I have a variety of user defined function objects that I will need to call.  Take the following examples:<div>template&lt;int N1, int N2 = 0&gt;</div><div>struct Func1{ double operator()(boost::array&lt;double, N1&gt;&amp; x1, boost::array&lt;double, N2&gt;&amp; x2){...}};</div>
<div><div><br></div><div>template&lt;int N1&gt;</div><div>struct Func2{ double operator()(boost::array&lt;double, N1&gt;&amp; x){...}};</div><div><br></div><div>With a function such as </div><div><br></div><div>template&lt;int N1,</div>
<div>               int N2 = 0,</div><div>               class F = boost::function&lt;double (boost::array&lt;double, N1&gt;&amp; x1, boost::array&lt;double, N2&gt;&amp; x2)&gt;</div><div>class DPP{ void solve(){...... uses F...to be discussed} }; </div>
<div><br></div><div>I have a few questions:</div><div>1) Is there a relatively easy way to use boost concept check to verify that F follows the first function signature so that I can detect compile time the problem?  I can&#39;t figure out how to do it from the concept check docs, and they say they are out of date.</div>
<div>Usage I want to check in the instantiation of DPP:</div><div>      F f;</div><div>      f(boost::array&lt;double, N1&gt;&amp; x1, boost::array&lt;double, N2&gt;&amp; x2)</div><div><br></div><div><br></div><div>2) I want the user to be able to pass in a simplified function type if N2 = 0</div>
<div><br></div><div>I assume that to call the actual function I would have some kind of impl function with partial specialization such as:</div><div>template&lt;bool use_simplified, int N1, int N2&gt;</div><div>struct use_f_impl();</div>
<div><br></div><div>template&lt;int N1, int N2&gt;</div><div>struct use_f_impl&lt;true, N1, N2&gt;{</div><div>   static double use_f()</div><div>   {</div><div>      STATIC_ASSERT(N2 == 0);</div><div>       F f;</div><div>
      boost::array&lt;double, N1&gt; x;</div><div>       return f(x);</div><div>   }</div><div>};</div><div><br></div><div><br></div><div><div>template&lt;int N1, int N2&gt;</div><div>struct use_f_impl&lt;false, N1, N2&gt;{</div>
<div>   static double use_f()</div><div>   {</div><div>       F f;</div><div>      boost::array&lt;double, N1&gt; x1;</div><div>      boost::array&lt;double, N2&gt; x2;</div><div>       return f(x1, x2);</div><div>   }</div>
<div>};</div></div><div><br></div><div>And then in my solve() function I go:</div><div>  double val = use_f&lt;(N2 == 0, N1, N2)&gt;::use_f();</div><div><br></div><div>Is this the right idiom, pattern, etc?  Do I need to use the struct with a static function since function templates don&#39;t have partial specialization?</div>
<div><br></div><div>3) Now what if I want to do a concept check on the F passed into DPP?  It has to be conditional on the N2 value now.  How would I do this?</div><div><br></div><div><br></div><div>4) Lets say that I don&#39;t want to force them to use the simplified version of the function signature if they don&#39;t want to.</div>
<div>Can I automatically detect the signature and put it into a flag integer in the class?</div><div>i.e. inside of the DPP class:<br>static bool use_simple = IsSimple&lt;F&gt;::value;</div><div>Then pass in the use_simple value when calling use_f_impl.</div>
<div>If so, what would the IsSimple metafunction look like and can concept check help?</div><div><br></div><div>Thanks,</div><div>Jesse</div></div>