Editing Spaghetti code

{{short description|Software source code with poor structure}}
'''Spaghetti code''' is a [[pejorative]] phrase for difficult-to-[[Software maintenance|maintain]] and unstructured [[computer]] [[source code]]. Code being developed with poor structure can be due to any of several factors, such as volatile project requirements, lack of [[programming style]] rules, and [[software engineer]]s with insufficient ability or experience.<ref name="Markus4">{{cite journal|last1=Markus|first1=Pizka|title=Straightening spaghetti-code with refactoring?|journal=Software Engineering Research and Practice|date=2004|pages=846–852|url=http://itestra.com/wp-content/uploads/2017/08/04_itestra_straightening_spaghetti_code_with_refactoring.pdf|access-date=5 March 2018|archive-date=5 March 2018|archive-url=https://web.archive.org/web/20180305202716/http://itestra.com/wp-content/uploads/2017/08/04_itestra_straightening_spaghetti_code_with_refactoring.pdf|url-status=dead}}</ref>

== Meaning ==
Code that overuses [[Goto|GOTO]] statements rather than [[structured programming]] constructs, resulting in convoluted and unmaintainable programs, is often called spaghetti code.<ref name="Cram5">{{cite journal|last1=Cram|first1=David|last2=Hedley|first2=Paul|title=Pronouns and procedural meaning: The relevance of spaghetti code and paranoid delusion|journal=Oxford University Working Papers in Linguistics, Philology and Phonetics|date=2005|volume=10|pages=187–210|url=http://mostlyharmless.org.uk/wp-content/uploads/2010/12/cramhedley-web.pdf|access-date=5 March 2018|archive-date=6 March 2018|archive-url=https://web.archive.org/web/20180306022905/http://mostlyharmless.org.uk/wp-content/uploads/2010/12/cramhedley-web.pdf|url-status=dead}}</ref>
Such code has a complex and tangled [[control structure]], resulting in a program flow that is conceptually like a [[Spaghetti#Serving|bowl of spaghetti]], twisted and tangled<!-- pages 235–236 -->.<ref>{{cite book|last1=Horstmann|first1=Cay|title=Java Concepts for AP Computer Science|date=2008|publisher=J. Wiley & Sons|location=Hoboken, NJ|isbn=978-0-470-18160-7|pages=235–236|edition=5th ed. [i.e. 2nd ed.].|chapter-url=http://horstmann.com/bigjava3.html|access-date=2 January 2017|language=en|chapter=Chapter 6 - Iteration}}</ref>

In a 1980 publication by the [[National Institute of Standards and Technology|United States National Bureau of Standards]], the phrase '''''spaghetti program''''' was used to describe older programs having "fragmented and scattered files".<ref>{{cite book|title=ASTM special technical publication|issue=500–565|author=United States National Bureau of Standards|publisher=United States Government Printing Office|year=1980}}</ref><!-- page 15 -->

Spaghetti code can also describe an [[anti-pattern]] in which [[Object-oriented programming|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 (computer science)|polymorphism]].<ref name="Moha10">{{cite journal|last1=Moha|first1=N.|last2=Gueheneuc|first2=Y. G.|last3=Duchien|first3=L.|last4=Meur|first4=A. F. Le|title=DECOR: A Method for the Specification and Detection of Code and Design Smells|journal=IEEE Transactions on Software Engineering|date=January 2010|volume=36|issue=1|pages=20–36|doi=10.1109/TSE.2009.50|issn=0098-5589|citeseerx=10.1.1.156.1524|s2cid=14767901}}</ref> The presence of this form of spaghetti code can significantly reduce the comprehensibility of a system.<ref name="Abbes11">{{cite book|last1=Abbes|first1=M.|last2=Khomh|first2=F.|last3=Gueheneuc|first3=Y. G.|last4=Antoniol|first4=G.|title=2011 15th European Conference on Software Maintenance and Reengineering |chapter=An Empirical Study of the Impact of Two Antipatterns, Blob and Spaghetti Code, on Program Comprehension |date=2011|pages=181–190|doi=10.1109/CSMR.2011.24|isbn=978-1-61284-259-2|citeseerx=10.1.1.294.1685|s2cid=14152638}}</ref>

