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From: saito@sdrvx2.sinet.slb.com (Naoki Saito, GEO-002, Ext. 5471)
Newsgroups: gnu.g++
Subject: Why operator() must be a member?
Message-ID: <8912291438.AA01110@ascsu1.SLCS.SLB.COM>
Date: 29 Dec 89 14:38:05 GMT
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	Hi!  I have a sort of vector class.  I want to define inner product
(or so-called dot product) using operator() as follows:

friend float operator()(vector a, vector b)
{
  if (a.size() != b.size()) error("Vector sizes are different!");
  float res = 0.0;
  for (i = 0; i < a.size(); i++)
     res += a[i]*b[i];
  return res;
}

Although g++-1.34.2 successfully compiled this(no complaint), Sun C++ 2.0 
produced an error as follows:

error: operator() must be a member

g++-1.36.x compiles this or behaves as the Sun C++?  Why does AT&T 2.0 restrict
the usage of the operator()?

Regards,
Naoki Saito (saito@sdr.slb.com)
Schlumberger-Doll Research