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POtemplated typedef?
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  1. POtemplated typedef?
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    copied!<p>I'm using libgc, a garbage collector for C and C++. To make STL containers garbage collectible one must use the gc_allocator. </p> <p>Instead of writing </p> <pre><code>std::vector&lt;MyType&gt; </code></pre> <p>one has to write </p> <pre><code>std::vector&lt;MyType,gc_allocator&lt;MyType&gt; &gt; </code></pre> <p>Could there be a way to define something like <p></p> <pre><code>template&lt;class T&gt; typedef std::vector&lt;T,gc_allocator&lt;T&gt; &gt; gc_vector&lt;T&gt;; </code></pre> <p>I checked some time ago and found out it was not possible. But I may have been wrong or there might be another way around. </p> <p>Defining maps in this way is particularly unpleasing.</p> <pre><code>std::map&lt;Key,Val&gt; </code></pre> <p>becomes</p> <pre><code>std::map&lt;Key,Val, std::less&lt;Key&gt;, gc_allocator&lt; std::pair&lt;const Key, Val&gt; &gt; &gt; </code></pre> <p>EDIT: After trying the use of macro I found out the following code breaks it:</p> <pre><code>#define gc_vector(T) std::vector&lt;T, gc_allocator&lt;T&gt; &gt; typedef gc_vector( std::pair&lt; int, float &gt; ) MyVector; </code></pre> <p>The comma inside the templated type definition is interpreted as a macro argument separator. </p> <p>So it seems the inner class/struct is the best solution.</p> <p>Here is an example on how it will be done in C++0X</p> <pre><code>// standard vector using my allocator template&lt;class T&gt; using gc_vector = std::vector&lt;T, gc_allocator&lt;T&gt; &gt;; // allocates elements using My_alloc gc_vector &lt;double&gt; fib = { 1, 2, 3, 5, 8, 13 }; // verbose and fib are of the same type vector&lt;int, gc_vector &lt;int&gt;&gt; verbose = fib; </code></pre>
 

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