@Monk:Thomas asked: Is this correct?
Um, I think you forgot the part where the parameters are passed in the use statement, so their values are available in the 2nd pass.
This is about the smallest snip I could create. It's a totally *concocted* case but one that does illustrate some of the things I was talking about.
I think I've gotten the answer to my question -- since no one jumped up and said "oh yeah, use the XXYZ module" or "why don't you just use the "%+" operator that is made for things like this...(i.e. I was thinking this was hard, and wanted to make sure I wasn't missing something). But in the following example,
main "is a" Data::Vars and is a 'Derived'.
Derived "is a" Data::Vars and is a Basic.
Basic "is a" Data::Vars.
All are assigning their values to members of the 'struct' that has member's labeled 'one', 'two', 'three'...eight.
'Derived' tries to assign something to 'eight' at definition time, and 'nine' at execution time. The attempt to assign a value to eight creates no error or warning by default with the idea that it might be legal in a more 'base' class (though was thinking of having a need for a flag (!!!) that might tell it to give an error anyway). I.e. the module might change it's configured behavior based on parameters.
As a whole, in this while 'main', Derived, and Basic try to assign to the 'blessed HASH' $p:
#!/usr/bin/env perl use warnings; use strict; { package Basic; use warnings; use strict; use mem; use P; our @flags; use mem (@flags = qw(one two three four five) ); use Data::Vars \@flags, {one=>1, two=>2, three=>3, four=>4, five=>5} +; sub Decimal() { my $p=shift; P "\nDecimal:p=%s", $p; my $q=__PACKAGE__->new(); $q->three="change 3 to 33/11"; P "Decimal: (one, two, three)=(%s, %s, %s)", $q->one, $q->two, $q- +>three; } } { package Derived; use warnings; use strict; use mem; use P; our @ISA; use mem (&{sub() {push @ISA, q(Basic)}}); use Data::Vars [qw(one two seven)], {one=>1.2, two=>2.2, seven=>7.2, eight=>8.2}; sub new ($) { my $p = shift; my $c=$p||ref $p; bless $p = Basic->new(@_), $c unless ref $p; $p = $p->Data::Vars::new($p); } sub Float() { my $p=shift; P "\nFloat:p=%s", $p; my $q=__PACKAGE__->new(); $q->three="Float: 3.3"; $q->four="Float: Derived 4.4"; my $val = eval { $q->nine="Float: 9.9"; }; if ($@) { P "\nassign to nine got:\n%s\n", $@; } P "Float:q=%s", $q; } 1} package main; use warnings; use strict; use P; use Data::Vars [ qw(one three four) ]; bless my $p = __PACKAGE__->new({one=>'I', three=>'III', four=>'IV'}); P "main:1: p=%s", $p; $p = Derived->new($p); P "main:2: %s", $p; $p->Decimal; $p->Float;
And it's output:
> perl multiuse.pl main:1: p=main{four=>"IV", one=>'I', three=>"III"} main:2: Derived{five=>5, four=>"IV", one=>1.20, seven=>7.20, three=>"I +II", two=>2.20} Decimal:p=Derived{five=>5, four=>"IV", one=>1.20, seven=>7.20, three=> +"III", two=>2.20} Decimal: (one, two, three)=(1, 2, change 3 to this txt) Float:p=Derived{five=>5, four=>"IV", one=>1.20, seven=>7.20, three=>"I +II", two=>2.20} assign to nine got: Can't locate object method "nine" via package "Derived" at multiuse.pl + line 37. eval {...} called at multiuse.pl line 37 Derived::Float(Derived=HASH(0x8e5648)) called at multiuse.pl line 56 Float:q=Derived{five=>5, four=>"Float: Derived 4.4", one=>1.20, seven= +>7.20, three=>"Float: 3.3", two=>2.20}
Comments: ...
Sorry... ran out of hit points again. Some of the comments and my rational should be more clear now (crossing fingers).... I do understand that this could be a bigger pain that I might want, BUT, I really wanted the 'flags' to mostly pass true/false values (debug, 'useperlonly'...etc).. but then I got to thinking why I shouldn't support other values... and if I didn't, how much might I flagellate myself for laziness. ;-/
Hope the above isn't too bad to look at... I just realized, that it won't run because Data::Vars isn't in CPAN. It's not that it is buggy, in fact it is fairly mature, but I don't consider it ready until I'm sure I've solved issues *exactly* like this -- the need to pass different flags for different behaviors at runtime.
If enough people want to try it, I think I can not have it index by CPAN if I put a letter in the VERSION? But I didn't want you to be in the dark about what I was trying to do and why, so forced myself to at least type up this much and create a simple demo case.
-l
In reply to Re^2: Design question: storing package 'flags'.
by perl-diddler
in thread Design question: storing package 'flags'.
by perl-diddler
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