The claim is that you make an ImmutableFoo by "freezing" a MutableFoo, after which the invariant is that no client will change that collection. It isn't a copy, it's a freeze of the thing, so the flag blocks you from changing via the original MutableFoo handle.
Contrast with vanilla Foo, which doesn't have an API for you to change it, but is allowed to change by some other bit (e.g. I have a MutableFoo, and return to you casting to Foo... I can change it, you can't). If you want a copy, copy it yourself (and pay the copy cost explicitly, then freeze one, and you can go on changing the other). Bruce wants to run pretty close to the wire, so if you mess it up assertions will tell you about the error, but optimized it doesn't, and YMMV w.r.t. the effects. Since devmode is always asssertions-on, the expectation is you'd find the error soon. On Mon, Mar 22, 2010 at 2:06 PM, Ray Ryan <[email protected]> wrote: > Can you outline a use case? I don't get it. My argument isn't with > isFrozen, it's with the freezing feature per se. I can't see a reasonable > use for it. > > > On Mon, Mar 22, 2010 at 11:03 AM, Rodrigo Chandia <[email protected]>wrote: > >> isFrozen allows assertions on the status of a mutable collection. During >> normal use (assertions disabled), there should be no need to call isFrozen. >> Moreover, using isFrozen outside of an assertion, or while assertions are >> disabled, is not guaranteed to work at all. The intention is to avoid having >> to pay a runtime penalty and discourage defensive programming. >> >> Related to the review, it was not my intention to introduce isFrozen just >> yet (but it slipped through, sorry). isFrozen is a construct that only makes >> sense when when Immutable classes are introduced, along with assertions and >> tests relevant to immutability. At this point I wanted to concentrate on the >> Mutable and the parent Read-only classes. >> >> Is isFrozen still a bad idea when used for assertions only? >> >> >> 2010/3/22 <[email protected]> >> >> Can someone explain why isFrozen is a good idea? It sounds really, >>> really bad to me. >>> >>> >>> http://gwt-code-reviews.appspot.com/232801/show >>> >> >> > -- http://groups.google.com/group/Google-Web-Toolkit-Contributors To unsubscribe from this group, send email to google-web-toolkit-contributors+unsubscribegooglegroups.com or reply to this email with the words "REMOVE ME" as the subject.
