From: Nic Daniau <Nic.Daniau@...>
Date: 2007-05-01T19:14:43+09:00
Subject: Ruby syntax question: instance.method(args) { more_stuff }

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Hi, I'm having difficulty working out the following construct:
img.write("myimage.jpg") { self.quality =3D 50 }
In this example (source
http://www.simplesystems.org/RMagick/doc/comtasks.html), img is a
RMagick::Image.
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The API says "You may also specify optional arguments by setting
Image::Info <http://www.simplesystems.org/RMagick/doc/info.html>
attributes in an associated block." Is this a standard syntax in Ruby or
is it specific to this write method? And how does it work, how can I
make my own method accept blocks too? any advantage over passing a array
of arguments?
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Also, I'm trying to pass my own instance variable in order to replace
the sample value of 50. So I've tried:
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img.write("myimage.jpg") { self.quality =3D @my_object_quality }
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Where @my_object_quality is defined as an instance variable on my class
def. But the interpreters seams to look for a @my_object_quality
instance variable *within* the RMagick class, which vaguely kind of make
sense. So how can I pass this instance variable into this method? and
why does it say "self.quality =3D 50" in the example and not "@quality =
=3D
50"?
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Thanks in adance for your help. I'm looking for a genuine explanation of
what's happening at a Ruby syntax level, not just a code sample that
would work with this RMagick example.
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Nic
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