Bash case statements are pretty powerful
I’ve been brushing up on my Bash skills. I worked on a problem to calculate the Scrabble score of a set of letters. In Scrabble, each letter has different values. For example, “A” has a value of one and “Z” has a value of 10.
In Python, you might do something like this.
letters_to_score = {
("A", "E", "I", "O", "U", "L", "N", "R", "S", "T") : 1,
("D", "G") : 2,
("B", "C", "M", "P") : 3,
("F", "H", "V", "W", "Y") : 4,
("K", ) : 5,
("J", "X") : 8,
("Q", "Z") : 10
}
def score(word):
sum = 0
for letter in list(word.upper()):
for letters, value in letters_to_score.items():
if letter in letters:
sum += value
return sum
When I tried to create a Bash version of the program, I was unsure of what to do. I could create a dictionary, but it seems that there’s not really an equivalent of tuples. So, you’d have to have an entry for each individual letter. In Bash, I opted to use case statements instead.
letters=${1^^}
sum=0
for letter in $(grep -o . <<< $letters); do
case $letter in
[AEIOULNRST]) ((sum++));;
[DG]) ((sum+=2));;
[BCMP]) ((sum+=3));;
[FHVWY]) ((sum+=4));;
[K]) ((sum+=5));;
[JX]) ((sum+=8));;
[QZ]) ((sum+=10));;
*) exit 1;;
esac
done
echo $sum
The case statements allow for fairly powerful pattern matching. Python doesn’t really have a direct equivalent to this. PEP 275 proposed adding a similar feature to Python. However, it was rejected with reasoning that there are already equivalent features in Python. You could use dictionaries, use getattr to do some dynamic dispatch, or class if/else statements.