Class: Symbol
Overview
********************************************************************
Symbol objects represent names inside the Ruby interpreter. They
are generated using the <code>:name</code> and
<code>:"string"</code> literals syntax, and by the various
<code>to_sym</code> methods. The same Symbol object will be
created for a given name or string for the duration of a program's
execution, regardless of the context or meaning of that name. Thus
if <code>Fred</code> is a constant in one context, a method in
another, and a class in a third, the Symbol <code>:Fred</code>
will be the same object in all three contexts.
module One
class Fred
end
$f1 = :Fred
end
module Two
Fred = 1
$f2 = :Fred
end
def Fred()
end
$f3 = :Fred
$f1.object_id #=> 2514190
$f2.object_id #=> 2514190
$f3.object_id #=> 2514190
Class Method Summary collapse
-
.all_symbols ⇒ Array
Returns an array of all the symbols currently in Ruby’s symbol table.
Instance Method Summary collapse
-
#<=>(other_symbol) ⇒ -1, ...
Compares
symbol
withother_symbol
after calling #to_s on each of the symbols. - #== ⇒ Object
- #=== ⇒ Object
-
#=~(obj) ⇒ Integer?
Returns
sym.to_s =~ obj
. -
#[](*args) ⇒ Object
Returns
sym.to_s[]
. -
#capitalize(*args) ⇒ Object
Same as
sym.to_s.capitalize.intern
. -
#casecmp(other_symbol) ⇒ -1, ...
Case-insensitive version of Symbol#<=>.
-
#casecmp?(other_symbol) ⇒ true, ...
Returns
true
ifsym
andother_symbol
are equal after Unicode case folding,false
if they are not equal. -
#downcase(*args) ⇒ Object
Same as
sym.to_s.downcase.intern
. -
#empty? ⇒ Boolean
Returns whether sym is :“” or not.
-
#encoding ⇒ Encoding
Returns the Encoding object that represents the encoding of sym.
-
#end_with?([suffixes]) ⇒ Boolean
Returns true if
sym
ends with one of thesuffixes
given. -
#id2name ⇒ Object
Returns the name or string corresponding to sym.
-
#inspect ⇒ String
Returns the representation of sym as a symbol literal.
-
#intern ⇒ Object
In general,
to_sym
returns the Symbol corresponding to an object. -
#length ⇒ Object
Same as
sym.to_s.length
. -
#match(*args) ⇒ Object
Returns
sym.to_s.match
. -
#match?(*args) ⇒ Object
Returns
sym.to_s.match?
. -
#succ ⇒ Object
Same as
sym.to_s.succ.intern
. -
#size ⇒ Object
Same as
sym.to_s.length
. -
#slice(*args) ⇒ Object
Returns
sym.to_s[]
. -
#start_with?([prefixes]) ⇒ Boolean
Returns true if
sym
starts with one of theprefixes
given. -
#succ ⇒ Object
Same as
sym.to_s.succ.intern
. -
#swapcase(*args) ⇒ Object
Same as
sym.to_s.swapcase.intern
. -
#to_proc ⇒ Object
Returns a Proc object which responds to the given method by sym.
-
#to_s ⇒ Object
Returns the name or string corresponding to sym.
-
#to_sym ⇒ Object
In general,
to_sym
returns the Symbol corresponding to an object. -
#upcase(*args) ⇒ Object
Same as
sym.to_s.upcase.intern
.
Methods included from Comparable
#<, #<=, #>, #>=, #between?, #clamp
Class Method Details
.all_symbols ⇒ Array
Returns an array of all the symbols currently in Ruby’s symbol table.
Symbol.all_symbols.size #=> 903
Symbol.all_symbols[1,20] #=> [:floor, :ARGV, :Binding, :symlink,
:chown, :EOFError, :$;, :String,
:LOCK_SH, :"setuid?", :$<,
:default_proc, :compact, :extend,
:Tms, :getwd, :$=, :ThreadGroup,
:wait2, :$>]
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# File 'string.c', line 11181 static VALUE sym_all_symbols(VALUE _) { return rb_sym_all_symbols(); } |
Instance Method Details
#<=>(other_symbol) ⇒ -1, ...
Compares symbol
with other_symbol
after calling #to_s on each of the symbols. Returns -1, 0, +1, or nil
depending on whether symbol
is less than, equal to, or greater than other_symbol
.
nil
is returned if the two values are incomparable.
See String#<=> for more information.
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# File 'string.c', line 10871 static VALUE sym_cmp(VALUE sym, VALUE other) { if (!SYMBOL_P(other)) { return Qnil; } return rb_str_cmp_m(rb_sym2str(sym), rb_sym2str(other)); } |
#== ⇒ Object
#=== ⇒ Object
#=~(obj) ⇒ Integer?
