Re: Boost::any typecasting issue(bad_any_cast)

From: Gavin Lambert (boost_at_[hidden])
Date: 2021-12-05 23:51:08

On 19/11/2021 04:57, Daggumati, Rajesh wrote:
>                typedef boost::tuple<std::string, BinaryBuffer_t> DecodeErrorPayload_t;
>    RegisterIONotification(NotifyType type;,boost::any payload)
[...]
> void RegisterIOThreaded::OnDecodeError( const std::string& error, BinaryBuffer_t data )
>      {
>          RegisterIONotification notify(RegisterIONotification::TypeDecodeError ,make_tuple(error, data));
[...]
>          ASSERT_NO_THROW(payload = boost::any_cast<RegisterIONotification::DecodeErrorPayload_t>(notify.Payload));// Here its got failed...Please help me to fix this.

You have to be *very* careful about using type inference and implicit 
casts when using boost::any.  For example, it's entirely possible that 
make_tuple is returning a type that is compatible with 
DecodeErrorPayload_t but is not actually DecodeErrorPayload_t, which 
will cause your later any_cast to fail.  (Especially if you're calling 
std::make_tuple rather than boost::make_tuple, which seems likely.)

You can inspect the payload in a debugger to determine what type it 
actually is (although it can be hard to interpret).  Or, (while 
undocumented) it does contain a type() method that you can call and log 
to inspect the actual type.

You may get better results if you explicitly static_cast your make_tuple 
call to the type that you're expecting, or use uniform construction 
syntax instead of make_tuple.