Module: Warning

Defined in:

error.c,
error.c

Overview

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.

By overriding Warning.warn, you can change how warnings are handled by Ruby, either filtering some warnings, and/or outputting warnings somewhere other than $stderr. When Warning.warn is overridden, super can be called to get the default behavior of printing the warning to $stderr.

Defined Under Namespace

Classes: buffer

Class Method Summary

• .[](category) ⇒ Object

  call-seq Warning -> true or false.

• .[]=(category, flag) ⇒ Object

  call-seq Warning = flag -> flag.

Instance Method Summary

• #warn(msg) ⇒ nil

  Writes warning message msg to $stderr.

Class Method Details

.[](category) ⇒ Object

call-seq

Warning[category]  -> true or false

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 186

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) ⇒ Object

call-seq

Warning[category] = flag -> flag

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

# File 'error.c', line 203

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.

Returns:

• (nil)

# File 'error.c', line 224

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;
}