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Re: Parser/Backend API proposals

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John Peacock
January 17, 2003 19:10
Re: Parser/Backend API proposals
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Dave Rolsky wrote:
>>	my $dt = DateTime->new($datestring);
> The default constructor is going take components (year, month, day ...),
> not a parseable string.

That's where we part ways, then.  I would rather see the contructor DWIM if 
handed a string.  I suppose I can write a class which does, in fact, wrap the 
parsing and object creation into a single call, say DateTime::Parse.

Have you decided to require all components to be defined in order to be 
well-formed?  In other words, if I only care about dates, can I undef all of the 
time related components and have the right thing happen?  At this point, I am 
not arguing one way or another; I can see both being useful.  Obviously, if I 
request an output that contains time fields, the undef would need to be rendered 
as 0's, but the information that certain fields were not specifically 
initialized can be useful.

>>No question.  Any implemention class will inherit all of the derivable methods
>>and only implement/override the minority of primitive methods (like $obj->year
>>for example).
> Can you explain what the class hierarchy for objects would
> be?
> Right now I'm thinking:
> - implements reference API, with completely functional
> internals
>   DateTime::Implementation::TAI64 - implements same API.  Inherits from
> and overrides some methods.
> Clearly you're thinking of something else but I don't understand what.

That *is* what I am thinking as well.  I'm not arguing _that_ point, just 
whether the parsing also needs to be an object.  I view the parsing more as a 
filter than anything else; get the messy realworld data into a standard form so 
I can do something useful with it.


John Peacock
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Rowman & Littlefield Publishing Group
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