Section: 29.6.8.6.2 [rand.dist.samp.pconst] Status: NAD Submitter: Stephan Tolksdorf Opened: 2007-09-21 Last modified: 2016-02-10
Priority: Not Prioritized
View all other issues in [rand.dist.samp.pconst].
View all issues with NAD status.
Discussion:
The design of the constructor
template <class InputIteratorB, class InputIteratorW> piecewise_constant_distribution( InputIteratorB firstB, InputIteratorB lastB, InputIteratorW firstW);
is unnecessarily unsafe, as there is no separate end-iterator given for the weights. I can't see any performance or convenience reasons that would justify the risks inherent in such a function interface, in particular the risk that input error might go unnoticed.
Possible resolution: I propose to add an InputIteratorW lastW argument to the interface.
[ Stephan Tolksdorf adds pre-Bellevue: ]
In reply to the discussion in N2424 I'd like to make the same comments as for 736.
[ Bellevue: ]
In N2424. There is already precedent elsewhere in the library. Follows existing convention. NAD.
Proposed resolution:
See N2424 for the proposed resolution.
[ Stephan Tolksdorf adds pre-Bellevue: ]
In 29.6.8.6.2 [rand.dist.samp.pconst]:
Proposed wording a)
Change in para. 2
Constructs a piecewise_constant_distribution object with n = 1, p_{0} = w_{0} = 1, b_{0} = 0, and b_{1} = 1
and change in para. 5
A vector<result_type> whose size member returns n and whose operator[] member returns
p_{k}the weight w_{k} as a double value when invoked with argument k for k = 0, ..., n-1Proposed wording b)
Change both occurrences of
"piecewise_constant_distribution(InputIteratorB firstB, InputIteratorB lastB, InputIteratorW firstW, InputIteratorW lastW)and change in para. 3
the length of the sequence w starting from firstW shall be at least n, *firstW shall return a value w_{0} that is convertible to double, and any w_{k} for k >= n shall be ignored by the distribution[firstW, lastW) shall form a sequence w of length n whose leading element w_{0} shall be convertible to double