Dynamic linking, was: Re: Dispelling BSD License Misconceptions

Russ Nelson nelson at crynwr.com
Sat Jan 27 19:16:02 UTC 2007

Arnoud Engelfriet writes:
 > If, as Matthew writes, part of the code is _specifically_ written to
 > work only with GNU readline and no other library, then the code is
 > a derivative work of GNU readline at the moment of creation. 

And if I later write a library compatible with GNU readline, that
makes the code NOT a derivative work?  How can that be?  It's either
derived in the sense that I incoporated parts of GNU readline into my
code, or else it's NOT derivative because no part of GNU readline was

The standard interpretation of linking forming a derivative work has
no basis in copyright law.  A staticly linked program is a collective
work, perhaps, but not derivative.  A derivative work is where I take
an existing library and add my own calls to it.  A dynamically linked
program which includes no portion of the library is neither derivative
nor collective.  The dynamic linking information is just a set of
names; it's not the code itself.

The dynamic linking argument has no legs unless you can claim
copyright on a list of names.  If somebody else produces a similar but
different list, does that infringe your copyright?  Not obvious.

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