I think I was channeling this line from the Style Guide section of the
manual when I made my earlier comment on preferring functions:
Don’t overuse macros
Be aware of when a macro could really be a function instead.
[then a sensible warning about not using @eval inside a macro]
But I suppose
You're right, and the manual even talks about the using eval to prevent
code reuse. I guess it also depends on whether you are creating a bunch of
functions in a one-time shot, or exposing a function creation interface
that will be called as needed. Your example seems to be a case of the
On Sun, May 31, 2015 at 8:48 AM, Tom Lee m...@tomlee.id.au wrote:
No, in that example you create an anonymous function. I'm not certain on the
semantics, but n effectively points to this nameless function. Anonymous
functions are not as fast as generic ones (at least in 0.3, at least
I'll concede that if you know the function name at runtime, Mauro's
solution may be a little cleaner, especially if it will be called a lot.
There are plenty of examples in Base of @eval being used to define
functions, such as lines 11-18
here:
Actually, it's name is n:
julia function getfn()
return function(); 1; end
end
getfn (generic function with 1 method)
julia const n = getfn()
(anonymous function)
julia n()
1
On Sat, May 30, 2015 at 5:09 PM, David P. Sanders dpsand...@gmail.com
wrote:
El domingo, 31 de mayo
No, in that example you create an anonymous function. I'm not certain on
the semantics, but n effectively points to this nameless function.
Anonymous functions are not as fast as generic ones (at least in 0.3, at
least sometimes) and you cannot add new methods to them for multiple
dispatch (as
But @eval is still a macro, so it is even better to rewrite this without
that:
function getfn()
return function(); 1; end
end
const n = getfn()
On Sat, May 30, 2015 at 2:30 PM David Gold david.gol...@gmail.com wrote:
Something to note about Tom's method is that the name function must be
passed
El domingo, 31 de mayo de 2015, 0:37:45 (UTC+2), Jameson escribió:
But @eval is still a macro, so it is even better to rewrite this without
that:
function getfn()
return function(); 1; end
end
const n = getfn()
This does not give quite the same answer, though, since the function does
Something to note about Tom's method is that the name function must be
passed to gf as a symbol, unlike in the case of a macro. However, in most
cases this slight difference probably will not warrant a macro.
On Friday, May 29, 2015 at 8:58:56 PM UTC-4, Tom Lee wrote:
You don't need to use a
You don't need to use a macro, a function can do this:
julia function gf(n::Symbol = gensym())
@eval function $(n)()
1
end
end
I've also made the n argument optional, with gensym creating a unique name
by default - the newly defined function is returned by gf, so
Like this:
julia macro gf(n)
quote
function $(esc(n))()
1
end
end
end
julia @gf foo
foo (generic function with 1 method)
julia foo()
1
On Thu, 2015-05-28 at 12:06, Vasudha Khandelwal vasudhakhandelw...@gmail.com
wrote:
Can I use macros to generate
Can I use macros to generate functions with names passed as argument to the
macro?
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