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Module: Warning

Relationships & Source Files
Namespace Children
Classes:
buffer
Defined in: error.c

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.

Changing the behavior of #warn is useful to customize how warnings are handled by ::Ruby, for instance by filtering some warnings, and/or outputting warnings somewhere other than $stderr.

If you want to change the behavior of #warn you should use Warning.extend(MyNewModuleWithWarnMethod) and you can use super to get the default behavior of printing the warning to $stderr.

Example:

module MyWarningFilter
def warn(message, category: nil, **kwargs)
  if /some warning I want to ignore/.match?(message)
    # ignore
  else
    super
  end
end
end
Warning.extend MyWarningFilter

You should never redefine #warn (the instance method), as that will then no longer provide a way to use the default behavior.

The warning gem provides convenient ways to customize #warn.

Class Method Summary

Instance Method Summary

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 <code>$,</code> and <code>$;</code>
* keyword arguments
etc.

:experimental ::

experimental features

:performance ::

performance hints
* Shape variation limit
[ GitHub ] 

  


# File 'error.c', line 228



static VALUE
rb_warning_s_aref(VALUE mod, VALUE category)
{
    rb_warning_category_t cat = rb_warning_category_from_name(category);
    return RBOOL(rb_warning_category_enabled_p(cat));
}


  








  

    .[]=(category, flag)  ⇒ flag   



  

    
Sets the warning flags for category.
See .[] for the categories.

  



  [ GitHub ]


  

  


# File 'error.c', line 243



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;
}


  








  

    .categories  ⇒ Array   



  

    
Returns a list of the supported category symbols.

  



  [ GitHub ]


  

  


# File 'error.c', line 263



static VALUE
rb_warning_s_categories(VALUE mod)
{
    st_index_t num = warning_categories.id2enum->num_entries;
    ID *ids = ALLOCA_N(ID, num);
    num = st_keys(warning_categories.id2enum, ids, num);
    VALUE ary = rb_ary_new_capa(num);
    for (st_index_t i = 0; i < num; ++i) {
        rb_ary_push(ary, ID2SYM(ids[i]));
    }
    return rb_ary_freeze(ary);
}


  







Instance Method Details



  

    #warn(msg, category: nil)  ⇒ nil   



  

    
Writes warning message msg to $stderr. This method is called by
::Ruby for all emitted warnings. A category may be included with
the warning.


See the documentation of the Warning module for how to customize this.

  



  [ GitHub ]


  

  


# File 'error.c', line 287



static VALUE
rb_warning_s_warn(int argc, VALUE *argv, VALUE mod)
{
    VALUE str;
    VALUE opt;
    VALUE category = Qnil;

    rb_scan_args(argc, argv, "1:", &str, &opt);
    if (!NIL_P(opt)) rb_get_kwargs(opt, &id_category, 0, 1, &category);

    Check_Type(str, T_STRING);
    rb_must_asciicompat(str);
    if (!NIL_P(category)) {
        rb_warning_category_t cat = rb_warning_category_from_name(category);
        if (!rb_warning_category_enabled_p(cat)) return Qnil;
    }
    rb_write_error_str(str);
    return Qnil;
}