Re: Proper place for functions in KVC paths?
Re: Proper place for functions in KVC paths?
- Subject: Re: Proper place for functions in KVC paths?
- From: Lachlan Deck <email@hidden>
- Date: Fri, 25 Aug 2006 10:57:53 +1000
Hi there,
On 22/08/2006, at 2:53 AM, Chuck Hill wrote:
On Aug 21, 2006, at 7:59 AM, John Huss wrote:
It seems that key-value coding allows serveral different ways of
using
functions (like @sum, @avg, etc) in key paths that all seem to work.
Like,
@sum.array.key.path
email@hidden
array.key.path.@sum
Is there a proper way to write these?
I am surprised that these all work. The NSArray documentation
implies :-) the that intended use is
<keyPath to array>@<operator>.<keyPath to value>
I think the api implies they all work and will have differing
outcomes depending on what you would like to 'sum' or 'count' etc.
e.g., Consider the keypath: 'company.people.accounts.totalLiability'.
If I want to know how much is owed in total:
Number total = ( Number )company.valueForKeyPath
( "@sum.people.accounts.totalLiability" );
If I would like to know how much each person owes:
NSArray totals = ( NSArray )group.valueForKeyPath
( "email@hiddenLiability" );
It's *very* expressive and useful...
with regards,
--
Lachlan Deck
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