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Postings from March 2023
On Sat, 11 Mar 2023 at 15:20, Matthew Persico <matthew.persico@gmail.com> wrote: > How about an MVP that creates just scalar constants? > Huh? We have two ways to create "constant" scalars: use constant var => "foo"; Internals::SvREADONLY((my $var = "x"),1); Am I missing something? > That's got to be 90% of what people need, and then we can add > constant hashes later? > We have constant (aka read-only) hashes as well. It is just that they are *restricted*, which renders them nearly useless for most purposes. use Hash::Util qw(lock_hash_recurse); lock_hash_recurse(\%hash); The "restricted" means that unlike normal hashes they throw an exception when you try to look something in them that they don't contain. (You can use lock_keys() to specify keys that are allowed to be in the hash but which do not yet have values.) The restricted API is sufficiently useless that I have never seen them used productively. I have /heard/ people claim they like them on this list, but I have never seen them used to advantage in my entire career, on the contrary every time I have seen someone try to use them they have reversed it out almost immediately afterwards. Ironically I wrote most of the modern code in Hash::Util to facilitate the advanced forms of read-only hash. But I did not create restricted hashes themselves. > After all, constant hashes are just a bunch of constants for those of us > with namespace OCD (including myself!). > Like I said, it turns out that reasonable people can disagree on what a constant hash should be. :-) I really wish we didnt have restricted hashes getting in the way, simple "readonly" hashes would be much more useful than restricted hashes are. MMMM, I wonder if there is a way we can extend restricted hashes so they behave as people would expect a readonly/constant hash to behave without throwing out restricted hashes entirely. Maybe something like lock_hash(\%hash, undef); ? Eg, the undef would signal "allow any key". Hrmmmm...... Watch this space, maybe I can come up with a hack for this. Yves -- perl -Mre=debug -e "/just|another|perl|hacker/"Thread Previous | Thread Next