Re: Mimicking a shell
On Sunday, 29 December 2019 at 17:03:14 UTC, Jan wrote: Hi, Is there a way to forward all input and output from a shell? This implies that e.g. pressing the left arrow on the keyboard is immediately being forwarded to the shell and that the output from a shell would be *exactly* the same as output from my D program (that would include the prompt and VGA colouring). Kind regards, Jan IMHO, this is kinda what you need: https://github.com/greenduck/shell-tunnel/blob/master/shell-tunnel.c Sorry, this code is in C, but converting it to D would be fairly straight forward.
Re: What is the point of a synchronized lock on a single return statement?
On Monday, 25 November 2019 at 08:22:17 UTC, Andrej Mitrovic
wrote:
From:
https://github.com/dlang/phobos/blob/10b9174ddcadac52f6a1ea532deab3310d3a8c03/std/concurrency.d#L1913-L1916:
-
///
final @property bool isClosed() @safe @nogc pure
{
synchronized (m_lock)
{
return m_closed;
}
}
-
I don't understand the purpose of this lock. The lock will be
released as soon as the function returns, and it returns a copy
of a boolean anyway. Am I missing something here?
I think this code can be rewritten as
---
final @property bool isClosed() @safe @nogc pure
{
bool ret;
synchronized (m_lock)
{
ret = m_closed;
}
return ret;
}
---
Normally, if the memory location of m_closed is aligned, the
assignment to 'ret' should be atomic, however if you cannot make
assumptions about alignment, the access should be protected.
Re: gtkDcoding Facelift
On Sunday, 23 June 2019 at 10:55:52 UTC, Ron Tarrant wrote: Stage 1 is now complete. Blog entries are color-associated in an effort to make things more visual. Each topic also has its own avatar. Points to anyone who can figure out why each avatar is associated with its topic. https://gtkdcoding.com/ Great work, thank you !
Re: Singleton in Action?
On Saturday, 2 February 2019 at 19:23:58 UTC, Ron Tarrant wrote: Thanks for the replies, fellow programmers. (generic, unisex, PC, and all-encompassing) If I could trouble someone for a complete working example so I have something to study, that would be excellent. I think that's what you really need: [1] https://davesdprogramming.wordpress.com/ [2] https://www.youtube.com/watch?v=ZHmIAdlNtiM
Re: Reverse and sort array elements
On Tuesday, 18 December 2018 at 12:07:37 UTC, Andrey wrote:
Hi,
Have array:
enum array = ["qwerty", "a", "baz"];
Need to reverse and sort array elements to get this result:
[a, ytrewq, zab]
Did this:
enum result = array.map!(value => value.retro()).sort();
Got:
Error: template std.algorithm.sorting.sort cannot deduce
function from argument types !()(MapResult!(__lambda1,
string[])), candidates are:
/usr/include/dmd/phobos/std/algorithm/sorting.d(1849,1):
std.algorithm.sorting.sort(alias less = "a < b", SwapStrategy
ss = SwapStrategy.unstable, Range)(Range r) if ((ss ==
SwapStrategy.unstable && (hasSwappableElements!Range ||
hasAssignableElements!Range) || ss != SwapStrategy.unstable &&
hasAssignableElements!Range) && isRandomAccessRange!Range &&
hasSlicing!Range && hasLength!Range)
How to solve the problem?
Did you try this ?
import std.stdio;
import std.algorithm;
import std.range;
import std.conv;
void main()
{
enum input = ["qwerty", "a", "baz"];
enum output = input.map!(value =>
value.retro().to!string()).array.sort();
writeln(input);
writeln(output);
}
Re: How to list all process directories under /proc/
On Sunday, 17 September 2017 at 08:15:58 UTC, Ky-Anh Huynh wrote:
Hi,
I want to list all processes by scanning /proc/. The following
code doesn't work
[code]
foreach (string fstatm; dirEntries("/proc/", "[0-9]*",
SpanMode.shallow)) {
writefln("pid %s", fstatm);
}
[/code]
as it only list a few entries before exiting
[code]
pid /proc/9
pid /proc/935
pid /proc/9146
pid /proc/9149
pid /proc/9150
pid /proc/9151
pid /proc/9756
pid /proc/9759
pid /proc/9760
pid /proc/9761
[/code]
I don't want to use `SpanMode.depth` or `SpanMode.breadth`
because it will scan so deeply and there would be a permission
problem.
