Facundo Batista schrieb:
Hi!
A thread in PyAr raised the question that, considering that strings are immutable, why a slice of a string is a copy and not a reference to a part of that string.
Because the reference approach is more complicated, harder to implement and may lead to unexpected behavior. For example:
a = "a long string with 500,000 chars ..." b = a[0] del a
With the slice-as-copy design the string 'a' is immediately freed. The slice-as-reference design would keep the 500kB string in memory although you are only interested in the first character. The buffer interface was designed for the slice-as-copy use case:
a = "abcdefg" b = buffer(a, 2, 3) b <read-only buffer for 0x839c2e0, size 3, offset 2 at 0x8391c40> str(b) 'cde' sys.getrefcount(a) 3 del b sys.getrefcount(a) 2
Christian