I'm not 100% how exactly to search to find out if someone else has posed
this question, but why does the following happen?
Given:
class Hash
def << (key, val=nil)
self.store(key, val)
end
end
h = {}
h << 'test'
h << 'test', 'bob'
Gives back:
test.rb:9: parse error, unexpected ',', expecting $
h << 'test', 'bob'
If I change the last line to:
h << ('test', 'bob')
I get back:
test.rb:9: parse error, unexpected ',', expecting ')'
h << ('test', 'bob')
···
--
Posted via http://www.ruby-forum.com/.
on occasion this space
def << (key, val=nil)
···
--
Posted via http://www.ruby-forum.com/.
The syntax rules for the << operator don't allow it to take multiple
arguments when called via infix notation:
h << arg1 # one argument only
you can call the method with multiple arguments but you've got to do it like:
h.<<(arg1, arg2) # dot-style method invocation
You can use an array to 'cheat':
h << [arg1, arg2]
But the method will only see one argument, an array, and you would have
to expect that and/or test for it in your definition for Hash#<<.
Gary Wright
···
On Feb 7, 2007, at 4:46 PM, Luke Ivers wrote:
I'm not 100% how exactly to search to find out if someone else has posed
this question, but why does the following happen?
Given:
class Hash
def << (key, val=nil)
self.store(key, val)
end
end
h = {}
h << 'test'
h << 'test', 'bob'
on occasion this space
def << (key, val=nil)
^
causes problems
···
--
Posted via http://www.ruby-forum.com/.
Robert_K1
(Robert K.)
5
Here's another variant:
class Hash
Proxy = Struct.new :parent, :key do
def <<(val)
parent[key] = val
parent
end
end
def <<(key)
Proxy.new self, key
end
end
irb(main):012:0> h ={}
=> {}
irb(main):013:0> h << "foo" << "bar" << "key" << 234
=> {"foo"=>"bar", "key"=>234}
irb(main):014:0> h << 2 << 3
=> {2=>3, "foo"=>"bar", "key"=>234}
irb(main):015:0> h
=> {2=>3, "foo"=>"bar", "key"=>234}
Not that I would recommend it...
Kind regards
robert
···
On 07.02.2007 22:58, Gary Wright wrote:
On Feb 7, 2007, at 4:46 PM, Luke Ivers wrote:
I'm not 100% how exactly to search to find out if someone else has posed
this question, but why does the following happen?
Given:
class Hash
def << (key, val=nil)
self.store(key, val)
end
end
h = {}
h << 'test'
h << 'test', 'bob'
The syntax rules for the << operator don't allow it to take multiple
arguments when called via infix notation:
h << arg1 # one argument only
you can call the method with multiple arguments but you've got to do it like:
h.<<(arg1, arg2) # dot-style method invocation
You can use an array to 'cheat':
h << [arg1, arg2]
But the method will only see one argument, an array, and you would have
to expect that and/or test for it in your definition for Hash#<<.
Robert Klemme wrote:
> [...]
irb(main):013:0> h << "foo" << "bar" << "key" << 234
[...]
Not that I would recommend it...
Yeah, i like
h <= "foo" > "bar" <= "key" > 42
unfortunately there is no => operator...
cheers
Simon