Feature #10395

erb: allow variables to be set from the command line

Added by josb (Jos Backus) over 6 years ago. Updated about 6 years ago.

Target version:


This would make erb more useful from the command line. Granted the use of Binding#eval is dangerous so one has to be careful. Newer versions of Ruby have Binding#local_variable_set which can be used instead but this works with Ruby 2.0.0.

jonagold:local jos$ cat /tmp/erb-template
This is <%= foo %>
And this is <%= bar %>
jonagold:local jos$ diff -u /usr/bin/erb /tmp/erb
--- /usr/bin/erb    2014-05-15 22:14:36.000000000 -0700
+++ /tmp/erb    2014-10-16 22:29:37.000000000 -0700
@@ -114,6 +114,13 @@
         exit 1

+      vars = ARGV.take_while {|arg| arg[/^\w+=/]}
+      ARGV.slice!(0, vars.size)
+      vars.each do |var|
+        k, v = var.split('=', 2)
+        TOPLEVEL_BINDING.eval %Q(#{k} = "#{v}")
+      end
       $<.set_encoding(Encoding::ASCII_8BIT, nil)
       src = $<.read
       filename = $FILENAME
jonagold:local jos$ /tmp/erb foo=FOO bar=123 /tmp/erb-template
This is FOO
And this is 123
jonagold:local jos$

Updated by nobu (Nobuyoshi Nakada) over 6 years ago

  • Description updated (diff)
  • Status changed from Open to Assigned
  • Assignee set to seki (Masatoshi Seki)
  • Target version set to Ruby 2.2.0

No new features for maintenance branches.
And your patch doesn't allow options after variables.

Updated by josb (Jos Backus) over 6 years ago

Thanks Nobu, that looks like a much better implementation. Appreciate your help.

Updated by nobu (Nobuyoshi Nakada) about 6 years ago

  • Status changed from Assigned to Closed
  • % Done changed from 0 to 100

Applied in changeset ruby-trunk:r48786.

erb: set variables from the command line

  • bin/erb (ARGV.switch, ERB::Main#run): allow variables to be set from the command line. [ruby-core:65772] [Feature #10395]

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