Databases
StackOverflow2013
Postsdbo
POstd::bind a bound function
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POstd::bind a bound function
    primarykey
    data
    text
    <p>I'm having trouble in detecting why the heck is this not compiling. I've got some lambda function that returns a <code>std::function</code> based on some argument. </p> <p>I've narrowed down my problem to this snippet(which doesn't use lambdas, but reproduces my error perfectly):</p> <pre><code>#include &lt;functional&gt; #include &lt;iostream&gt; struct foo { template&lt;class T&gt; void bar(T data) { std::cout &lt;&lt; data &lt;&lt; "\n"; } }; void some_fun(const std::function&lt;void(int)&gt; &amp;f) { f(12); } int main() { foo x; auto f = std::bind(&amp;foo::bar&lt;int&gt;, x, std::placeholders::_1); auto w = std::bind(some_fun, f); w(); } </code></pre> <p>The call to <code>w()</code> produces one of those lovely gcc error outputs in which I can't figure out what's going wrong. This is the error echoed by gcc 4.6.1:</p> <pre><code>g++ -std=c++0x test.cpp -o test test.cpp: In function ‘int main()’: test.cpp:20:7: error: no match for call to ‘(std::_Bind&lt;void (*(std::_Bind&lt;std::_Mem_fn&lt;void (foo::*)(int)&gt;(foo, std::_Placeholder&lt;1&gt;)&gt;))(const std::function&lt;void(int)&gt;&amp;)&gt;) ()’ /usr/include/c++/4.6/functional:1130:11: note: candidates are: /usr/include/c++/4.6/functional:1201:2: note: template&lt;class ... _Args, class _Result&gt; _Result std::_Bind&lt;_Functor(_Bound_args ...)&gt;::operator()(_Args&amp;&amp; ...) [with _Args = {_Args ...}, _Result = _Result, _Functor = void (*)(const std::function&lt;void(int)&gt;&amp;), _Bound_args = {std::_Bind&lt;std::_Mem_fn&lt;void (foo::*)(int)&gt;(foo, std::_Placeholder&lt;1&gt;)&gt;}] /usr/include/c++/4.6/functional:1215:2: note: template&lt;class ... _Args, class _Result&gt; _Result std::_Bind&lt;_Functor(_Bound_args ...)&gt;::operator()(_Args&amp;&amp; ...) const [with _Args = {_Args ...}, _Result = _Result, _Functor = void (*)(const std::function&lt;void(int)&gt;&amp;), _Bound_args = {std::_Bind&lt;std::_Mem_fn&lt;void (foo::*)(int)&gt;(foo, std::_Placeholder&lt;1&gt;)&gt;}] /usr/include/c++/4.6/functional:1229:2: note: template&lt;class ... _Args, class _Result&gt; _Result std::_Bind&lt;_Functor(_Bound_args ...)&gt;::operator()(_Args&amp;&amp; ...) volatile [with _Args = {_Args ...}, _Result = _Result, _Functor = void (*)(const std::function&lt;void(int)&gt;&amp;), _Bound_args = {std::_Bind&lt;std::_Mem_fn&lt;void (foo::*)(int)&gt;(foo, std::_Placeholder&lt;1&gt;)&gt;}] /usr/include/c++/4.6/functional:1243:2: note: template&lt;class ... _Args, class _Result&gt; _Result std::_Bind&lt;_Functor(_Bound_args ...)&gt;::operator()(_Args&amp;&amp; ...) const volatile [with _Args = {_Args ...}, _Result = _Result, _Functor = void (*)(const std::function&lt;void(int)&gt;&amp;), _Bound_args = {std::_Bind&lt;std::_Mem_fn&lt;void (foo::*)(int)&gt;(foo, std::_Placeholder&lt;1&gt;)&gt;}] </code></pre> <p>Here, <code>f</code> should be some callable object which takes an int as argument and calls <code>x.bar(int)</code> using it. On the other hand, <code>w</code> is just a callable object which calls <code>some_fun(f)</code>, being <code>f</code> the callable object mentioned above, which has the signature expected by <code>some_fun</code>'s parameter.</p> <p>Am I missing something? I probably don't know how to actually mix <code>std::bind</code> and <code>std::function</code>. </p>
    singulars
    1. PO
      singulars
      1. PTAnswer
    1. This table or related slice is empty.
    1. PTQuestion
    1. USmfontanini
    1. USmfontanini
    plurals
    1. PL
      singulars
      1. LTLinked
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTDuplicate
    3. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POstd::bind a bound function
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POstd::bind a bound function
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. POstd::bind a bound function
      1. This table or related slice is empty.
      1. VTUpMod
    1. COIt seems to work when you replace auto with `std::function<void(int)>` for f.
      singulars
      1. POstd::bind a bound function
      1. USLalaland
    2. COThis might not be an answer to your problem.. but have you considered using the native lambda-functions coming with C++11 (which make std::bind unnecessary)?
      singulars
      1. POstd::bind a bound function
      1. UScoldfix
    3. COIn Boost we have `protect` for cases like this, but it doesn't seem to have make it to the standard.
      singulars
      1. POstd::bind a bound function
      1. USK-ballo
 

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