Databases
StackOverflow2013
Postsdbo
POPolicy based design and best practices - C++
Body
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POPolicy based design and best practices - C++
    text
    copied!<pre><code>struct InkPen { void Write() { this-&gt;WriteImplementation(); } void WriteImplementation() { std::cout &lt;&lt; "Writing using a inkpen" &lt;&lt; std::endl; } }; struct BoldPen { void Write() { std::cout &lt;&lt; "Writing using a boldpen" &lt;&lt; std::endl; } }; template&lt;class PenType&gt; class Writer : public PenType { public: void StartWriting() { PenType::Write(); } }; int main() { Writer&lt;InkPen&gt; writer; writer.StartWriting(); Writer&lt;BoldPen&gt; writer1; writer1.StartWriting(); return 0; } </code></pre> <p>I wrote the above code as part of learning <em>policy based designs</em>. I have few questions on the above code</p> <p>1 - Does this implementation look correct? I mean: does it really look like a policy based design?</p> <p>2 - I can now hook any kind of pens to writer. But what will I do when I got a pen with no default constructor (only parameterized constructors)? How will I handle this situation?</p> <pre><code>template&lt;class PenType&gt; class Writer : public PenType { public: void StartWriting() { PenType::Write(); } }; </code></pre> <p>3 - When the above code is used like</p> <pre><code>Writer&lt;InkPen&gt; writer; </code></pre> <p>I guess compiler will replace <em>PenType</em> with <em>InkPen</em>. If yes, why I am not able to call just <em>Write()</em> from <em>StartWriting()</em> instead of prefixing base class name (<em>PenType::Write()</em>)? </p> <p>4 - I think policy based design forces you to derive from classes which is semantically invalid. In the above code, a writer is derived from a pen only because writer uses a pen. But saying writer is a pen is semantically invalid. Is there any other better way to address this or I am missing something here?</p> <p>Any thoughts?</p>
 

Querying!

 
Guidance
An individual column

Larger individual text columns get their own page to allow for proper reading.

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