[erlang-questions] Newbie question about Erlang style
Wed Feb 27 22:57:53 CET 2008
Kevin Scaldeferri wrote:
> On Feb 27, 2008, at 12:04 PM, Convey Christian J NPRI wrote:
>> Is there any non-aesthetic reason prefer one of the following
>> approaches over the other?
>> if Foo -> X = 1;
>> true -> X = 2
>> X = if
>> Foo -> 1;
>> true -> 2
> A related question: are all variables function scoped in Erlang?
> Obviously, the first example wouldn't work at all if the branches of
> an if or case created a new scope. Is there any way to explicitly
> create a new scope?
Variables are usually defined from the point where they are introduced
until the end of the function - so they are essentially defined in the
entire function as one can't declare a variable without binding a value
One exception is list comprehensions where one can shadow previously
It is also possible to introduce the same variable in different branches
of a if/case which works as expected, but may raise compiler complaints
if one tries to use them in code outside, following the if/case - which
requires the variable/s to be defined in all branches (even ones that
always call exit/throw/error ...), to ensure that there is always a
value bound to the variable.
I think it's possible to declare funs that have input variables, with
the same names as existing ones, which shadow the previous variablenames
- this is probably a bad idea because one might want to use those
variables inside the fun and because the complier will (probably) create
warnings about it.
> erlang-questions mailing list
More information about the erlang-questions