currently the AND operator evaluates all template operators that are its parameters, before the "and" operation is done.
This is not optimized and causes unexpected warnings/errors.

Example:

{if and(ezhttp_hasvariable( 'SearchContentClassID', 'get' ), ezhttp( 'SearchContentClassID', 'get')|ne("-1")) }
    ...
    ...
{else}
    ...
{/if}

executes both operators (ezhttp_hasvariable and ezhttp) even if SearchContentClassID does not exist. This causes template error:

Error: eZTemplate:ezhttp 	Dec 22 2011 15:52:37
Unknown get variable 'SearchContentClassID'