== History ==
It is not clear when the phrase spaghetti code came into common usage; however, a references appeared in 1972 including ''The principal motivation behind eliminating the goto statement is the hope that the resulting programs will not look like a bowl of spaghetti.'' by [[Martin E. Hopkins.|Martin Hopkins]].<ref>Hopkins, M. E. (1972): A Case fo the GOTO. In: ACM '72: Proceedings of the ACM annual conference - Volume 2, August 1972, pp 787–790, p 59 DOI:https://dl.acm.org/doi/10.1145/800194.805860</ref> In the 1978 book ''A primer on disciplined programming using PL/I, PL/CS, and PL/CT'', [[Richard W. Conway|Richard Conway]] described programs that "have the same clean logical structure as a plate of spaghetti",<ref>{{cite book|title=A primer on disciplined programming using PL/I, PL/CS, and PL/CT|last=Conway|first=Richard|publisher=Winthrop Publishers|year=1978|isbn=978-0-87626-712-7}}</ref><!-- page 186 --> a phrase repeated in the 1979 book ''An Introduction to Programming'' he co-authored with [[David Gries]].<ref>{{cite book|title=An Introduction to Programming|last1=Conway|first1=Richard|last2=Gries|first2=David|edition=3rd|publisher=Little, Brown|year=1979|isbn=978-0-316-15414-7}}</ref><!-- page 158 --> 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]].<ref>{{cite journal|journal=IEEE Computer|title=A spiral model of software development and enhancement|last=Boehm|first=Barry W.|volume=21|issue=2|date=May 1988|pages=61–72|doi=10.1109/2.59|s2cid=1781829}}</ref><!-- page 63 --> 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.<ref>{{cite book|title=Structured programming for the COBOL programmer: design, documentation, coding, testing|last=Noll|first=Paul|publisher=M. Murach & Associates|year=1977}}</ref><!-- page 15 -->

In the ''Ada – Europe '93'' conference, [[Ada (programming language)|Ada]] was described as forcing the programmer to "produce understandable, instead of spaghetti code", because of its restrictive exception propagation mechanism.<ref>{{cite conference|conference=Ada – Europe '93 (Proceedings)|book-title=Lecture Notes in Computer Science|title=Use and abuse of exceptions — 12 guidelines for proper exception handling|last=Schwille|first=Jürgen |series=Lecture Notes in Computer Science |volume=688|year=1993|publisher=Springer Berlin Heidelberg|pages=142–152|doi=10.1007/3-540-56802-6_12|isbn=978-3-540-56802-5 }}</ref>

In a 1981 computer languages spoof in ''The Michigan Technic'' titled "BASICally speaking...FORTRAN bytes!!", the author described [[FORTRAN]] stating that "it consists entirely of spaghetti code".<ref>{{cite journal|journal=The Michigan Technic|title=BASICally speaking...FORTRAN bytes!!|author=MTSBS{{clarify|date=April 2015}}|
volume=99|issue=4|date=March–April 1981}}</ref><!-- page 18 -->

[[Richard Hamming]] described in his lectures<ref>{{cite book |last1=Hamming |first1=Richard |title=The Art of Doing Science and Engineering |date=1996 |publisher=Taylor & Francis |isbn=9056995006}}</ref> the etymology of the term in the context of early programming in binary codes:

