[boost] passing temporaries to mutating algorithms

From: Thorsten Ottosen (nesotto_at_[hidden])
Date: 2004-04-12 09:26:35

Dear All,

I think I have found a safe way to
bind a temporary to a const reference and cast away the constness.

This means that a temporary can be passed (relatively) safely to an
algorithm
with a prototype like

void foo( T& t )
{
  // do something with t, but don't store the reference.
}

for example, we might want to call foo() like

vector<int> make_vec();
foo( make_vec() );

but we cannot. Using a little macro, we can say

foo( BOOST_LVALUE( make_vec() ) );

assuming these prototypes

const vector<int> make_cvec();
const vector<int>& make_crvec();

these uses will fail at ct

foo( BOOST_LVALUE( make_cvec() ) );
foo( BOOST_LVALUE( make_crvec() ) );

Comments are welcome.

br

Thorsten

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end