Design by Contract and Error Handling
Design by Contract and Error Handling
Context Design by Contract (DbC) Systematic Approaches for Error Handling Internal and external errors
Miguel Oliveira e Silva (
[email protected]) and Pedro G. Francisco (
[email protected]) DETI / IEETA, Universidade de Aveiro
SLATE’14, Bragança, 19th and 20th June, 2014
Defensive Programming Typed Exceptions and Try/Catch DbC Exception Mechanism Fault Tolerance in DbC
Conclusions
1
Context
Design by Contract and Error Handling
Context Design by Contract (DbC)
The Problem
Easy the construction of correct and robust programs. • A program always contains a precise meaning . . . but
frequently is not what the programmer intended. • Modular approaches to programming aid in reducing this
Systematic Approaches for Error Handling Internal and external errors
Defensive Programming Typed Exceptions and Try/Catch DbC Exception Mechanism Fault Tolerance in DbC
Conclusions
gap . . . but a proper confrontation with programmer’s semantic goals is required. • Commenting programs might be a first approach towards
this goal . . . but not only programmers neglect them, but also frequently is not the program’s meaning. • A better approach is to explicitly attach meaning to
programs is required! 2
Design by Contract and Error Handling
Design by Contract (DbC)
Context Design by Contract (DbC)
DbC
Programming methodology in which the meaning of program entities is made explicit by the use assertions.
Internal and external errors
Defensive Programming Typed Exceptions and Try/Catch DbC Exception Mechanism
Native Java s t a t i c double s q r t ( double x ) { a s s e r t x >= 0 ; double r e s u l t ; ··· a s s e r t Math . abs ( r e s u l t ∗ r e s u l t − x ) = 0 ; { ··· } ensures Math . abs ( r e s u l t ∗ r e s u l t − x ) = 1 && month = 28 && r e s u l t
