Re: static class vs. static struct
On Monday, 26 January 2015 at 14:02:54 UTC, ref2401 wrote: What's the difference between static class and static struct? What should i use? In simple words, Singleton is a pattern and not a keyword. The Singleton pattern has several advantages over static classes. A singleton allows a class for which there is just one, persistent instance across the lifetime of an application. That means, it created a single instance and that instance (reference to that instance) can be passed as a parameter to other methods, and treated as a normal object. While a static class allows only static methods and and you cannot pass static class as parameter. Full Source: http://net-informations.com/faq/netfaq/singlestatic.htm Vyar
Re: static class vs. static struct
In simple words, Singleton is a pattern and not a keyword. The Singleton pattern has several advantages over static classes. A singleton allows a class for which there is just one, persistent instance across the lifetime of an application. That means, it created a single instance and that instance (reference to that instance) can be passed as a parameter to other methods, and treated as a normal object. While a static class allows only static methods and and you cannot pass static class as parameter. More about. http://net-informations.com/faq/netfaq/singlestatic.htm Lee
Re: static class vs. static struct
On 01/27/2015 08:58 AM, Piotrek wrote:
Nice list. :)
1. static variable
struct A{int a} // no static before declaration
static A s; //note that static is used for struct variable storage class
(lifetime)
static int b;
etc.
2. static declaration
static struct A{int a}; //static used for context unnesting
static int fun(){}; // static used also for removing scope context
Of course that includes static member functions, where the 'this'
pointer is removed.
Actually, static opCall is kind of different because it makes the type
itself callable.
etc.
3. static if
static if(compile_time_cond)
{
//this section of code will be taken into the binary, used for meta
programming
}
Another use of 'static' that means at compile time:
static assert
4. Module initialization and deinitialization:
static this
shared static this
static ~this
shared static ~this
5. Module import:
static import std.stdio;
Ali
Re: static class vs. static struct
On 01/27/2015 08:33 AM, Piotrek wrote: Non-static means nested. Hmm,this can be misleading. Nesting in structs doesn't introduce context pointer. You must be thinking of structs nested inside user-defined types. Structs that are nested inside functions do have the context pointer. Ali
Re: static class vs. static struct
For several times I've met struct(or static struct) usage in Phobos for singleton pattern implementation. Unfortunately now i can remember only core.runtime.Runtime. So I've got a question. Why do Phobos guys use struct or static struct for or singleton pattern implementation? Why don't use static final class for this purpose?
Re: static class vs. static struct
On Tuesday, 27 January 2015 at 09:01:39 UTC, ref2401 wrote: For several times I've met struct(or static struct) usage in Phobos for singleton pattern implementation. Unfortunately now i can remember only core.runtime.Runtime. So I've got a question. Why do Phobos guys use struct or static struct for or singleton pattern implementation? Why don't use static final class for this purpose? I do not think this is a singleton pattern (no instance). I see it much more like namespace in case of core.runtime.Runtime. And yes static final class could do that too but struct looks better than final class and you can disable this on structs
Re: static class vs. static struct
On Tue, 27 Jan 2015 09:40:08 +, Daniel Kozak wrote:
import std.stdio;
import std.conv;
struct S {
@disable this();
}
final class C {
}
void main() {
writeln(C.sizeof);
writeln(S.sizeof);
}
blind guess: vmt with toString() from Object? ;-)
signature.asc
Description: PGP signature
Re: static class vs. static struct
On Tuesday, 27 January 2015 at 09:36:49 UTC, Daniel Kozak wrote:
On Tuesday, 27 January 2015 at 09:01:39 UTC, ref2401 wrote:
For several times I've met struct(or static struct) usage in
Phobos for singleton pattern implementation. Unfortunately now
i can remember only core.runtime.Runtime.
So I've got a question. Why do Phobos guys use struct or
static struct for or singleton pattern implementation? Why
don't use static final class for this purpose?
I do not think this is a singleton pattern (no instance). I see
it much more like namespace in case of core.runtime.Runtime.
And yes static final class could do that too but struct looks
better than final class and you can disable this on structs
import std.stdio;
import std.conv;
struct S
{
@disable this();
}
final class C
{
}
void main() {
writeln(C.sizeof);
writeln(S.sizeof);
}
Re: static class vs. static struct
On Tuesday, 27 January 2015 at 18:24:29 UTC, Ali Çehreli wrote: On 01/27/2015 08:33 AM, Piotrek wrote: Non-static means nested. Hmm,this can be misleading. Nesting in structs doesn't introduce context pointer. You must be thinking of structs nested inside user-defined types. Structs that are nested inside functions do have the context pointer. Ali What you wrote about the structs is true. However I was referring to other thing. I just wanted to emphasize (with my poor English) that also classes and structs *nested in struct* doesn't contain the additional context pointer. As opposed to class nested in class. Then I think we'd better not say that non-static means nested. Piotrek
Re: static class vs. static struct
On Tuesday, 27 January 2015 at 18:18:02 UTC, Ali Çehreli wrote:
On 01/27/2015 08:58 AM, Piotrek wrote:
Nice list. :)
1. static variable
struct A{int a} // no static before declaration
static A s; //note that static is used for struct variable
storage class
(lifetime)
static int b;
etc.
