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(g-wrap.info)Why Create a Wrapper Generator?

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Why Create a Wrapper Generator?
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When accessing a given foreign API from a variety of target languages,
the description of the foreign API is a common bit of information that
will be needed by the infrastructure supporting each of the target
languages.  Further, since the internal mechanisms by which a given
target language can access a foreign API are often in flux, it makes
sense to consider automatically generating the "glue code" that binds
the library API and the target language together.  This means that
whenever the foreign function access mechanisms in a target language
change, only g-wrap (or some similar tool) will need to be updated.
Then all of the relevant glue code can be trivially re-generated.  This
is the job that g-wrap was designed to handle.

In truth, one of the primary goals of g-wrap is also to acumulate as
many language independent definitions of various APIs as possible, so
that interfaces for other languages may be generated automatically,
whether by g-wrap, or some other program.

The original motivation for g-wrap came from Aubrey Jaffer's suggestion
to Christopher Lee that using Scheme to parse a language neutral API
specification and generate glue code would be a good way to address this
problem for Scheme interpreters.  G-wrap may well evolve beyond that to
support other languages, but for now, it only handles access to C APIs
from Guile.

In fact, the original implementation of g-wrap was much more declarative
than programmatic.  The API specification files were not executable
Scheme code, but rather declarative Scheme forms.  In the long run, this
might be preferable, if g-wrap decides to move in the direction of
language independence, or an alternate possibility is to design a
language neutral API spec file (as gnome-guile is trying to do) and then
just have a translator from that to native g-wrap calls.

g-wrap can be found at <ftp://ftp.gnucash.org/pub/g-wrap/>.