diff options
Diffstat (limited to 'doc/manual.txt')
| -rw-r--r-- | doc/manual.txt | 33 |
1 files changed, 26 insertions, 7 deletions
diff --git a/doc/manual.txt b/doc/manual.txt index d2fc7e5c9..0a2009961 100644 --- a/doc/manual.txt +++ b/doc/manual.txt @@ -1451,7 +1451,7 @@ But it seems all this boilerplate code needs to be repeated for the ``TEuro`` currency. This can be solved with templates_. .. code-block:: nimrod - template Additive(typ: typeDesc): stmt = + template Additive(typ: typedesc): stmt = proc `+` *(x, y: typ): typ {.borrow.} proc `-` *(x, y: typ): typ {.borrow.} @@ -1459,13 +1459,13 @@ currency. This can be solved with templates_. proc `+` *(x: typ): typ {.borrow.} proc `-` *(x: typ): typ {.borrow.} - template Multiplicative(typ, base: typeDesc): stmt = + template Multiplicative(typ, base: typedesc): stmt = proc `*` *(x: typ, y: base): typ {.borrow.} proc `*` *(x: base, y: typ): typ {.borrow.} proc `div` *(x: typ, y: base): typ {.borrow.} proc `mod` *(x: typ, y: base): typ {.borrow.} - template Comparable(typ: typeDesc): stmt = + template Comparable(typ: typedesc): stmt = proc `<` * (x, y: typ): bool {.borrow.} proc `<=` * (x, y: typ): bool {.borrow.} proc `==` * (x, y: typ): bool {.borrow.} @@ -3323,10 +3323,10 @@ The template body does not open a new scope. To open a new scope a ``block`` statement can be used: .. code-block:: nimrod - template declareInScope(x: expr, t: typeDesc): stmt {.immediate.} = + template declareInScope(x: expr, t: typedesc): stmt {.immediate.} = var x: t - template declareInNewScope(x: expr, t: typeDesc): stmt {.immediate.} = + template declareInNewScope(x: expr, t: typedesc): stmt {.immediate.} = # open a new scope: block: var x: t @@ -3419,7 +3419,7 @@ In templates identifiers can be constructed with the backticks notation: .. code-block:: nimrod - template typedef(name: expr, typ: typeDesc) {.immediate.} = + template typedef(name: expr, typ: typedesc) {.immediate.} = type `T name`* {.inject.} = typ `P name`* {.inject.} = ref `T name` @@ -3480,7 +3480,7 @@ template cannot be accessed in the instantiation context: .. code-block:: nimrod - template newException*(exceptn: typeDesc, message: string): expr = + template newException*(exceptn: typedesc, message: string): expr = var e: ref exceptn # e is implicitly gensym'ed here new(e) @@ -3728,6 +3728,25 @@ instantiation type using the param name: var n = TNode.new var tree = new(TBinaryTree[int]) +When multiple typedesc params are present, they act like a distinct type class +(i.e. they will bind freely to different types). To force a bind-once behavior +one can use a named alias or an explicit `typedesc` generic param: + +.. code-block:: nimrod + + # `type1` and `type2` are aliases for typedesc available from system.nim + proc acceptOnlyTypePairs(A, B: type1; C, D: type2) + proc acceptOnlyTypePairs[T: typedesc, U: typedesc](A, B: T; C, D: U) + +Once bound, typedesc params can appear in the rest of the proc signature: + +.. code-block:: nimrod + + template declareVariableWithType(T: typedesc, value: T) = + var x: T = value + + declareVariableWithType int, 42 + When used with macros and .compileTime. procs on the other hand, the compiler does not need to instantiate the code multiple times, because types then can be manipulated using the unified internal symbol representation. In such context |