I want a Structlike class that takes a hash constructor, so I can say
class A < MyStruct.new(*keys); end
a = A.new(:key1 => val1, :key2 => val2)
Is there any way to base this off Struct?
martin
Martin DeMello wrote:
I want a Structlike class that takes a hash constructor, so I can say
class A < MyStruct.new(*keys); end
a = A.new(:key1 => val1, :key2 => val2)
Is there any way to base this off Struct?
martin
It'standard:
require 'ostruct'
(...)
hash = { "country" => "Australia", :population => 20_000_000 }
data = OpenStruct.new(hash)
p data # -> <OpenStruct country="Australia"
population=20000000>
(code from documentation)
hth,
Siep
···
--
Posted via http://www.ruby-forum.com/\.
Martin DeMello wrote:
I want a Structlike class that takes a hash constructor, so I can say
class A < MyStruct.new(*keys); end
a = A.new(:key1 => val1, :key2 => val2)
Is there any way to base this off Struct?
martin
Something based on this, maybe? I hope Struct#members preserves order...
class A < Struct.new(:a, :b)
def initialize(h)
super *h.values_at(*self.class.members.map {|s| s.intern})
end
end
a = A.new(:a => 1, :b => 2)
p a # ==> #<struct A a=1, b=2>
···
--
vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407
Hi --
I want a Structlike class that takes a hash constructor, so I can say
class A < MyStruct.new(*keys); end
a = A.new(:key1 => val1, :key2 => val2)
Is there any way to base this off Struct?
Do you need to use inheritance, as opposed to just instantiating
MyStruct directly? I'm thinking of, for example:
class MyStruct < Struct
def self.new(*keys)
s = super
s.class_eval do
define_method(:initialize) do |hash|
hash.each {|k,v| send("#{k}=",v) }
end
end
s
end
end
A = MyStruct.new(:a,:b)
a = A.new(:a => 1, :b => 2)
p a.b # 2
David
···
On Thu, 23 Oct 2008, Martin DeMello wrote:
--
Rails training from David A. Black and Ruby Power and Light:
Intro to Ruby on Rails January 12-15 Fort Lauderdale, FL
Advancing with Rails January 19-22 Fort Lauderdale, FL *
* Co-taught with Patrick Ewing!
See http://www.rubypal.com for details and updates!
No, OpenStruct pulls in other things I don't want (the whole 'open' thing).
martin
···
On Wed, Oct 22, 2008 at 4:04 PM, Siep Korteling <s.korteling@gmail.com> wrote:
Martin DeMello wrote:
I want a Structlike class that takes a hash constructor, so I can say
class A < MyStruct.new(*keys); end
a = A.new(:key1 => val1, :key2 => val2)
Is there any way to base this off Struct?
martin
It'standard:
require 'ostruct'
Doh - of course, since you aren't inheriting from Struct, you
shouldn't be inheriting from MyStruct either 
Wasn't thinking
clearly enough about the problem. Thanks!
martin
···
On Wed, Oct 22, 2008 at 4:34 PM, David A. Black <dblack@rubypal.com> wrote:
Do you need to use inheritance, as opposed to just instantiating
MyStruct directly? I'm thinking of, for example:class MyStruct < Struct
def self.new(*keys)
s = super
s.class_eval do
define_method(:initialize) do |hash|
hash.each {|k,v| send("#{k}=",v) }
end
end
s
end
end
Why inheritance at all? Why do too much?
irb(main):001:0> MyStruct = Struct.new :foo, :bar do
irb(main):002:1* def initialize(h={})
irb(main):003:2> members.each {|m| self[m] = h[m.to_sym]}
irb(main):004:2> end
irb(main):005:1> end
=> MyStruct
irb(main):006:0> ms = MyStruct.new(:bar => 1, :foo => 2)
=> #<struct MyStruct foo=2, bar=1>
Kind regards
robert
···
On 23.10.2008 01:42, Martin DeMello wrote:
On Wed, Oct 22, 2008 at 4:34 PM, David A. Black <dblack@rubypal.com> wrote:
Do you need to use inheritance, as opposed to just instantiating
MyStruct directly? I'm thinking of, for example:class MyStruct < Struct
def self.new(*keys)
s = super
s.class_eval do
define_method(:initialize) do |hash|
hash.each {|k,v| send("#{k}=",v) }
end
end
s
end
endDoh - of course, since you aren't inheriting from Struct, you
shouldn't be inheriting from MyStruct either
clearly enough about the problem. Thanks!
Hey, neat! I didn't know you could do that!
I've always reopened the class.
···
On Oct 22, 2008, at 23:03 PM, Robert Klemme wrote:
Why inheritance at all? Why do too much?
irb(main):001:0> MyStruct = Struct.new :foo, :bar do
irb(main):002:1* def initialize(h={})
irb(main):003:2> members.each {|m| self[m] = h[m.to_sym]}
irb(main):004:2> end
irb(main):005:1> end
=> MyStruct
irb(main):006:0> ms = MyStruct.new(:bar => 1, :foo => 2)
=> #<struct MyStruct foo=2, bar=1>
Why inheritance at all? Why do too much?
Because I'd have to repeat that for every new struct I created. But
that's a very neat trick indeed!
martin
···
On Wed, Oct 22, 2008 at 11:03 PM, Robert Klemme <shortcutter@googlemail.com> wrote:
irb(main):001:0> MyStruct = Struct.new :foo, :bar do
irb(main):002:1* def initialize(h={})
irb(main):003:2> members.each {|m| self[m] = h[m.to_sym]}
irb(main):004:2> end
irb(main):005:1> end
=> MyStruct
irb(main):006:0> ms = MyStruct.new(:bar => 1, :foo => 2)
=> #<struct MyStruct foo=2, bar=1>
Oh, you want another Struct implementation that does this? I wasn't
aware of this. That's easily fixed.
class MyStruct < Struct
def initialize(h={})
members.each {|m| self[m] = h[m.to_sym]}
end
end
s1 = MyStruct.new :foo, :bar
p s1.ancestors, s1.new(:bar => 123)
Kind regards
robert
···
2008/10/23 Martin DeMello <martindemello@gmail.com>:
On Wed, Oct 22, 2008 at 11:03 PM, Robert Klemme > <shortcutter@googlemail.com> wrote:
Why inheritance at all? Why do too much?
Because I'd have to repeat that for every new struct I created. But
that's a very neat trick indeed!
--
remember.guy do |as, often| as.you_can - without end