• lili (3/3) Sep 21 2019 Hi：
• Paul Backus (3/6) Sep 21 2019 It means that `fn` is looked up in the module's top-level scope.
• Jonathan M Davis (15/23) Sep 21 2019 which includes any top-level imports, so the symbol in question isn't

lili <akozhao tencent.com> writes:

Hi：
    yesterday I saw some d code， where is an .fn() call syntax, 
what is it mean.

Paul Backus <snarwin gmail.com> writes:

On Sunday, 22 September 2019 at 04:15:53 UTC, lili wrote:
 Hi：
    yesterday I saw some d code， where is an .fn() call syntax, 
 what is it mean.

It means that `fn` is looked up in the module's top-level scope.

Source: https://dlang.org/spec/expression.html#identifier

Jonathan M Davis <newsgroup.d jmdavisprog.com> writes:

On Saturday, September 21, 2019 10:32:08 PM MDT Paul Backus via Digitalmars-
d-learn wrote:
 On Sunday, 22 September 2019 at 04:15:53 UTC, lili wrote:
 Hi：

    yesterday I saw some d code， where is an .fn() call syntax,

 what is it mean.

 It means that `fn` is looked up in the module's top-level scope.

 Source: https://dlang.org/spec/expression.html#identifier

which includes any top-level imports, so the symbol in question isn't
necessarily within the module. The key thing is that when a symbol is
preceded by a dot, no local or member symbols are taken into account. It
makes it so that if you have a local or member symbol which has the same
name as a top-level symbol, you're able to directly reference the top-level
symbol without providing the entire module path.

So, for instance, if a socket class had a close method, that close method
could call the C function, close, with .close, whereas otherwise, it would
have to do something like core.sys.posix.unistd.close (at least on POSIX
systems) to call the C function, since if it called close without any kind
of path, it would end up recursively calling the close member function,
because the module-level function is shadowed by the member function.

- Jonathan M Davis