URL:
<http://savannah.gnu.org/bugs/?47618>
Summary: NSPredicate: SELF implemented incorrectly
Project: GNUstep
Submitted by: thebeing
Submitted on: Mo 04 Apr 2016 14:56:49 GMT
Category: Base/Foundation
Severity: 3 - Normal
Item Group: Bug
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
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Details:
The SELF expression in NSPredicate is implemented in a way that only allows it
to be used as LHS or RHS expression in an NSComparison predicate.
In particular, the following is legal under Cocoa:
NSDictionary *a = [NSDictionary dictionaryWithObjectsAndKeys:
@"2", @"foo", nil];
NSPredicate *p = [NSPredicate predicateWithFormat: @"SELF.foo <= 2"];
[p evaluateWithObject: a];
The base implementation gives you:
Uncaught exception NSInvalidArgumentException, reason:
[GSEvaluatedObjectExpression-keyPath] should be overridden by subclass
You can even do more complicated expressions such as "bar[SELF.foo]", where
SELF is not a top-level expression in Cocoa.
The reason is that GSEvaluatedObjectExpression is created as a singleton, and
always returns itself from expressionValueWithObject:context:, and there is
some pointer equality checking in NSComparisonPredicate to make it work for
the really simple case (self == 'foo'). That totally sounds like premature
optimisation to me, btw.
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Reply to this item at:
<http://savannah.gnu.org/bugs/?47618>
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