Re^2: Method parameters validation and inheritance

This must that "pirate software" I keep hearing about!

Really, there's no reason to stop there!

use Acme::Lingua::Pirate::Perl;

...

my $context_derived = $file_derived->open_for_reading( { 
    'path' => $file, 
    'join_longcalls' => 1 
} );

scuttle her matey "Avast! Context error - " $file_derived->error
    if $context_derived be '' curse ye deadlights;
[download]

Of course, roman may prefer other dialects.

Time for a brief lapse into serious commentary, and nitpicking. The problem I see with "join_longcalls" is that isn't "join_long_calls". Consistent formatting of parameter names, variables and function/method names is important. Otherwise you wind up with PHP.

TGI says moo

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Re^3: Method parameters validation and inheritance by roman (Monk) on Sep 21, 2008 at 18:41 UTC
Thanks for your comments. I should probably give some longcalls explanation. Code sample given is a simplified but real world example: `$file` encapsulates a binary file (log) produced by a phone switch. It contains cdrs (Call Data Records) describing voice calls carried out. The file is used as a source for several target applications (billing, dwh). If a call continues longer than say half an hour it is logged by parts. If `join_longcalls` is set for `open_for_reading` only complete calls are produced by `read_cdr` and the total duration of the call is summed up. So the `join_longcalls` flag really causes the long calls to be joined. In such case I am not sure whether to use `join_long_calls` or `joins_long_calls`? I think `open_for_reading` is clearer than plain `reading` since I try to use imperative for my subs. As kyle suggested, I could avoid some of the "SUPERs" and turns the code into: `my $context = $file->open_for_reading({'path' => $path}); $context->joins_long_calls(1); # or better like this, # because there is no property join_long_calls $context->join_long_calls;` [download] The `open_for_reading`, actually returns Class::Prototyped based object, so `join_longcalls` - whatever its implementation is - actually wraps `read_cdr` method. This approach has some advantages: The interface of open_for_reading remains same across classes. It is more self checking - since the parameters were turned into method calls, which fail when called but not defined. This approach has also some disadvatages: Although `$lc->join_long_calls` can be called anytime, it make sense only immediately after open. When I have target file (representation of the billing, dwh file) I could have previously used a declaratory `source_params` method containing the parameters to be passed to `open_for_reading`, now I had to redefine some `open_source` method.	[reply] [d/l]

Replies are listed 'Best First'.

Re^3: Method parameters validation and inheritance
by roman (Monk) on Sep 21, 2008 at 18:41 UTC

Thanks for your comments. I should probably give some longcalls explanation.

Code sample given is a simplified but real world example: $file encapsulates a binary file (log) produced by a phone switch. It contains cdrs (Call Data Records) describing voice calls carried out. The file is used as a source for several target applications (billing, dwh).

If a call continues longer than say half an hour it is logged by parts. If join_longcalls is set for open_for_reading only complete calls are produced by read_cdr and the total duration of the call is summed up.

So the join_longcalls flag really causes the long calls to be joined. In such case I am not sure whether to use join_long_calls or joins_long_calls?

I think open_for_reading is clearer than plain reading since I try to use imperative for my subs.

As kyle suggested, I could avoid some of the "SUPERs" and turns the code into:

my $context = $file->open_for_reading({'path' => $path});
$context->joins_long_calls(1); 
# or better like this, 
# because there is no property join_long_calls
$context->join_long_calls;
[download]

The open_for_reading, actually returns Class::Prototyped based object, so join_longcalls - whatever its implementation is - actually wraps read_cdr method.

This approach has some advantages:

The interface of open_for_reading remains same across classes.
It is more self checking - since the parameters were turned into method calls, which fail when called but not defined.

This approach has also some disadvatages:

Although $lc->join_long_calls can be called anytime, it make sense only immediately after open.
When I have target file (representation of the billing, dwh file) I could have previously used a declaratory source_params method containing the parameters to be passed to open_for_reading, now I had to redefine some open_source method.

[reply]
[d/l]