Southern (P) submitted a telephone bid to C.V. (D) for furnishing and installing acoustical tile on a public construction job. D sued that bid on his prime contract. P was listed on that bid as required under law. D was awarded the contract, and P found out about the award through trade papers. P then refrained from bidding other jobs in order to remain within its bonding limits. D then requested a substitution of P from the contract, and it was granted by the school district. D claims that P was inadvertently listed in place of the intended subcontractor. P then sought a writ of mandamus to change the subcontractor designation back to what was previously listed. That proceeding was dismissed, and P did not appeal. P then sued D for damages. D demurred, and that was sustained. P appealed.