Re: eval trouble

[dkcombs@panix.com (David Combs)]

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In article <mailman.17522.1219697977.18990.help-gnu-emacs@gnu.org>,
Lennart Borgman (gmail) <lennart.borgman@gmail.com> wrote:
>David Kastrup wrote:
>> "Lennart Borgman (gmail)" <lennart.borgman@gmail.com> writes:
>> 
>>> Pascal J. Bourguignon wrote:
>>>> "Lennart Borgman (gmail)" <lennart.borgman@gmail.com> writes:
>>>>>> Here is the code that does NOT work:
>>>>>>
>>>>>> (defun mumamo-define-no-mode (mode-sym)
>>>>>>   (let ((mumamo-repl4 (make-symbol (format "mumamo-repl4-%s" mode-sym)))
>>>>> It works if I replace make-symbol with intern. But why does eval care
>>>>> about that?
>>>> eval doesn't care, but how would you be able to refer again to the
>>>> defined thing if you don't have its name in some dictionary?
>>>
>>> Thanks. I see. I thought eval interned the symbol, or perhaps rather
>>> created an interned symbol. In this case it does not do that.
>> 
>> Eval _does_ create an interned symbol.  But it is not EQ to the unique
>> uninterned symbol that make-symbol creates.
>> 
>
>I am a bit confused, but I guess you mean if the symbol does not exist:
>
>(let ((sym (make-symbol "xýzw")))
>  (eval `(progn (setq ,sym 1)
>                (put ',sym 'some 'value))))
>
>(mapatoms (lambda (atom)
>            (when (string= (symbol-name atom)
>                           "xyzw")
>              (error "Found %s" atom))))
>
>
>


Please, why the comma before sym -- quoted, no less:

>                (put ',sym 'some 'value))))

Thanks!

David