TypeError: Type uint256 is not implicitly convertible to expected type bool

Question

 function allowance (address _owner, address _spender) constant returns (uint remaining )
      if **(__allowances[_owner][msg.sender])**{
          **^-------------------------------^**
            return __allowances[_owner][msg.sender];
      }
            return 0;
   }

Answer 1

The "if statement" returns a bool condition,(being true or false), and likely should have a comparison going on..

In your case there is no comparison (> == etc) going on, and just returning a number.