[erlang-questions] Can I do var-assignment in a function?
Wed Jul 23 15:29:39 CEST 2008
Circular Function wrote:
> extract(Str) ->
> A = string:tokens(Str," ").
I think the comma was just a typo and not the actual question. Am I right?
You want var-assignment because you want to write something like:
A = string:tokens(Str," "),
A = lists:sort(A),
A = do_something_else(A),
A = and_finalize(A).
But that doesn't work. You have to use a new variable each time.
A1 = string:tokens(Str," "),
A2 = lists:sort(A1),
A3 = do_something_else(A2),
A4 = and_finalize(A3).
Or this hard to read version
A = and_finalize(do_something_else(lists:sort(string:tokens(Str," ")))).
This approach of functional languages has at least two big advantages:
1. You don't accidentally overwrite variables
2. You can see all results in the debugger.
And there should be no runtime penalty. Since the processor had to allocate and de-allocate the same amount of memory in each of the 3 cases -even if you don't see this in the code.
mit freundlichen Grüßen / with kind regards
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