The "code injection" was just a quick and dirty demonstration of a side-effect. Its shows that on a threaded build, the expression which defines the pattern is assembled each time, but then thrown away unused apart from the first iteration. Think for example of a tied array. The following: 
for my $i (0,1) {
    /abc$tied_array[$i]/;
}

[download]
will, on threaded builds, invoke both $tied_array->FETCH(0) and $tied_array->FETCH(1), but will discard the second value.

Dave.

In reply to Re^19: Reusing a complex regexp in multiple spots, escaping the regexp by dave_the_m
in thread Reusing a complex regexp in multiple spots, escaping the regexp by ecm

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