Treating 'string'+var as method


#1

I am a new Ruby recruit (thanks to ahem, Rails)…
What is the best way to do this:

  • obj.‘string’+var as a method?

I am currently using:

  • obj.send(‘string’+var)

…which works fine, but is this correct or bad practice?


#2

On Thu, 15 Dec 2005 10:22:47 -0000, bmgz removed_email_address@domain.invalid wrote:

I am a new Ruby recruit (thanks to ahem, Rails)…
What is the best way to do this:

  • obj.‘string’+var as a method?

I am currently using:

  • obj.send(‘string’+var)

…which works fine, but is this correct or bad practice?

I’m not sure what’s the best way, but here are a few things you could
try:

A hash to play with

h = Hash.new
=> {}
irb(main):112:0> suff = “ore”
=> “ore”

You can use ‘eval’ but this is pretty heavy on time and space:

irb(main):113:0> eval(“h.st#{suff}(‘k’,‘v’)”)
=> “v”
irb(main):114:0> h
=> {“k”=>“v”}

You can use send, as you did. I’d replace ‘str’+var with “str#{var}”,

but it’s not required:
irb(main):115:0> h.send(“st#{suff}”, ‘k’, ‘g’)
=> “g”
irb(main):117:0> h
=> {“k”=>“g”}

You can get the method and call it as a proc

irb(main):119:0> store = h.method(“st#{suff}”)
=> #<Method: Hash#store>
irb(main):121:0> store.call(‘k’,‘g’)
=> “g”
irb(main):122:0> store[‘k’,‘g’] # (shortcut, maybe a bit confusing here
though ;))
=> “g”

Hope that helps,
Ross


#3

bmgz wrote:

I am a new Ruby recruit (thanks to ahem, Rails)…
What is the best way to do this:

  • obj.‘string’+var as a method?

I am currently using:

  • obj.send(‘string’+var)

…which works fine, but is this correct or bad practice?

That’s ok. As Ross pointed out you can also use
obj.send(“string#{var}”).
But I would not use eval - there’s just too much that can go wrong
security wise.

Kind regards

robert