Il pagamento del prezzo nell'appalto.

The application of the contract discipline when the consideration is different from money derives from a compatibility judgment to be conducted on a case-by-case basis. If, on the other hand, the consideration is completely missing, a liberal cause can be recognized in the contract and it can be subjected to the rules of indirect donations; but the possible effectiveness of the regulation of natural obligations or unjustified enrichment must also be considered. In any case, the specification of the contract price does not constitute an essential element of the agreement between the parties, since the law pre-establishes suitable criteria for its determination a posteriori.