Well, I do use splice occasionally, but not for argument passing. I'd either do

my $arg1=shift;
my $arg2=shift;
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or as in your second alternative, the point still being that multiple shift's on one line can be confusing albeit potentially correct, and IMHO clearly neither particularly concise nor expressive in terms of readability. Anyway what I choose depends on the emphasis I want to put on each argument. Fortunately in a not (any more) so remote future we will avoid all these parameter passing acrobatics...