Hello,
I have the following:
class DSL
def DSL.load filename
dsl = new
dsl.instance_eval(File.read(filename))
dsl
end
def to sym,*args,&block
if block_given?
b=class << self;self;end
b.instance_eval {
define_method(sym,*args,&block)
}
end
end
def method_missing sym,*args
“#{sym}”
end
alias :say puts
end
foo=DSL.load(“sample.dsl”)
sample.dsl:
to smile do
say “:)”
end
to be_polite {
say “thank you”
}
smile
be_polite
The resulting output is:
moonwolf@trantor:~/ruby/dsl/todo$ ./dsl.rb
moonwolf@trantor:~/ruby/dsl/todo$
be_polite and indeed, anything enclosded in {} doesn’t seem to be
eval-ed as
blocks. Why is this?
Jayanth
This is definitely not a block_given thing.
block is coming through as a NilClass it seems.
puts block.class yields NilClass. The strange bit is that when I do it
outside of instance_eval with just a define_method under irb, it works
as
expected. I am lost.
Anyone?
Jayanth
Le 08 mai à 11:42, Srijayanth S. a écrit :
[Note: parts of this message were removed to make it a legal post.]
This is definitely not a block_given thing.
It’s an operator precedence thing. {} binds at a higher precedence than
do/end, meaning that, in the absence of parentheses, in one case, it’s
the first function that takes the block and in the other, it’s the
second one.
For instance :
def test ; (block_given? ? ‘block’ : ‘no block’) ; end
=> nil
puts test do end
no block
=> nil
puts test { }
block
In the first case, it’s puts who gets the block (and discards it). In
the second case, it’s my function. Compare to :
puts(test) do end
no block
=> nil
puts(test) {}
no block
=> nil
puts(test do end)
block
=> nil
puts(test {})
block
Fred
