Issue #2975 has been updated by nahi.

Description updated
Status changed from Open to Closed

I mark as Closed since it seems we already have it in docs.

Please file a new ticket for the proposed API change since it's dated...
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Feature #2975: Kernel.warn always writes despite $VERBOSE value
https://bugs.ruby-lang.org/issues/2975#change-24708

Author: DanRathbun
Status: Closed
Priority: Normal
Assignee: 
Category: DOC
Target version: 2.0.0


=begin
 Kernel.warn always writes despite $VERBOSE value
 
 The RDoc say:
 http://www.ruby-doc.org/core/classes/Kernel.html#M005921
 warn(msg) => nil
 Display the given message (followed by a newline) on STDERR unless warnings are disabled (for example with the -W0 flag). 
 
 (from Ruby.h, ver 1.8.6, line 562..564, Language="C" )
 void rb_warning __((const char*, ...)); /* reports if `-w' specified */
 void rb_sys_warning __((const char*, ...)); /* reports if `-w' specified */
 void rb_warn __((const char*, ...)); /* reports always */
 
 In ver 1.8.6, in practice Kernel.warn (and by inclusion,) anyobject's instance method warn, outputs no matter what the setting of $VERBOSE. It then appears to work as though it's calling rb_warn in the core, but the RDoc seems to say it should act like it's calling rb_warning in the core.
 
 This has forced me to make my 'warn' calls work the way they should, by doing this:
 
 # Send warning only if in Verbose mode
 warn('My Informational Message') if $VERBOSE
 
 # Send warning unless in Silent mode
 warn('My Important Message') unless $VERBOSE.nil?
 
 # Send warning no matter what Verbose mode
 warn('My Critical Message that MUST be displayed!')
 
 I'm tired of this workaround:
 I think we need something like this overrride, where I define 3 methods,
 warn, warn?, warn!
 and in addition, I have them return a boolean result (the original warn just returned nil.)
 
 #!ruby warn_ovr.rb
 # Make Warnings work the way they should.
 # by: Dan Rathbun - 16 MAR 2010 - Palm Bay, FL, USA
 # TERMS: Public Domain, Take it, Use it, Abuse it!
 
 module Kernel
 
   # alias the old warn method
   alias_method(:old_warn,:warn)
 
   # warn! will always send to $stderr
   # regardless of $VERBOSE setting
   def warn!(msg)
     unless msg.is_a?(String)
       raise(TypeError,'String argument expected.',caller(1))
     end
     $stderr.write(msg + "\n")
     return true # no IO error occured
   end
 
   # warn will now send to $stderr
   # ONLY if $VERBOSE is not Silent mode (nil)
   def warn(msg)
     unless msg.is_a?(String)
       raise(TypeError,'String argument expected.',caller(1))
     end
     unless $VERBOSE.nil?
       $stderr.write(msg + "\n")
       return true
     else
       return false
     end
   end
 
   # warn? will send to $stderr
   # ONLY if $VERBOSE is in Verbose mode (true)
   def warn?(msg)
     unless msg.is_a?(String)
       raise(TypeError,'String argument expected.',caller(1))
     end
     if $VERBOSE
       $stderr.write(msg + "\n")
       return true
     else
       # We return false if $VERBOSE is nil or false
       return false
     end
   end
 
 end # Kernel
 
 NOTE: The above override script does not override the Module method Kernel.warn, only the instance method. (I could have just run the script in the ObjectSpace without the Kernel wrapper, and added the methods to class Object. Their use either way is the same.)
=end



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