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discard """
file: "toop1.nim"
output: "34[]o 5"
"""
# Test the stuff in the tutorial
import macros
type
TFigure = object of TObject # abstract base class:
draw: proc (my: var TFigure) # concrete classes implement this proc
proc init(f: var TFigure) =
f.draw = nil
type
TCircle = object of TFigure
radius: int
proc drawCircle(my: var TCircle) = stdout.writeln("o " & $my.radius)
proc init(my: var TCircle) =
init(TFigure(my)) # call base constructor
my.radius = 5
my.draw = drawCircle
type
TRectangle = object of TFigure
width, height: int
proc drawRectangle(my: var TRectangle) = stdout.write("[]")
proc init(my: var TRectangle) =
init(TFigure(my)) # call base constructor
my.width = 5
my.height = 10
my.draw = drawRectangle
macro `!` (n: expr): stmt =
result = newNimNode(nnkCall, n)
var dot = newNimNode(nnkDotExpr, n)
dot.add(n[1]) # obj
if n[2].kind == nnkCall:
# transforms ``obj!method(arg1, arg2, ...)`` to
# ``(obj.method)(obj, arg1, arg2, ...)``
dot.add(n[2][0]) # method
result.add(dot)
result.add(n[1]) # obj
for i in 1..n[2].len-1:
result.add(n[2][i])
else:
# transforms ``obj!method`` to
# ``(obj.method)(obj)``
dot.add(n[2]) # method
result.add(dot)
result.add(n[1]) # obj
type
TSocket* = object of TObject
FHost: int # cannot be accessed from the outside of the module
# the `F` prefix is a convention to avoid clashes since
# the accessors are named `host`
proc `host=`*(s: var TSocket, value: int) {.inline.} =
## setter of hostAddr
s.FHost = value
proc host*(s: TSocket): int {.inline.} =
## getter of hostAddr
return s.FHost
var
s: TSocket
s.host = 34 # same as `host=`(s, 34)
stdout.write(s.host)
# now use these classes:
var
r: TRectangle
c: TCircle
init(r)
init(c)
r!draw
c!draw()
#OUT 34[]o 5
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