2. static declaration
static struct A{int a}; //static used for context unnesting
static int fun(){}; // static used also for removing scope
context
Of course that includes static member functions, where the
'this' pointer is removed.
Actually, static opCall is kind of different because it makes
the type itself callable.
etc.
3. static if
static if(compile_time_cond)
{
//this section of code will be taken into the binary, used
for meta
programming
}
Another use of 'static' that means at compile time:
static assert
4. Module initialization and deinitialization:
static this
shared static this
static ~this
shared static ~this
5. Module import:
static import std.stdio;
Ali
Thanks for comments, Mr. Professor. On duty as usual ;)
Let me here thank for your book which I've been reading for some
time.
Piotrek
Re: static class vs. static struct
On 01/27/2015 01:33 PM, Piotrek wrote: On Tuesday, 27 January 2015 at 18:24:29 UTC, Ali Çehreli wrote: On 01/27/2015 08:33 AM, Piotrek wrote: Non-static means nested. Hmm,this can be misleading. Nesting in structs doesn't introduce context pointer. Oh, I misread what you wrote. Sorry... classes and structs *nested in struct* doesn't contain the additional context pointer. As opposed to class nested in class. Then I think we'd better not say that non-static means nested. Piotrek Makes sense. Ali
Re: static class vs. static struct
On 01/27/2015 01:44 PM, Piotrek wrote: Let me here thank for your book I am glad that it is useful. which I've been reading for some time. Me too! I browsed the index section to remember the other uses of 'static'. :) Ali
Re: static class vs. static struct
On 01/27/15 10:40, Daniel Kozak via Digitalmars-d-learn wrote:
On Tuesday, 27 January 2015 at 09:36:49 UTC, Daniel Kozak wrote:
On Tuesday, 27 January 2015 at 09:01:39 UTC, ref2401 wrote:
For several times I've met struct(or static struct) usage in Phobos for
singleton pattern implementation. Unfortunately now i can remember only
core.runtime.Runtime.
So I've got a question. Why do Phobos guys use struct or static struct for
or singleton pattern implementation? Why don't use static final class for
this purpose?
I do not think this is a singleton pattern (no instance). I see it much more
like namespace in case of core.runtime.Runtime. And yes static final class
could do that too but struct looks better than final class and you can
disable this on structs
import std.stdio;
import std.conv;
struct S
{
@disable this();
}
final class C
{
}
void main() {
writeln(C.sizeof);
writeln(S.sizeof);
}
D's `class` magically adds a level of indirection, so C.sizeof
gives you just the size of the _reference_.
For the true (ie instance/payload) size you'd have to use
__traits(classInstanceSize, C)
artur
Re: static class vs. static struct
On Tuesday, 27 January 2015 at 09:01:39 UTC, ref2401 wrote:
For several times I've met struct(or static struct) usage in
Phobos for singleton pattern implementation. Unfortunately now
i can remember only core.runtime.Runtime.
So I've got a question. Why do Phobos guys use struct or static
struct for or singleton pattern implementation? Why don't use
static final class for this purpose?
You probably saw static member function.
Please take the following with a big grain of salt as I took it
out of my head:
We can divide the D static keyword usage into 3 types:
1. static variable
struct A{int a} // no static before declaration
static A s; //note that static is used for struct variable
storage class (lifetime)
static int b;
etc.
2. static declaration
static struct A{int a}; //static used for context unnesting
static int fun(){}; // static used also for removing scope context
etc.
3. static if
static if(compile_time_cond)
{
//this section of code will be taken into the binary, used for
meta programming
}
I don't think there is much (if any) use of static (type 1) for
singleton.
Piotrek
Re: static class vs. static struct
On Monday, 26 January 2015 at 21:55:19 UTC, anonymous wrote: On Monday, 26 January 2015 at 21:33:10 UTC, Piotrek wrote: On Monday, 26 January 2015 at 14:11:32 UTC, bearophile wrote: Non-static structs/classes have an extra pointer. Bye, bearophile Since when structs have an extra pointer? Maybe you are talking about nested structs? Non-static means nested. Hmm,this can be misleading. Nesting in structs doesn't introduce context pointer. But I agree that if we take into account a hypothetical inferred static attribute for nesting in struct and the module scope cases, then the static and non-static classification looks the most suitable. Piotrek
static class vs. static struct
What's the difference between static class and static struct? What should i use?
Re: static class vs. static struct
On Monday, 26 January 2015 at 14:02:54 UTC, ref2401 wrote: What's the difference between static class and static struct? What should i use? Non-static structs/classes have an extra pointer. Static ones don't have it, so their differences are the usual ones: a class is used by reference and they are often on the heap, while a struct is handled by value (or pointer to value). A class has two extra hidden fields. Bye, bearophile
Re: static class vs. static struct
On Monday, 26 January 2015 at 21:33:10 UTC, Piotrek wrote: On Monday, 26 January 2015 at 14:11:32 UTC, bearophile wrote: Non-static structs/classes have an extra pointer. Bye, bearophile Since when structs have an extra pointer? Maybe you are talking about nested structs? Non-static means nested.
Re: static class vs. static struct
On Monday, 26 January 2015 at 14:11:32 UTC, bearophile wrote: Non-static structs/classes have an extra pointer. Bye, bearophile Since when structs have an extra pointer? Maybe you are talking about nested structs? Piotrek
