This answer made me wonder:
Did COBOL also handle that other newbie mistake, allowing one to write
if a == 'orange' or 'apple' or 'banana'
instead of
if a == 'orange' or a == 'apple' or a == 'banana'
(or using some set membership operator if your favourite language has one)?
The language defined in the original COBOL report from 1960 did indeed (see section 3.2.2). A normal “compound condition” consisted of a series of “simple conditions” (relations) separated by AND and OR; however, there were two abbreviated forms:
X = Y AND X = Z could be abbreviated to X = Y AND Z. The report gives the tricky example A = B OR C AND D, which turns out to be equivalent to A = B OR (A = C AND A = D).A = B, C OR D is the same as A = B OR A = C OR A = D.COBOL also has Level 88 conditions. Not quite what you are asking, but related.
For example:
01 WS-FRUIT PIC X(20).
88 APPLE VALUE "Apple".
88 BANANA VALUE "Banana".
88 ORANGE VALUE "Orange".
Now I can use:
IF APPLE OR BANANA OR ORANGE
The variable name is not even necessary because it knows which variable those level 88 conditions are associated with.
I can also do this:
01 WS-FOOD PIC X(20).
88 FRUIT VALUE "Apple" "Banana" "Orange.
88 VEGGIE VALUE "Corn" "Bean" "Potato".
88 SNACK VALUE "Pretzels" "Chips".
Then I can do this:
MOVE "Bean" TO WS-FOOD.
..
..
IF VEGGIE
DISPLAY "It's a vegetable"
ELSE
DISPLAY "Not a vegetable".
88 Level conditionals were amazingly useful at simplifying huge, broken IF clauses. COBOL was an amazingly effective language if you were taught by experts, and didn't blanch at using GOTO.
if statement could possibly be a good idea in the first place was either incompetent (in which case it's not too surprising that it can be refactored to a fraction of the size), or was forced to that desparate move by the limitations of a language that is more concerned with having the code read “like English” than implementing actually efficient, consistent semantics. Anyway, how you find these 88-thingies read “like a sentence” eludes me... the example here certainly isn't readable, despite being easily expressable as very English-like e.g. Python.
Commented
Jun 25, 2021 at 10:07
if statements, which are really just a very specific instance of the refactorability problem. Apparently 88 gets the job done, but it wouldn't work in many other situations, and it looks like it doesn't come with any of the other advantages of OO or functional programming – like making it easy to write unit tests.
Commented
Jun 25, 2021 at 11:05
You can do
if a = 'orange' or 'apple' or 'banana'
in COBOL, it translates as
if a = 'orange' or a = 'apple' or a ='banana'
You need to be careful when doing this as it does not always work the way you expect when you mix in And or not clauses. I would suggest using brackets and keeping it simple i.e.
if (a == 'orange' or 'apple' or 'banana')
and fruit-age < 12
This question https://stackoverflow.com/questions/4342218/issues-with-ands-and-ors-cobol/4342263 shows an example of the problems.
Taken from the above
IF DL-CLASS-STANDING = 'First Yr' OR 'Second Yr' AND
GRAD-STAT-IN = ' ' OR 'X'
From memory means
IF DL-CLASS-STANDING = 'First Yr'
OR (DL-CLASS-STANDING = 'Second Yr' AND GRAD-STAT-IN = ' ')
OR GRAD-STAT-IN ='X'
COBOL has an EVALUATE statement that takes the first form (need to use ALSO for multiple conditions).
EVALUATE TRUE ALSO TRUE
WHEN WS-A = 'ORANGE' OR 'APPLE' OR 'BANANA' ALSO ANY
DISPLAY 'A FRUIT.'
WHEN WS-A = 'ONION' OR 'PEPPER' ALSO WS-COURSE = 'DESSERT'
DISPLAY 'A VEGETABLE. DO NOT SERVE THIS FOR DESSERT!'
END-EVALUATE
