Assignments and high level data types

ABSTRACT

If x and y are integer variables or any other variables of a “simple” type, then the meaning of the assignment x:&equil;y is quite similar in different programming languages. The value of y is copied (into a register) and then stored into x so that a fresh copy of the value of y becomes the current value of x. On the other hand if x and y are compound objects the the situation is quite different: some languages don't allow assignments at all, and other languages call for a conditional copying depending on the form of the right hand side. This paper argues for a unified view on assignment with semantics, that can be described in terms independent of the complexity of the type of the variables involved. We also present some alternatives to assignments and discuss their consequences for programming with complex data types.

REFERENCES

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INDEX TERMS

Primary Classification:
  D. Software
  D.3 PROGRAMMING LANGUAGES
      D.3.3 Language Constructs and Features
          Subjects: Data types and structures

Additional Classification:
  F. Theory of Computation
  F.3 LOGICS AND MEANINGS OF PROGRAMS
      F.3.2 Semantics of Programming Languages
          Subjects: Algebraic approaches to semantics

General Terms:
Languages

Keywords:
Adress, Assignment, Data types, Mathematical semantics, Pointers