Re: shift doesn't DWIM

Where would the line be drawn? Would using map in "void context" spew its return value into @_ ?

DWIMery shouldn't venture into the "Do What I Wish" if doing so creates serious language inconsistancies, IMHO.

My memory may be incomplete or in need of refreshing, but I can't think of any subs that populate $_ as a default lvalue. Yes, there is the diamond operator in the special case of a while() loop, there is foreach(), the m// and s/// operators, and there are subs that utilize $_ as a default parameter. But there aren't any subs I can think of that populate $_ as though it were an lvalue.

Dave

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Re^2: shift doesn't DWIM by TimToady (Parson) on Jul 12, 2005 at 16:49 UTC
Yes, and Perl 6 even the special `while` loop exception is going away. Instead you typically use topicalizers to set `$_`: `given shift { do something with $_; }` [download] or `for @ARGS { do something with $_; }` [download] And in particular, `while` on a filehandle turns into a (lazy) `for`: `for =$fh { do something with $_; }` [download] In general, the only dwimming on void context in the standard Perl 6 dialect will be deciding whether to turn an unthrown exception (aka undef) into a thrown exception because someone forgot to check the return value.	[reply] [d/l] [select]
Re^2: shift doesn't DWIM by itub (Priest) on Jul 12, 2005 at 11:26 UTC
Where would the line be drawn? Would using map in "void context" spew its return value into @_ ? `split` does exactly that, but that use is deprecated: http://perldoc.perl.org/functions/split.html . So I certainly doubt that such a feature will be added to `map`. ;-)	[reply] [d/l] [select]
Re^2: shift doesn't DWIM by tlm (Prior) on Jul 12, 2005 at 10:14 UTC
My memory may be incomplete or in need of refreshing, but I can't think of any subs that populate $_ as a default lvalue. Yes, there is the diamond operator in the special case of a while() loop, there is foreach(), the m// and s/// operators, and there are subs that utilize $_ as a default parameter. But there aren't any subs I can think of that populate $_ as though it were an lvalue. Interesting question. I'm also having a hard time thinking of such functions... `map` and `grep` assign to an implicitly localized `$_` (as does `foreach` if no loop variable is given), but not their results. The function `readline` clobbers `$_` if it is in the test clause of a `while` loop: `% date\|perl -le '$_="x";while(readline *STDIN){printf uc};print"<$_>"' TUE JUL 12 01:56:04 EDT 2005 <>` [download] It wouldn't surprise me if there are more examples, but I can't think of any ATM. the lowliest monk	[reply] [d/l]