class KeyError - Documentation for Ruby 4.0
Description: class KeyError: Raised when the specified key is not found. It is a subclass of IndexError.
Keywords: ruby,class,KeyError

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# class KeyError

Raised when the specified key is not found. It is a subclass of `IndexError`.

    h = {"foo" => :bar}
    h.fetch("foo") #=> :bar
    h.fetch("baz") #=> KeyError: key not found: "baz"

### Public Class Methods

new(message=nil, receiver: nil, key: nil) → key_error
Source

    static VALUE
    key_err_initialize(int argc, VALUE *argv, VALUE self)
    {
        VALUE options;

        rb_call_super(rb_scan_args(argc, argv, "01:", NULL, &options), argv);

        if (!NIL_P(options)) {
            ID keywords[2];
            VALUE values[numberof(keywords)];
            int i;
            keywords[0] = id_receiver;
            keywords[1] = id_key;
            rb_get_kwargs(options, keywords, 0, numberof(values), values);
            for (i = 0; i < numberof(values); ++i) {
                if (!UNDEF_P(values[i])) {
                    rb_ivar_set(self, keywords[i], values[i]);
                }
            }
        }

        return self;
    }

Construct a new `KeyError` exception with the given message, receiver and key.

### Public Instance Methods

key → object
Source

    static VALUE
    key_err_key(VALUE self)
    {
        VALUE key;

        key = rb_ivar_lookup(self, id_key, Qundef);
        if (!UNDEF_P(key)) return key;
        rb_raise(rb_eArgError, "no key is available");
    }

Return the key caused this `KeyError` exception.

receiver → object
Source

    static VALUE
    key_err_receiver(VALUE self)
    {
        VALUE recv;

        recv = rb_ivar_lookup(self, id_receiver, Qundef);
        if (!UNDEF_P(recv)) return recv;
        rb_raise(rb_eArgError, "no receiver is available");
    }

Return the receiver associated with this `KeyError` exception.