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Re: <<= and << [message #12958 is a reply to message #12957]

Fri, 30 November 2007 13:52

mirek
Messages: 14255
Registered: November 2005

Ultimate Member

waxblood wrote on Fri, 30 November 2007 07:13

Quote:

<<= sets the WhenAction callback

<< adds a new callback to existing one; if there were any callbacks before assigned, they will be called as well.

In fact, "<<" is sort of experiment and is very rarely used

Reading code snippets in documentation '<<=' is always used instead of <<, but isn't the '<<' behaviour much more natural than the first one? Writing code with '<<' allows the programmer to modify callbacks stack of ancestor classes freely being at least a little more confident that those callbacks will always be executed before any one other callbacks in derived classes.
Using always '<<=' precludes this possibility.

I think it would be useful to develop plugin-oriented programs, too.

Interesting thoughts, yes, something like this is definitely possible path.

I guess using "<<=" is a result of two issues:

1. "<<=" existed long before "<<"
2. In real world applications, single action per callback is simply 99% of cases.

Quote:

I'm wondering, given the fact quite nobody uses the '<<' form, would it be possible to convert the '<<=' behaviour to '<<'?

Well, once again interesting idea... But here I am a bit afraid about changed semantics.

Mirek

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