diff options
| author | Tanaka Akira <[email protected]> | 2025-04-18 21:10:18 +0900 |
|---|---|---|
| committer | Tanaka Akira <[email protected]> | 2025-04-18 21:10:18 +0900 |
| commit | ad69f4ddffb639dca7313dda10865735529b4325 (patch) | |
| tree | 94b14b925c4ebd16ba7892e7f412a24c46989fb0 /enum.c | |
| parent | ccc7493308ae327fb6c089e88e0cd4436c4dc513 (diff) | |
[doc] update {Enumerator,Enumerable}#size document.
at Code Party RubyKaigi 2025.
Diffstat (limited to 'enum.c')
| -rw-r--r-- | enum.c | 41 |
1 files changed, 36 insertions, 5 deletions
@@ -5114,11 +5114,42 @@ enum_compact(VALUE obj) * * === #size * - * Returns the size of elements. The size is defined as the number of iterations - * the #each method would perform over the elements. - * If #each method won't finish and its elements are Numeric, the size is +Infinite+. - * If #each method won't finish and its elements are not Numeric, the size is +nil+. - * If #each method don't work fine, raise TypeError. + * \Enumerator has #size method. + * It uses the size function argument for +Enumerator.new+. + * It should returns the number of iterations (number of #each method yields). + * The result is integer or +Float::INFINITY+. + * However it may also return nil when it is difficult to determine the result. + * + * Examples: + * + * ["a", "b", "c"].each.size #=> 3 + * {a: "x", b: "y", c: "z"}.each.size #=> 3 + * (0..20).to_a.permutation.size #=> 51090942171709440000 + * loop.size #=> Float::INFINITY + * (1..100).drop_while.size #=> nil # the size depends on the block values + * File.open("/etc/resolv.conf").each.size #=> nil # not computable without actually read the file. + * + * The behavior of #size of Range-based enumerator depends on the #begin element. + + * * If the #begin element is an integer, #size methd returns integer or +Float::INFINITY+. + * * If the #begin element is an object with #succ method except integer, #size methd returns nil. + * (It is too slow to compute the size by calling #succ repeatedly) + * * If the #begin element is an object without #succ method, #size method raises TypeError. + * + * Examples: + * + * (10..42).each.size #=> 33 + * (10..42.9).each.size #=> 33 (#end element can be numeric other than integer) + * (10..).each.size #=> Float::INFINITY + * ("a".."z").each.size #=> nil + * ("a"..).each.size #=> nil + * (1.0..9.0).each.size # raises TypeError (There is no Float#succ) + * (..10).each.size # raises TypeError (beginless range has nil as #begin element) + * + * \Enumerable classes may have #size method. + * It returns the result same as Enumerator#size in most cases: Array, Hash. + * Some classes have no #size method: IO, Dir. + * (Note that File#size is not related to File#each. It returns nubmer of bytes instead of number of lines.) * */ |