It's hard to make things fool proof, fool's are too ingenius.
On Jul 2, 2018 6:14 PM, "Wolf" <wv99...@gmail.com> wrote: > Not so long ago, Florian was proudly bragging about "Pascal does not allow > you to shoot yourself in the foot > <http://www.toodarkpark.org/computers/humor/shoot-self-in-foot.html>" > > What about this little program: > > program Project1; > > var a,b: byte; > begin > a:=1; > b:=a*(-1); > writeln(b); // result: 255 > end. > > > The result is obviously correct, given how the variables are declared. But > there are no compiler warnings / errors that the assignment b:=a*(-1) is > fishy, to put it mildly. And if you are serious about strong typing, it > ought to be illegal, with a suitable complaint from the compiler. > > Who is shooting whom in the foot? > > Wolf > > On 02/07/2018 20:22, Santiago A. wrote: > > El 01/07/2018 a las 10:27, C Western escribió: > > On 29/06/18 21:55, Sven Barth via fpc-pascal wrote: > > More confusingly, if a single variable is used, the expected Max(Double, > Double) is called: > > function Max(a, b: Double): Double; overload; > begin > WriteLn('Double'); > if a > b then Result := a else Result := b; > end; > > function Max(a, b: Single): Single; overload; > begin > WriteLn('Single'); > if a > b then Result := a else Result := b; > end; > > var > v1: Double; > v2: Single; > begin > v1 := Pi; > v2 := 0; > WriteLn(v1); > WriteLn(Max(v1,0)); > WriteLn(Max(v1,0.0)); > WriteLn(Max(v1,v2)); > end. > > Prints: > 3.1415926535897931E+000 > Single > 3.141592741E+00 > Double > 3.1415926535897931E+000 > Double > 3.1415926535897931E+000 > > If this is not a bug, it would be very helpful if the compiler could print > a warning whenever a value is implicitly converted from double to single. > > Well, pascal is a hard typed language, but not that hard in numeric > issues. I think it is a little inconsistent that it implicitly converts > '0.0' to double but '0 to single. > > Nevertheless, I think it is a bug. It doesn't choose the right overloaded > function > > But the main is this: > you have several overload options for max > 1 extended, extended > 2 double, double > 3 single, single > 4 int64, int64 > 5 integer, integer > > When it finds (double, single), why does it choose (single, single) > instead of (double, double)? > The natural behavior should be to widen to the greater parameter, like it > does in expressions. > > > > _______________________________________________ > fpc-pascal maillist - fpc-pascal@lists.freepascal.org > http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal >
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