SliceMem: change newSliceMem(ptr, len...) to match an example, add another.

libs/arr_ref/slice_mem.nim

@@ -35,7 +35,8 @@ proc newSliceMem*[T, U](container: sink U; p: pointer, byte_len: int): SliceMem[
     ## Create a SliceMem from a container, a pointer, and a length in bytes.
     runnableExamples:
         let x = @[1,2,3,4,5]
-        let s = newSliceMem(x, x[0].addr, x.len * sizeof(x[0]))
+        # You can omit the [int] here because the container is iterable
+        let s = newSliceMem[int](x, x[0].addr, x.len * sizeof(x[0]))
     
     result = SliceMem[T](
         data: cast[ptr UncheckedArray[T]](p),
@@ -48,9 +49,9 @@ proc newSliceMem*[T, U](container: sink U; p: pointer, byte_len: int): SliceMem[
         ),
     )
 
-proc newSliceMem*[T](p: ptr T, byte_len: int, destructor: proc() {.closure, raises: [].}): SliceMem[T] =
+proc newSliceMem*[T](p: ptr T, len: int, destructor: proc() {.closure, raises: [].}): SliceMem[T] =
-    ## Create a SliceMem from a pointer to a type, a length in bytes, and a
+    # Create a SliceMem from a pointer to a type, a length, and a destructor
-    ## destructor closure.
+    # closure.
     runnableExamples:
         let x = createShared(int, 5)
         proc destroy() = deallocShared(x)
@@ -58,7 +59,7 @@ proc newSliceMem*[T](p: ptr T, byte_len: int, destructor: proc() {.closure, rais
     
     result = SliceMem[T](
         data: cast[ptr UncheckedArray[T]](p),
-        byte_len: byte_len,
+        byte_len: len * sizeof(T),
         destroy_ref: (ref CustomDestructor)(destroy: destructor),
     )
 
@@ -85,6 +86,11 @@ proc newSliceMem*[T, U](container: sink U; first, last: pointer): SliceMem[T] =
 
 proc newSliceMem*[T](size: int): SliceMem[T] =
     ## Create a SliceMem from new memory, similar to ArrRef[T].
+    runnableExamples:
+        let s = newSliceMem[int](10)
+        for i,n in s.mpairs:
+            n = (i+1)*11
+        doAssert $s == "SliceMem([11, 22, 33, 44, 55, 66, 77, 88, 99, 110])"
     var r: ref byte
     unsafeNew(r, size * sizeof(T))
     result = SliceMem[T](