[erlang-questions] matching binary against a file
Sat Jun 23 13:30:18 CEST 2007
--- Jeff Rogers <dvrsn@REDACTED> wrote:
> This does raise a style issue I've wondered about:
> is it better to use
> guards or match patterns? Where you have
> read_utf8(N, S, Data) when N > 0 -> .... ;
> read_utf8(0, S, Data) -> ... .
> I would be inclined to use
> read_utf8(0, S, Data) -> ... ;
> read_utf8(N, S, Data) -> ... .
> without using guards. Is one generally preferred,
> or it is just a style
> choice? I assume that the compiler optimizes then
> to pretty much the
> same thing.
Once upon a time, I think the compiler did a better
job with the first version, but I'm not sure it does
today. So it's mostly a stylistic issue for me. There
are a couple of nits, though:
1. With an explicit test of (N > 0), the two clauses
don't overlap (ie, at most one of them can match for
any input), so you can reorder them freely.
2. And (N > 0) also avoids an infinite loop if you
pass a negative N for some reason. That might not be
applicable in this case.
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