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| <div class="titlepage"><div><div><h4 class="title"> |
| <a name="phoenix.modules.bind.binding_member_variables"></a><a class="link" href="binding_member_variables.html" title="Binding Member Variables">Binding |
| Member Variables</a> |
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| <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">phoenix</span><span class="special">/</span><span class="identifier">bind</span><span class="special">/</span><span class="identifier">bind_member_variable</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> |
| </pre> |
| <p> |
| Member variables can also be bound much like member functions. Member variables |
| are not functions. Yet, like the <a class="link" href="../core/references.html" title="References"><code class="computeroutput"><span class="identifier">ref</span><span class="special">(</span><span class="identifier">x</span><span class="special">)</span></code></a> |
| that acts like a nullary function returning a reference to the data, member |
| variables, when bound, act like a unary function, taking in a pointer or |
| reference to an object as its argument and returning a reference to the |
| bound member variable. For instance, given: |
| </p> |
| <pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">xyz</span> |
| <span class="special">{</span> |
| <span class="keyword">int</span> <span class="identifier">v</span><span class="special">;</span> |
| <span class="special">};</span> |
| </pre> |
| <p> |
| <code class="computeroutput"><span class="identifier">xyz</span><span class="special">::</span><span class="identifier">v</span></code> can be bound as: |
| </p> |
| <pre class="programlisting"><span class="identifier">bind</span><span class="special">(&</span><span class="identifier">xyz</span><span class="special">::</span><span class="identifier">v</span><span class="special">,</span> <span class="identifier">obj</span><span class="special">)</span> <span class="comment">// obj is an xyz object</span> |
| </pre> |
| <p> |
| As noted, just like the bound member function, a bound member variable |
| also expects the first (and only) argument to be a pointer or reference |
| to an object. The object (reference or pointer) can be lazily bound. Examples: |
| </p> |
| <pre class="programlisting"><span class="identifier">xyz</span> <span class="identifier">obj</span><span class="special">;</span> |
| <span class="identifier">bind</span><span class="special">(&</span><span class="identifier">xyz</span><span class="special">::</span><span class="identifier">v</span><span class="special">,</span> <span class="identifier">arg1</span><span class="special">)</span> <span class="comment">// arg1.v</span> |
| <span class="identifier">bind</span><span class="special">(&</span><span class="identifier">xyz</span><span class="special">::</span><span class="identifier">v</span><span class="special">,</span> <span class="identifier">obj</span><span class="special">)</span> <span class="comment">// obj.v</span> |
| <span class="identifier">bind</span><span class="special">(&</span><span class="identifier">xyz</span><span class="special">::</span><span class="identifier">v</span><span class="special">,</span> <span class="identifier">arg1</span><span class="special">)(</span><span class="identifier">obj</span><span class="special">)</span> <span class="special">=</span> <span class="number">4</span> <span class="comment">// obj.v = 4</span> |
| </pre> |
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