System programming in D (Was: The God Language)

[Timon Gehr]

On 12/31/2011 07:50 AM, Walter Bright wrote:
> On 12/30/2011 10:50 PM, Walter Bright wrote:
>> On 12/30/2011 8:34 PM, Timon Gehr wrote:
>>> On 12/31/2011 05:19 AM, Walter Bright wrote:
>>>> On 12/30/2011 8:02 PM, Timon Gehr wrote:
>>>>> On 12/31/2011 04:50 AM, Walter Bright wrote:
>>>>>> Because inevitably someone will write:
>>>>>>
>>>>>> #define FOO a + FOO
>>>>>>
>>>>>> and expect it to work (the correct expansion would be "a + FOO",
>>>>>> not a
>>>>>> stack overflow). The C preprocessor works this way, as do makefile
>>>>>> macros, as Ddoc does.
>>>>>
>>>>> Makes sense, but why is it an issue if expansion is explicit?
>>>>>
>>>>> enum FOO = q{a + FOO};
>>>>>
>>>>> mixin(FOO);
>>>>
>>>> Because the expanded text is then rescanned for further macro
>>>> replacement.
>>>>
>>>
>>> Yes, but in q{a + FOO} there is none.
>>
>> #define FOO a+Foo
>> FOO;
>>
>> What is the text after macro expansion?
>
> Blast, I meant
>
> #define FOO a+FOO
> FOO;

FOO; -> a + FOO;

mixin(FOO~";"); -> a + FOO;

The two do the same thing.