Am 21.04.2021 um 20:05 schrieb Ryan Joseph via fpc-devel:
On Apr 20, 2021, at 11:38 PM, Sven Barth <pascaldra...@googlemail.com> wrote:
All four string types provide built in > and < operators:
On a side note how do you even make overloads (or type helpers for that matter)
for short strings because String[10] isn't the same type as String[100]?
You need to use named types, though for operators this is less useful,
because the compiler will implicitly convert different ShortString types
to find a suitable operator overload:
=== code begin ===
{$mode objfpc}
type
TString20 = String[20];
TString40 = String[40];
TString60 = String[60];
operator >< (aLeft: TString60; aRight: TString40): TString20;
begin
Result := 'foo';
end;
var
ss10: String[10];
ss20: TString20;
ss40: TString40;
begin
ss10 := ss40 >< ss20;
end.
=== code end ===
For type helpers the compiler is stricter and does not allow the usage
on unnamed variables in that case (this is currently first and foremost
a technical restriction due to how the lookup is done):
=== code begin ===
{$mode objfpc}
type
TString20 = String[20];
TString40 = String[40];
TString60 = String[60];
TString40Helper = type helper for TString40
procedure Test;
end;
procedure TString40Helper.Test;
begin
end;
var
ss40: TString40;
ss40_2: String[40];
ss60: TString60;
begin
ss40.Test; // ok
ss40_2.Test; // not ok
ss60.Test; // not ok
end.
=== code end ===
Regards,
Sven
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