Re: throwing dtors...
"Chris M. Thomasson" <no@spam.invalid> wrote in message
news:aoXEk.16204$hX5.2055@newsfe06.iad...
"Chris M. Thomasson" <no@spam.invalid> wrote in message
news:k4XEk.16199$hX5.2021@newsfe06.iad...
Is it every appropriate to throw in a dtor? I am thinking about a simple
example of a wrapper around a POSIX file...
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[...]
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[...]
how would you advise me to handle the case above? I am interested in how
throwing in a dtor effects dynamic destruction... Would something like
the following be legal?
[...]
I am doing some experimenting, and found that throwing from a dtor
apparently leaves the object fully intact wrt the memory that makes it up
so that proper disaster cleanup can indeed be performed... For example,
the following program goes into infinite loop:
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#include <cstdio>
struct throw_on_dtor {};
class foo {
public:
~foo() {
throw throw_on_dtor();
}
};
int main(void) {
foo* f = new foo();
retry:
try {
delete f;
} catch (throw_on_dtor const& e) {
std::puts("throw_on_dtor caught!");
goto retry;
}
return 0;
}
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So, AFAICT, throwing from a dtor will complicate some odd complications.
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
let me rephrase:
So, AFAICT, throwing from a dtor will _create_ some odd complications...
Humm... I am now thinking that instead of throwing from dtor, all error
handling should be preformed within dtor... However, what if user wants to
be informed of any failure case within dtor? Should I provide a simple
callback function to inform user of such condition? Something like:
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class file {
FILE* m_handle;
bool (*m_fp_on_dtor_error) (file&, int);
public:
foo(fp_on_dtor_error fp = NULL)
: m_fp_on_dtor_error(fp) {
[...]
};
~foo() {
retry:
if (! fclose(m_handle)) {
if (m_fp_on_dtor_error) {
if (m_fp_on_dtor_error(*this, errno)) {
goto retry;
}
}
}
}
};
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Humm... I need ADVISE!
;^o