Huh, you are correct. It's only for keyword arguments that interpolating
the symbol doesn't work. That puts me out of my depth then.
On Sunday, February 8, 2015 at 11:08:16 PM UTC-5, Dominique Orban wrote:
>
> That's why I tried *@eval $(arg)*. In your example, if you change
> *eval(:myarg)* to *@eval $(myarg)*, the call prints *10*.
>
> On Sunday, February 8, 2015 at 10:57:43 PM UTC-5, Josh Langsfeld wrote:
>>
>> At least for why is doesn't work, the eval runs in the scope of the
>> current module, not in the local scope of the function:
>>
>> julia> myarg = "a string"
>> "a string"
>>
>>
>> julia> f(myarg::Int) = println(eval(:myarg))
>> f (generic function with 1 method)
>>
>>
>> julia> f(10)
>> a string
>>
>> I don't know if there is a way to get the value associated with a symbol
>> inside a function.
>>
>> On Sunday, February 8, 2015 at 8:45:55 PM UTC-5, Dominique Orban wrote:
>>>
>>> I'm writing a function that takes optional arguments. Many of them must
>>> be arrays of a certain size. I'd like to perform a quick check of their
>>> size at the top of the function and thought it would be a good use case for
>>> meta programming, but I can't seem to get the syntax right. Here's an
>>> example that hopefully illustrates what I'm trying to do:
>>>
>>> function test(a; x=zeros(5), y=zeros(5))
>>> for arg in {:x, :y}
>>> if length(eval(arg)) != 5 # ERROR: x not defined
>>> error(@eval $(string(arg, " must have length 5")))
>>> end
>>> end
>>> # ...
>>> end
>>>
>>> I tried *@eval $(arg)* in the argument to *length*, but without
>>> success. Line 3 always causes "ERROR: x not defined" to be raised.
>>>
>>> Thanks!
>>>
>>
