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Postings from January 2017
On 01/28/2017 09:31 AM, demerphq wrote: > My experience with locked hashes is that as currently implemented they > are nearly useless. A simple read of a non-existent key becomes a > fatal exception, which makes them nearly unusable in conventional > code. At work we have tried to use them for a few purposes, and > generally it is has been a failure. They impose a run time penalty on > all hash access even though they are barely used. > > As far as I can tell locked hashes were invented as a way to work > around our lack of core support for true objects/structs. Let's have some research to see if that was indeed the rational for this feature. > (Where > accessing a non-existent member *should* throw an exception, but > preferably a compile time one.) However with perls standard object > model and usage patterns I have never really seen anyone use them this > way. > > Steffen has started working on a patch series to make hashes > pluggable. (Big big fricking A to him on that!) This is only going to > be more complex if we support locking (does every hash implementation > have to support locking? Does the hash api have to support > "clear_placeholders"? > > I propose that we get rid of locked hashes. I have written tons of > code to help support them, and I consider them a total failed > experiment. > > Also, use of clear_placeholders and related functionality is one of > the "hidden apis" which we have in Internals that really has no > business being exposed to end users. > > Once we have a pluggable API for hashes, we can implement lockable > hashes using them and if people really want them we can provide them. > > What do people think? Should every hash access and store pay a penalty > for locked hashes when they are almost unused? > Before we do anything else, we should grep CPAN to estimate the frequency of their use. I'd also recommend that organizations that have a big investment in Perl and/or a large Perl codebase conduct the same search. For reference (as I had to do this to remember what locked hashes were): $ ack -il 'locked[\s_]?hash' . dist/Storable/t/downgrade.t dist/Storable/t/make_downgrade.pl ext/Hash-Util/t/Util.t ext/Hash-Util/lib/Hash/Util.pm t/op/tie.t lib/Internals.pod Thank you very much. Jim KeenanThread Previous | Thread Next