Re: [julia-users] I don't understand the behaviour of macros and let.

[Jameson Nash]

You also need to call `esc()` on any symbol you want to "leak" into the
outer scope. Otherwise, it will be turned into a unique symbol name visible
only to the code generated by that macro.


On Sat, Sep 12, 2015 at 5:45 PM Diego Javier Zea  wrote:

> I don't understand why am I getting this error? My macros can not find the
> variables inside *let* blocks. How Can I fix it? Thanks in advance
>
> julia> macro example(var)
>dump(var)
>@eval dump($var)
>end
>
> julia> msg = "hola"
> "hola"
>
> julia> @example msg
> Symbol msg
> ASCIIString "hola"
>
> julia> let m = "hola"
>@example m
>end
> Symbol m
> ERROR: UndefVarError: m not defined
>  in eval_user_input at REPL.jl:64
>  [inlined code] from REPL.jl:93
>  in anonymous at task.jl:68
>
>
>
>
>

Re: [julia-users] I don't understand the behaviour of macros and let.

[Diego Javier Zea]

Thank you Jameson!* esc()* does the trick :)

El sábado, 12 de septiembre de 2015, 21:56:19 (UTC-3), Jameson escribió:
>
> You also need to call `esc()` on any symbol you want to "leak" into the 
> outer scope. Otherwise, it will be turned into a unique symbol name visible 
> only to the code generated by that macro.
>
>
> On Sat, Sep 12, 2015 at 5:45 PM Diego Javier Zea  > wrote:
>
>> I don't understand why am I getting this error? My macros can not find 
>> the variables inside *let* blocks. How Can I fix it? Thanks in advance
>>
>> julia> macro example(var)
>>dump(var)
>>@eval dump($var)
>>end
>>
>> julia> msg = "hola"
>> "hola"
>>
>> julia> @example msg
>> Symbol msg
>> ASCIIString "hola"
>>
>> julia> let m = "hola"
>>@example m
>>end
>> Symbol m
>> ERROR: UndefVarError: m not defined
>>  in eval_user_input at REPL.jl:64
>>  [inlined code] from REPL.jl:93
>>  in anonymous at task.jl:68
>>
>>
>>
>>
>>