Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!wuarchive!emory!att!att!cbnewsk!pegasus!hansen
From: hansen@pegasus.att.com (Tony L. Hansen)
Newsgroups: comp.std.c++
Subject: Re: Compiled templates?
Summary: it will be very implementation dependent
Keywords: templates, precompilation
Message-ID: <1991Mar29.184915.9063@cbnewsk.att.com>
Date: 29 Mar 91 18:49:15 GMT
References: <ARI.HUTTUNEN.91Mar29143801@punisher.hut.fi>
Sender: hansen@cbnewsk.att.com (tony.l.hansen)
Distribution: comp
Organization: AT&T Bell Laboratories
Lines: 34

< From: Ari.Huttunen@hut.fi (Ari Juhani Huttunen)
< Is it possible to distribute compiled templates in binary form, so that
< the user can use them as templates, or do you have to supply the source
< code for them?
< (As I understand it, distribution of compiled libraries is something
< that is required of c++ to be successful.)

Since templates don't exist yet, the answer is certainly no right now.

However, in the future, the answer will be a definite maybe! :-)

Seriously, consider what a template consists of: a model (the template) for a
class or function in which some type information is missing. The application
program will supply a type at compile time which will be melded with the
model to form a real class or function definition. The template will have to
be presented to the compiler in some form, but it won't necessarily have to
be in source form. If a vendor chooses, it may decide to permit some form of
"pre-parsing" to occur on templates. This would allow a library creator to
distribute a pre-parsed form of the template instead of raw source. Templates
pre-instantiated with certain types might be included in a library, but that
is a separate issue. For the application to create a version of the template
function or class at compile time, it needs access to the definition of the
template and not object. The object code for a class instantiated for one
type will be considerably different from the object code for a class
instantiated for another type, particularly if one is a built-in type and the
other is a class type. Is a pre-parsed version of a template close enough to what
you call a compiled template? I think the market place will have to decide.

By the way, there are many people who argue the premise that compiled libraries are
a must. It is certainly not a given.

					Tony Hansen
			    hansen@pegasus.att.com, tony@attmail.com
				att!pegasus!hansen, attmail!tony