Re: [boost] Review Request: Boost Exception

From: Martin Bonner (martin.bonner_at_[hidden])
Date: 2006-11-16 03:31:39

----Original Message----
From: boost-bounces_at_[hidden]
[mailto:boost-bounces_at_[hidden]] On Behalf Of Janek Kozicki Sent:
16 November 2006 07:04 To: boost_at_[hidden]
Subject: Re: [boost] Review Request: Boost Exception

> Peter Dimov said:     (by the date of Wed, 15 Nov 2006 19:18:22 +0200)
> 
>> Janek Kozicki wrote:
>>> Peter Dimov said:     (by the date of Wed, 15 Nov 2006 15:54:14
>>> +0200) 
>>> 
>>>>     e.dismiss();
>>> 
>>> why this? destructor of e does the work. No need to e.dismiss()
>>> Dave pointed out that std::uncaught_exception() inside e's
>>> destructor can check the conditions upon which the destructor is
>>> called and to the necessary work depending on it.
>> 
>> uncaught_exception may still return true in a destructor that is
>> called during an ordinary return. 
>> 
>> ~X: called during stack unwinding
>> 
>> calls f()
>> 
>> void f()
>> {
>>     Y y;
>> } // ~Y is called here, uncaught_exception is true
> 
> So I have an idea - maybe put catch{} block inside destructor? :)
> 
> X::~X()
> {
>    try
>    {
>       // try nothing. If exception is active, the catch() will get
>       // activated :) 

This is wrong.  The catch will be activated ONLY by exceptions thrown
from within the try block.  Just because ~X() is being called because of
stack unwinding caused by an active exception does NOT mean that the
catch block will be entered.
... or did you mean something else?
>    }
>    catch(boost::exception& e)
>    {
>       e.gotcha();
>       throw; // wow. It is a throwing destructor. What do you think?
>    }
> }
> 
> I haven't tested that, maybe I'm just wrong :>

-- 
Martin Bonner
Martin.Bonner_at_[hidden]
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