Module: Warning
Overview
The Warning module contains a single method named #warn, and the module extends itself, making #warn available. #warn is called for all warnings issued by Ruby. By default, warnings are printed to $stderr.
By overriding #warn, you can change how warnings are handled by Ruby, either filtering some warnings, and/or outputting warnings somewhere other than $stderr. When #warn is overridden, super can be called to get the default behavior of printing the warning to $stderr.
Class Method Summary
- 
    
      .[](category)  ⇒ Boolean 
    
    Returns the flag to show the warning messages for category.
- 
    
      .[]=(category, flag)  ⇒ flag 
    
    Sets the warning flags for category.
Instance Method Summary
- 
    
      #warn(msg)  ⇒ nil 
    
    Writes warning message msgto $stderr.
Class Method Details
    .[](category)  ⇒ Boolean   
Returns the flag to show the warning messages for category. Supported categories are:
- :deprecated
- 
deprecation warnings 
- 
assignment of non-nil value to $,and$;
- 
keyword arguments 
- 
proc/lambda without block 
etc.
- :experimental
- 
experimental features 
- 
Pattern matching 
# File 'error.c', line 188
static VALUE
rb_warning_s_aref(VALUE mod, VALUE category)
{
    rb_warning_category_t cat = rb_warning_category_from_name(category);
    if (rb_warning_category_enabled_p(cat))
        return Qtrue;
    return Qfalse;
}
  
    .[]=(category, flag)  ⇒ flag   
Sets the warning flags for category. See .[] for the categories.
# File 'error.c', line 205
static VALUE
rb_warning_s_aset(VALUE mod, VALUE category, VALUE flag)
{
    unsigned int mask = rb_warning_category_mask(category);
    unsigned int disabled = warning_disabled_categories;
    if (!RTEST(flag))
        disabled |= mask;
    else
        disabled &= ~mask;
    warning_disabled_categories = disabled;
    return flag;
}
  Instance Method Details
    #warn(msg)  ⇒ nil   
Writes warning message msg to $stderr. This method is called by Ruby for all emitted warnings.
# File 'error.c', line 226
static VALUE
rb_warning_s_warn(VALUE mod, VALUE str)
{
    Check_Type(str, T_STRING);
    rb_must_asciicompat(str);
    rb_write_error_str(str);
    return Qnil;
}