I am setting up a few variables based on user input with the following
code snippet:
···
==================================
vars = %w{a b c}
vars.each do |var|
print "#{var} = "
val = gets
eval("$#{var}=#{val.chomp}")
end
#use a, b, c here for something
What I don't like about this code is the use of global variables.
However, I have to use them - or otherwise a,b,c will be already out of
scope at the place I need them.
Another possibility would be to use constants, i.e.
vars = %w{A B C}
which would work well - however, since I am repeating the process more
times, from the second iteration on I am getting warnings that A, B, C
etc were already initialized, which is not nice.
I guess yet another possibility would be to wrap a class around this
stuff and use instance_eval or something like that - but a class that
serves solely this purpose looks to heavy to me...
I am setting up a few variables based on user input with the following
code snippet:
==================================
vars = %w{a b c}
vars.each do |var|
print "#{var} = "
val = gets
eval("$#{var}=#{val.chomp}")
end
#use a, b, c here for something
What I don't like about this code is the use of global variables.
However, I have to use them - or otherwise a,b,c will be already out of
scope at the place I need them.
Use a hash?
vars = {
"a" => nil,
"b" => nil,
"c" => nil,
}
def get_input vars
vars.keys.each do |var|
print "#{var} = "
val = gets
vars[var] = val.chomp
eval("$#{var}=#{val.chomp}")
end
end
get_input vars
p vars
__END__
a = 1
b = 2
c = 3
{"a"=>"1", "b"=>"2", "c"=>"3"}
You can use instance_eval with the hash, as you suggested:
module AcessibleKeys
def method_missing(m, *rest)
if rest.empty?
fetch(m.to_s)
else
super
end
end
end
vars.extend AcessibleKeys
get_input vars
p vars
vars.instance_eval do
puts "a+b+c = #{a+b+c}"
end
__END__
a = 1
b = 2
c = 3
{"a"=>"1", "b"=>"2", "c"=>"3"}
a+b+c = 123
···
--
vjoel : Joel VanderWerf : path berkeley edu : 510 665 3407
def goforit(w, bind)
w.each do |v|
eval("#{v} = 'heehee'", bind)
end
end
goforit %w{a b c}, binding
puts a, b, c
m.
···
Peter Szinek <peter@rubyrailways.com> wrote:
Hi,
I am setting up a few variables based on user input with the following
code snippet:
==================================
vars = %w{a b c}
vars.each do |var|
print "#{var} = "
val = gets
eval("$#{var}=#{val.chomp}")
end
#use a, b, c here for something
What I don't like about this code is the use of global variables.
However, I have to use them - or otherwise a,b,c will be already out of
scope at the place I need them.
Another possibility would be to use constants, i.e.
vars = %w{A B C}
which would work well - however, since I am repeating the process more
times, from the second iteration on I am getting warnings that A, B, C
etc were already initialized, which is not nice.
I guess yet another possibility would be to wrap a class around this
stuff and use instance_eval or something like that - but a class that
serves solely this purpose looks to heavy to me...
Just two tiny improvements
* Do not use globals
* Do not use eval
#!/usr/bin/ruby
vars = %w{a b c}
vars.each do |var|
print "#{var} = "
val = gets.chomp
instance_variable_set "@#{var}", val
end
puts "a = #{@a}"
Maybe you prefer this?
But if you want to access the instance variables by name you can also define
an attribute_reader/writer/accessor inside the vars.each loop.
Cheers
Robert
···
On 11/11/06, Peter Szinek <peter@rubyrailways.com> wrote:
Hi,
I am setting up a few variables based on user input with the following
code snippet:
==================================
vars = %w{a b c}
vars.each do |var|
print "#{var} = "
val = gets
eval("$#{var}=#{val.chomp}")
end
#use a, b, c here for something
What I don't like about this code is the use of global variables.
However, I have to use them - or otherwise a,b,c will be already out of
scope at the place I need them.
Another possibility would be to use constants, i.e.
vars = %w{A B C}
which would work well - however, since I am repeating the process more
times, from the second iteration on I am getting warnings that A, B, C
etc were already initialized, which is not nice.
I guess yet another possibility would be to wrap a class around this
stuff and use instance_eval or something like that - but a class that
serves solely this purpose looks to heavy to me...
--
The reasonable man adapts himself to the world; the unreasonable one
persists in trying to adapt the world to himself. Therefore all progress
depends on the unreasonable man.
