Georg Wrede wrote:
Don wrote:
Georg Wrede wrote:
Don wrote:
bearophile wrote:
This post is mostly for Andrei.
I have played with D2 a bit; probably I'll need months to digest it
and its new Phobos2. While I explore Phobos I'll probably post some
comments/bugs around here.
After reading this:
http://blogs.msdn.com/vcblog/archive/2009/04/22/decltype-c-0x-features-in-vc10-part-3.aspx
I have tried to write a toy implementation of it in D2 (not using
Phobos2 yet):
import std.stdio: writeln;
import std.string: format;
struct Watts {
...
Two things to improve:
1) All structs must have a default built-in opString, a good
representation can be:
StructName(field_value1, field_value2, field_value1, ...).
It's not a perfect textual representation, but it's WAY better than
the current one (currently it shows just the struct name).
(Printing the module name before the struct name is bad, most times
is just noise)
No!
<rant>
toString() is one of the most dreadful features in D. Trying to
slightly improve it is a waste of time -- the whole concept needs to
be redone.
It's horribly inflexible, tedious, and hugely inefficient. What more
could there be to hate?
- the object being called has no context. It doesn't know what
format is desired, for example.
- you can't emulate formatting of built-in types, NOT EVEN int! You
can't do left-align, pad with zeros, include + sign, display in hex.
- it's got no stream concept. Every object has to create and manage
its own buffer, and nobody knows if anyone actually needs it.
It ought to be at least as simple as:
struct Foo(A, B, C){
A[10] a;
B b;
C c;
void toString(Sink sink){
foreach(x; a) sink(x);
sink(b);
sink(c);
}
}
... but it's not, you have to create a silly buffer to put all your
strings in, even if there are 200 million of them and your giant
string is just going to be written to a file anyway.
I'd like to see version(debug) {} put around Object.toString(). It's
a deathtrap feature that's got no business being used other than for
debugging.
</rant>
First of all, printing stuff "struct.toString()" style is for two
things:
o Debugging
o Small throwaway code snippets
The latter mainly being for two purposes:
o Testing quick concepts, trying out library functions, etc.
o For the newbie, when he's learning D, but not output formatting.
No "Real Program" uses this, because there you typically do proper
formatting of the output anyway, and almost never print entire
structs or objects as such. Instead, rather the information that they
represent.
How about something like BigInt? Why can't you just print it out?
?? Why couldn't you?
They're not stored as strings (not Janice's anyway), but I don't
understand the question.
You can write:
int a, b;
a=10; b=20;
writefln("%d %x", a, b);
I'd like to be able to write:
BigInt a, b;
a=10; b=20;
writefln("%d %x", a, b);
and have it behave exactly the same.
BTW to everyone, 'Sink' was not a proposal. I was just saying that
almost anything's better than the current toString().
