Template code inline

[Steve]

Hi all,

Is template code "always" inlined???
Or will compilers instantiate template functions separately if they
are large?

Also, what happens to the code if explicit instantiation mechanism is
used? ]
Are template functions, objects and member functions then placed as
separate entities within the object file, as with any non templated
functions.???

[tom_usenet]

Re: Template code inline

On 14 Nov 2003 03:17:34 -0800, me@stevejpurves .info (Steve) wrote:
[color=blue]
>Hi all,
>
>Is template code "always" inlined???[/color]

No. It might be if you define the functions inside the class
definition, since that implicitly inlines the code.
[color=blue]
>Or will compilers instantiate template functions separately if they
>are large?[/color]

Yes. The function may be instantiated in multiple translation units
and the code used in a number of places, but compilers employ a number
of techniques to ensure that you only end up with a single copy of the
code in your exe (instantiation databases and linker based
instantiation merging are two techniques). Of course, the
implementation may choose to inline the code anyway.
[color=blue]
>Also, what happens to the code if explicit instantiation mechanism is
>used? ][/color]

You control the translation unit that gets the instantiation, and
avoid having the template implicitly instantiated in multiple
translation units.
[color=blue]
>Are template functions, objects and member functions then placed as
>separate entities within the object file, as with any non templated
>functions.?? ?[/color]

Yes. Templates are never compiled to object code, only template
specializations . These can be explicit specializations , implicit
instatiations or explicit instantiations. This is independent of
inlining.

Tom

[Rolf Magnus]

Re: Template code inline

Steve wrote:
[color=blue]
> Hi all,
>
> Is template code "always" inlined???[/color]

Templates don't have any special connections to inline functions.
[color=blue]
> Or will compilers instantiate template functions separately if they
> are large?[/color]

They can do that and probably will. There are even cases in which it's
impossible to inline a function (think recursion or calling the
function through a pointer)
[color=blue]
> Also, what happens to the code if explicit instantiation mechanism is
> used? ][/color]

Code for the template instance is generated.
[color=blue]
> Are template functions, objects and member functions then placed as
> separate entities within the object file, as with any non templated
> functions.???[/color]

Yes.