Any ideas?
Thanks a lot
Are you familiar with libprocps ?
Maybe you had better make use of this library, or, at least, peek
into its code, for reference.
Re: real simple delegate question.
On Saturday, 19 August 2017 at 18:33:37 UTC, WhatMeWorry wrote: On Friday, 18 August 2017 at 20:39:38 UTC, angel wrote: On Friday, 18 August 2017 at 02:38:15 UTC, WhatMeForget wrote: [...] This actually appears correct ... The 1-st example: Each call to makeCalculator() increments a static (i.e. shared among all makeCalculator() instances) variable - context. In addition, makeCalculator() generates a random variable. Whereas the delegate merely captures these variables, and the displayed results reflect this. The 2-nd example: There is a single call to makeCalculator(). After this call, context == 1, randy == _apparently 2_. Now the delegate, as has already been said, merely captures these values, so consecutive calls do not change the result. Thanks. So, auto calculator = makeCalculator(); is the actual call of the delegate? "Delegate is function pointer with context" But what is ...calculator(0)); Or maybe another approach would be to ask, what type is the compiler replacing auto with. No ! The actual call to the delegate is calculator(0). But this delegate does not induce change on its context variables, so it is expectable that consecutive calls to calculator(0) produce the same results, isn't it ? makeCalculator(), while not a delegate, also has a context variable - "static int context" - this is an "old-school" context variable implemented by the means of static variable. Consecutive calls to makeCalculator() return delegates having different contexts, so each call to calculator(0) produces different results.
Re: real simple delegate question.
On Friday, 18 August 2017 at 02:38:15 UTC, WhatMeForget wrote:
Can someone explain what is the difference between the two?
Thanks.
module gates;
import std.stdio;
import std.random;
alias Calculator = int delegate(int);
Calculator makeCalculator()
{
static int context = 0;
int randy = uniform(1, 7);
context++;
writeln("context = ", context);
writeln("randy = ", randy);
return value => context + randy + value;
}
void main()
{
for (int i = 0; i < 3; i++)
{
auto calculator = makeCalculator();
writeln("The result of the calculation: ",
calculator(0));
}
}
returns:
context = 1
randy = 5
The result of the calculation: 6
context = 2
randy = 2
The result of the calculation: 4
context = 3
randy = 6
The result of the calculation: 9
while the following
void main()
{
auto calculator = makeCalculator(); // thought just one
would work
for (int i = 0; i < 3; i++)
{
writeln("The result of the calculation: ",
calculator(0));
}
}
returns:
The result of the calculation: 3
The result of the calculation: 3
The result of the calculation: 3
This actually appears correct ...
The 1-st example:
Each call to makeCalculator() increments a static (i.e. shared
among all makeCalculator() instances) variable - context.
In addition, makeCalculator() generates a random variable.
Whereas the delegate merely captures these variables, and the
displayed results reflect this.
The 2-nd example:
There is a single call to makeCalculator().
After this call, context == 1, randy == _apparently 2_.
Now the delegate, as has already been said, merely captures these
values, so consecutive calls do not change the result.
Re: Create class on stack
On Saturday, 5 August 2017 at 17:08:32 UTC, Johnson Jones wrote: using gtk, it has a type called value. One has to use it to get the value of stuff but it is a class. Once it is used, one doesn't need it. Ideally I'd like to treat it as a struct since I'm using it in a delegate I would like to minimize unnecessary allocations. Is there any way to get D to allocate a class on the stack like a local struct? Emplace ? https://dlang.org/phobos/std_conv.html#emplace
Re: Factory using an alias template parameter to set a member of the new tool ?
On Thursday, 9 February 2017 at 14:39:41 UTC, angel wrote:
On Thursday, 9 February 2017 at 13:30:07 UTC, jkpl wrote:
I'm looking for a better way to do this, if possible:
```
class Tool
{
string name;
}
T namedTool(alias Variable, T)()
{
T result = new T;
result.name = Variable.stringof;
return result;
}
void main()
{
Tool grep;
grep = namedTool!(grep,Tool);
assert(grep.name == "grep");
}
```
Ideally this would work like this:
```
Tool grep = namedTool!Tool;
assert(grep.name == "grep");
```
Possible ?
