Proxy objects...

[barcaroller]

What are proxy objects used for in C++? Currently, the only use of proxy
objects I know of is that one can write one-liner code such as:

myobj.foo() (a,b) (c,d) (e,f) ;

where myobj.foo() returns a proxy object with an overloaded operator()
member function, which returns a reference to the proxy object itself. But
writing one-liners cannot be reason enough to use proxy objects.

[James Kanze]

On 19 avr, 18:18, "barcaroller" <[e-mail]:

What are proxy objects used for in C++? Currently, the only
use of proxy objects I know of is that one can write one-liner
code such as:

myobj.foo() (a,b) (c,d) (e,f) ;

where myobj.foo() returns a proxy object with an overloaded
operator() member function, which returns a reference to the
proxy object itself. But writing one-liners cannot be reason
enough to use proxy objects.

The two most frequent reasons I know of are for context
dependent implicit type conversions (where the proxy has a:
template< typename T Proxy::operator T() const
function), and for distinguishing between lvalue and rvalue
accesses (where the proxy will have an implicit conversion to
the target type for rvalue accesses, and an operator= which
modifies the source, rather than the proxy, for lvalue
accesses).

I don't think I've ever seen a proxy used as you've described.

--
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[barcaroller]

"James Kanze" <ja*********@gmail.comwrote in message
news:ba**********************************@d45g2000 hsc.googlegroups.com...

I don't think I've ever seen a proxy used as you've described.

boost::program_options

Example:

options_description desc("Allowed options");

desc.add_options()
("help", "help message")
("level", value<int>(), "set level");