Title
unordered containers are required to have an initial max load factor of 1.0
Status
nad
Section
[unord.req]
Submitter
Alisdair Meredith

Created on 2012-10-09.00:00:00 last changed 89 months ago

Messages

Date: 2016-11-15.00:00:00

[ 2016-11-12, Issaquah ]

NAD - if someone wants to come back with a paper exploring design alternatives, we can re-open.

Date: 2013-03-15.00:00:00

[ 2013-03-15 Issues Teleconference ]

Moved to Open.

Alisdair to provide wording.

Marshall: It seems to me that what you really want is to be able to pass a max load factor in the constructor, but that's a different issue.

Alisdair agrees in principle, but concerned with adding yet more constructors to these classes.

Date: 2012-11-09.18:57:47

The default constructor, allocator-aware constructor, and range-based constructors for the unordered containers do not offer a means to control the initial max_load_factor, so the standard mandates the value 1.0. This seems overly restrictive, as there is plenty of research suggesting a value between 0.5 and 1.0 is more often optimal for unique-key containers, and perhaps a slightly higher value might be appropriate for multi-containers.

Rather than guess at the appropriate max_load_factor, it seems reasonable that the standard should allow vendors to pick a value at their discretion, with perhaps a note of advice. It is less clear whether the default value should be implementation-defined or unspecified, given the ease of a user determining this by querying this attribute immediately after construction.

History
Date User Action Args
2016-11-21 05:09:01adminsetmessages: + msg8657
2016-11-21 05:09:01adminsetstatus: open -> nad
2013-03-18 14:33:00adminsetmessages: + msg6419
2013-03-18 13:02:36adminsetstatus: new -> open
2012-10-09 00:00:00admincreate