Robert Haas <robertmhaas@gmail.com> writes:
> Why do you keep insisting on changing case where I've written "which"
> to instead say "that" in situations where AFAIK either is perfectly
> correct? I find such changes at best neutral, and in some cases
> worse.
What I was taught in school was that "that" introduces a restrictive
clause, i.e. one that limits the membership of whatever group was
just mentioned, while "which" introduces a descriptive clause, i.e.
one that just provides more information about the group. So for
example
Functions that return a pass-by-reference type must do X.
is correct, while
Functions, which return a pass-by-reference type, must do X.
carries an implication that *all* functions in the system return
pass-by-reference types. Even if you think that that's obviously
silly, it may confuse readers who are accustomed to this distinction
being drawn. On the other hand, this is fine:
Functions that return text, which is a pass-by-reference type,must do X.
I've made the point more obvious in the above by setting off descriptive
clauses with commas, which is a common thing to do. But the punctuation
is optional.
I realize that this is nitpickery, and wouldn't usually bother about
the distinction in, say, code comments. But we are striving to be
somewhat formal in the user-facing documentation, no?
regards, tom lane