Returns sym.to_s =~ obj
.
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# File 'string.c', line 10945 static VALUE sym_match(VALUE sym, VALUE other) { return rb_str_match(rb_sym2str(sym), other); } |
#[](idx) ⇒ String #[](b, n) ⇒ String #slice(idx) ⇒ String #slice(b, n) ⇒ String
Returns sym.to_s[]
.
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# File 'string.c', line 10989 static VALUE sym_aref(int argc, VALUE *argv, VALUE sym) { return rb_str_aref_m(argc, argv, rb_sym2str(sym)); } |
#capitalize ⇒ Object #capitalize([options]) ⇒ Object
Same as sym.to_s.capitalize.intern
.
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# File 'string.c', line 11058 static VALUE sym_capitalize(int argc, VALUE *argv, VALUE sym) { return rb_str_intern(rb_str_capitalize(argc, argv, rb_sym2str(sym))); } |
#casecmp(other_symbol) ⇒ -1, ...
Case-insensitive version of Symbol#<=>. Currently, case-insensitivity only works on characters A-Z/a-z, not all of Unicode. This is different from Symbol#casecmp?.
:aBcDeF.casecmp(:abcde) #=> 1
:aBcDeF.casecmp(:abcdef) #=> 0
:aBcDeF.casecmp(:abcdefg) #=> -1
:abcdef.casecmp(:ABCDEF) #=> 0
nil
is returned if the two symbols have incompatible encodings, or if other_symbol
is not a symbol.
:foo.casecmp(2) #=> nil
"\u{e4 f6 fc}".encode("ISO-8859-1").to_sym.casecmp(:"\u{c4 d6 dc}") #=> nil
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# File 'string.c', line 10900 static VALUE sym_casecmp(VALUE sym, VALUE other) { if (!SYMBOL_P(other)) { return Qnil; } return str_casecmp(rb_sym2str(sym), rb_sym2str(other)); } |
#casecmp?(other_symbol) ⇒ true, ...
Returns true
if sym
and other_symbol
are equal after Unicode case folding, false
if they are not equal.
:aBcDeF.casecmp?(:abcde) #=> false
:aBcDeF.casecmp?(:abcdef) #=> true
:aBcDeF.casecmp?(:abcdefg) #=> false
:abcdef.casecmp?(:ABCDEF) #=> true
:"\u{e4 f6 fc}".casecmp?(:"\u{c4 d6 dc}") #=> true
nil
is returned if the two symbols have incompatible encodings, or if other_symbol
is not a symbol.
:foo.casecmp?(2) #=> nil
"\u{e4 f6 fc}".encode("ISO-8859-1").to_sym.casecmp?(:"\u{c4 d6 dc}") #=> nil
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# File 'string.c', line 10929 static VALUE sym_casecmp_p(VALUE sym, VALUE other) { if (!SYMBOL_P(other)) { return Qnil; } return str_casecmp_p(rb_sym2str(sym), rb_sym2str(other)); } |
#downcase ⇒ Object #downcase([options]) ⇒ Object
Same as sym.to_s.downcase.intern
.
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# File 'string.c', line 11044 static VALUE sym_downcase(int argc, VALUE *argv, VALUE sym) { return rb_str_intern(rb_str_downcase(argc, argv, rb_sym2str(sym))); } |
#empty? ⇒ Boolean
Returns whether sym is :“” or not.
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# File 'string.c', line 11016 static VALUE sym_empty(VALUE sym) { return rb_str_empty(rb_sym2str(sym)); } |
#encoding ⇒ Encoding
Returns the Encoding object that represents the encoding of sym.
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# File 'string.c', line 11125 static VALUE sym_encoding(VALUE sym) { return rb_obj_encoding(rb_sym2str(sym)); } |
#end_with?([suffixes]) ⇒ Boolean
Returns true if sym
ends with one of the suffixes
given.
:hello.end_with?("ello") #=> true
# returns true if one of the +suffixes+ matches.
:hello.end_with?("heaven", "ello") #=> true
:hello.end_with?("heaven", "paradise") #=> false
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# File 'string.c', line 11112 static VALUE sym_end_with(int argc, VALUE *argv, VALUE sym) { return rb_str_end_with(argc, argv, rb_sym2str(sym)); } |
#id2name ⇒ String #to_s ⇒ String
Returns the name or string corresponding to sym.
