May 26, 2018
Companion module for Readonly.pm, to speed up read-only scalar variables
This module corrects the speed problem, at least with respect to scalar variables. When ReadonlyXS is installed, Readonly uses it to access the internals of scalar variables. Instead of creating a scalar variable object and tying it, Readonly simply flips the SvREADONLY bit in the scalar’s FLAGS structure.
Readonly arrays and hashes are not sped up by this, since the SvREADONLY flag only works for scalars. Arrays and hashes always use the tie interface.
Programs that you write do not need to know whether ReadonlyXS is installed or not. They should just “use Readonly” and let Readonly worry about whether or not it can use XS. If the ReadonlyXS is present, Readonly will be faster. If not, it won’t. Either way, it will still work, and your code will not have to change.
Your program can check whether Readonly.pm is using XS or not by examining the $ReadonlyXSokay variable. It will be true if the XS module was found and is being used. Please do not change this variable.