use <./base.scad>;

ERROR_BEGIN="<font color='red'>";
ERROR_END="</font>";

module precondition(test,error,m=undef) {
    if(!test) {
        echo(str(ERROR_BEGIN,default(m,parent_module(1)),": ",error,ERROR_END));
        assert(false);
    } else children();
}

function precondition(test,value,error)=test ? value : echo(str(ERROR_BEGIN,error,ERROR_END)) assert(false);

module check_defined(val,error,m=undef) {
  precondition(val != undef,error) children();
}

function check_defined(value,error)=precondition(value != undef,error);

module check_parent(parent,statement,error,m=undef) {
    precondition(parent_module(3) == parent,str(statement,"(): ",error)) children();
}