Conditions with common logic: question of style, readability, efficiency, ...
- by cdonner
I have conditional logic that requires pre-processing that is common to each of the conditions (instantiating objects, database lookups etc). I can think of 3 possible ways to do this, but each has a flaw:
Option 1
if A
prepare processing
do A logic
else if B
prepare processing
do B logic
else if C
prepare processing
do C logic
// else do nothing
end
The flaw with option 1 is that the expensive code is redundant.
Option 2
prepare processing // not necessary unless A, B, or C
if A
do A logic
else if B
do B logic
else if C
do C logic
// else do nothing
end
The flaw with option 2 is that the expensive code runs even when neither A, B or C is true
Option 3
if (A, B, or C)
prepare processing
end
if A
do A logic
else if B
do B logic
else if C
do C logic
end
The flaw with option 3 is that the conditions for A, B, C are being evaluated twice. The evaluation is also costly.
Now that I think about it, there is a variant of option 3 that I call option 4:
Option 4
if (A, B, or C)
prepare processing
if A
set D
else if B
set E
else if C
set F
end
end
if D
do A logic
else if E
do B logic
else if F
do C logic
end
While this does address the costly evaluations of A, B, and C, it makes the whole thing more ugly and I don't like it.
How would you rank the options, and are there any others that I am not seeing?
