Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Non-type template arguments can also be pointers or references, provided they point or refer to an object with external linkage.</p> <pre><code>template&lt;typename T, T&amp; t&gt; struct ref { static T&amp; get() { return t; } }; int i = 0; int&amp; ri = ref&lt;int, i&gt;::get(); // ok static int j = 0; int&amp; rj = ref&lt;int, j&gt;::get(); // not ok const int jj = 0; // here, const implies internal linkage; whoops const int&amp; rjj = ref&lt;const int, jj&gt;::get(); // not ok extern const int k = 0; const int&amp; rk = ref&lt;const int, k&gt;::get(); // ok namespace { int l = 0; } int&amp; rl = ref&lt;int, l&gt;::get(); // ok, and l is specific to the TU </code></pre> <p>I don't think you'd really want to init the elements with extern references though, since that would end up with twice the number of objects. You <em>could</em> initialize the elements of the array from literals, but unfortunately you can't <a href="https://stackoverflow.com/questions/2033110/passing-a-string-literal-as-a-parameter-to-a-c-template-class">use string literals as template arguments</a>. <s>So you'd need the proverbial layer of indirection:</s> It's painful because arrays or array references can't appear in a template parameter list (I guess this is why string literals can't):</p> <pre><code>// Not possible: // const char* lits[] = { "Hello, ", "World!" }; // lit accepts const char*&amp;, not const char* // typedef array_&lt;T, lit&lt;lits[0]&gt;, lit&lt;lits[1]&gt;, int_&lt;42&gt; &gt; array; // instead, but painful: const char* hello = "Hello"; const char* world = "World!"; typedef array_&lt;T, lit&lt;hello&gt;, lit&lt;world&gt;, int_&lt;42&gt; &gt; array; /* * here array::data would be an array of T, size 3, * initialized from { hello, world, 42 } */ </code></pre> <p>I can't see how to avoid dynamic initialization without C++0x's <code>constexpr</code>, and even then there are limitations. Using some kind of tuple to build composite initializers (e.g. initialize from <code>{ { hello, world, 42 }, ... }</code>) left as an exercise. But <a href="http://ideone.com/knlFA" rel="nofollow noreferrer">here's an example</a>.</p>
    singulars
    1. This table or related slice is empty.
    1. POCreate static array with variadic templates
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USCommunity
    1. USLuc Danton
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. CO`std::string` can't be constructed `constexpr`, since it uses dynamic allocation.
      singulars
      1. PO
      1. USBen Voigt
    2. CO@Ben Actually since I'm using literals the problem arises when initializing from a composite of literals (please don't quote me out of context). If the element type `T` cannot be statically initialized, then obviously that can't happen, but that's unrelated (to both the question and my answer).
      singulars
      1. PO
      1. USLuc Danton
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload