The other constructors: Object.create() and String.fromCharCode()
On Jun 5, 2011, at 11:00 AM, Peter Michaux wrote:
(I remember the idea of being able to write "String.new" rather than having to write "String['new']" was discussed in the past. I don't know if keywords as bare object keys are allowed in ECMAScript but it seems to work in Firefox.)
It's in ES5. See 7.6, specifically the IdentifierName production and its uses.
On 05.06.2011 22:00, Peter Michaux wrote:
ES has "new Constructor()" as its basic syntax for construction. This means that if other constructors are also beneficial that the syntax to call them is inconsistent. For example, ES3 had the "String.fromCharCode" and ES5 added "Object.create".
This is a basic idea of class-factory-methods, i.e. when an instance is created not directly by specified arguments, but with prior actions applied on the different kind of argument(s) passed to the factory. That is (pseudo-code):
class Point new: (x, y) -> this.x = x this.y = y end
Point.fromString(s) = -> Point.new(...s.split(":")) end
a = Point.new(1, 2) b = Point.fromString("1:2")
and this kind of methods are placed on constructors (the main idea which
I'm saying, is that String.fromCharCode isn't here because of
inconsistency, but because of it's such a class-method, which is
constructor of an instance).
These are both constructors of sorts. Would it be possible to add "String.new" etc so that construction is consistent?
Sure, I also used such a notation with .new in my experiments. BTW,
this is the approach used in Ruby too -- new is just (class-) method
there.
Unfortunately Date.now, Date.parse, Date.UTC don't return Date objects as they would be elegant cases of being other constructors.
Yes in order to get consistent syntax, host objects would need to implement the static "new" method.
It can be done with a simple library though -- just wrappers for all kind of cases.
(I remember the idea of being able to write "String.new" rather than having to write "String['new']" was discussed in the past. I don't know if keywords as bare object keys are allowed in ECMAScript but it seems to work in Firefox.)
Yes, it's possible per ES5.
Dmitry.
ES has "new Constructor()" as its basic syntax for construction. This means that if other constructors are also beneficial that the syntax to call them is inconsistent. For example, ES3 had the "String.fromCharCode" and ES5 added "Object.create". These are both constructors of sorts. Would it be possible to add "String.new" etc so that construction is consistent?
Unfortunately Date.now, Date.parse, Date.UTC don't return Date objects as they would be elegant cases of being other constructors.
Yes in order to get consistent syntax, host objects would need to implement the static "new" method.
(I remember the idea of being able to write "String.new" rather than having to write "String['new']" was discussed in the past. I don't know if keywords as bare object keys are allowed in ECMAScript but it seems to work in Firefox.)
Peter