Re^2: Why doesn't this die with "Can't use an undefined value as an ARRAY reference"?"

One more thing I've just noticed:

The perldelta fragment mentions for(scalar($#foo)) { ... }. But what does this even mean? Why would anybody do this? $#foo is already a scalar (the index of the last element of @foo), why would anybody call scalar on it, and why would anybody use it in a foreach?

If you want to enlarge or shrink the array via $#foo, you can do it simply by $#foo = 43;. This foreach nonsense is just obfuscation and I don't see why was it "corrected".

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Re^3: Why doesn't this die with "Can't use an undefined value as an ARRAY reference"?" by haukex (Archbishop) on Oct 19, 2017 at 16:01 UTC
But what does this even mean? Why would anybody do this? I would guess that it is maybe just a simplification of a different case; using `for` as a topicalizer can be pretty useful. Clicking through the commits seems to show that the change to scalar was a bugfix resulting from the discussion in #24346. I found that an enlightening point was: "Since scalar is just a directive to change context, I don't see why it should change anything else." In general, I think what this boils down to is a problem caused by autovivification, which, while of course powerful and nice, is also sometimes the source for such confusion. There is of course `no autovivification;` from CPAN, but personally I like to just be explicit and use exists and friends to avoid things vivifying when I don't want them to.	[reply] [d/l] [select]

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Re^3: Why doesn't this die with "Can't use an undefined value as an ARRAY reference"?"
by haukex (Archbishop) on Oct 19, 2017 at 16:01 UTC

But what does this even mean? Why would anybody do this?

I would guess that it is maybe just a simplification of a different case; using for as a topicalizer can be pretty useful. Clicking through the commits seems to show that the change to scalar was a bugfix resulting from the discussion in #24346. I found that an enlightening point was: "Since scalar is just a directive to change context, I don't see why it should change *anything* else."

In general, I think what this boils down to is a problem caused by autovivification, which, while of course powerful and nice, is also sometimes the source for such confusion. There is of course no autovivification; from CPAN, but personally I like to just be explicit and use exists and friends to avoid things vivifying when I don't want them to.

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