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POIs type checking for references in a template class less strict?
 

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  1. POIs type checking for references in a template class less strict?
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    <p>The following is allowd in C++ through promotion:</p> <pre><code>int ivalue = true; bool bvalue = 1; </code></pre> <p>Thats okay. And this is not allowed, through type-checking:</p> <pre><code>int&amp; ivalue = false; bool&amp; bvalue = 0; </code></pre> <p>Thats okay.</p> <p>Look on this, from Wikipedia. <a href="http://en.wikipedia.org/wiki/Property_(programming)#C.2B.2B" rel="nofollow">http://en.wikipedia.org/wiki/Property_(programming)#C.2B.2B</a></p> <pre><code>#include &lt;iostream&gt; template &lt;typename T&gt; class property { T value; public: T &amp; operator = (const T &amp;i) { ::std::cout &lt;&lt; "T1: " &lt;&lt; i &lt;&lt; ::std::endl; return value = i; } // This template class member function template serves the purpose to make // typing more strict. Assignment to this is only possible with exact identical // types. template &lt;typename T2&gt; T2 operator = (const T2 &amp;i) { ::std::cout &lt;&lt; "T2: " &lt;&lt; i &lt;&lt; ::std::endl; T2 &amp;guard = value; return value = i; throw guard; // Never reached. }/**/ operator T const &amp; () const { return value; } }; struct Bar { // Using the property&lt;&gt;-template. property &lt;bool&gt; alpha; property &lt;unsigned int&gt; bravo; }; int main () { Bar bar; bar.alpha = true; bar.bravo = true; // This line will yield a compile time error // due to the guard template member function. ::std::cout &lt;&lt; foo.alpha &lt;&lt; ", " &lt;&lt; foo.bravo &lt;&lt; ", " &lt;&lt; bar.alpha &lt;&lt; ", " &lt;&lt; bar.bravo &lt;&lt; ::std::endl; bool bvar = 22; int ivar = true; //int &amp;newvar = bvar; print(bvar); ::std::cout &lt;&lt; bvar &lt;&lt; " and " &lt;&lt; ivar &lt;&lt; "\n"; return 0; } </code></pre> <p>I think with using of templates the type-checking for references get lost? Am I right?</p>
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    1. USTshepang
    1. USPeter
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    1. COReally? Where exactly?
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    2. COThe preface is misleading. `int & i = 5;` is equally disallowed. Nothing to do with type promotions.
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      1. POIs type checking for references in a template class less strict?
      1. USKerrek SB
    3. CO@Kerrek SB: I'm completely lost now... Doesn't he said that the second block of code is NOT allowed?
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      1. USK-ballo
 

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