1041822 - Add a lookupOrAdd to nsClassHashtable

Status: RESOLVED FIXED

(Core :: XPCOM, defect)

Description

[Blake Kaplan (:mrbkap) (inactive)]

Currently, there's no way to avoid having to do two lookups when using an nsClassHashtable if I want to look up an object that may have already been created that I then want to modify. This operation is easy to do using PLDHashTable (operate using PL_DHASH_ADD and use the resulting array).

For nsClassHashtable, we could add this functionality pretty easily. Its users would have to have a default constructor, but IMO we could live with that. Is there a reason that we haven't done this before?

Comment 1

[Blake Kaplan (:mrbkap) (inactive)]

Attachment: patch v1

I didn't add an infallible version of this, but one could be added pretty easily.

Is there any reason not to do this?

Comment 2

[Blake Kaplan (:mrbkap) (inactive)]

s/infallible/fallible/

Comment 3

[Andrew McCreight [:mccr8]]

You might have better luck with a review from :froydnj, as I think bsmedberg is away for another week or so.

Comment 4

[Benjamin Smedberg]

Comment on attachment 8459910 [details] [diff] [review]
patch v1

The magic of templates means that this only has to compile if somebody uses it. This is fine. I wonder if we should do something similar for nsDataHashtable, but I guess we don't need to until somebody needs it there.

Comment 5

[Blake Kaplan (:mrbkap) (inactive)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/d20cfaa4220b

Comment 6

[Ed Morley [:emorley]]

https://hg.mozilla.org/mozilla-central/rev/d20cfaa4220b