[Swift-user] tutorial/understanding issue 7

[Mihael Hategan]

Inline

On Thu, 2010-10-14 at 12:08 -0500, Daniel S. Katz wrote:

> Continuing my journey through the Swift tutorial
> (http://www.ci.uchicago.edu/swift/guides/tutorial.php), though the
> previous 6 messages are waiting for approval, as I was not a member of
> the swift-users list when I sent them...
> 
> 
> In section 3.5, why can't I do this:
> 
> 
> 
> 
> type messagefile;
> 
> 
> app (messagefile t) greeting (string s[]) {
>     echo s[0] s[1] s[2] stdout=@filename(t);
> }
> 
> 
> messagefile outfile <"q5out.txt">;
> 
> 
> #string words[] = ["how","are","you"];
> string words[];
> words[0] = "how;
> words[1] = "are";
> words[2] = "you";
> 
> 
> outfile = greeting(words);
> 
There is no theoretical reason why you shouldn't be able to do so. It
follows that we are talking about a bug. It was likely not addressed (or
reported) because there is a way to deal with the situation.
> 
> 
> is the issue that swift doesn't know how large to make words[]?
> 
Arrays are dynamic, so not quite. 
> 
> I also tried:
> 
> 
> string words[3];
> 
> 
> but this also didn't work.
> 
A good point. There is, when iterating over an array, a distinction
between an array whose size you know and one whose size is not known
statically. The above type of declaration could be used to provide that
information, and I think it should be added to swift (if missing).
> 
> Do strings need to be assigned when they are declared?  Is this a
> general rule for Swift variables?
> 
No in theory. Variables need to eventually be assigned, otherwise they
are considered "input" variables. But that does not apply to primitives.
So in the case of strings your code should work.

Mihael