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1438. No definition for base()

Section: 28.5.5.2 [rand.adapt.disc] Status: C++11 Submitter: INCITS Opened: 2010-08-25 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

Addresses US-126

Each adaptor has a member function called base() which has no definition.

[ Resolution proposed by ballot comment: ]

Give it the obvious definition.

[ 2010-11-03 Daniel comments and provides a proposed resolution: ]

The following proposal adds noexcept specifiers to the declarations of the base() functions as replacement for a "Throws: Nothing" element.

[ 2010 Batavia: The working group reviewed this issue, and recommended to add the following to the Proposed Resolution. ]

• Append to paragraph 1 of [rand.req.adapt] (or at the Editor's discretion insert as a new paragraph following that paragraph): The expression a.base() shall be valid and shall return a const reference to a's base engine.

After further review, the working group concurred with the Proposed Resolution.

[Batavia: waiting for WEB to review wording]

Proposed resolution:

1. Add the following sentence to the end of 28.5.3.5 [rand.req.adapt]/1:

   A random number engine adaptor (commonly shortened to adaptor) a of type A is a random number engine that takes values produced by some other random number engine, and applies an algorithm to those values in order to deliver a sequence of values with different randomness properties. An engine b of type B adapted in this way is termed a base engine in this context. The expression a.base() shall be valid and shall return a const reference to a's base engine.

2. Change in [rand.adapt.disc]/3, class template discard_block_engine synopsis, the following declaration:

   // property functions
   const Engine& base() const noexcept;
   

3. Add the following new prototype description at the end of sub-clause 28.5.5.2 [rand.adapt.disc]:

   const Engine& base() const noexcept;
   

   ? Returns: e.

4. Change in [rand.adapt.ibits]/4, class template independent_bits_engine synopsis, the following declaration:

   // property functions
   const Engine& base() const noexcept;
   

5. Add the following new prototype description at the end of sub-clause 28.5.5.3 [rand.adapt.ibits]:

   const Engine& base() const noexcept;
   

   ? Returns: e.

6. Change in 28.5.5.4 [rand.adapt.shuf]/3, class template shuffle_order_engine synopsis, the following declaration:

   // property functions
   const Engine& base() const noexcept;
   

7. Add the following new prototype description at the end of sub-clause 28.5.5.4 [rand.adapt.shuf]:

   const Engine& base() const noexcept;
   

   ? Returns: e.