Re^2: subroutine bewilderment: how to mimic builtins

Note that ;$ doesn't parse the same as a builtin like uc:

$ perl -we'print uc 1, 2'
12

$ perl -we'sub myuc(;$) { $_[0]||$_ } print myuc 1, 2'
Too many arguments for main::myuc at -e line 1, at EOF
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Also, in the presence of my $_, myuc won't be able to see the right $_. Implementing a _ prototype is on the todo list, but not on any particular person's plate that I know of.

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Re^3: subroutine bewilderment: how to mimic builtins by ikegami (Patriarch) on Feb 08, 2006 at 03:55 UTC
I know, but it's as close as possible. Considering the case that is different is an illegal case, I didn't bother confusing the issue by mentioning it. `my $_;` doesn't compile for me with Perl v5.8.6. Did you mean `tie $_`? There's some kind of problem with `local $_` when `$_` is tied, but 1) that's not likely, and 2) it can be avoided by localizing `*_` instead of `$_` (as I did in one of my examples).	[reply] [d/l] [select]
Re^4: subroutine bewilderment: how to mimic builtins by ysth (Canon) on Feb 08, 2006 at 04:39 UTC
`my $_;` is intended as a replacement for the not-ideal `local $_;` or `local *_;`. perl591delta: =head2 Lexical `$_` The default variable `$_` can now be lexicalized, by declaring it like any other lexical variable, with a simple `my $_;` [download] The operations that default on `$_` will use the lexically-scoped version of `$_` when it exists, instead of the global `$_`. In a `map` or a `grep` block, if `$_` was previously my'ed, then the `$_` inside the block is lexical as well (and scoped to the block). In a scope where `$_` has been lexicalized, you can still have access to the global version of `$_` by using `$::_`, or, more simply, by overriding the lexical declaration with `our $_`.	[reply] [d/l] [select]


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