Thanks, LeuGim. **`When`** does work. However
[https://nim-lang.org/docs/manual.html#statements-and-expressions-when-statement](https://nim-lang.org/docs/manual.html#statements-and-expressions-when-statement)
still be Greek for me.
* * *
more question I, a lazy none programmer practitioner, met: How to make an
auto-converted type? Sorry, I don't know its exact name. I will explain it as
folows:
for example, in the original functions in DLL, Widecstring type arg is need. So
the actual code should be
proc original_Clang_FunctionA(value: Widecstring) {.cdecl,
importc: "functon1", dynlib: xldll}.
...
proc original_Clang_FunctionZ(value: Widecstring) {.cdecl,
importc: "functon26", dynlib: xldll}.
var value1 = newWideCString(convert("你好", "utf8", "gb2312"))
original_Clang_FunctionA(value1)
or we can make a function
proc s(val: string|Widecstring): Widecstring =
when not type(val) is Widecstring:
return newWideCString(convert(val, "utf8", "gb2312"))
else:
return val
then user writes
original_Clang_FunctionA("你好".s)
...
original_Clang_FunctionZ("世界".s)
...
both are tedious for user.
So We can wrap the DLL function like this:
proc original_Clang_FunctionA(value: Widecstring) {.cdecl,
importc: "functon26", dynlib: xldll}.
proc FunctionA(value: string|Widecstring) =
var value1 = value
when not type(value1) is Widecstring:
value1 = newWideCString(convert(value1, "utf8", "gb2312"))
original_Clang_FunctionA(value1)
then the user only need to write in a clean way:
FunctionA("你好")
However the problem is that we have to supply every wrapped functions for so
many functions, which is a repetitive work for library supplier.
So if there is something like this
type
someString from object(string|Widecstring) =
when not type(someString) is Widecstring:
someString.value = newWideCString(convert(value1, "utf8",
"gb2312"))
someString.type = Widecstring
proc FunctionA(value: someString) {.cdecl,
importc: "functon1", dynlib: xldll}.
...
proc FunctionZ(value: someString) {.cdecl,
importc: "functon26", dynlib: xldll}.
and the user only writes like before
FunctionA("你好")
...
FunctionA("世界")
is this possible? Thanks
