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Re^2: multiple method calls against the same object, revisited

by Aristotle (Chancellor)
on Dec 28, 2004 at 22:30 UTC ( #417860=note: print w/replies, xml ) Need Help??

in reply to Re: multiple method calls against the same object, revisited
in thread multiple method calls against the same object, revisited

Except that style is awful.

There is temptation to mix calls to setters in front of method calls with useful return values, which results in pretty confusing to read code:

my $label = $button->border( 20 )->label;

It gets really bad when some of the object's methods return aggregated objects. Suddenly there are multiple different kinds of call chains, and the reader has to juggle far too much knowledge to keep affairs straight.

In the worst case you get code like this:

my $label_formatting = $window->title( 'foo' ) ->child->border( 20 ) ->child->font_style;

If that's not ugly as all sin, you tell me what is. Transgressions like those shown above are rare, to be sure (and thankful).

But $self-returning mutators blur the lines between different types of methods. If you don't think it's an issue in practice, just look at the encouraged OO syntax in the Data::Dumper POD. That API actually encourages mixing mutators and with non-mutator calls. That Tk in particular does things this way does everything but speak for it; the Tk API is a mess few others get even close to.

And methods should not return different things depending on the number of their arguments anyway.

Makeshifts last the longest.

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[marto]: ah, so this is payback :P
[LanX]: problem with booking venues is that you only know the number of participants a week in advance. ..
[marto]: I guess most cities have areas similar to this, I tend not to mind personally, but would not go out of my way to head down that way
[marto]: it'll probably be fine.
[marto]: LanX: I appreciate that, it's honestly a difficult thing, a fine balance
[marto]: I'm sure it'll be fun :)
[marto]: of course I can take you to some of the best/worst bars in Glasgow ;)
[LanX]: is Glasgow that city where catholics and protestants fight in bars? ; )
[marto]: not really, but pick your side, we'll visit some real dumps

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