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documents changes on byref and bycopy (#21882)

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Juan M Gómez
2023-05-22 16:39:54 +01:00
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doc/manual.md
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@@ -8444,8 +8444,7 @@ is available and a literal dollar sign must be written as ``$$``.
Bycopy pragma
-------------
The `bycopy` pragma can be applied to an object or tuple type and
instructs the compiler to pass the type by value to procs:
The `bycopy` pragma can be applied to an object or tuple type or a proc param. It instructs the compiler to pass the type by value to procs:
```nim
type
@@ -8453,14 +8452,19 @@ instructs the compiler to pass the type by value to procs:
x, y, z: float
```
The Nim compiler automatically determines whether a parameter is passed by value or by reference based on the parameter type's size. If a parameter must be passed by value or by reference, (such as when interfacing with a C library) use the bycopy or byref pragmas.
The Nim compiler automatically determines whether a parameter is passed by value or
by reference based on the parameter type's size. If a parameter must be passed by value
or by reference, (such as when interfacing with a C library) use the bycopy or byref pragmas.
Notice params marked as `byref` takes precedence over types marked as `bycopy`.
Byref pragma
------------
The `byref` pragma can be applied to an object or tuple type and instructs
the compiler to pass the type by reference (hidden pointer) to procs.
The `byref` pragma can be applied to an object or tuple type or a proc param.
When applied to a type it instructs the compiler to pass the type by reference
(hidden pointer) to procs. When applied to a param it will take precedence, even
if the the type was marked as `bycopy`. When using the Cpp backend, params marked
as byref will translate to cpp references `&`.
Varargs pragma
--------------