Hello Michael!

You wrote 2010-08-09 [Proposal: Enhanced replacement for assignment operators]:

BTW.: are there "inout" Parameters that are set on entry and written on exit of a procedure, but not modified during the course of the procedure ?

One could propose a new kinds of parameter transmission: copy-in-copy-out and copy-out. In Ada this is a valid method to transmit scalar parameters (as a alternative to reference ("var") parameters). See http://archive.adaic.com/standards/83lrm/html/lrm-06-02.html These kinds of parameter transmission can be used for properties.

Jasper
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You should at least have used the 1995 version. Ada83 is pretty outdated, even here[tm], considering that Ada2005 compilers are available for about five years now. :D

<http://www.adahome.com/rm95/rm9x-06-02.html>

These kinds of parameter transmission can be used for properties.

Well, it would involve a function call to the getter upon entry and another one to the setter upon exit. So it would be much more than just a by-copy transfer (which usually is nothing more than just using a register holding the value instead of a pointer to the actual memory location).

Vinzent.

Hello Vinzent!

You wrote 2010-08-09:

You should at least have used the 1995 version. Ada83 is pretty outdated, even here[tm], considering that Ada2005 compilers are available for about five years now. :D <[http://www.adahome.com/rm95/rm9x-06-02.html]>

You're right. I was lazy. This was the first report I've found. Has something changed for the specs of copy-[in]-out-parameters?

...but only if the properties are implemented via functions. Nevertheless it works whereas a simple reference parameter does not directly, and that's the point of the proposal.

Copy-in-out-parameters can be simulated via a temporary variable which is transferred by reference, like the example I've given for op:= for properties, i.e. tmp:=obj.read_prop; function_call(tmp); obj.write_prop:=tmp;. Probably this simulation is too good and kills the proposal. On the other hand real copy-in-out-parameters can sometimes be a tad faster than reference-parameters...

Regards
Jasper
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Yes, the rules have relaxed a bit, but not substantially. The biggest change was that Ada95 made out-mode parameters readable, in Ada83 they were write-only, which many people considered a bit awkward. But that's a language detail which wouldn't concern us in FPC, out mode parameters are already read-write, and there's no reason to "fix" that.

Yes. In that way, properties would behave like normal variables again. I'd like that. ;) But there was a reason, why FPC doesn't support that anymore.

Vinzent.