swap() macro

[aka at cbrma.UUCP]

In article <2225 at umcp-cs.UUCP> chris at maryland.UUCP (Chris Torek) writes:
>In article <1836 at brl-smoke.ARPA> gwyn at brl.arpa (Doug Gwyn
>(VLD/VMB) <gwyn>) writes:
>>It may be amusing and/or instructive to contemplate the fact that
>>there is no way to write a function that exchanges the contents of
>>two variables in a language where parameters are passed "by name".
>
>How so?  It seems rather simple.  I have here a C program that effects
>call-by-name and does indeed perform a swap:

[ ... fragmen
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