Map
Index
Random
Help
th

QuoteRef: parnDL5_1978

topics > all references > ThesaHelp: references p-r



ThesaHelp:
references p-r
Topic:
general purpose computer systems
Topic:
families of programs
Topic:
intermediate representation of code
Topic:
uniform representation of files and sequences
Topic:
program module as encapsulation
Topic:
incremental testing
Topic:
design for change
Topic:
virtual machine
Topic:
the 'uses' hierarchy for organizing systems
Topic:
dependency analysis
Topic:
design documentation
Topic:
system builds
Topic:
managing a Thesa database
Topic:
information hiding

Reference

Parnas, D.L., "Designing software for ease of extension and contraction", Proceedings International Conference on Software Engineering, IEEE, pp. 264-277, May 1978. Google

Other Reference

IEEE Trans. Software Engineering, 128-137, May 1979

Quotations
265 ;;Quote: a mathematician proves a general theorem instead of closely related ones; but in software, generality is too expensive for unlikely events
265 ;;Quote: a system is hard to extend or contract if too many programs assume given features
266 ;;Quote: in multi-pass programs with different intermediate formats, can not remove a pass
266 ;;Quote: should not combine simple functions into one component
266 ;;Quote: using routines from untested modules can lead to systems that only work when everything works; e.g., a task scheduler that depends on the file system
266 ;;Quote: in design for change, must anticipate change before beginning a design
267 ;;Quote: identification of modules for a program family is difficult; first find a minimal subset and then add minimal increments
267 ;;Quote: virtual machine approach--instead of writing functions, we should design software machine extensions that will be useful for many programs
268 ;;Quote: 'A uses B' if the correct functioning of A depends on a correct implementation of B
268 ;;Quote: a program may invoke a program without using it; e.g., if A's specifications only require that it invoke B on some condition
268 ;;Quote: a program may use another without invoking it; e.g., most programs depend on interrupt handlers working correctly
269 ;;Quote: each level of a 'uses' hierarchy is a testable and usable subset of the system
269+;;Quote: can test and use subsets of a level in the 'uses' hierarchy
269 ;;Quote: A uses B when it simplifies A, B doesn't use A, a useful subset includes B alone, and useful subsets with A must include B
269 ;;Quote: if A and B use each other, then split into more than one program; called sandwiching
269 ;;Quote: a program is at the right 'uses' level if it doesn't need functions above it but does need ones below it
269 ;;Quote: the design of the 'uses' hierarchy should be a major design milestone
270 ;;Quote: example of design for change in processing street addresses
274 ;;Quote: for an application, identify the programs needed from the 'uses' hierarchy and include everything else that is used
274 ;;Quote: flexibility can not be added to a software design; choice of usable subsets must be a preliminary step
274 ;;Quote: no feature or function is always needed in a system
275 ;;Quote: software is general if it can be used without change; it is flexible if it can be easily changed
275+;;Quote: generalized software is less efficient than flexible software
276 ;;Quote: in a 'uses' hierarchy, low level operations may assume a data structure, next level may allow similar data structures, and top level doesn't know

Related Topics up

ThesaHelp: references p-r (245 items)
Topic: general purpose computer systems (9 items)
Topic: families of programs (11 items)
Topic: intermediate representation of code (29 items)
Topic: uniform representation of files and sequences (14 items)
Topic: program module as encapsulation (28 items)
Topic: incremental testing (25 items)
Topic: design for change (75 items)
Topic: virtual machine (13 items)
Topic: the 'uses' hierarchy for organizing systems (18 items)
Topic: dependency analysis (31 items)
Topic: design documentation (43 items)
Topic: system builds (36 items)
Topic: managing a Thesa database (34 items)
Topic: information hiding (50 items)

Collected barberCB 1980
Copyright © 2002-2008 by C. Bradford Barber. All rights reserved.
Thesa is a trademark of C. Bradford Barber.