Fantastic - thanks a lot!
The final form of the macro is then the following:
macro quickload(m)
_m = Expr(:quote, m)
quote
if isdefined(:LastMain) && isdefined(LastMain, $_m)
using LastMain.$m
else
using $m
end
end
end
This works very well - except that I have to define it in each new
workspace… Adding it to .juliarc.jl does make it available on start, but
after workspace() it’s not available anymore, and kind-of looses its point…
Any suggestions?
// T
On Sunday, July 26, 2015 at 12:58:28 AM UTC+2, David Gold wrote:
This seems to work:
>
> julia> macro foo(bar)
> _bar = Expr(:quote, bar)
> res = Expr(:call, :isdefined, :($_bar))
> return res
> end
>
> julia> macroexpand(:( @foo(baz) ))
> :(isdefined(:baz))
>
>
>
> On Saturday, July 25, 2015 at 6:30:08 PM UTC-4, Tomas Lycken wrote:
>>
>> Hi everybody!
>>
>> Is there a way to use a macro argument as an actual Symbol in the quote
>> that the macro returns? The following can hopefully help explaining what I
>> want:
>>
>> ```
>> julia> macro foo(bar)
>> :(isdefined($bar))
>> end
>>
>> julia> macroexpand(:(@foo baz))
>> :(isdefined(baz)) # I had hoped for :(isdefined(:baz)) - with :baz
>> instead of baz
>> ```
>>
>> I've tried various combinations of interpolation, escaping and passing
>> arguments to `symbol`, but to no avail. Is there a way to accomplish this?
>>
>> --- Actual use case below ---
>>
>> I noticed a very common pattern in my workflow that I wanted to abstract
>> away to make it quicker and easier:
>>
>> *I want to load module X. If it's in LastMain, it's much faster to get it
>> from there, but otherwise I need to load it from scratch.*
>>
>> I can easily write code that does this. Take, for example, Gadfly:
>>
>> ```
>> (isdefined(:LastMain) && isdefined(LastMain, :Gadfly) && using
>> LastMain.Gadfly) || using Gadfly
>> ```
>>
>> When I execute that code, Gadfly will load from LastMain if available
>> there, and from scratch otherwise. And it won't error out if I haven't
>> called `workspace()` at all yet. Perfect! But having to type that for each
>> module I want to use the workflow for is a hassle - what if `@quickload
>> Gadfly` would do the same thing? This is my attempt so far:
>>
>> ```
>> julia> macro quickload(m)
>> :((isdefined(:LastMain) && isdefined(LastMain, $m #= what do I put
>> here?=#) && using LastMain.$m) || using $m)
>> end
>>
>> julia> macroexpand(:(@quickload Gadfly))
>> :((isdefined(:LastMain) && isdefined(LastMain,Gadfly #= <-- ...to make
>> that :Gadfly instead of Gadfly =#)) && using LastMain.Gadfly || using
>> Gadfly)
>>
>> ```
>>
>> Thanks in advance!
>>
>> // T
>>
>
