From: Bertolt Mildner (Bertolt.Mildner_at_[hidden])
Date: 2002-09-10 12:03:29
> shared_ptr reuses shared_ptr::get as the nonnull value, without a dummy
> nested class:
>
> // implicit conversion to "bool"
>
> typedef T * (this_type::*unspecified_bool_type)() const;
>
> operator unspecified_bool_type() const // never throws
> {
> return px == 0? 0: &this_type::get;
> }
>
> Perhaps something along these lines will work for boost::function.
Ok, here is my next try:
diff -r1.33 function_base.hpp
271c271
< function_base() : manager(0), functor(static_cast<void*>(0)) {}
---
> inline function_base() : manager(0), functor(static_cast<void*>(0)) {}
274c274
< bool empty() const { return !manager; }
---
> inline bool empty() const { return !manager; }
284c284
< operator bool () const { return !this->empty(); }
---
> inline operator bool () const { return !this->empty(); }
287,291c287
< struct dummy {
< void nonnull() {};
< };
<
< typedef void (dummy::*safe_bool)();
---
> typedef bool (function_base::*safe_bool)() const;
294,295c290,294
< operator safe_bool () const
< { return (this->empty())? 0 : &dummy::nonnull; }
---
> inline operator safe_bool () const
> { return (this->empty())? 0 : &function_base::empty; }
>
> inline bool operator!() const
> { return !this->empty(); }
297,298d295
< safe_bool operator!() const
< { return (this->empty())? &dummy::nonnull : 0; }
which again results in this error:
Error : illegal use of precompiled header
(included from:
function.hpp:22
KeyStorage.h:12
HostMemoryKeyStorage.h:9
DesKey.h:10
MWPrefixWin32.pch++:15)
function_base.hpp line 274 inline bool empty() const { return !manager; }
Bertolt
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