rsc3/doc-schelp/HelpSource/Classes/Symbol.schelp

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class::Symbol
summary::unique name
categories::Core
description::
A Symbol is a name that is guaranteed to be unique. They can be used to represent
symbolic constant values, link::Classes/Dictionary:: keys, etc.
Symbols are represented syntactically as literals which are described in link::Reference/Literals#Symbols::.
subsection::Creating a Symbol
A symbol can be written by surrounding characters by single quotes (may include whitespace):
code::'foo bar'::
Or by a preceding backslash (then it may not include whitespace):
code::\foo::
A String can be converted into a symbol:
code::"arbeit".scramble.asSymbol;::
classmethods::
private::new
instancemethods::
subsection::Testing
method::isClassName
Answer whether the symbol can be a class name. This does not say if the class exists.
code::
\Array.isClassName;
\Bauxite.isClassName;
::
method::isMetaClassName
Answer whether the symbol can be meta class name. This does not say if the class exists.
code::
\Meta_Array.isMetaClassName;
::
method::isSetter
Answer whether the symbol has a trailing underscore.
code::
'action_'.isSetter;
::
method::isPrimitiveName
Answer whether the symbol is a valid primitive name
code::
'_SymbolIsClassName'.isPrimitiveName;
::
subsection::Conversion
method::asString
Convert to a String
method::asInteger
Convert to an Integer
method::asClass
Answer the Class named by the receiver.
method::asSetter
Return a symbol with a trailing underscore added.
method::asGetter
Return a symbol with a trailing underscore removed.
method::ascii
return the ascii codes as an array
method::asSpec
Convert to a ControlSpec
method::asTuning
Convert to a Tuning
method::asScale
Convert to a Scale
subsection::Environments
Symbols are used as keys to look up objects in dictionaries and environments, but also in arrays.
See link::Classes/IdentityDictionary::, link::Classes/Environment::, link::Classes/Event::
code::
a = ();
a.put(\commune, 1871);
a.at(\commune);
::
method::envirPut
put a value to the current environment using receiver as key
method::envirGet
return a value from the current environment using receiver as key
discussion::
code::
\foo.envirPut(100);
\foo.envirGet;
\foo.envirPut(nil);
::
subsection::Math
Symbols respond to all unary and binary math operations by returning themselves. The result of any math operation between a Number or other math object and a Symbol is to return the Symbol. This allows for example operations on lists of notes which contain 'rest's to preserve the rests.
code::Pseq([1, 3, \rest, 2, 4] + 8);::
method::applyTo
Use the symbol as a method selector and perform the message on firstArg, with args as arguments. This is used for mixing functions with method selectors (see also: Function).
discussion::
code::
'%'.applyTo(2553, 345);
['+', '-', '*', { |a, b| a.rand + b.rand } ].choose.applyTo(2, 3);
::
subsection::Synthesis
Inside SynthDefs and UGen functions, symbols can be used to conveniently specify control inputs of different rates and with lags (see: NamedControl, ControlName, and Control).
method::kr
Return a control rate NamedControl input with a default value (val), and if supplied, with a lag. If val is an array, the control will be multichannel.
discussion::
code::
a = { SinOsc.ar(\freq.kr(440, 1.2)) }.play;
a.set(\freq, 330);
a.release;
a = { SinOsc.ar(\freq.kr([440, 460], 1.2)) }.play;
a.setn(\freq, [330, 367]);
a.release;
::
method::ar
Return an audio rate NamedControl input with a default value (val), and if supplied, with a lag. If val is an array, the control will be multichannel.
method::ir
Return an initialization rate NamedControl input with a default value (val). If val is an array, the control will be multichannel.
method::tr
Return a TrigControl input with a default value (val). If val is an array, the control will be multichannel.
discussion::
code::
a = { Ringz.ar(T2A.ar(\trig.tr), \freq.kr(500, 1), 0.8) }.play;
a.set(\freq, 330, \trig, 1);
a.set(\freq, 830, \trig, 1);
a.release;
::