[erlang-questions] leading underscores on variables versus _

Matthias Lang <>
Fri Feb 2 15:14:09 CET 2007


Ulf Wiger writes:

 > Underscores are always ignored. The variables that begin
 > with an underscore are actually real variables. The
 > linter interprets them as "don't care" patterns, but the
 > compiler does not.

This seems to catch many or even most beginners. It seems natural (?)
to expect _name to be a longer way of writing _, i.e. that any
variable starting with _ means exactly the same thing as if you'd just
written _.

An example where that doesn't hold:

  f(_x, _x) -> same;
  f(_,_) -> different.

Changing _x to behave as many (most?) initially expect would break
backwards compatibility, but only for misleading code such as the
above...

Matthias



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