print has a quite complex signature. It must distinguish between print $this; and print TO_THIS;, for example. So it also can tell between print @empty; and print;.

push is quite simple. You can write your own sub that offers the exact same interface: 

sub Push(\@@);

[download]

So what to push onto the array is simply a (flattened) list (of scalar values). So push can't tell the difference between push @a; and push @a, @empty;... unless its simple interface gets special-cased for this. I'm not surprised that such special-casing was not deemed worth allowing the questionable usage of an implied $_.

At some point, somebody did some extra work to add the warning you get. The code you want would be added at the same point, but it would have to synthesize code to push the current value of $_ onto the stack before the push opnode (or thereabouts). That is certainly more work than just emitting a warning.

But then you'd have to fight the backward-compatibility battle -- which, frankly, I would consider a rather silly battle since transforming something that is useless and emits a warning into something useful (but perhaps of dubious wisdom) seems quite reasonable regarding backward compat.

- tye        

In reply to Re: why does push not default to $_? (simple) by tye
in thread why does push not default to $_? by LanX

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