Re: Why export templates would be useful
On 03/30/2010 10:30 PM, Jerry Coffin wrote:
While you're right that exported templates could sometimes provide
some benefit, the benefit really was fairly minimal and the cost
really was quite high.
I wouldn't use the word "minimal". When you are implementing eg. a
template-based library with a relatively small and simple public
interface and an enormous implementation (with tons and tons of private
types, classes, functions and data, most of which can be shared among
all the template instantiations), the benefit of being able to put
things in file-local scope is huge.
Currently you basically have two choices:
1) Accept that your private implementation has to be exposed and simply
document it with a big warning like "this is private data of the
library, don't use it directly".
2) Use "manual export templates" by using explicit template
instantiation. While this achieves the same modularity as export
templates would, this is a limited and awkward technique which can only
be used if you know in advance all the types with which the templates
will be instantiated.
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