[ruby-core:30996] Ruby/DL problem

ruby-talk
1

Hello,

I have very little experience with dl. But I want to use it to
call SetEnvironmentVariable() from Win32. I could use FFI but cannot, since this
script will be supplied to a customer where it is difficult to install.

SetEnvironmentVariable on
MSDN http://msdn.microsoft.com/en-us/library/ms686206(v=VS.85).aspx

reading sparse, old, and cryptic documentation I came up with this snippet,
which of course does not work

require 'dl/import'

module Win32
extend DL::Importer
extern "int SetEnvironmentVariableA( char* lpName, char* lpValue)"
extern "int GetEnvironmentVariableA( char* lpName, char* lpValue, int size)"
end

buff = Array.new( 256, 0).pack("c*")
Win32.GetEnvironmentVariableA( "ENV_VAR", buff, 255)
puts buff.unpack("a*")

this is the error i get
D:/ruby/usr/lib/ruby/1.9.1/dl/import.rb:194:in `import_function': undefined
method `sym' for nil:NilClass (NoMethodError)
        from D:/ruby/usr/lib/ruby/1.9.1/dl/import.rb:118:in `extern'
        from test.rb:5:in `<module:Win32>'
        from test.rb:3:in `<main>'

machine is WinXP
ruby 1.9.1 (2008-10-28 revision 19983) [i386-mswin32_80]

can anybody suggest a better signature ?

Aston

2

I can't help you with your issue, but I'm curious why it's necessary.
The MSDN page you link to says SetEnvironmentVariable is only for the
current process. Doesn't ENV do what you need?

irb(main):001:0> ENV['FOO']='bar'
=> "bar"
irb(main):002:0> `echo %FOO%`
=> "bar\n"
irb(main):003:0>

···

On Fri, Jul 2, 2010 at 10:37 AM, Aston <blackapache512-ticket@yahoo.com> wrote:

Hello,

I have very little experience with dl. But I want to use it to
call SetEnvironmentVariable() from Win32. I could use FFI but cannot, since this
script will be supplied to a customer where it is difficult to install.

SetEnvironmentVariable on
MSDN http://msdn.microsoft.com/en-us/library/ms686206(v=VS.85).aspx

reading sparse, old, and cryptic documentation I came up with this snippet,
which of course does not work

require 'dl/import'

module Win32
extend DL::Importer
extern "int SetEnvironmentVariableA( char* lpName, char* lpValue)"
extern "int GetEnvironmentVariableA( char* lpName, char* lpValue, int size)"
end

buff = Array.new( 256, 0).pack("c*")
Win32.GetEnvironmentVariableA( "ENV_VAR", buff, 255)
puts buff.unpack("a*")

this is the error i get
D:/ruby/usr/lib/ruby/1.9.1/dl/import.rb:194:in `import_function': undefined
method `sym' for nil:NilClass (NoMethodError)
from D:/ruby/usr/lib/ruby/1.9.1/dl/import.rb:118:in `extern'
from test.rb:5:in `<module:Win32>'
from test.rb:3:in `<main>'

machine is WinXP
ruby 1.9.1 (2008-10-28 revision 19983) [i386-mswin32_80]

can anybody suggest a better signature ?

Aston

3

hmm, nobody here using Ruby.DL ?

···

----- Original Message ----

From: Aston <blackapache512-ticket@yahoo.com>
To: Ruby Talk <ruby-talk@ruby-lang.org>; Ruby Core <ruby-core@ruby-lang.org>
Sent: Fri, 2 July, 2010 9:07:00 PM
Subject: [ruby-core:30996] Ruby/DL problem

Hello,

I have very little experience with dl. But I want to use it to
call SetEnvironmentVariable() from Win32. I could use FFI but cannot, since
this

script will be supplied to a customer where it is difficult to install.

