> On 11 Feb 2017, at 09:41, lb <liangbin...@126.com> wrote: > > Thank you, Sven > gradually clear. > 1. Symbol as String subclass, only guarantees a symbol object only one in > system, use ==; > 2. keywords (selector name method name) are spectial symbols, without space > or forbided characters; > 3. perform: aSymbol, means perform: aKeyword, > Should we add asKeyword to String, > let > perform: aString asKeyword > not > perform: aString asSymbol ?
Good point, there has been discussion about a Selector class in the past, but I think the conclusion was, more or less, that it was not worth it (too much work/complexity for little gain). > Regards! > > Bing Liang > > At 2017-02-11 15:51:49, "Sven Van Caekenberghe" <s...@stfx.eu> wrote: > >Hi Bing, > > > >Yes, any character is allowed in a Symbol. There is even special syntax that > >allows such Symbols to be represented literally. > > > >'a b' asSymbol. > > > > => #'a b' > > > >Although it might be confusing, I don't see any problem. > > > >The concept of 'meaning' is defined by the user, the usage, not by the > >Symbol itself. A Symbol with a space cannot be a selector (message/method) > >name, but that does not mean a Symbol with a space could not be useful in > >some other context. > > > >Regards, > > > >Sven > > > >> On 11 Feb 2017, at 05:56, lb <liangbin...@126.com> wrote: > >> > >> Hi, > >> I know Symbol is subclass of String. > >> Any string object can become symbol object by sending 'asSymbol' message.. > >> I think symbol must has its meaning in comon use, so the symbol should be > >> composed of alphabet or number ‘without space“. > >> > >> BUT There are not compliant below > >> 1. ' ' asSymbol >>>> no meaning > >> 2. '$%%&' asSymbol >>>> no meaning > >> 3. 'sign' asSymbol = 'sign ' asSymbol >>> false because of space. > >> 3. ' one two three ' asSymbol >>> I think It should > >> become three symbols = #one, #two, #three > >> > >> > >> Mybe my understanding is wrong. > >> > >> Bing Liang > >> > >> > > > > >
