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Re: ForkBlock

by belg4mit (Prior)
on Dec 25, 2008 at 02:04 UTC ( #732530=note: print w/replies, xml ) Need Help??

in reply to ForkBlock

Currently the only problem I have with it is that it doesn't croak if you forget the Parent or Child blocks, but I think that's pretty minor.
Easy enough:
--- Wed Dec 24 20:18:01 2008 +++ Wed Dec 24 21:02:50 2008 @@ -31,6 +31,9 @@ my $parent=$params{"parent"}; my $child =$params{"child"} ; my $error =$params{"error"} ; + + croak "No Child defined" unless $child; + croak "No Parent defined" unless $parent; local $!;
Although one could make the case that it ought to fall-through without a Parent. You can achieve that with DumbFork { Parent {return} ...}

This patch exposes the child PID in a non-collisiony way, as a parameter to the parent; you could also copy $ForkBlock::CHILD_PID immediately after fork.

--- Wed Dec 24 21:02:50 2008 +++ Wed Dec 24 21:14:35 2008 @@ -40,7 +40,7 @@ FORK_IT: { if($CHILD_PID=fork()) { #i'm the parent - &$parent; + &$parent($CHILD_PID); } elsif(defined($CHILD_PID)) { #i'm the child
Also note that the prototype permits this alternate invocation:
Fork { Parent \&manager, Child \&worker };
And with this patch:
--- Wed Dec 24 21:14:35 2008 +++ Thu Dec 25 02:08:18 2008 @@ -27,10 +27,10 @@ #private--implements the actual forking sub phork { my %params=%{shift()}; - - my $parent=$params{"parent"}; - my $child =$params{"child"} ; - my $error =$params{"error"} ; + + my $parent=$params{parent}|| $params{Parent}; + my $child =$params{child} || $params{Child}; + my $error =$params{error} || $params{Error}; croak "No Child defined" unless $child; croak "No Parent defined" unless $parent;
You can also do:
Fork { Parent=>sub{ ... }, #The comma's important here. Child =>sub{ ... } };
The distinction between DumbFork and Fork seems backwards/unnecessary. What if the exit has a condition of if $CHILD_PID == 0 added? Another interesting change might be an optional/default Reaper that's invoked before the phork...

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[Corion]: choroba: Ooooh - I didn't think of that! I write my presentations as POD and if it "roughly" looks like Perl code, I should also syntax-check that...
[haukex]: Yes sorry I don't run them all the time, my POD tests are only run as author tests (and are excluded when I'm using Devel::Cover)
[Corion]: choroba: Hmm - no, I keep the snippets inline, but as my framework also has support for capturing output etc., maybe I should do the same...
[Corion]: haukex: Yes, that approach is sane, and it heals the fragility of Pod parsers in a nice way while still syntax-checking stuff
[choroba]: Unfortunately, none of it is online
[haukex]: I figured that POD tests make sense, but only as author tests
[choroba]: I mean, the slides are, but not the makefile with scripts to create them
[Corion]: haukex: I've only now arrived at that revelation ;)
[Corion]: choroba: I use spod5, which also has that support, and also implements its own kinda-make stuff
[haukex]: But that module I just linked to assumes that most verbatim blocks are runnable code, I have other modules where that's not the case, so there I just copy-and-paste the synopsis into the author tests...

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