I hope Andrei appreciated my efforts :-)
- The non-alphabetical index page 439 is a good idea.
- The page thickness is OK for me.
--------------------
More comments on Chapter 1:
Page 17: using null to represent empty arrays is not good. In D there is []
that's better for this.
P 18: "foo in associativeArray" returns a pointer. So can this work in SafeD
too? Maybe it can be accepted by SafeD is the pointer is not used and just
tested if it's null or not.
P 22: In this code:
Object.factory("stats." ~ arg);
This code is OK, but in my code I'd like to apply the DRY principle and use
something similar to (that keeps workins even if I change the name fo the
module):
Object.factory(__traits(thisModuleName) ~ arg);
This currently works, but it's not nice:
Object.factory(split(to!string({class C {}; return new C;}()), ".")[0] ~
".Foo");
(Probably there are already better ways to do it, but all of them, including
the __traits one can't be used in the first pages of the book, so the book page
is OK).
--------------------
Chapter 2:
P 35: adjacent string concatenation: this is bug-prone, see:
http://d.puremagic.com/issues/show_bug.cgi?id=3827
P 38, first code example: the D strings contain immutable chars as the text
says, but the book has to show this gotcha, that true immutable strings as
Python ones don't have (this code runs):
void main() {
string s = "Hello";
s.length += 1;
}
P 49: the explanations on is() don't seem complete:
is ( Type Identifier : TypeSpecialization, TemplateParameterList )
is ( Type Identifier == TypeSpecialization, TemplateParameterList )
But I think this is for the better, that syntax becomes unreadable.
P 50: The part 2.3.5.3 on function calls is good. I hope dmd will eventually do
what is written here.
P 55: part 2.3.9: there's an error, the concat (~) is not an addition because
it's not commutative, generally:
(s1 ~ s2) != (s2 ~ s1)
P 56, usage examples of 'in':
- LDC has shown to be able to optimize away to nearby associative array lookups
in all situations (and storing the pointer for a much later usage is not a
common usage pattern), and the usage of pointers in SafeD is not easy to do. So
consider returning a more clean boolean and improving the compiler instead.
- I have just filed this bug:
http://d.puremagic.com/issues/show_bug.cgi?id=4463
- For being an usage example it is OK. In D1 I have avoided that if/else using:
typedef double Double1 = 0.0;
So you can just increment the default double initialization.
Now you can probably use:
static struct Double2 { double d = 0.0; alias d this; }
But there's a bug and Double2 can't be used yet as associative array value.
P 57: a small note can be added for the equality among associative arrays.
P 58 part 2.3.12.2: Thanks to Don too those FP exceptions can be loud, this
helps debug code (I can even appreciate the severeExceptions to be switched on
on default in nonrelease builds):
import std.math: FloatingPointControl;
void main() {
FloatingPointControl fpctrl;
fpctrl.enableExceptions(FloatingPointControl.severeExceptions);
double x;
double y = x * 2.0;
}
P 59: using void with && and || is a ugly hack, if I find a line like this in
production code I kill it with fire. This is not a good example to be present
in the D2 reference book:
line == "#\n" && writeln("...");
P 60: this is another bad example, it's a cute trick, but it's bad for
production code:
(predicate ? x : y) += 5
P 61: this is so hard to read that I don't want to see anything similar even in
small script-like programs. The D compiler can even disallow such long chains:
int c = (a = b, b = 7, 8);
Bye,
bearophile
