Reordering arguments using recursion (pro, cons, alternatives)
- by polygenelubricants
I find that I often make a recursive call just to reorder arguments.
For example, here's my solution for endOther from codingbat.com:
Given two strings, return true if either of the strings appears at the very end of the other string, ignoring upper/lower case differences (in other words, the computation should not be "case sensitive"). Note: str.toLowerCase() returns the lowercase version of a string.
public boolean endOther(String a, String b) {
return a.length() < b.length() ? endOther(b, a)
: a.toLowerCase().endsWith(b.toLowerCase());
}
I'm very comfortable with recursions, but I can certainly understand why some perhaps would object to it.
There are two obvious alternatives to this recursion technique:
Swap a and b traditionally
public boolean endOther(String a, String b) {
if (a.length() < b.length()) {
String t = a;
a = b;
b = t;
}
return a.toLowerCase().endsWith(b.toLowerCase());
}
Not convenient in a language like Java that doesn't pass by reference
Lots of code just to do a simple operation
An extra if statement breaks the "flow"
Repeat code
public boolean endOther(String a, String b) {
return (a.length() < b.length())
? b.toLowerCase().endsWith(a.toLowerCase())
: a.toLowerCase().endsWith(b.toLowerCase());
}
Explicit symmetry may be a nice thing (or not?)
Bad idea unless the repeated code is very simple
...though in this case you can get rid of the ternary and just || the two expressions
So my questions are:
Is there a name for these 3 techniques? (Are there more?)
Is there a name for what they achieve? (e.g. "parameter normalization", perhaps?)
Are there official recommendations on which technique to use (when)?
What are other pros/cons that I may have missed?
