Spaghetti code

Spaghetti code is a

Code that overuses GOTO statements rather than structured programming constructs, resulting in convoluted and unmaintainable programs, is often called spaghetti code.^[2] Such code has a complex and tangled

In a 1980 publication by the United States National Bureau of Standards, the phrase spaghetti program was used to describe older programs having "fragmented and scattered files".^[4]

Spaghetti code can also describe an anti-pattern in which object-oriented code is written in a procedural style, such as by creating classes whose methods are overly long and messy, or forsaking object-oriented concepts like polymorphism.^[5] The presence of this form of spaghetti code can significantly reduce the comprehensibility of a system.^[6]

History

It is not clear when the phrase spaghetti code came into common usage; however, several references appeared in 1977 including Macaroni is Better Than Spaghetti by Guy Steele.^[7] In the 1978 book A primer on disciplined programming using PL/I, PL/CS, and PL/CT, Richard Conway described programs that "have the same clean logical structure as a plate of spaghetti",^[8] a phrase repeated in the 1979 book An Introduction to Programming he co-authored with David Gries.^[9] In the 1988 paper A spiral model of software development and enhancement, the term is used to describe the older practice of the code and fix model, which lacked planning and eventually led to the development of the waterfall model.^[10] In the 1979 book Structured programming for the COBOL programmer, author Paul Noll uses the phrases spaghetti code and rat's nest as synonyms to describe poorly structured source code.^[11]

In the Ada – Europe '93 conference, Ada was described as forcing the programmer to "produce understandable, instead of spaghetti code", because of its restrictive exception propagation mechanism.^[12]

In a 1981 computer languages spoof in The Michigan Technic titled "BASICally speaking...FORTRAN bytes!!", the author described

Richard Hamming described in his lectures^[14] the etymology of the term in the context of early programming in binary codes:

If, in fixing up an error, you wanted to insert some omitted instructions then you took the immediately preceding instruction and replaced it by a transfer to some empty space. There you put in the instruction you just wrote over, added the instructions you wanted to insert, and then followed by a transfer back to the main program. Thus the program soon became a sequence of jumps of the control to strange places. When, as almost always happens, there were errors in the corrections you then used the same trick again, using some other available space. As a result the control path of the program through storage soon took on the appearance of a can of spaghetti. Why not simply insert them in the run of instructions? Because then you would have to go over the entire program and change all the addresses which referred to any of the moved instructions! Anything but that!

Related phrases

Ravioli code

Ravioli code is a term specific to object-oriented programming. It describes code that comprises well-structured classes that are easy to understand in isolation, but difficult to understand as a whole.^[15]

Lasagna code

Lasagna code refers to code whose layers are so complicated and intertwined that making a change in one layer would necessitate changes in all other layers.^[16]

Examples

Here follows what would be considered a trivial example of spaghetti code in

1 i=0
2 i=i+1
3 PRINT i;"squared=";i*i
4 IF i>=100 THEN GOTO 6
5 GOTO 2
6 PRINT "Program Completed."
7 END

Here is the same code written in a structured programming style:

1 FOR i=1 TO 100
2     PRINT i;"squared=";i*i
3 NEXT i
4 PRINT "Program Completed."
5 END

The program jumps from one area to another, but this jumping is formal and more easily predictable, because

  INPUT "How many numbers should be sorted? "; T
  DIM n(T)
  FOR i = 1 TO T
    PRINT "NUMBER:"; i
    INPUT n(i)
  NEXT i
  'Calculations:
  C = T
E180:
  C = INT(C / 2)
  IF C = 0 THEN GOTO C330
  D = T - C
  E = 1
I220:
  f = E
F230:
  g = f + C
  IF n(f) > n(g) THEN SWAP n(f), n(g)
  f = f - C
  IF f > 0 THEN GOTO F230
  E = E + 1
  IF E > D THEN GOTO E180
  GOTO I220
C330:
  PRINT "The sorted list is"
  FOR i = 1 TO T
    PRINT n(i)
  NEXT i

• Big ball of mud
  , a piece of software with no perceivable architecture
• International Obfuscated C Code Contest, a competition to produce pleasingly obscure C code
• Technical debt
• The Elements of Programming Style

References