Simply stated, its because the diamond operator does dual service as both readline and glob. If the value or variable inside looks like a file handle at compile time, then it is interpreted and compiled as readline, if it doesn't, then it is interpreted and compiled as glob. At compile time a hash element is deemed more likely to contain a glob pattern than a filehandle.

As for why, you'd have to ask the author(s), but it is probably a throwback to when perl didn't have lexical filehandles; and it's never been seen as high enough priority to attempt a fix.

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority". The enemy of (IT) success is complexity.
In the absence of evidence, opinion is indistinguishable from prejudice.

In reply to Re^3: Using an IO::File object stored in a Hash. by BrowserUk
in thread Using an IO::File object stored in a Hash. by jjs04

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