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Re: object-model: Wrapping Subversion C-structs in C++

From: Hyrum K. Wright <hyrum_wright_at_mail.utexas.edu>
Date: Wed, 22 Sep 2010 19:16:22 +0100

On Wed, Sep 22, 2010 at 5:35 PM, Hyrum K. Wright
<hyrum_wright_at_mail.utexas.edu> wrote:
> For the C++ folks out there, I've got a question about an approach to
> take on the object-model branch.  At issue is how to wrap the various
> C structures returned to callers, particularly in a backward
> compatible manner.  Currently, I'm looking at svn_wc_notify_t *.  As I
> see it, there are a few options:
> 1) Just wrap the pointer to the C struct as a member of the wrapper class.
>    Pros: Easy to implement; lightweight constructor.
>    Cons: Getters would need to translate to C++ types; would need to
> implement a copy constructor which deep copies the C struct; would
> also introduce pools, since creating and duplicating C structs
> requires them.
> 2) Wrap each C struct member individually
>    Pros: C->C++ complexity is constrained to the constructor,
> everything else is C++ types
>    Cons: Hard to extend for future compatibility
> 3) Just pass the C-struct pointer around; don't even bother with a class
>    Pros: Dead simple.
>    Cons: Requires more memory management thought by consumers; not
> C++-y enough; may introduce wrapping difficulties.
> I'd like to come up with something consistent, which would be used
> throughout the C++ bindings.  I'm also interested in a solution which
> ensures the C++ bindings can be used as the basis for other
> object-oriented bindings models (Python, Perl, etc.)

After lunch, and some thought, it feels like #1 is the best solution.
This doesn't change the external class interface, which is good, and
can still provide C++ values to callers who want them. The pool
issues are a bit messy, but at least the object can manage it's own
memory (albeit at a significant overhead).

Received on 2010-09-22 20:17:13 CEST

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