[Ironruby-core] IronRuby internals - How can I get the full path to the current file?

Tomas Matousek Tomas.Matousek at microsoft.com
Tue Jan 3 23:11:20 EST 2012

I'd recommend to start with some simpler features than this one. This seems to be quite non-trivial to implement efficiently and correctly.
Note that getting the current stack trace is very expensive, so you'd probably want to encode the path into Ruby call-sites (RubyCallAction) or something like that. But also adding more information to all call-sites consumes more memory so maybe we need a special call-site for methods called "require_relative" and fall back to the slow stack trace capture only when the method is called via an alias.


From: ironruby-core-bounces at rubyforge.org [mailto:ironruby-core-bounces at rubyforge.org] On Behalf Of Orion Edwards
Sent: Tuesday, January 03, 2012 2:02 PM
To: ironruby-core at rubyforge.org
Subject: [Ironruby-core] IronRuby internals - How can I get the full path to the current file?

I thought I'd be a good samaritan and implement require_relative in IronRuby, but I'm having real trouble figuring out what the current file's path actually is.

The closest I've got is something like this:

* Pull apart the the caller/backtrace to get the file name
* File.expand_path(file,  File.dirname(dir))
* require that file

This is equivalent to the existing ruby idiom of "require File.join(File.dirname(__FILE__), 'lib/file1')", but this doesn't work reliably because __FILE__ is already relative, so File.dirname(__FILE__) often just returns "."
Without the full path to the current file however, this is as good as we can get.

I've looked through various parts of the IronRuby source code...
- as far as I can tell the Parser/Syntax tree code (which has access to the file path) doesn't keep the information around
- and even if it did, I'm not sure how regular ruby code could access the parser/AST??

If anyone could help at all, even with a small bit of detail, it'd be much appreciated.
Thanks, Orion


Here's my test program, which works correctly in MRI 1.92, but I cannot get it to work in IronRuby

require_relative 'lib/file1'
Dir.chdir 'c:/windows/system32'
require_relative 'lib/file2'

Other things I tried

- eval("__FILE__") - is hard-coded to return "(eval)"

- I thought about poking around in RubyContext.Loader.LoadedFiles, but the Loader doesn't know about the entry-point file (is this a bug??), which is a big stumbling block
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