Am 24.01.2013 22:26, schrieb Alexander Klenin: > On Fri, Jan 25, 2013 at 7:56 AM, Florian Klämpfl <flor...@freepascal.org> > wrote: >>>> Just an example: what happens with i if I start to delete from s during >>>> the for loop? >>> >>> Exactly the same thing as in the current for-in loop: either a range check >>> error >>> of nothing, depending on what you delete. >> >> How do you ensure this if I delete a char already processed? Will i be >> adjusted? Or will the loop continue to run with an invalid i? > > Depends on whom you mean by "you".
"You": the designers of this extension. > If you mean the programmer who uses > the feature, > then the answer is the usual one -- "by thinking". Or a good possibilty to create hard to find bugs. > If you mean the > compiler, then the answer is also > the usual one -- "you can not". Consider these examples: > > for i := 1 to Length(s) do begin > Writeln(i, ' ', s[i]); > DeleteSomePartOfS; > end; > > i := 1; > for c in s do begin > Writeln(i, ' ', c); > DeleteSomePartOfS; > i += 1; > end; > > for c in s index i do begin > Writeln(i, ' ', c); > DeleteSomePartOfS; > end; > > in all three cases, the effect will be more-or-less the same. In the first two cases the programmer knows that he does something strange, actually he can even adjust i if needed. In the last he might expect that i is always correct because it is a language construct and he has no change to fix i. _______________________________________________ fpc-devel maillist - fpc-devel@lists.freepascal.org http://lists.freepascal.org/mailman/listinfo/fpc-devel
