Re^7: Aspect-Oriented Programming: Couple of Short Examples

I would look at AOP slightly differently, at least from a Perl point of view. It allows you to inject a bunch of arbitrary opcodes at any defined point in the optree.

This is all "how" not "why". This isn't describing AOP - it's describing a way AOP can be implemented. You could equally be talking about a method for implementing pre-conditions, post-conditions and class invariance in a design by contract system ;-)

Right now, we would do this using source filters, similar to what adrianh has done.

I haven't done anything with source filters - I mostly think they're evil ;-)

Comment on Re^7: Aspect-Oriented Programming: Couple of Short Examples

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Re8: Aspect-Oriented Programming: Couple of Short Examples by dragonchild (Archbishop) on Aug 06, 2003 at 13:30 UTC
What's the difference? As far as I'm concerned, AOP allows me to create pre- and post-conditions, as does design-by-contract. At some point, the rubber's got to hit the road and, if the 'how' is the same, who cares? ------ We are the carpenters and bricklayers of the Information Age. The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6 Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.	[reply]
Re^9: Aspect-Oriented Programming: Couple of Short Examples by adrianh (Chancellor) on Aug 06, 2003 at 14:37 UTC
It matters because the "how" and the "why" are different. AOP is not the ability "inject a bunch of arbitrary opcodes at any defined point in the optree". Neither is it just the ability to add pre- and post-conditions to a subroutine. You can have AOP without opcode insertion (e.g. via wrapping subroutines in Perl's Aspect or AspectR in Ruby. You can have opcode insertion without something being AOP - many macro systems for example. You can have pre- and post- conditions without something being AOP (e.g. Class::Contract does not allow you to do AOP). AOP is about creating "aspects" that describe functionality that cross-cuts a traditional OO class hierarchy. If you're interested you might find some of the early Parc papers useful (Aspect-Oriented Programming and RG: A Case-Study For Aspect-Oriented Programming).	[reply]