Re: How to test that the IP port is reachable?
On Saturday, 6 April 2019 at 03:24:04 UTC, FrankLike wrote:
Hi,everyone,...
Do you have some better code than this?
import std.stdio;
import std.socket;
void main()
{
testIPPort();
}
bool testIPPort()
{
try
{
auto results =
getAddressInfo("127.0.0.1",AddressInfoFlags.NUMERICHOST);
auto sock = new Socket(results[0]);
auto address = getAddress("127.0.0.1",8080);
sock.connect(address[0]);
writeln(address," connect ok");
return true;
}
catch(SocketException e)
{ return false;
}
}
---
Thanks.
Re: Block statements and memory management
On Saturday, 16 March 2019 at 15:53:26 UTC, Johan Engelen wrote:
On Saturday, 16 March 2019 at 03:47:43 UTC, Murilo wrote:
Does anyone know if when I create a variable inside a scope as
in
{int a = 10;}
it disappears complete from the memory when the scope
finishes? Or does it remain in some part of the memory? I am
thinking of using scopes to make optimized programs that
consume less memory.
Others have made good points in this thread, but what is
missing is that indeed scopes _can_ be used beneficially to
reduce memory footprint.
-Johan
I would like to thank everyone for your help, those informations
were very helpful.
How to test that the IP port is reachable?
Hi,everyone,
How to test that the IP port is reachable?
In C,you can do this like that, what should I do in D?
/* C Code*/
https://blog.csdn.net/zhangyingchuang/article/details/51957552
#include
#include
#include
#include
#include /* inet(3) functions */
#define bool int
#define false 0
#define true 1
bool checkIPandPort(const char* ip, const char* port) {
struct sockaddr_in addr;
int fd = socket(AF_INET, SOCK_STREAM, 0);
memset(&addr, 0, sizeof(addr));
addr.sin_family = AF_INET;
addr.sin_port = htons(atoi(port));
addr.sin_addr.s_addr = inet_addr(ip);
if (connect(fd, (struct sockaddr *) &addr, sizeof(struct
sockaddr)) < 0) {
printf("connect error \n");
return false;
}
return true;
}
--
But how to do it in D?
Thanks.
Re: Undescriptive linker error. (bug?)
On Friday, 5 April 2019 at 22:08:50 UTC, Adam D. Ruppe wrote: Weird combination of cases that maybe should be illegal. It errors with the highly descriptive errormessage: app.obj(app) Error 42: Symbol Undefined __D8mymodule3BarFZ3fooMFZCQx3Foo Error: linker exited with status 1
Re: Undescriptive linker error. (bug?)
On Friday, 5 April 2019 at 21:59:35 UTC, Sjoerd Nijboer wrote:
Foo Bar()
{
Foo foo();
It looks like the compiler is treating that as a function
prototype without a body (that just happens to be nested in
another function).
return foo;
And then, this foo is given the optional parens treatment, as if
it was a call to foo() of the given function, which is why the
linker complains.
Weird combination of cases that maybe should be illegal.
Undescriptive linker error. (bug?)
module mymodule;
class Foo{}
Foo Bar()
{
Foo foo();
return foo;
}
int main()
{
auto foo = Bar();
return 0;
}
This code doesn't compile with a linker error that there's a
missing symbol for `Foo Bar()` on windows.
After all, `Foo foo();` isn't legitimate D.
But why does it return a linker error?
shouldn't it give an error that is more descriptive about a class
instance being wrong?
I feel like this would be a common thing people try to write.
Especially in templates this would become difficult to narrow
down.
Re: Using opOpAssign, cannot assign sequence
On Friday, 5 April 2019 at 13:59:27 UTC, Alex wrote: class X(T) void opOpAssign(string op)(T d) If T has more than length of one then x += We can work around this but it seems to me that we should be able to get it to work in some way x += Alias!(a,b,c) fails to package it up as do all other things I have tried. Works for me if you make opOpAssign a variadic template: void opOpAssign(string op, Args...)(Args args) Full example: https://run.dlang.io/is/dPk3BN
Re: Using opOpAssign, cannot assign sequence
On 05.04.19 16:00, Alex wrote:
I was thinking using tuple would work(of course is longer than Add but
would allow for a more general approach, it would require automatic
unpacking though and so doesn't work.
