Databases
StackOverflow2013
Postsdbo
POstd::vector<> derivate with resize() that doesn't initialize primitives & forwarding construct_back
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POstd::vector<> derivate with resize() that doesn't initialize primitives & forwarding construct_back
    primarykey
    data
    text
    <p>So there's a ton of cases where this it needed in performance sensitive applications, and I'm finally at the straw that broke the camels back. It needs to compile in C++98, as at least one of our platform only guarantees C++98 compliance.</p> <p>Edited hopefully to be a bit more clear with what I want.</p> <p>Example:</p> <pre><code>// This will allocate storage for 1024, and then loop 1024 times touching all of it just to place a 0 in it std::vector&lt; char &gt; buffer( 1024 ); // Now read will write into that buffer, overwriting the 0s ( we payed for the fill unnecessarily ) buffer.resize( read( someSource, &amp;buffer[0], buffer.size() ) ); </code></pre> <p>This is the common C interface, used with nearly all C libraries for writing data to a buffer. The same problems arise when dealing with buffers containing primitives in general. New resize would instead look something like this:</p> <pre><code>// Disabled for anything which doesn't pass boost::is_POD&lt; T &gt;, they get the standard version void resize( size_t a_NewSize ) { reserve( a_NewSize ); _end = _begin + a_NewSize; } </code></pre> <p>construct_back would be a forwarding constructor, for 1 const argument it would look something like this ( untested ):</p> <pre><code>template&lt; typename T1 &gt; void construct_back( const T1&amp; a_Arg1 ) { if( capacity() &lt;= size() ) // No room reserve( size() + 1 ); // Construct in place using Ts constructor that accepts const T1&amp; new (&amp;(*end()) T( T1 ); ++_end; // Account for new element } </code></pre> <p>construct_back would have to have all the possible number of arguments^2 overloads, this is the common brute force approach for perfect forwarding in C++98. </p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USYlisar
    1. USYlisar
    plurals
    1. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POstd::vector<> derivate with resize() that doesn't initialize primitives & forwarding construct_back
      1. This table or related slice is empty.
      1. VTUpMod
    1. COis it the simplest way you could ask?
      singulars
      1. POstd::vector<> derivate with resize() that doesn't initialize primitives & forwarding construct_back
      1. USRohit Vipin Mathews
    2. CO@Ylisar I hear you mate, it seems no one has understood your question. I reference this http://stackoverflow.com/questions/1461276/stdvector-reserve-and-push-back-is-faster-than-resize-and-array-index-w to hopefully make it clearer to others.
      singulars
      1. POstd::vector<> derivate with resize() that doesn't initialize primitives & forwarding construct_back
      1. USdcousens
 

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