Why is typeid not constant like sizeof
<p>Why is typeid(someType) not constant like sizeof(someType) ?</p>

<p>This question came up because recently i tried something like:</p>

<pre><code>template &lt;class T&gt;
class Foo
{
    BOOST_STATIC_ASSERT(typeid(T)==typeid(Bar) || typeid(T)==typeid(FooBar));
};
</code></pre>

<p>And i am curious why the compiler knows the size of types (sizeof) at compile time, but not the type itself (typeid)</p>