`tuple` works for me:
import std.typecons: tuple;
class X(T ...)
{
void opOpAssign(string op)(T d) {}
}
void main()
{
auto x = new X!(int, float, string);
int a = 42;
float b = 4.2;
string c = "foo";
x += tuple(a, b, c);
}
== comparison of string literals, and their usage
Hello,
Since literal strings are interned (and immutable), can I count on the fact that
they are compared (==) by pointer?
Context: The use case is a custom lexer for a custom language. I initially
wanted to represent lexeme classes by a big enum 'LexClass'. However, this makes
me write 3 times all constant lexemes (keywords and keysigns):
1- in the enum of lexeme classes
2- in an array of constants (for the contant-scanning func)
3- in an associative array mapping constants to their classes
However, if literal strings are compared by equality, then they are kinds of
Scheme or Ruby symbols: read enum values representing *cases*, which is exactly
what I need. I would thus use the constants' strings themselves as lexeme
classes... the parser would not be slown down.
What do you think?
--
diniz {la vita e estranj}
Re: Overloads not returning appropriate info. [Field reflunkory]
BTW `T.stringof` is usually a bug waiting to happen. You are using mixin in a lot of places where you shouldn't be and this is going to lead to name conflicts, import problems, and more. Just use `T`. If you need a member, use __traits(getMember, T, "name").
Re: Overloads not returning appropriate info. [Field reflunkory]
On Friday, 5 April 2019 at 14:38:21 UTC, Alex wrote:
No one has a clue about this?
Your code has a lot of layers to unfold, but instead let me just
show you a working example and then maybe you can fix your own
code:
---
class A {
void foo(int a) {}
void foo(int b, int c) {}
}
void main() {
import std.stdio;
foreach(overload; __traits(getOverloads, A, "foo")) {
writeln(typeof(overload).stringof);
static if(is(typeof(overload) Params == __parameters))
static foreach(idx, _; Params) {{
alias param = Params[idx .. idx + 1];
writeln("\t", __traits(identifier, param));
}}
}
}
---
I don't know if your bug is in your code or in std.traits or
what, but this example works and prints out
void(int a)
a
void(int b, int c)
b
c
The one bizarre thing is the `param = Params[idx .. idx + 1]`
bit. I wrote a little about this for parameter attributes too
http://dpldocs.info/this-week-in-d/Blog.Posted_2019_02_11.html#how-to-get-uda-on-a-function-param
but it also applies to getting the identifier out.
Re: gtkDcoding Blog: Post #0024 - Switch and LightSwitch
On Friday, 5 April 2019 at 14:05:55 UTC, Russel Winder wrote: I get the feeling this blog is going to become an important tutorial resource for people wanting to do GtkD stuff with D. Given D and GtkD is currently the best way of writing Gtk+ applications, this blog is a great resource. Thanks for the kind words, Russell. I certainly won't mind if that's where this goes. It's nice to feel like I'm contributing something of value.
Re: template with enum parameter doesn't compile
On Friday, 5 April 2019 at 14:52:05 UTC, lithium iodate wrote: You are just having a little issue with operator precedence there. Your code attempts to get the member `A` from `MyClass!MyEnum`, if you add braces around it, it'll work just fine `MyClass!(MyEnum.A)`. That's really funny acutally. It works. Thank you!
Re: template with enum parameter doesn't compile
On Friday, 5 April 2019 at 14:47:42 UTC, Sjoerd Nijboer wrote:
So the following code doesn't compile for some reason, and I
can't figure out why.
enum MyEnum { A, B, C }
class MyClass(MyEnum myEnum)
{
/*...*/
}
int main()
{
MyClass!MyEnum.A a;
}
The error: Error: template instance `MyClass!(MyEnum)` does
not match template declaration `MyClass(MyEnum myEnum)`
pops up, no matter what I do.
