Can not find variable in the current scope!

Hello,

when trying to add tracing output to an erb template I hit the following
issue when trying to find where variable ex_title comes from.

Tried to list all possible variables in the current scope, but there
simply does not exist:
<%= instance_variables.grep(/ex_title/) %> # renders an empty array
<%= global_variables.grep(/ex_title/) %> # renders an empty array
<%= local_variables.grep(/ex_title/) %> # renders an empty array

<%= instance_variables.sort %> # renders array with many elements
<%= global_variables.sort %> # renders array with many elements
<%= local_variables.sort %> # renders array with many elements

Whereas ex_title variable provably does exists:
<%= ex_title %> # renders value “Categories - Online
store”
<%= ex_title.class %> # renders “String”
<%= ex_title.object_id %> # renders “15825900”

Where else can be found if not in global, local or instance variables ?

It could be a method. Or erb is doing some crazy stuff.

On Sat, Feb 16, 2013 at 1:53 PM, David U. [email protected]
wrote:

Hello,

when trying to add tracing output to an erb template I hit the following
issue when trying to find where variable ex_title comes from.

I cannot reproduce this issue

irb(main):001:0> e = ERB.new ‘(<%= x %>)’
=> #<ERB:0x802ae510 @safe_level=nil, @src="#coding:UTF-8\n_erbout =
‘’; _erbout.concat “(”; _erbout.concat(( x ).to_s); _erbout.concat
“)”; _erbout.force_encoding(ENCODING)", @enc=#Encoding:UTF-8,
@filename=nil>
irb(main):002:0> x = 99
=> 99
irb(main):003:0> e.result binding
=> “(99)”

irb(main):004:0> e = ERB.new ‘(<%= x %>)(<%= local_variables.inspect
%>)(<%= local_variables.grep(/x/) %>)’
=> #<ERB:0x8029f8e4 @safe_level=nil, @src="#coding:UTF-8\n_erbout =
‘’; _erbout.concat “(”; _erbout.concat(( x ).to_s); _erbout.concat
“)(”; _erbout.concat(( local_variables.inspect ).to_s);
_erbout.concat “)(”; _erbout.concat(( local_variables.grep(/x/)
).to_s); _erbout.concat “)”; _erbout.force_encoding(ENCODING)",
@enc=#Encoding:UTF-8, @filename=nil>
irb(main):005:0> e.result binding
=> “(99)([:erbout, :x, :e, :])([:x])”

Also outside IRB

$ ruby -r erb -e ‘e=ERB.new("<%= x %>|<%= local_variables.sort.inspect
%>");x=99;puts e.result’
99|[:_erbout, :e, :x]
$ ruby -r erb -e ‘e=ERB.new("<%= x %>|<%= local_variables.grep(/x/)
%>");x=99;puts e.result’
99|[:x]

Tried to list all possible variables in the current scope, but there
simply does not exists:
<%= instance_variables.grep(/ex_title/) %> # renders an empty array
<%= global_variables…grep(/ex_title/) %> # renders an empty array
<%= local_variables…grep(/ex_title/) %> # renders an empty array

Did you really execute this? I get this

irb(main):008:0> f = ERB.new ‘<%= local_variables…grep(/x/) %>’
=> #<ERB:0x80253890 @safe_level=nil, @src="#coding:UTF-8\n_erbout =
‘’; _erbout.concat(( local_variables…grep(/x/) ).to_s);
_erbout.force_encoding(ENCODING)", @enc=#Encoding:UTF-8,
@filename=nil>
irb(main):009:0> f.result binding
NoMethodError: undefined method grep' for main:Object from (erb):1 from /usr/lib/ruby/1.9.1/erb.rb:838:ineval’
from /usr/lib/ruby/1.9.1/erb.rb:838:in result' from (irb):9 from /usr/bin/irb:12:in

$ ruby -r erb -e ‘e=ERB.new("<%= x %>|<%= local_variables…grep(/x/)
%>");x=99;puts e.result’
(erb):1:in <main>': undefined methodgrep’ for main:Object
(NoMethodError)
from /usr/lib/ruby/1.9.1/erb.rb:838:in eval' from /usr/lib/ruby/1.9.1/erb.rb:838:inresult’
from -e:1:in `’

If I omit the second dot I get

irb(main):010:0> f = ERB.new ‘<%= local_variables.grep(/x/) %>’
=> #<ERB:0x8022ed4c @safe_level=nil, @src="#coding:UTF-8\n_erbout =
‘’; _erbout.concat(( local_variables.grep(/x/) ).to_s);
_erbout.force_encoding(ENCODING)", @enc=#Encoding:UTF-8,
@filename=nil>
irb(main):011:0> f.result binding
=> “[:x]”

Where else can be found if not in global, local or instance variables ?
You would have to show us how you evaluate those ERB templates.

Cheers

robert

On Sat, Feb 16, 2013 at 6:53 AM, David U. [email protected]
wrote:

Where else can be found if not in global, local or instance variables ?


Posted via http://www.ruby-forum.com/.

You have two dots, which would be a range. If that doesn’t solve it, but
more probably, ex_title is a method

<%= methods.grep(/ex_title/) %>

-Josh

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