{{Quote
|text=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 [[Class (computer programming)|classes]] that are easy to understand in isolation, but difficult to understand as a whole.<ref name="Troyer91">{{cite conference|last1=De Troyer|first1=O.|title=The OO-binary relationship model : A truly object oriented conceptual model|conference=Advanced Information Systems Engineering|volume=498|date=13 May 1991|pages=561–578|doi=10.1007/3-540-54059-8_104|language=en|series=Notes on Numerical Fluid Mechanics and Multidisciplinary Design|isbn=978-3-319-98176-5|s2cid=10894568 |editor-last=Andersen |editor-first=Rudolf|editor2-last=Bubenko |editor2-first=Janis A. |editor3-last=Sølvberg |editor3-first=Arne|url=https://pure.uvt.nl/ws/files/5292185/DTO5613576.pdf}}</ref>

===Lasagna code===
{{See also|Architectural layer|Layer (object-oriented design)}}
[[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.<ref name="Latchezar18">{{cite journal|last1=Tomov|first1=Latchezar|last2=Ivanova|first2=Valentina|title=Teaching Good Practices In Software Engineering by Counterexamples|journal=Computer Science and Education in Computer Science|date=October 2014|issue=1|pages=397–405|url=https://www.researchgate.net/publication/301298530|access-date=5 March 2018}}</ref>

== Examples ==
Here follows what would be considered a trivial example of spaghetti code in [[BASIC programming language|BASIC]]. The program prints each of the numbers 1 to 100 to the screen along with its square. Indentation is not used to differentiate the various actions performed by the code, and the program's <code>[[Goto|GOTO]]</code> statements create a reliance on [[line number]]s. The flow of execution from one area to another is harder to predict. Real-world occurrences of spaghetti code are more complex and can add greatly to a program's maintenance costs.

<syntaxhighlight lang="basic">
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
</syntaxhighlight>

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

<syntaxhighlight lang="basic">
1 FOR i=1 TO 100
2     PRINT i;"squared=";i*i
3 NEXT i
4 PRINT "Program Completed."
5 END
</syntaxhighlight>

The program jumps from one area to another, but this jumping is formal and more easily predictable, because [[for loop]]s and [[Subroutine|functions]] provide [[control flow|flow control]] whereas the ''goto'' statement encourages arbitrary flow control. Though this example is small, real world programs are composed of many lines of code and are difficult to maintain when written in a spaghetti code fashion.

Here is another example of spaghetti code with embedded GOTO statements.
<syntaxhighlight lang="basic">
  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
</syntaxhighlight>

== See also ==
{{Portal|Computer programming|Engineering}}
* [[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 ==
{{Reflist}}

== External links ==
* [http://portal.acm.org/citation.cfm?id=362929.362947 Go To Statement Considered Harmful]. The classic repudiation of spaghetti code by [[Edsger Dijkstra]]
* [http://www.fortran.com/fortran/come_from.html ''We don't know where to GOTO if we don't know where we've COME FROM'' by R. Lawrence Clark from DATAMATION, December, 1973] {{Webarchive|url=https://web.archive.org/web/20180716171336/http://www.fortran.com/fortran/come_from.html |date=2018-07-16 }}
* [http://yost.com/computers/java/java-spaghetti/ Refactoring Java spaghetti code into Java bento code] separating out a bowl full of code from one class into seven classes
* [https://archive.today/20130201082958/http://www.remotesynthesis.com/post.cfm/Objects-and-Frameworks--Taking-a-Step-Back Objects and Frameworks – Taking a Step Back] by Brian Rinaldi
* [https://blog.docsity.com/en/study-tips/programming-2/programming-pasta-spaghetti-lasagna-ravioli-macaroni-code/ Programming Pasta - Spaghetti, Lasagna, Ravioli and Macaroni Code] {{Webarchive|url=https://web.archive.org/web/20230121050907/https://blog.docsity.com/en/study-tips/programming-2/programming-pasta-spaghetti-lasagna-ravioli-macaroni-code/ |date=2023-01-21 }}
* [https://www.techopedia.com/definition/24994/pasta-theory Pasta Theory of Programming]

[[Category:Anti-patterns]]
[[Category:Articles with example BASIC code]]
[[Category:Software engineering folklore]]
[[Category:Pejorative terms related to technology]]
[[Category:Metaphors referring to spaghetti]]