(Using Ruby 1.6.6)
I am writing a game. A “splash” screen displays four buttons to the
user. Each button has an action assigned to it, loaded from a file.
When a user clicks a button, I want to execute a class method such as
Game.new. First, I thought I wanted a Proc for this purpose, so I
tried:
ba = proc {ba} # ba = “Game.new”
…
ba.call
This approach didn’t work. Didn’t produce errors. So I switched to
eval(ba)
which does work, but I was hoping for a better technique. Eval seems
crude and unsafe to me, particularly since the button actions are
loaded from a file. I am wondering if there might be another approach
such as something like “instance_method” for class methods, or send,
or yield. Any advice appreciated. Thanks,
James Davis wrote:
(Using Ruby 1.6.6)
I am writing a game. A “splash” screen displays four buttons to the
user. Each button has an action assigned to it, loaded from a file.
When a user clicks a button, I want to execute a class method such as
Game.new. First, I thought I wanted a Proc for this purpose, so I
tried:
ba = proc {ba} # ba = “Game.new”
…
ba.call
This approach didn’t work. Didn’t produce errors.
Note that you reassign ba in the same context as the proc is defined,
which means ba will point to the proc itsef. So when you call the proc,
it just returns itself.
So I switched to
eval(ba)
which does work, but I was hoping for a better technique. Eval seems
crude and unsafe to me, particularly since the button actions are
loaded from a file. I am wondering if there might be another approach
such as something like “instance_method” for class methods, or send,
or yield.
If they all are Game class objects, then Game.send(method_name) should
suffice.
You could also use Game.method(method_name) to get similar to
instance_method, however it won’t be an UnboundedMethod (since you’ve
bound it to the class Game object)
HTH
···
–
([ Kent Dahl ]/)_ ~ [ http://www.stud.ntnu.no/~kentda/ ]/~
))_student/(( _d L b_/ NTNU - graduate engineering - 5. year )
( __õ|õ// ) )Industrial economics and technological management(
_/ö____/ (_engineering.discipline=Computer::Technology)
James Davis wrote:
(Using Ruby 1.6.6)
I am writing a game. A “splash” screen displays four buttons to the
user. Each button has an action assigned to it, loaded from a file.
When a user clicks a button, I want to execute a class method such as
Game.new. First, I thought I wanted a Proc for this purpose, so I
tried:
ba = proc {ba} # ba = “Game.new”
…
ba.call
This approach didn’t work. Didn’t produce errors. So I switched to
eval(ba)
which does work, but I was hoping for a better technique. Eval seems
crude and unsafe to me, particularly since the button actions are
loaded from a file. I am wondering if there might be another approach
such as something like “instance_method” for class methods, or send,
or yield. Any advice appreciated. Thanks,
This is one way of limiting what actions the file can do:
module GameModule
class Game
def self.new
super
end
end
end
cmd = “Game.new”
klass_str, meth = cmd.split(/./)
unless GameModule.constants.include? klass_str
raise “Unrecognized class #{klass_str}”
end
klass = GameModule.const_get(klass_str)
unless klass.singleton_methods.include? meth
raise “Unrecognized method #{meth} for class #{klass}”
end
p klass.send(meth)
It’s not clear to me what the “action” can be, however, I’ll offer the
following thoughts.
If the “action” is always a the name of a Game class method, convert
the name to a symbol and send it to the Game class:
m = “new”
Game.send m.intern
If the “action” is always the name of a class and the name of a class
method in the class (i.e. “Game” and “new”) then you can get the class
id from the class name with Class.get_const.
c = Class.get_const “Game”
m = “new”
c.send m.intern
···
On Mon, 09 Dec 2002 20:55:42 GMT, jd204c@nih.gov (James Davis) wrote:
(Using Ruby 1.6.6)
I am writing a game. A “splash” screen displays four buttons to the
user. Each button has an action assigned to it, loaded from a file.
When a user clicks a button, I want to execute a class method such as
Game.new. First, I thought I wanted a Proc for this purpose, so I
tried:
ba = proc {ba} # ba = “Game.new”
…
ba.call
This approach didn’t work. Didn’t produce errors. So I switched to
eval(ba)
which does work, but I was hoping for a better technique. Eval seems
crude and unsafe to me, particularly since the button actions are
loaded from a file. I am wondering if there might be another approach
such as something like “instance_method” for class methods, or send,
or yield. Any advice appreciated. Thanks,