SetEnvironmentVariable on
MSDN SetEnvironmentVariableA function (processenv.h) - Win32 apps | Microsoft Learn

reading sparse, old, and cryptic documentation I came up with this snippet,
which of course does not work

require 'dl/import'

module Win32
extend DL::Importer
extern "int SetEnvironmentVariableA( char* lpName, char* lpValue)"
extern "int GetEnvironmentVariableA( char* lpName, char* lpValue, int size)"
end

buff = Array.new( 256, 0).pack("c*")
Win32.GetEnvironmentVariableA( "ENV_VAR", buff, 255)
puts buff.unpack("a*")

this is the error i get
D:/ruby/usr/lib/ruby/1.9.1/dl/import.rb:194:in `import_function': undefined
method `sym' for nil:NilClass (NoMethodError)
         from D:/ruby/usr/lib/ruby/1.9.1/dl/import.rb:118:in `extern'
        from test.rb:5:in `<module:Win32>'
        from test.rb:3:in `<main>'

machine is WinXP
ruby 1.9.1 (2008-10-28 revision 19983) [i386-mswin32_80]

can anybody suggest a better signature ?

Aston

4

Is not DL the problem, but the version you're using. revision 19983 is
*way* older than latest released one:

Pathlevel 378 was revision 26273

Lurking in the NEWS and ChangeLog pointed several changes in DL.

Trying your example with latest RubyInstaller 1.9.1 release:

C:\Users\Luis\Desktop>ruby -v t.rb
ruby 1.9.1p378 (2010-01-10 revision 26273) [i386-mingw32]
C:/Users/Luis/Tools/Ruby/ruby-1.9.1-p378-i386-mingw32/lib/ruby/1.9.1/
dl/import.rb:116: warning: instance variable @type_alias not
initialized
C:/Users/Luis/Tools/Ruby/ruby-1.9.1-p378-i386-mingw32/lib/ruby/1.9.1/
dl/import.rb:194: warning: instance variable @handler not initialized
C:/Users/Luis/Tools/Ruby/ruby-1.9.1-p378-i386-mingw32/lib/ruby/1.9.1/
dl/import.rb:194:in `import_function': undefined method `sym' for
nil:NilClass (NoMethodError)
        from C:/Users/Luis/Tools/Ruby/ruby-1.9.1-p378-i386-mingw32/lib/
ruby/1.9.1/dl/import.rb:118:in `extern'
        from t.rb:5:in `<module:Win32>'
        from t.rb:3:in `<main>'

Which brings the question, why bother on doing this way when Ruby does
it out of the box?

···

On Jul 3, 12:20 pm, Aston <blackapache512-tic...@yahoo.com> wrote:

----- Original Message ----
> From: Aston <blackapache512-tic...@yahoo.com>
> To: Ruby Talk <ruby-t...@ruby-lang.org>; Ruby Core <ruby-c...@ruby-lang.org>
> Sent: Fri, 2 July, 2010 9:07:00 PM
> Subject: [ruby-core:30996] Ruby/DL problem

> Hello,

> I have very little experience with dl. But I want to use it to
> call SetEnvironmentVariable() from Win32. I could use FFI but cannot, since
>this

> script will be supplied to a customer where it is difficult to install.

> SetEnvironmentVariable on
> MSDNhttp://msdn.microsoft.com/en-us/library/ms686206(v=VS.85).aspx

> reading sparse, old, and cryptic documentation I came up with this snippet,
> which of course does not work

> require 'dl/import'

> module Win32
> extend DL::Importer
> extern "int SetEnvironmentVariableA( char* lpName, char* lpValue)"
> extern "int GetEnvironmentVariableA( char* lpName, char* lpValue, int size)"
> end

> buff = Array.new( 256, 0).pack("c*")
> Win32.GetEnvironmentVariableA( "ENV_VAR", buff, 255)
> puts buff.unpack("a*")

> this is the error i get
> D:/ruby/usr/lib/ruby/1.9.1/dl/importrb:194:in `import_function': undefined
> method `sym' for nil:NilClass (NoMethodError)
> from D:/ruby/usr/lib/ruby/1.9.1/dl/import.rb:118:in `extern'
> from test.rb:5:in `<module:Win32>'
> from test.rb:3:in `<main>'

> machine is WinXP
> ruby 1.9.1 (2008-10-28 revision 19983) [i386-mswin32_80]

> can anybody suggest a better signature ?

> Aston

hmm, nobody here using Ruby.DL ?

--
Luis Lavena