[erlang-questions] Reassigning variables
Hans Bolinder
hans.bolinder@REDACTED
Wed Mar 18 10:45:44 CET 2009
[Matthew Dempsky:]
> I like pattern matching in the majority of cases, but I find I write
> enough code where I need to incrementally update a data structure, and
> maintaining that code is a pain when I have code like:
>
> X = foo(),
> X1 = bar(X),
> X2 = xyzzy(X1),
> blah(X2).
>
> and later want to change it to:
>
> X = foo(),
> X1 = whee(X),
> X2 = bar(X1),
> X3 = xyzzy(X2),
> blah(X3).
>
> This means having to change four lines of code, when really it's
> conceptually just one change.
Maybe I'm missing the point, but wouldn't a BASIC way of numbering
variables be useful here? It would let you maintain an increasing
sequence of variable names while doing just one change:
X = foo(),
X10 = bar(X),
X20 = xyzzy(X10),
blah(X20).
and
X = foo(),
X5 = whee(X),
X10 = bar(X5),
X20 = xyzzy(X10),
blah(X20).
Best regards,
Hans Bolinder, Erlang/OTP team, Ericsson
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