Re: System calls - GNAT library vs. direct bindings

["Jeffrey R. Carter" <spam.jrcarter.not@acm.nospam.org>]

Maciej Sobczak wrote:
> 
> Bingo. And calling system API directly also requires a wrapper - at
> least for convenience. Interestingly, for funcions as simple as read/
> write/listen/etc., both wrappers will have comparable complexity.
> Note that no matter how the wrapper is written, it isolates two
> parties and as such can be later used to achieve freedom from both
> compiler and system.

IIRC, you were talking about a thin binding. To my mind, at least, a 
thin binding is not comparable to a portable wrapper. Depending on 
circumstances, a thin binding can sometimes be a single package spec 
with some pragma-Import subprograms (probably not in this case). Many 
difficult issues are left to the client.

More importantly, a binding, thin or otherwise, has to deal with the 
vagaries of interfacing to C, and is more difficult to get right than a 
wrapper around an Ada library, which is simply Ada calling Ada.

-- 
Jeff Carter
"Propose to an Englishman any principle, or any instrument, however
admirable, and you will observe that the whole effort of the English
mind is directed to find a difficulty, a defect, or an impossibility
in it. If you speak to him of a machine for peeling a potato, he will
pronounce it impossible: if you peel a potato with it before his eyes,
he will declare it useless, because it will not slice a pineapple."
Charles Babbage
92