Get attributes of a RegExp. Throws AttrNotFound if attr is not one of the allowed values. You should not use this directly. Use "~" and "~~" operators.
attr
"options" or "names"
Returns
Int for "options". Hash of names/indexes of named groups for "names".
Example
/abc/i.options # 1 - case insensitive (C_PCRE_CASELESS)
/(?P<name1>abc)/i.names # Name to index Hash: {name1=1}