Reminder to self: remember which of the open source libraries have:
- a generic
TProc<T> alike with an const values: array of const T parameter
- a generic
TProc<T> alike with a const value: T parameter
Google returned none that stuck:
The Delphi RTL does not contain them, and because they forgot setting them up with const parameters, these can never be changed:
[WayBack] System.SysUtils.TProc – RAD Studio API Documentation
TProc = reference to procedure;
TProc<T> = reference to procedure (Arg1: T);
TProc<T1,T2> = reference to procedure (Arg1: T1; Arg2: T2);
TProc<T1,T2,T3> = reference to procedure (Arg1: T1; Arg2: T2; Arg3: T3);
TProc<T1,T2,T3,T4> = reference to procedure (Arg1: T1; Arg2: T2; Arg3: T3; Arg4: T4);
More people are annoyed by this, for instance [WayBack] SysUtils.pas Why parameters of these anonymous not const? TProc = reference to procedure (Arg1: T1; Arg2: T2); TProc = reference … – Jacek Laskowski – Google+
SysUtils.pas
Why parameters of these anonymous not const?
TProc<T1,T2> = reference to procedure (Arg1: T1; Arg2: T2);
TProc<T1,T2,T3> = reference to procedure (Arg1: T1; Arg2: T2; Arg3: T3);
TFunc<T,TResult> = reference to function (Arg1: T): TResult;
TFunc<T1,T2,TResult> = reference to function (Arg1: T1; Arg2: T2): TResult;
Because the designer made a bloody terrible mistake
To be fair, const-ness is a bloody mess in Delphi…
It could have been solved if the const’ness had been seen as a implementation detail by the compiler (which it really is) and made const and non-const signatures assignment compatible.
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+Marco Cantu Any chance of a compiler improvement in the future with regards to relaxing const matching in signature assignments…? :)
I’ve taken to defining
TConstProc<T1,T2> = reference to procedure (const Arg1: T1; const Arg2: T2);for cases where I have full control.
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+Vincent Parrett I’m sure we all have our own versions of this. But it’s not much use for composition of course.
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+David Heffernan Yup. Since it’s unlikely the compiler will every be updated to make const an automatic thing, perhaps they could add const versions to the RTL.
Yeah, we end up making our own versions of these to add the consts in all our projects.
Do file a QP, please. Major releases like the upcoming 10.3 are the time to make interface-breaking changes.
–jeroen
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