parameter/argument terminology

Terry Reedy tjreedy at
Sun Jan 5 20:24:03 CET 2003

"Donnal Walter" <donnalcwalter at> wrote in message
news:mailman.1041769928.7987.python-list at
> In writing Python documentation for functions/methods, are the terms
> 'argument' and 'parameter' essentially interchangeable? Or is it
true that
> parameter usually refers to the definition and argument to the call?

I can't speak to 'are' and 'is' and 'usually'.  But I try to follow
the second choice.
The closest we have to an authority,
D. Knuth, Art of Comp. Prog. 1, Fund. Algo. 2nd ed, p 183, says...

"When a subroutine is written to handle a general case, it is often
written in terms of *parameters*, ...Particular values of parameters,
supplied when the subroutine is called, are know as *arguments*."

Since we have two terms and two separate but related concepts, it
seems more more useful for clear communication to use one term for
each than to use both interchangebly for both.

Terry J. Reedy

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