1. A method of developing a program by assigning an extended language specification with respect to variables and functions included in the program, the method comprising: gathering, by a computer, first assignment candidate information indicating an assignment of the extended language specification in the program, second assignment candidate information indicating an assignment of the extended language specification in a project including a plurality of programs, and third assignment candidate information indicating an assignment of the extended language specification in an optional setting of a compiler; storing, by the computer, a list of assigned states of the extended language specification with respect to one or more variables and one or more functions of the programs by analyzing the first assignment candidate information, the second assignment candidate information, and the third assignment candidate information, by assigning a state of the extended language specification to the one or more variables and one or more functions when the one or more variables or functions are contained in a program indicated in the first, second or third assignment candidate information wherein the third assignment candidate information indicates that all variables or functions in all programs or projects to be compiled are assigned the state indicated by the optional setting of the compiler; determining, by the computer, a final assignment of the extended language specification, so that the assignments of the extended language specification do not overlap with each other with respect to the variables and the functions, based on the list of the assigned states and information related to priorities of assignments with respect to the functions and assignments with respect to the variables; assigning, by the computer, the extended language specification with respect to the functions or the variables, based on the assigned state final assignment determined by the determining; and creating, by the computer, the programs, by parsing and compiling the functions and the variables to which the extended language specification is assigned according to the assigned extended language specification.