1. A method for operating a computer which has access to data of a data source, having the steps: creating a spreadsheet using a table calculation program; defining logic operations between various cells of the spreadsheet; defining an assignment of the data from the data source to the cells of the spreadsheet; and generating a source code of a procedural, re-entrant-compatible programming language from the spreadsheet, which when called, reads data from the data source, executes a logic operation on it and outputs the result of the logic operation.