suresh suresh - 4 months ago 38
Ruby Question

how to run the bytecode generated by ruby?

I am new to the Ruby scripting language.

I was learning how to generate the byte code in Ruby.
I found the answer for generating the byte code.

But I don't know how to run that generated byte code. I searched the internet, but I didn't get the answer for this.

Generating a byte code:-

puts RubyVM::InstructionSequence.compile("x = 50; x > 100 ? 'foo' : 'bar'").disassemble


The output is,

== disasm: <RubyVM::InstructionSequence:<compiled>@<compiled>>==========
local table (size: 2, argc: 0 [opts: 0, rest: -1, post: 0, block: -1] s1)
[ 2] x
0000 trace 1 ( 1)
0002 putobject 50
0004 setlocal x
0006 trace 1
0008 getlocal x
0010 putobject 100
0012 opt_gt <ic:1>
0014 branchunless 20
0016 putstring "foo"
0018 leave
0019 pop
0020 putstring "bar"
0022 leave


I don't know how to execute the same script, by using the generated byte code.

Anyone please explain me how to execute this.

Thanks in advance!

Answer

TL;DR; You are looking for .eval method.

The .compile method would return an instance of RubyVM::InstructionSequence class, which has .eval method that evaluates/runs your "compiled" instructions.

iseq = RubyVM::InstructionSequence.compile("x = 50; x > 100 ? 'foo' : 'bar'")    
iseq.eval       # => "bar"

Or, a oneliner:

RubyVM::InstructionSequence.compile("x = 50; x > 100 ? 'foo' : 'bar'").eval
Comments