Re: ANN: AutoNewPtr (oh yes, yet another smartpointer)

* Alf P. Steinbach:


OK, I'm reposting. Ironically, the reason for line length 80 in the
news client was to avoid problems with wrapping of headers when
processing clc++m articles for moderation. <ot>When do we, if ever,
get programs that do not try to "help" us by changing our data?</ot>

Original article text reformatted to 70 columns + added shortlinks:

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I just coded this up, and hopefully by mentioning it here I'll get
some useful feedback, like, bugs, shortcomings, improvements...

http://code.google.com/p/alfps/source/browse/trunk/alfs/pointers/AutoNewPtr.hpp
(http://preview.tinyurl.com/3puorr)

AutoNewPtr ("new" Berkeley open source license)

   * Is not initialized with a raw pointer, but with constructor
     arguments for the to-be referent: AutoNewPtr takes responsibility
     for 'new'.

   * By doing that, it has the ability to add a notifier to the created
     object, so that the smart pointer gets notified when referred
     object self-destructs, if it does (e.g., a window or file closing,
     or a non-correctable error).

   * After referred object destroyed, pointer reports that it's void
     and throws on access via ->.

   * Also, the default constructor sets the pointer to void state.

   * Otherwise much like shared_ptr, except customization of deleter is
     per type (via c++0x-like std::default_delete) rather than per
     instance.

Since I haven't yet used this beast, other than testing the basic
functionality,
http://code.google.com/p/alfps/source/browse/trunk/test/pointers/auto_new_ptr/01/main.cpp
(http://preview.tinyurl.com/4vnv69), I really don't know how it fares.
  I suspect -> access is not the most efficient since it's checking
for voidness. But that shouldn't be a problem with e.g. files and
windows and such objects where this pointer would be relevant, I
think, and the main objective here is programmer productivity, not
efficiency.

It's not just one file (AutoNewPtr just wraps CheckedPtr, which uses
various things), so I think one would need the whole shebang, which
Google says

   # Non-members may check out a read-only working copy anonymously
   # over HTTP.
   svn checkout http://alfps.googlecode.com/svn/trunk/ alfps-read-only

In there is also an adapted version of Howard Hinnants C++0x
unique_ptr emulation, and an adapted version of Turkani's (et.al.'s)
move_ptr. I'd hoped to be able to use unique_ptr instead of e.g.
auto_ptr, looking to the future! But unfortunately MSVC 7.1 doesn't
really like the unique_ptr code, and neither adaption has been used by
  me for anything, or seriously tested by me. I will probably remove
these smart pointer adaptions. Just didn't think of it before putting
the code out there.

Praise and lashings and wild ideas all welcome.

Note that this is just freshly coded, it's currently more idea stuff
than anything else, but, might still be useful as-is!

Cheers,

- Alf

PS: Yes I'm aware that adding things to namespace std is formally
prohibited, except specializations of existing templates. The stuff
added is such things that will be added by C++0x. I think it's better
  to just use namespace std than to keep changing code as things
migrate boost -> tr1 -> std.

--
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

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