"It ought to be easy to recognize an unquoted $1 as a function argument and issue a warning"

The problem occurs in:

return $1 + sub_that_does_regex_capturing(...);

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$1 is not a function argument in that. $1 hasn't been a function argument in any of the examples in this thread.

The problem is writing an expression where one of the operands has a side-effect that can alter the value of another operand. This is very hard to detect through static analysis of source code; it's probably not especially easy to detect at run-time either. Heuristics may be able to catch some common cases.

perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'

In reply to Re^4: $1 not "freezing" in an addition by tobyink
in thread $1 not "freezing" in an addition by grondilu

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