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Diffstat (limited to 'doc/tut2.txt')
| -rw-r--r-- | doc/tut2.txt | 42 |
1 files changed, 21 insertions, 21 deletions
diff --git a/doc/tut2.txt b/doc/tut2.txt index 9d3409164..2ae0f18f6 100644 --- a/doc/tut2.txt +++ b/doc/tut2.txt @@ -35,7 +35,7 @@ Object Oriented Programming =========================== While Nim's support for object oriented programming (OOP) is minimalistic, -powerful OOP technics can be used. OOP is seen as *one* way to design a +powerful OOP techniques can be used. OOP is seen as *one* way to design a program, not *the only* way. Often a procedural approach leads to simpler and more efficient code. In particular, prefering composition over inheritance is often the better design. @@ -77,8 +77,8 @@ section. Inheritance is done with the ``object of`` syntax. Multiple inheritance is currently not supported. If an object type has no suitable ancestor, ``RootObj`` -can be used as its ancestor, but this is only a convention. Objects that have -no ancestor are implicitly ``final``. You can use the ``inheritable`` pragma +can be used as its ancestor, but this is only a convention. Objects that have +no ancestor are implicitly ``final``. You can use the ``inheritable`` pragma to introduce new object roots apart from ``system.RootObj``. (This is used in the GTK wrapper for instance.) @@ -199,7 +199,7 @@ This method call syntax is not restricted to objects, it can be used for any type: .. code-block:: nim - + echo("abc".len) # is the same as echo(len("abc")) echo("abc".toUpper()) echo({'a', 'b', 'c'}.card) @@ -212,7 +212,7 @@ So "pure object oriented" code is easy to write: .. code-block:: nim import strutils - + stdout.writeln("Give a list of numbers (separated by spaces): ") stdout.write(stdin.readLine.split.map(parseInt).max.`$`) stdout.writeln(" is the maximum!") @@ -226,7 +226,7 @@ the same. But setting a value is different; for this a special setter syntax is needed: .. code-block:: nim - + type TSocket* = object of RootObj FHost: int # cannot be accessed from the outside of the module @@ -236,7 +236,7 @@ is needed: proc `host=`*(s: var TSocket, value: int) {.inline.} = ## setter of hostAddr s.FHost = value - + proc host*(s: TSocket): int {.inline.} = ## getter of hostAddr s.FHost @@ -294,15 +294,15 @@ Procedures always use static dispatch. For dynamic dispatch replace the method eval(e: PExpr): int = # override this base method quit "to override!" - + method eval(e: PLiteral): int = e.x method eval(e: PPlusExpr): int = eval(e.a) + eval(e.b) - + proc newLit(x: int): PLiteral = PLiteral(x: x) proc newPlus(a, b: PExpr): PPlusExpr = PPlusExpr(a: a, b: b) - + echo eval(newPlus(newPlus(newLit(1), newLit(2)), newLit(4))) - + Note that in the example the constructors ``newLit`` and ``newPlus`` are procs because they should use static binding, but ``eval`` is a method because it requires dynamic binding. @@ -316,16 +316,16 @@ dispatching: TThing = object of RootObj TUnit = object of TThing x: int - + method collide(a, b: TThing) {.inline.} = quit "to override!" - + method collide(a: TThing, b: TUnit) {.inline.} = echo "1" - + method collide(a: TUnit, b: TThing) {.inline.} = echo "2" - + var a, b: TUnit collide(a, b) # output: 2 @@ -526,7 +526,7 @@ containers: yield n.data add(stack, n.ri) # push right subtree onto the stack n = n.le # and follow the left pointer - + var root: PBinaryTree[string] # instantiate a PBinaryTree with ``string`` add(root, newNode("hello")) # instantiates ``newNode`` and ``add`` @@ -578,7 +578,7 @@ simple proc for logging: proc log(msg: string) {.inline.} = if debug: stdout.writeln(msg) - + var x = 4 log("x has the value: " & $x) @@ -595,7 +595,7 @@ Turning the ``log`` proc into a template solves this problem: template log(msg: string) = if debug: stdout.writeln(msg) - + var x = 4 log("x has the value: " & $x) @@ -622,11 +622,11 @@ via a special ``:`` syntax: close(f) else: quit("cannot open: " & fn) - + withFile(txt, "ttempl3.txt", fmWrite): txt.writeln("line 1") txt.writeln("line 2") - + In the example the two ``writeln`` statements are bound to the ``body`` parameter. The ``withFile`` template contains boilerplate code and helps to avoid a common bug: to forget to close the file. Note how the @@ -739,7 +739,7 @@ Term rewriting macros --------------------- Term rewriting macros can be used to enhance the compilation process -with user defined optimizations; see this `document <trmacros.html>`_ for +with user defined optimizations; see this `document <trmacros.html>`_ for further information. |