module Warning
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/.match?(message) # ignore 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
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
etc.
-
:experimental
-
experimental features
-
Pattern matching
-
:performance
-
performance hints
-
Shape variation limit
-
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)); }
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
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; }