[fpc-devel] An extension of fpc language: the BASED construct

Mark Morgan Lloyd markMLl.fpc-devel at telemetry.co.uk
Wed Dec 27 10:12:51 CET 2017

On 26/12/17 23:15, Giuliano Colla wrote:
> Il 26/12/2017 14:27, Mark Morgan Lloyd ha scritto:> What does gdb (and 
> possibly other debuggers) make of this? What currently gdb tells (and 
> any other debugger would tell) is :
> No symbol "Item" in current context.
> Once the appropriate entries are implemented in the debugger symbol 
> table, it will behave like it does in similar conditions, i.e. 
> displaying a value referenced by a pointer. I didn't mention in my ToDo 
> list because I'm a bit lazy, but this too has to be done.

I'm getting uncomfortable with the amount of "magic" required here.

> Is it really 
> appropriate to declare Item as a variable, when it's > really more akin 
> to a macro? It's not different from the declarations:
> myString: string;myObject: TObject;
> where your declaration only reserves a pointer, while the actual string 
> or object will be instantiated only at run time.
> Item is a variable, whose location isn't known at compile time, but will 
> be known only at run time.

Except that you've already said above that "Item" doesn't actually 
exist, while "myString" does even if the compiler etc. knows that it's 
to be implicitly dereferenced.

I'd suggest that this would be better approached either as a 
generalisation of managed types- strings and the rest, or as a final 
resolution of the "with" controversy including full consideration of the 
scope issues.

Mark Morgan Lloyd
markMLl .AT. telemetry.co .DOT. uk

[Opinions above are the author's, not those of his employers or colleagues]

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