:fred.id2name #=> "fred"
:ginger.to_s #=> "ginger"
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# File 'string.c', line 10792 VALUE rb_sym_to_s(VALUE sym) { return str_new_shared(rb_cString, rb_sym2str(sym)); } |
#inspect ⇒ String
Returns the representation of sym as a symbol literal.
:fred.inspect #=> ":fred"
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# File 'string.c', line 10753 static VALUE sym_inspect(VALUE sym) { VALUE str = rb_sym2str(sym); const char *ptr; long len; char *dest; if (!rb_str_symname_p(str)) { str = rb_str_inspect(str); len = RSTRING_LEN(str); rb_str_resize(str, len + 1); dest = RSTRING_PTR(str); memmove(dest + 1, dest, len); } else { rb_encoding *enc = STR_ENC_GET(str); RSTRING_GETMEM(str, ptr, len); str = rb_enc_str_new(0, len + 1, enc); dest = RSTRING_PTR(str); memcpy(dest + 1, ptr, len); } dest[0] = ':'; return str; } |
#to_sym ⇒ Object #intern ⇒ Object
In general, to_sym
returns the Symbol corresponding to an object. As sym is already a symbol, self
is returned in this case.
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# File 'string.c', line 10809 static VALUE sym_to_sym(VALUE sym) { return sym; } |
#length ⇒ Integer #size ⇒ Integer
Same as sym.to_s.length
.
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# File 'string.c', line 11003 static VALUE sym_length(VALUE sym) { return rb_str_length(rb_sym2str(sym)); } |
#match(pattern) ⇒ MatchData? #match(pattern, pos) ⇒ MatchData?
Returns sym.to_s.match
.
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# File 'string.c', line 10959 static VALUE sym_match_m(int argc, VALUE *argv, VALUE sym) { return rb_str_match_m(argc, argv, rb_sym2str(sym)); } |
#match?(pattern) ⇒ Boolean #match?(pattern, pos) ⇒ Boolean
Returns sym.to_s.match?
.
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# File 'string.c', line 10973 static VALUE sym_match_m_p(int argc, VALUE *argv, VALUE sym) { return rb_str_match_m_p(argc, argv, sym); } |
#succ ⇒ Object
Same as sym.to_s.succ.intern
.
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# File 'string.c', line 10851 static VALUE sym_succ(VALUE sym) { return rb_str_intern(rb_str_succ(rb_sym2str(sym))); } |
#length ⇒ Integer #size ⇒ Integer
Same as sym.to_s.length
.
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# File 'string.c', line 11003 static VALUE sym_length(VALUE sym) { return rb_str_length(rb_sym2str(sym)); } |
#[](idx) ⇒ String #[](b, n) ⇒ String #slice(idx) ⇒ String #slice(b, n) ⇒ String
Returns sym.to_s[]
.
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# File 'string.c', line 10989 static VALUE sym_aref(int argc, VALUE *argv, VALUE sym) { return rb_str_aref_m(argc, argv, rb_sym2str(sym)); } |
#start_with?([prefixes]) ⇒ Boolean
Returns true if sym
starts with one of the prefixes
given. Each of the prefixes
should be a String or a Regexp.
:hello.start_with?("hell") #=> true
:hello.start_with?(/H/i) #=> true
# returns true if one of the prefixes matches.
:hello.start_with?("heaven", "hell") #=> true
:hello.start_with?("heaven", "paradise") #=> false
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# File 'string.c', line 11093 static VALUE sym_start_with(int argc, VALUE *argv, VALUE sym) { return rb_str_start_with(argc, argv, rb_sym2str(sym)); } |
#succ ⇒ Object
Same as sym.to_s.succ.intern
.
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# File 'string.c', line 10851 static VALUE sym_succ(VALUE sym) { return rb_str_intern(rb_str_succ(rb_sym2str(sym))); } |
#swapcase ⇒ Object #swapcase([options]) ⇒ Object
Same as sym.to_s.swapcase.intern
.
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# File 'string.c', line 11072 static VALUE sym_swapcase(int argc, VALUE *argv, VALUE sym) { return rb_str_intern(rb_str_swapcase(argc, argv, rb_sym2str(sym))); } |
#to_proc ⇒ Object
Returns a Proc object which responds to the given method by sym.
(1..3).collect(&:to_s) #=> ["1", "2", "3"]
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# File 'string.c', line 10837 VALUE rb_sym_to_proc(VALUE sym) { } |
#id2name ⇒ String #to_s ⇒ String
Returns the name or string corresponding to sym.
:fred.id2name #=> "fred"
:ginger.to_s #=> "ginger"
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# File 'string.c', line 10792 VALUE rb_sym_to_s(VALUE sym) { return str_new_shared(rb_cString, rb_sym2str(sym)); } |