call
call(x, args...)
If x
is not a Function
, then x(args...)
is equivalent to call(x, args...)
. This means that function-like behavior can be added to any type by defining new call
methods.
Examples
-
Call a function with arguments:
julia> function add_numbers(a, b) return a + b end julia> call(add_numbers, 5, 3) 8
In this example, the
call
function is used to invoke theadd_numbers
function with arguments5
and3
. It returns the sum of the two numbers. -
Call a function-like object:
julia> struct MultiplyByTwo value::Int end julia> (m::MultiplyByTwo)(x) = m.value * x julia> m = MultiplyByTwo(5) julia> call(m, 3) 15
Here, the
call
function is used to invoke the function-like behavior of theMultiplyByTwo
object. Thecall
method defined forMultiplyByTwo
multiplies the object'svalue
field with the argumentx
. - Handle non-function objects:
julia> x = 10 julia> call(x, "Hello, world!") ERROR: MethodError: objects of type Int64 are not callable
If the provided
x
is not a function or a function-like object, an error will be thrown. In this example, callingcall
with an integerx
results in aMethodError
because integers are not callable.
Common mistake example:
julia> call(5, 3)
ERROR: MethodError: objects of type Int64 are not callable
In this example, the mistake is passing an integer 5
as the first argument to call
. Since integers are not callable, a MethodError
is thrown. Make sure to pass a callable object or a function as the first argument to call
.
See Also
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