module Warning - RDoc Documentation (original) (raw)

The Warning module contains a single method named warn, and the module extends itself, making Warning.warn available. Warning.warn is called for all warnings issued by Ruby. By default, warnings are printed to $stderr.

Changing the behavior of Warning.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 Warning.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/.matches?(message)

else
  super
end

end end Warning.extend MyWarningFilter

You should never redefine Warning#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 Warning.warn.

Public Class Methods

Warning[category] → true or false click to toggle source

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

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; }

Warning[category] = flag → flag click to toggle source

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

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; }

Public Instance Methods

warn(msg, category: nil) → nil click to toggle source

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.

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;

}