Jump to content

Search the Community

Showing results for tags 'tip'.

  • Search By Tags

    Type tags separated by commas.
  • Search By Author

Content Type


Forums

  • Welcome
    • Announcements / News
    • Introductions & Off-Topic Discussion
    • Help & Feedback
  • 0 A.D.
    • General Discussion
    • Gameplay Discussion
    • Game Development & Technical Discussion
    • Art Development
    • Game Modification
    • Project Governance
    • Testing

Find results in...

Find results that contain...


Date Created

  • Start

    End


Last Updated

  • Start

    End


Filter by number of...

Joined

  • Start

    End


Group


AIM


MSN


Website URL


ICQ


Yahoo


Jabber


Skype


Location


Interests


First Name


Last Name


Skype ID

Found 1 result

  1. We talked with @elexis about constant references and I gave an example why passing by value may be better than passing by constant reference. During todays refactoring I met another important things that you need to know about constant references. Aliasing Take a look at the following code. Do you see a problem? (It's our code from ps/Shapes.h). // Interface class CSize { public: // ... void operator/=(const float& a); // ... public: float cx, cy; } // Implementation void CSize::operator/=(const float& a) { cx /= a; cy /= a; } If not, would the following usage example help you? CSize size(2560, 1440); // Normalize the size. if (size.cx) size /= size.cx; debug_printf("%f %f", size.cx, size.cy); You'll get: 1.0 1440.0 Because the a references to cx, and the first line of the operator modifies the cx. And in the next we just divide the cy by 1. It may happen in each case where we get the same class. I fixed the problem in D1809. Lifetime Another important thing is a lifetime. Let's take another look at another example (fictional, because I didn't find more detailed example in our code yet): std::vector<Node> nodes; // ... duplicate(nodes[0], 10); // ... void duplicate(const Node& node, size_t times) { for (size_t i = 0; i < times; ++i) nodes.push_back(node); } From first look it seems ok. But, if you know how std::vector works then you know, that on each push_back std::vector can reallocate array to extend it. And then all iterators and raw pointers are invalid, including our constant reference. So after few duplication calls it may contain a trash. So, you need to be careful with such cases.
×
×
  • Create New...