Am 07.04.2021 um 18:16 schrieb Ryan Joseph via fpc-devel:
On Apr 6, 2021, at 11:34 PM, Sven Barth <pascaldra...@googlemail.com> wrote:
In the second case the compiler will have the non-generic Test(String) due to the
implicit operator as well as Test<LongInt>(LongInt) due to the implicit
specialization. Here it will pick the generic one, because a call without a type
conversion is considered better.
I finally get what you're saying and get the correct results now after moving
my check inside the if/then block. I didn't realize that the operator overload
was causing a type conversion that the overloading system knew about. So the
non-generic still wins unless the type conversion happened due to the operator
overload and then the generic wins.
Writeln(Test('Hello World')); // Test(String)
Writeln(Test(42)); // Test<String>
Writeln(Test(String(42))); // Test(String)
Good. :)
As for $H+ do we really want string literals likes 'ABC' to change? I wouldn't
think so. Here's my string literal type symbol conversion in
create_unamed_typesym I'm using now:
case tstringdef(def).stringtype of
st_shortstring:
newtype:=search_system_type('SHORTSTRING');
st_longstring,
st_ansistring:
newtype:=search_system_type('ANSISTRING');
st_widestring:
newtype:=search_system_type('WIDESTRING');
st_unicodestring:
newtype:=search_system_type('UNICODESTRING');
end;
'Hello World' is parsed as st_shortstring so we use System.ShortString for
specialization. Given that I don't think I need to do anything with $H+.
Yes, we want to change that for two reasons:
- the constant string might be larger than 255 characters
- ShortString is worse for passing as a by-value parameter (which will
be the default after all) than AnsiString or UnicodeString as
ShortString is completely copied while Ansi-/UnicodeString are only
references with reference count adjustments
Also your check is wrong as the def that returns True for is_stringlike
might not be a stringdef. In the case of a constant string it's an
arraydef with ado_ConstantString in arrayoptions (and that's how you can
detect constant strings which *need* this treatment).
Regards,
Sven
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