WOW

I understand that Perl's breakpoint mechanism works only on a line bases at the level of support from the runtime.

Nope. From perldebug 


b           Sets breakpoint on current line

b [line] [condition]
            Set a breakpoint before the given line. If a condition is
            specified, it's evaluated each time the statement is
            reached: a breakpoint is taken only if the condition is
            true. Breakpoints may only be set on lines that begin an
            executable statement. Conditions don't use "if":

                b 237 $x > 30
                b 237 ++$count237 < 11
                b 33 /pattern/i

b subname [condition]
            Set a breakpoint before the first line of the named
            subroutine. *subname* may be a variable containing a code
            reference (in this case *condition* is not supported).

b postpone subname [condition]
            Set a breakpoint at first line of subroutine after it is
            compiled.

b load filename
            Set a breakpoint before the first executed line of the
            *filename*, which should be a full pathname found amongst
            the %INC values.

b compile subname
            Sets a breakpoint before the first statement executed afte
+r
            the specified subroutine is compiled.

[download]
Subname can be Some::Package::Name::subname

In reply to Re: Identifying a location with finer granularity than a line number by Anonymous Monk
in thread Identifying a location with finer granularity than a line number by rockyb

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