in reply to how organize code in callback mode

xiaoyafeng:

I like the version that Khen1950x, but as you suggest in your last question, I'd also pass $hl to the callback function so you don't have to rely on the global. Here's his version with the (untested) change:

#!/usr/bin/perl

use strict;
use warnings;

sub cell_walk {
    my $self = shift @_;
    my ( $sheet_name, $x, $y, $callback, $callback_data ) = @_;
    my $Sheet = $$self{'book_handle'}->Worksheets($sheet_name);
    foreach $row( $row = $$x[0] ; $row <= $$y[0] ; ++$row ) {
        for ( my $col = $$x[1] ; $col <= $$y[1] ; ++$col ) {
            &$callback( $Sheet->Cells( $row, $col ), $callback_data );
        }
    }
}

sub callback {
    # $_[0] = excel cell reference, $_[1] = XYZ object reference
    return if not defined $_[0]{'Value'};
    if ( $_[0]{'Value'} =~ /^~~~/ ) {
        my (@a) = split( /__/, substr( $_[0]{'Value'}, 3 ), 0 );
        if ( scalar @a == 3 ) {
            $_[0]{'Value'} = $_[1]->get_single_LP( 'ADAS_VAL_RAW', @a 
+);
        }
        if ( scalar @a == 4 ) {
            $_[0]{'Value'} = $_[1]->accu_LP( 'ADAS_VAL_NORM', @a );
        }
    }
}

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...roboticus

When your only tool is a hammer, all problems look like your thumb.

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Re^2: how organize code in callback mode
by xiaoyafeng (Deacon) on Nov 29, 2011 at 12:38 UTC

    Thanks for your reply. this version of code looks better, but now, I suspect i am on the right way. In order to avoid exposing variables in global, I have to pass 5 paras to cell_work function. and as a module, $callback_data does confuse end user.

    to my primitive intention, I just want to separate code into subs and modules for managing. But it now seems to raise complexity of code. do I have to come back to below tedious code? 

    
# main, use below to substitute cell_walk and callback routine

for ( my $row = 1 ; $row <= $LastRow ; $row++ ) {
    for ( my $col = 1 ; $col <= $LastCol ; $col++ ) {
        next if !defined $Sheet->Cells( $row, $col )->{Value};
        if ( $Sheet->Cells( $row, $col )->{Value} =~ /^~~~/ ) {
            my @a =
              split( /__/, substr( $Sheet->Cells( $row, $col )->{Value
+}, 3 ) );  #grab useful string
              if( scalar @a == 3){
            $Sheet->Cells( $row, $col )->{Value} =
              $hl->get_single_LP( 'ADAS_VAL_RAW', @a );
              }
              if( scalar @a == 4){
            $Sheet->Cells( $row, $col )->{Value} =
              $hl->accu_LP( 'ADAS_VAL_NORM', @a );
              }
        }
    }
}

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    I am trying to improve my English skills, if you see a mistake please feel free to reply or /msg me a correction

[reply]
[d/l]
      I would say yes. You can break the loop whenever you want, and you have access to all the lexicals, and therefore can jump cells if 1 cell relies on data on column to left or right of it or on another sheet . If its code that only you will ever use (or your successor) will use, it doesn't matter since you can add new parameters to your callback or get rid of the callback whenever you want and you understand how it works, but if this is an API that is to be used without having to look at its source code, don't use callbacks. There is nothing wrong with the large loop that doesn't use callbacks. Put a comment on the block ending curly bracket line if your editor doesn't show the whole thing at once or your confused by long conditional trees. If you want code organization, your callback becomes a good old plain sub/function when you don't pass sub reference to the caller looping sub and hard code the cell processing sub in. This is assuming your writing a perl app/script and not writing a reusable API.
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