On Saturday, 5 February 2022 at 15:10:19 UTC, step8 wrote:
I'm trying to study D programming
Following is code from vibe's example(web_ajax) code:
~~~~
void getDataFiltered(Fields field, string value)
{
auto table = users.filter!((a) => value.length==0 ||
a[field]==value)().array();
render!("createTable.dt", table)();
}
~~~~
I can't understand the expression "(a) =>"，there is no
defination of "a",how does this work?
thanks for help
`(a) => value.length==0 || a[field]==value`
is a https://dlang.org/spec/expression.html#FunctionLiteral (see
e.g. #10 there).
This one is polymorphic, somewhat equivalent to defining a
function such as
`bool func(T)(T a) { return value.length==0 || a[field]==value; }`
(assuming `value` is accessible to `func`).
