On 07/12/2010 03:04 AM, Lars Tandle Kyllingstad wrote:
(Sorry, sent this to Andrei's private address. Resending to list.)
That sounds like a good idea. Should fmt include the '%' character of
the format specifier?
I'd think so. Also, types could define their own format specifiers if
they want to.
BTW I've changed the grammar of the format specifiers to allow unlimited
nesting. A format string may contain a nested format string by enclosing
it in %( and %). The intent is to print elaborate types comfortably. For
example, this:
int[string] a = ["abc":1, "def":5];
writefln("Here's the map:\n"
"%(=== %2$ is mapped by %1$ ===\n%) ===\n\nThat was it", a);
produces:
Here's the map:
=== 1 is mapped by abc ===
=== 2 is mapped by def ===
(I've also showcased positional parameters.) Note how the nested
specifier is used for each <key,value> pair in the map. The last time
around the trailing specifier is not printed in order to allow e.g.
printing arrays without a trailing comma. This time I did want the
trailing portion to be present for the last element, so I added it after
the nested specifier.
The format string above is parsed correctly but the current version
doesn't support associative arrays yet.
Now getting back to types defining their own format specifiers, for
example Data could define its own spec that understands %D, %M, and %Y.
Then you could print stuff like this:
Date d;
double x;
writefln("I paid $%g on %(%M/%D/%Y%)", x, d);
producing:
I paid $5 on 07/12/2010
The nested specifier is passed to Date's toString function along with a
delegate that writes to the standard output.
Andrei
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