| A bit deeper insight into Nim's procedures. | |
| Overloading | |
| Multiple procedures with the same name can be declared, providing that their number and/or types of arguments differ. |
proc what_is(a: int) = echo "an int"
proc what_is(a, b: int) = echo "two ints"
proc what_is(a: int, b: float) = echo "an int and a float"
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what_is(3)
what_is(3, 6)
what_is(4, 8.99)
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| Variadic procedures | |
A procedure with variadic number of arguments can be defined
using varargs statement.
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proc int_sum(numbers: varargs[int]): int =
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| In the procedure, varargs argument acts as an array. |
echo numbers
for number in numbers:
result = result + number
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echo int_sum(5, 5, 2, 2, 1)
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| Mutable arguments | |
Proc arguments are immutable. They can be made mutable by
declaring it with var statement.
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proc half(number: var float) =
number = number / 2
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Notice how half proc has no return type, and my_number variable
is modified directly.
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var my_number: float = 25
half my_number
echo "My number is ", my_number
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| Named arguments | |
A procedure with first and second arguments.
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proc concat(first, second: string) = echo first & second
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| When calling a proc, arguments can be addressed by name. |
concat(first="cool", second=" and good")
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| When addressing arguments by name, their order does not matter. |
concat(second=" and well", first="alive")
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| Naming and not-naming arguments can mix. Note that in such cases, order of the not-named arguments is important. |
concat("nice", second=" and easy")
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| Default argument values | |
| Proc arguments can be initialized with a default value. |
proc divide(number: float = 10, divisor = 2.0): float =
number / divisor
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| Default value is used if argument is not specified. |
echo divide(12) # using default divisor
echo divide(divisor = 4) # using default number
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$ nim c -r procedures2.nim an int two ints an int and a float [5, 5, 2, 2, 1] 15 My number is 12.5 cool and good alive and well nice and easy 6.0 2.5 |
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