Sorry, but this does not make much sense to me ...
You expect "namedTool!Tool" to know that the name of the Tool
must be set to "grep".
The expression evaluation proceeds from right to left, so at
the time of analyzing "namedTool!Tool", the compiler knows
nothing about "grep".
On the other hand, if you supplied the "grep" variable, the
compiler could infer its type, like this:
```
...
auto namedTool(alias Variable)()
{
alias T = typeof(Variable);
T result = new T;
result.name = Variable.stringof;
return result;
}
void main()
{
Tool grep;
grep = namedTool!(grep);
assert(grep.name == "grep");
}
```
Or actually, maybe this will suite your case better:
```
template namedTool(T, alias Variable)
{
enum namedTool = T.stringof ~ " " ~ Variable ~ " = new " ~
T.stringof ~ ";" ~
Variable ~ ".name = \"" ~ Variable ~ "\";";
}
void main()
{
mixin(namedTool!(Tool, "grep"));
assert(grep.name == "grep");
}
```
Re: Factory using an alias template parameter to set a member of the new tool ?
On Thursday, 9 February 2017 at 13:30:07 UTC, jkpl wrote:
I'm looking for a better way to do this, if possible:
```
class Tool
{
string name;
}
T namedTool(alias Variable, T)()
{
T result = new T;
result.name = Variable.stringof;
return result;
}
void main()
{
Tool grep;
grep = namedTool!(grep,Tool);
assert(grep.name == "grep");
}
```
Ideally this would work like this:
```
Tool grep = namedTool!Tool;
assert(grep.name == "grep");
```
Possible ?
Sorry, but this does not make much sense to me ...
You expect "namedTool!Tool" to know that the name of the Tool
must be set to "grep".
The expression evaluation proceeds from right to left, so at the
time of analyzing "namedTool!Tool", the compiler knows nothing
about "grep".
On the other hand, if you supplied the "grep" variable, the
compiler could infer its type, like this:
```
...
auto namedTool(alias Variable)()
{
alias T = typeof(Variable);
T result = new T;
result.name = Variable.stringof;
return result;
}
void main()
{
Tool grep;
grep = namedTool!(grep);
assert(grep.name == "grep");
}
```
Re: capture stdout or stderr
On Wednesday, 1 February 2017 at 01:08:19 UTC, Emil wrote:
is it possible to intercept the STDOUT or STDERR and capture
the output into a variable ?
some pseudocode to explain what I mean
string[] output_buffer;
stdout.capture_to(output_buffer);
writeln("test 1"); # not printed
writeln("test 2"); # not printed
stdout.release(output_buffer);
writeln("test 3"); # printed
writeln(output_buffer); # prints '["test 1","test 2"]'
No.
Please keep in mind, that in Linux, for example, stdout is a file
...
writeln() interacts with OS API, which, of course, has nothing to
do with internal data structures of your application.
What you could probably do is replace writeln() with a custom
logger. In your logger implementation you can add such
functionality.
Re: @property get/set or public varaible?
On Sunday, 4 December 2016 at 15:30:22 UTC, vladdeSV wrote: Hello! I have a question not directly related to D as it is with coding standards. My issue at hand is if I have one variable for a class, which I want to be directly accessible for anything else, should it be 1. public, or 2. private, with @property get/setters? From what I have been told is that variables should be private. But if I do not want to make any checks whatsoever when setting a variable, I see no benefit to the private approach. Are there any other reasons to use get/setters? Make the member variable public, if it serves your purpose. If (and when) you feel like taking some control over setting and getting its value, you will upgrade it to @property setter/getter, making the actual member variable private. For most reasonable use cases the upgrade should pass with no problems. ... If you envision such an upgrade possibility, try to keep away from taking your member variable address, and other not method-friendly operations, that might hold the upgrade back.
Re: spawnProcess() not child?
The parent / child relationship always exists. In POSIX OSs, you may ignore SIGCHLD signal (announcing child process death), so that in case of child process exit it will not become zombie, rather it will be disposed on the spot. As a side note, in Linux, there exist a system call allowing process re-parenting, but it is intended for use in experimenting, rather than in normal use case. Side note II, there is no real chance of wrapping PID numbers around in a reasonable time frame.
