jmp <jeanmichel@sequans.com> - 2015-09-24 11:12 +0200
  Re: Idiosyncratic python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-24 14:09 +0100
  Re: Idiosyncratic python jmp <jeanmichel@sequans.com> - 2015-09-24 16:07 +0200
  Re: Idiosyncratic python Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-24 08:26 -0600
  Re: Idiosyncratic python Chris Angelico <rosuav@gmail.com> - 2015-09-25 02:57 +1000
  Re: Idiosyncratic python jmp <jeanmichel@sequans.com> - 2015-09-24 20:04 +0200
  Re: Idiosyncratic python Ian Kelly <ian.g.kelly@gmail.com> - 2015-09-24 12:19 -0600
  Re: Idiosyncratic python Ned Batchelder <ned@nedbatchelder.com> - 2015-09-24 13:46 -0700
    Re: Idiosyncratic python Laura Creighton <lac@openend.se> - 2015-09-24 23:08 +0200
    Re: Idiosyncratic python Chris Angelico <rosuav@gmail.com> - 2015-09-25 07:49 +1000
    Re: Idiosyncratic python Steven D'Aprano <steve@pearwood.info> - 2015-09-25 10:55 +1000
  Re: Idiosyncratic python sohcahtoa82@gmail.com - 2015-09-24 15:32 -0700
  Re: Idiosyncratic python Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-09-25 00:40 +0100
  Re: Idiosyncratic python Akira Li <4kir4.1i@gmail.com> - 2015-09-25 03:04 +0300
  Re: Idiosyncratic python Steven D'Aprano <steve@pearwood.info> - 2015-09-25 10:08 +1000

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