The canonical form of a subroutine invocation is: 
$result = &  { something_that_returns_coderef } ( @args );

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The braces around the coderef expression can be dropped only when the coderef is in a simple scalar variable. Yours was not. So you'd have to use: 
& { $functions{$func} }();

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However, as of fairly recent Perls, you can also use an arrow form: 
$functions{$func}->();

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This was added by Chip in 5.4 under some urging by me based on a bet I made that I couldn't get a new feature into 5.4 during the gamma golden release phase. I won. {grin}

-- Randal L. Schwartz, Perl hacker

update: for more details, check out my Linux magazine column on subroutine references, and an older column from UnixReview.

In reply to Re: using a hash of functions by merlyn
in thread using a hash of functions by Anonymous Monk

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