Re: [Boost-users] templates: parts of functions

Hi, As I am not overly familiar with boost or it's mpl library yet, I cannot provide any specific advice along these lines. According to your description, my advice would be to create helper template classes or functions that rely only on some of the template parameters of your actual template class, but not N. For these helper functions and classes you do not need partial specialization, and thus no duplicate code. Depending on the complexity of your functions you might also extract those parts that do not depend on N into more template functions. If these helpers need access to private members of your makeTree class, you can declare them friend. (you might need to replicate those friend declarations in your partial specializations) For those parts of the code that do depend on N, but do not need a different implementation, you may still provide templated helper classes. The compiler will still generate multiple class implementations for different values of N, but you won't need to replicate the actual code yourself. Hope this helps. Cheers, Stefan

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Message: 6 Date: Sat, 1 Mar 2008 14:38:34 +0100 From: "Hicham Mouline" Subject: [Boost-users] templates: parts of functions To: Message-ID: <000001c87ba1$8cfe0d30$a6fa2790$@org> Content-Type: text/plain; charset="us-ascii"

Hi,

I have a function makeTree whose behavior depends on 3 different policies

typename T1

typename T2

int N

For performance reasons, I need to write the 2- and 3- specializations alongside the general N case. That is, the 2- and 3- default

instantiations generated from the N case by the compiler are not optimal.

As it is impossible to write function templates partial specializations, I encapsulate the

template< typename T1, typename T2, int N> void makeTree(Head<N>&, const T2&, const C&) ;

function in a class template

template< typename T1, typename T2, int N> class makeTree{

void makeTree(Head<N>&, const T2&, const C&);

};

and write the partial specializations and .

Now, this makeTree function is quite large. It includes code that :

. doesn't depend on any of the template arguments

. code that depends only T1

. code that depends only on T2

. code that depends only on N

. code that depends only on .

I am worried about code bloat, and the effect on overall performance of the actual code generated even if it is not run

(I noticed substantial effects depending on the size of object files and final shared library generated).

Besides this, I suppose it is a better design to have these segments of code put in template functions

with the right template arguments.

Is it MPL the library that I should look into for such work?

Perhaps nothing in Boost particularly facilitates this work, and std c++ templates are enough,

Thoughts, comments are appreciated,

Rds,