Re^2: Copy a builtin sub to a different name and then override

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Re^3: Copy a builtin sub to a different name and then override (robust) by LanX (Saint) on Jun 02, 2018 at 18:34 UTC
> still the same problem with this: > ... > `my $actual_sleep = \&CORE::GLOBAL::sleep;` This should solve it in a robust manner: `my $actual_sleep = exists &CORE::GLOBAL::sleep # already overridden + ? ? \&CORE::GLOBAL::sleep : \&CORE::sleep` [download] Point is you are changing sleep globally, but some other modules might be trying to do the same thing already. (well ...) If you install your override later, you'll be playing safe. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery} update even more robust with `defined` instead of `exists` , see Haarg's comment in this thread for details.	[reply] [d/l] [select]
Re^3: Copy a builtin sub to a different name and then override by LanX (Saint) on Jun 01, 2018 at 23:30 UTC
> still the same problem with this: Really? You still have `Deep recursion on anonymous subroutine` ? As I said that's the normal way to install a wrapper, but in the case of builtins it seems risky. calling CORE::sleep() should be the recommended way. ... but I seem to remember reading that overriding sleep used to be problematic.(?) I'll look tomorrow into it. Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l]
Re^4: Copy a builtin sub to a different name and then override by bliako (Abbot) on Jun 01, 2018 at 23:36 UTC
No that's fine, your later suggestion `CORE::sleep()` worked great! thanks	[reply] [d/l]
Re^5: Copy a builtin sub to a different name and then override by LanX (Saint) on Jun 02, 2018 at 00:19 UTC
and here is the reason why, at least with 5.16 `warn $]; warn \&CORE::GLOBAL::sleep; warn \&CORE::sleep; &CORE::GLOBAL::sleep(3);` [download] `5.016003 at d:/Users/lanx/pm/core_sleep.pl line 1. CODE(0x328420) at d:/Users/lanx/pm/core_sleep.pl line 4. CODE(0x349718) at d:/Users/lanx/pm/core_sleep.pl line 5. <-- differen +t! Undefined subroutine &CORE::GLOBAL::sleep called at d:/Users/lanx/pm/c +ore_sleep.pl line 7.` [download] You are trying to build a wrapper around an non-existent function. You haven't told us which version you use, but I doubt that `CORE::GLOBAL::` is populated by default. What you originally tried, something like: `old = CORE::GLOBAL::sleep` is aliasing the two symbols (two symbols pointing to the same typeglob) But after populating the code slot with `CORE::GLOBAL::sleep = sub{}` both will point to the same sub. `old = CORE::GLOBAL::sleep; CORE::GLOBAL::sleep = sub { warn " ** beware of morons "}; &old(); # oops warn \&CORE::GLOBAL::sleep; warn \&old;` [download] ` beware of morons at d:/Users/lanx/pm/core_sleep.pl line 2. CODE(0x4c9478) at d:/Users/lanx/pm/core_sleep.pl line 7. CODE(0x4c9478) at d:/Users/lanx/pm/core_sleep.pl line 8. <-- identical +!` [download] That's why you get a circular call! Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery} update same with 5.18 on linux** `lanx@ubuntu14-large:~$ perl warn $]; warn \&CORE::GLOBAL::sleep; warn \&CORE::sleep; &CORE::GLOBAL::sleep(3); __END__ 5.018002 at - line 1. CODE(0x1804cb8) at - line 2. CODE(0x1830398) at - line 3. Undefined subroutine &CORE::GLOBAL::sleep called at - line 4.` [download] `lanx@ubuntu14-large:~$ perl old = CORE::GLOBAL::sleep; CORE::GLOBAL::sleep = sub { warn " * beware of morons "}; &old(); # oops warn \&CORE::GLOBAL::sleep; warn \&old; __END__ beware of morons ** at - line 2. CODE(0x2089448) at - line 5. CODE(0x2089448) at - line 6.` [download]	[reply] [d/l] [select]
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