Comment by JamesBarney
5 years ago
The problem is abstraction isn't free. Sometimes it frees up your brain from unnecessary details and sometimes the implementation matters or the abstraction leaks.
Even something as simple as Substring which is a method we use all the time and is far more clear than most helper functions I've seen in code bases.
Is it Substring(string, index, length) or Substring(string, indexStart, indexEnd)
What happens when you pass in "abc".Substring(0,4) do you get an exception or "abc"?
What does Substring(0,-1) do? or Substring (-2,-3).
What happens when you call it on null? Sometimes this matters, sometimes it doesn't.
Also:
- Does it destructively modify the argument, or return a substring? Or both?
- If it returns a substring, is it a view over the original string, or a fresh substring that doesn't share memory with the original?
- If it returns a fresh substring, how does it do it? Is it smart or dumb about allocations? This almost never matters, except when it does.
- How does it handle multibyte characters? Do locales impact it in any way?
With the languages we have today, a big part of the function contract cannot be explicitly expressed in function signatures. And it only gets worse with more complicated tools of abstraction.