On Sun, 29 Mar 2015 20:29:49 +, bitwise wrote:
The verbosity and blatant disregard for DRY makes me CRY.
See what I did there.. ;)
you can always `alias` it to something funny or obscene.
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I'm a little confused at this point why this doesn't work either:
const(Test) test = new Test(); // fine
test = new Test(); // error
In C++, There is a clear distinction:
const Test *test1 = nullptr; // const before type
test1 = new Test(); // fine
Test
perhaps something like Rebindable could be used.
Looking at Rebindable now, there is a useful example. There
should probably be a mention of this on the const/immutable docs.
For people coming from C++, this will not be obvious.
auto a = Rebindable!(const Widget)(new Widget);
a.y();
bitwise:
I'm a little confused at this point why this doesn't work
either:
const and immutable are rather different between C++ and D, I
suggest you to take a look at the documentation:
http://dlang.org/const-faq.html
Bye,
bearophile
On Sunday, 29 March 2015 at 19:04:30 UTC, anonymous wrote:
Notice how you have that '*' there that allows you to
distinguish the data from the reference.
You can have a mutable pointer to const data in D, too:
struct Test {}
const(Test)* test1 = null;
test1 = new Test; /* fine */
Although, I suppose this is still a step up from C# which has not
const at all =O
On Sunday, 29 March 2015 at 19:13:32 UTC, bitwise wrote:
Interesting, but I still don't understand why D doesn't have
something like this:
const Test test;// or const(Test) test;
test = new Test() // fine, underlaying data is const, the
reference is not
Test const test = new Test();
1) Such placement based syntax is foreign to D.
I would have to agree that this is a strange way to do things in
any language.
The great int* a vs int *a debate...
2) It would be special syntax just for class types.
IMO, it would be worth it
3) It's not how C++ rolls.
`const Test test;`
On Sunday, 29 March 2015 at 18:43:32 UTC, bitwise wrote:
I'm a little confused at this point why this doesn't work
either:
const(Test) test = new Test(); // fine
test = new Test(); // error
In C++, There is a clear distinction:
const Test *test1 = nullptr; // const
On Sunday, 29 March 2015 at 20:29:50 UTC, bitwise wrote:
3) It's not how C++ rolls.
`const Test test;` and `Test const test;` are equivalent in
C++. You need that '*' in C++, too, to make a distinction
between reference and data.
I'm a little confused. I was comparing a C++ pointer-to-class
of const
objects?
You meant to say associative array with const objects as
values. I think the short answer is that you can't. This is a
breaking change, I think, it broke some of my code too. But
perhaps something like Rebindable could be used.
Bye,
bearophile
I insert an item into an associative array of const
objects?
FWIW, it was changed in
https://github.com/D-Programming-Language/dmd/pull/4148
It seems Kenji argues that the first assignment (like in your
case) should be allowed, because it's supposed to be a
construction rather than
I insert an item into an associative array of const
objects?
Generally speaking, you can insert an item in a constructor:
---
class Test{}
const (Test)[string] tests;
static this()
{
tests[test] = new Test();
}
class Bar
{
immutable (Test)[string] tests2
class Test{}
void main()
{
const(Test)[string] tests;
tests[test] = new Test();
}
This code used to work, but after upgrading to dmd 2.067, it no
longer does.
--Error: cannot modify const expression tests[test]
How do I insert an item into an associative array of const
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