sub by reference - assigning to an object?

ethrbunny has asked for the wisdom of the Perl Monks concerning the following question:

I have a project where a start-up script forks N sub scripts which do various pieces of work. Each of these instantiates 1-M modules depending on the type of work each has to do. I have some code for getting MySQL connections that I want to share between the various pieces. At the moment the sub is in a module along with the code for instantiating the separate modules.

I want to pass a reference to the connection sub into each module as it gets created. I can get the reference using the '\&sub' notation but I can't seem to get it made available to the new module.

########### snip
eval( require( 'Parser/' . $parser_name . '.pm'));
$self->{ 'parser' }->{ $parser_name } = $parser_name->new();

####This is the problematic line:
$self->{ 'parser' }->{ $parser_name }->getDBH = \&getDBH;
[download]

What syntax do I use for this?

PS yes - this does need to be re-engineered into a class hierarchy. That will probably occur later this year.

Comment on sub by reference - assigning to an object? Download Code

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Re: sub by reference - assigning to an object? by Fletch (Bishop) on Mar 26, 2008 at 15:51 UTC
You're trying to assign to a method, which isn't going to work without some deep magic (and even then that's probably not what you want to do). You really want the subref to either be passed as a parameter to the constructor (`$parser_name->new( getDBH => \&getDBH )`) and/or stored in an attribute (`$self->{ 'getDBH_sub' } = \&getDBH`) and then the parser instances use that to call the proper routine that way. Update: So to elaborate, basically each parser class' `getDBH` routine would look something like this: `sub getDBH { my $self = shift; my $getDBH_ref = $self->{ 'getDBH_sub' }; $getDBH_ref->( ); }` [download] The cake is a lie. The cake is a lie. The cake is a lie.	[reply] [d/l] [select]
Re^2: sub by reference - assigning to an object? by ethrbunny (Monk) on Mar 26, 2008 at 16:47 UTC
What if I want to do something like: `my $common = common_class->new(); my $parser = parser_class->new(); ### this is the ugly part $parser->{ 'getDBH' } = \&$common->getDBH;` [download] In my original code this is more like what I was attempting.	[reply] [d/l]
Re^3: sub by reference - assigning to an object? by Arunbear (Prior) on Mar 26, 2008 at 17:23 UTC
If getDBH() doesn't actually depend on $common and it's state you could do `$parser->{ 'getDBH' } = \&common_class::getDBH;` [download] otherwise you could store a wrapper to the getDBH() invocation: `$parser->{ 'getDBH' } = sub { $common->getDBH; };` [download]	[reply] [d/l] [select]
Re: sub by reference - assigning to an object? by ysth (Canon) on Mar 26, 2008 at 15:53 UTC
Without knowing what $self->{parser}{$parser_name} is, it's hard to say, but maybe `$self->{ 'parser' }->{ $parser_name }->getDBH(\&getDBH);` would work? Also, your parsers could just call the original getDBH sub fully qualified, like `$dbh = main::getDBH(...)`. -- Online Fortune Cookie Search	[reply] [d/l] [select]