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PODoes using lambda functions to simulate lexical clousures have unforseen performace / implementation issues?
 

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  1. PODoes using lambda functions to simulate lexical clousures have unforseen performace / implementation issues?
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    <p><strong>Program 1:</strong></p> <pre><code>#include &lt;iostream&gt; std::string Hello(void){return "Hello";} std::string World(void){return "world!";} int main(){ std::cout &lt;&lt; Hello() &lt;&lt; " " &lt;&lt; World() &lt;&lt; std::endl; } </code></pre> <p>The functions Hello() and World() exist in the global namespace.<br> This means they can be called by any other function that comes after their declaration (or in this case, I provided the definition and did not need the declaration first). </p> <p>I have a problem with this, because as my project gets bigger, I include more header files that fill the global namespace with lots of functions, and I risk having function signature collisions, or worse, accidentally calling the wrong function that should only be called as a sub-task of another function. </p> <p>I am trying to follow the paradaim of functionally decomposing a task into sub-tasks, and thus it would not make sense for particular functions to ever be called outside the scope of another particular function. </p> <p>Here is a work-around, and apart from the code becoming unreadable due to the indentation depth, I want to know if there are any performance or implementation gotchas. lambda functions are a bit of magic for me at the moment, so I'm curious about the unforeseen dangers.</p> <p><strong>Program 2:</strong></p> <pre><code>#include &lt;iostream&gt; int main(){ auto Hello = [](void) -&gt; std::string{return "Hello";}; auto World = [](void) -&gt; std::string{return "world!";}; std::cout &lt;&lt; Hello() &lt;&lt; " " &lt;&lt; World() &lt;&lt; std::endl; } </code></pre> <p>Hello() and World() are encapsulated inside main() and <strong>can not</strong> be called from outside main()'s scope.<br> Is that all that's different?</p>
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    1. USTrevor Hickey
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      1. USAce7k3
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    1. COWhat's wrong with namespaces?
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    2. CO'Use namespaces' is too simple an answer because the same namespace can be used across several modules. A good example simply being the global, well, namespace.
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      1. USLuc Danton
 

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