All symbols within symbol that have the given UDA attribute.
Note: This is not recursive; it will not search for symbols within symbols such as nested structs or unions.
enum Attr; struct A { @Attr int a; int b; } static assert(getSymbolsByUDA!(A, Attr).length == 1); static assert(hasUDA!(getSymbolsByUDA!(A, Attr)[0], Attr));
enum Attr; static struct A { @Attr int a; int b; @Attr void doStuff() {} void doOtherStuff() {} static struct Inner { // Not found by getSymbolsByUDA @Attr int c; } } // Finds both variables and functions with the attribute, but // doesn't include the variables and functions without it. static assert(getSymbolsByUDA!(A, Attr).length == 2); // Can access attributes on the symbols returned by getSymbolsByUDA. static assert(hasUDA!(getSymbolsByUDA!(A, Attr)[0], Attr)); static assert(hasUDA!(getSymbolsByUDA!(A, Attr)[1], Attr));
Finds multiple attributes
static struct UDA { string name; } static struct B { @UDA("X") int x; @UDA("Y") int y; @(100) int z; } // Finds both UDA attributes. static assert(getSymbolsByUDA!(B, UDA).length == 2); // Finds one `100` attribute. static assert(getSymbolsByUDA!(B, 100).length == 1); // Can get the value of the UDA from the return value static assert(getUDAs!(getSymbolsByUDA!(B, UDA)[0], UDA)[0].name == "X");
Checks for UDAs on the aggregate symbol itself
static struct UDA { string name; } @UDA("A") static struct C { @UDA("B") int d; } static assert(getSymbolsByUDA!(C, UDA).length == 2); static assert(getSymbolsByUDA!(C, UDA)[0].stringof == "C"); static assert(getSymbolsByUDA!(C, UDA)[1].stringof == "d");
Finds nothing if there is no member with specific UDA
static struct UDA { string name; } static struct D { int x; } static assert(getSymbolsByUDA!(D, UDA).length == 0);