Got tired of perpetually writing if-then-else code to accumulate the
results of an iterator and return an array if no block was passed in.
(The somewhat hacked-up gensym class could probably use work - how
threadsafe is Singleton? Would using a class instance variable be
better?)
···
require ‘singleton’
class Gensym
include Singleton
def initialize
@n = 0
end
def next
@n += 1
"G#{@n}".intern
end
end
def gensym
Gensym.instance.next
end
class Module
def make_collector(*args)
args.each {|meth|
oldmeth = gensym
module_eval <<-here
alias #{oldmeth} #{meth}
def #{meth}(*args)
retval = []
#{oldmeth}(*args) {|x|
if block_given?
yield x
else
retval << x
end
}
end
here
}
end
end
class Foo
def initialize
@ary = (1…10).to_a
end
def traverse
@ary.each {|x| yield x}
end
make_collector(:traverse)
end
a = Foo.new
a.traverse {|x| p x}
p a.traverse
Got tired of perpetually writing if-then-else code to accumulate the
results of an iterator and return an array if no block was passed in.
(The somewhat hacked-up gensym class could probably use work - how
threadsafe is Singleton? Would using a class instance variable be
better?)
require ‘singleton’
class Gensym
include Singleton
def initialize
@n = 0
end
def next
@n += 1
“G#{@n}”.intern
end
end
def gensym
Gensym.instance.next
end
Why not simply use some prefix?
class Module
def make_collector(*args)
args.each {|meth|
module_eval <<-EOF
alias_method :_foo_bar_baz#{meth}, :#{meth}
def #{meth}(*args)
retval =
_foo_bar_baz#{meth}(*args) {|x|
if block_given?
yield x
else
retval << x
end
}
end
EOF
}
end
end
···
On Sat, May 17, 2003 at 02:00:35AM +0900, Martin DeMello wrote:
class Foo
def initialize
@ary = (1…10).to_a
end
def traverse
@ary.each {|x| yield x}
end
make_collector(:traverse)
end
a = Foo.new
a.traverse {|x| p x}
p a.traverse
–
_ _
__ __ | | ___ _ __ ___ __ _ _ __
'_ \ / | __/ __| '_ _ \ / ` | ’ \
) | (| | |__ \ | | | | | (| | | | |
.__/ _,|_|/| || ||_,|| |_|
Running Debian GNU/Linux Sid (unstable)
batsman dot geo at yahoo dot com
I’m an idiot… At least this [bug] took about 5 minutes to find…
Disquieting …
– Gonzalo Tornaria in response to Linus Torvalds’s
I dunno - for some reason I’m always a bit uneasy about using alias wth
an arbitrary prefix. I haven’t sat down and examined it, but it feels
fragile.
martin
···
Mauricio Fern?ndez batsman.geo@yahoo.com wrote:
Why not simply use some prefix?
class Module
def make_collector(*args)
args.each {|meth|
module_eval <<-EOF
alias_method :_foo_bar_baz#{meth}, :#{meth}