macro mymac(args...)
typname = esc(args[1])
priv_typname= esc(string("priv_",args[1]))
#code
code = quote
#create a type
eval(parse(string("type ", $(priv_typname), " end")))
end
return code
end
Here is the macro,
and i don't still understand what is going wrong?
and I also have another question, is it a good idea to use eval within a
macro?
Thanks
On Tuesday, October 20, 2015 at 12:14:37 PM UTC-7, Isaiah wrote:
>
> Please do work through the examples in the Metaprogramming section of the
> manual to learn how to take apart and reassemble expressions to do what you
> need:
>
> http://docs.julialang.org/en/release-0.4/manual/metaprogramming/
>
> There are tools (such as `macroexpand`) introduced in the manual that will
> help you debug this kind of issue.
>
> In general, when asking questions on the list, please:
> - search for previous discussions (such as this one:
> https://groups.google.com/forum/#!searchin/julia-users/type$20macro/julia-users/r9sGn-k7SDw/Xm0nKsKBBJYJ
> )
> - provide a complete example. "this is what i am doing in the macro" does
> not provide enough context.
>
> Thanks!
>
> On Tue, Oct 20, 2015 at 3:02 PM, <[email protected] <javascript:>> wrote:
>
>> Hi fellows,
>>
>> Question 1:
>>
>> I am trying to generate a type in a macro and expect to see it in the
>> calling context.
>> this is what i am doing in the macro:
>> code = quote eval(parse(string("type ", $(priv_typname), " end"))) end
>>
>> here is what is returned from the macro
>> eval(parse(string("type ",$(Expr(:escape, "priv_Eq"))," end")))
>>
>> but in the julia shell, when i try to do this :
>>
>> julia> a = priv_Eq()
>> ERROR: UndefVarError: priv_Eq not defined
>>
>> can somebody tell me why and what I am doing wrong?
>>
>>
>> Question 2:
>>
>> I am also trying to generate a parametrized type like:
>>
>> type Eq{T,S}
>> end
>>
>> any suggestions to append the type_params to the type programmatically?
>>
>> Thanks
>>
>>
>>
>>
>>
>>
>
