instance method

Symbol#to_proc

() -> ::Proc

to_proc

VALUE
rb_sym_to_proc(VALUE sym)
{
    enum {SYM_PROC_CACHE_SIZE = 67};

    if (rb_ractor_main_p()) {
        if (!sym_proc_cache) {
            sym_proc_cache = rb_ary_hidden_new(SYM_PROC_CACHE_SIZE);
            rb_ary_store(sym_proc_cache, SYM_PROC_CACHE_SIZE - 1, Qnil);
        }

        ID id = SYM2ID(sym);
        long index = (id % SYM_PROC_CACHE_SIZE);
        VALUE procval = RARRAY_AREF(sym_proc_cache, index);
        if (RTEST(procval)) {
            rb_proc_t *proc;
            GetProcPtr(procval, proc);

            if (proc->block.as.symbol == sym) {
                return procval;
            }
        }

        procval = sym_proc_new(rb_cProc, sym);
        RARRAY_ASET(sym_proc_cache, index, procval);

        return RB_GC_GUARD(procval);
    }
    else {
        return sym_proc_new(rb_cProc, sym);
    }
}

Returns a Proc object which calls the method with name of self on the first parameter and passes the remaining parameters to the method.

Example

proc = :to_s.to_proc   # => #<Proc:0x000001afe0e48680(&:to_s) (lambda)>
proc.call(1000)        # => "1000"
proc.call(1000, 16)    # => "3e8"
(1..3).collect(&:to_s) # => ["1", "2", "3"]

Ruby version changes

3.0
- Symbol#to_proc now returns a lambda Proc. [Feature #16260]

See also #to_json #to_s #swapcase #to_sym also in 4.1 · 3.4 · 3.3 · 3.2 · 3.1 · 3.0

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