You wrote:
MyClass!MyEnum.A a;
Which is equivalent to
MyClass!(MyEnum).A a;
What you want is
MyClass!(MyEnum.A) a;
Re: template with enum parameter doesn't compile
On Friday, 5 April 2019 at 14:47:42 UTC, Sjoerd Nijboer wrote: So the following code doesn't compile for some reason, and I can't figure out why. The error: Error: template instance `MyClass!(MyEnum)` does not match template declaration `MyClass(MyEnum myEnum)` pops up, no matter what I do. I'm quite puzzled actually You are just having a little issue with operator precedence there. Your code attempts to get the member `A` from `MyClass!MyEnum`, if you add braces around it, it'll work just fine `MyClass!(MyEnum.A)`.
template with enum parameter doesn't compile
So the following code doesn't compile for some reason, and I
can't figure out why.
enum MyEnum { A, B, C }
class MyClass(MyEnum myEnum)
{
/*...*/
}
int main()
{
MyClass!MyEnum.A a;
}
The error: Error: template instance `MyClass!(MyEnum)` does not
match template declaration `MyClass(MyEnum myEnum)`
pops up, no matter what I do.
I'm quite puzzled actually
Re: Overloads not returning appropriate info. [Field reflunkory]
No one has a clue about this?
Re: gtkDcoding Blog: Post #0024 - Switch and LightSwitch
I get the feeling this blog is going to become an important tutorial resource for people wanting to do GtkD stuff with D. Given D and GtkD is currently the best way of writing Gtk+ applications, this blog is a great resource. On Fri, 2019-04-05 at 13:44 +, Ron Tarrant via Digitalmars-d-learn wrote: > Since the forum seems to have trouble with replies to existing > posts, for now I'll be doing a separate post for each. Hope that > doesn't get anyone's nose out of joint. > > Anyway... > > Today we explore the GTK Switch widget with two examples, a > simple one and a complex one. Enjoy. -- Russel. === Dr Russel Winder t: +44 20 7585 2200 41 Buckmaster Roadm: +44 7770 465 077 London SW11 1EN, UK w: www.russel.org.uk signature.asc Description: This is a digitally signed message part
Re: Using opOpAssign, cannot assign sequence
On Friday, 5 April 2019 at 13:59:27 UTC, Alex wrote:
class X(T)
void opOpAssign(string op)(T d)
If T has more than length of one then
x +=
We can work around this but it seems to me that we should be
able to get it to work in some way
x += Alias!(a,b,c)
fails to package it up as do all other things I have tried.
void Add(Ts d) { opOpAssign!("+")(d); }
Then x.Add(a,b,c) works fine.
But of course defeats the entire purpose of opOpAssigns short
hand notation.
I was thinking using tuple would work(of course is longer than
Add but would allow for a more general approach, it would require
automatic unpacking though and so doesn't work.
Using opOpAssign, cannot assign sequence
class X(T)
void opOpAssign(string op)(T d)
If T has more than length of one then
x +=
We can work around this but it seems to me that we should be able
to get it to work in some way
x += Alias!(a,b,c)
fails to package it up as do all other things I have tried.
void Add(Ts d) { opOpAssign!("+")(d); }
Then x.Add(a,b,c) works fine.
But of course defeats the entire purpose of opOpAssigns short
hand notation.
Re: gtkDcoding Blog: Post #0024 - Switch and LightSwitch
On Friday, 5 April 2019 at 13:44:35 UTC, Ron Tarrant wrote: Since the forum seems to have trouble with replies to existing posts, for now I'll be doing a separate post for each. Hope that doesn't get anyone's nose out of joint. Anyway... Today we explore the GTK Switch widget with two examples, a simple one and a complex one. Enjoy. I think I can get away with one repost so, here's the link: http://gtkdcoding.com/2019/04/05/0024-switch-and-light-switch.html
gtkDcoding Blog: Post #0024 - Switch and LightSwitch
Since the forum seems to have trouble with replies to existing posts, for now I'll be doing a separate post for each. Hope that doesn't get anyone's nose out of joint. Anyway... Today we explore the GTK Switch widget with two examples, a simple one and a complex one. Enjoy.
