Middlebrook (D) signed a sales agreement with Toch for the sale of his property. The agreement required D to pay a broker's commission once a purchaser for D's property has been found. Horowitz aided Toch in finding a buyer, and Toch gave Horowitz a writing entitling him to half the commission due. The writing said nothing explicit about transferring any claim which Toch might have against D. Horowitz assigned his commissions to Donovan (P). P sued to get paid. The trial court dismissed P's complaint; the Toch-Horowitz document was not an assignment, but merely a promise by Toch to pay Horowitz one-half of what was owed. P's complaint was dismissed. P appealed.