Re: Setting a list of values
On Monday, 2 May 2016 at 10:15:04 UTC, Marc Schütz wrote: This check can be done purely by looking at the tokens. In other words it's trivial for D-Scanner to warn about this. https://github.com/Hackerpilot/Dscanner/issues/341
Re: Setting a list of values
On Monday, 2 May 2016 at 23:41:39 UTC, Steven Schveighoffer wrote:
On 5/2/16 6:00 PM, sigod wrote:
On Monday, 2 May 2016 at 10:15:04 UTC, Marc Schütz wrote:
On Monday, 2 May 2016 at 08:46:31 UTC, Ali Çehreli wrote:
[...]
Warning (better: disallowing altogether) about `=>` directly
followed
by `{` should be enough to cover all cases. To express that
you really
want a lambda returning a lambda, it can be rewritten either
as:
(x) => () { assert(x); }
or as:
(x) => ({ assert(x); })
This check can be done purely by looking at the tokens.
Should we
someday introduce tuples with `{}`, the check needs to be
done after
the node starting with `{` has been parsed to distinguish
between
delegate and tuple literals.
It's good idea. I myself stumbled into this before.
Agree.
-Steve
https://issues.dlang.org/show_bug.cgi?id=16001
Re: Setting a list of values
On Wednesday, 4 May 2016 at 04:56:54 UTC, Joel wrote:
On Sunday, 1 May 2016 at 05:42:00 UTC, Ali Çehreli wrote:
[...]
This seems to work the best:
arr.each!(a => { writeln(a); }());
And the ugliest. And probably slowest.
Re: Setting a list of values
On Sunday, 1 May 2016 at 05:42:00 UTC, Ali Çehreli wrote:
On 04/30/2016 10:05 PM, Joel wrote:
> This has no effect:
> _bars.each!(a => { a._plots.fillColor = Color(255, 180, 0);
});
This is a common issue especially for people who know lambdas
from other languages. :)
Your lambda does not do any work. Rather, your lambda returns
another lambda, which is promptly ignored:
import std.stdio;
import std.algorithm;
void main() {
auto arr = [ 1, 2 ];
arr.each!(a => { writeln(a); }); // returns lambda for
each a
}
The lambda that 'each' takes above is "given a, produce this
lambda". . To do the intended work, you need to remove the
curly braces (and the semicolon):
arr.each!(a => writeln(a));
Or, you could insert empty () to call the returned lambda but
that would completely be extra work in this case:
arr.each!(a => { writeln(a); }());
Ali
This seems to work the best:
arr.each!(a => { writeln(a); }());
Re: Setting a list of values
On 5/2/16 6:00 PM, sigod wrote:
On Monday, 2 May 2016 at 10:15:04 UTC, Marc Schütz wrote:
On Monday, 2 May 2016 at 08:46:31 UTC, Ali Çehreli wrote:
[...]
Warning (better: disallowing altogether) about `=>` directly followed
by `{` should be enough to cover all cases. To express that you really
want a lambda returning a lambda, it can be rewritten either as:
(x) => () { assert(x); }
or as:
(x) => ({ assert(x); })
This check can be done purely by looking at the tokens. Should we
someday introduce tuples with `{}`, the check needs to be done after
the node starting with `{` has been parsed to distinguish between
delegate and tuple literals.
It's good idea. I myself stumbled into this before.
Agree.
-Steve
Re: Setting a list of values
On Monday, 2 May 2016 at 10:15:04 UTC, Marc Schütz wrote:
On Monday, 2 May 2016 at 08:46:31 UTC, Ali Çehreli wrote:
[...]
Warning (better: disallowing altogether) about `=>` directly
followed by `{` should be enough to cover all cases. To express
that you really want a lambda returning a lambda, it can be
rewritten either as:
(x) => () { assert(x); }
or as:
(x) => ({ assert(x); })
This check can be done purely by looking at the tokens. Should
we someday introduce tuples with `{}`, the check needs to be
done after the node starting with `{` has been parsed to
distinguish between delegate and tuple literals.
It's good idea. I myself stumbled into this before.
Re: Setting a list of values
On Monday, 2 May 2016 at 08:46:31 UTC, Ali Çehreli wrote:
On 05/01/2016 12:54 PM, Xinok wrote:
> On Sunday, 1 May 2016 at 05:42:00 UTC, Ali Çehreli wrote:
>> On 04/30/2016 10:05 PM, Joel wrote:
>> > This has no effect:
>> > _bars.each!(a => { a._plots.fillColor = Color(255, 180, 0);
>> });
>>
>> This is a common issue especially for people who know
lambdas from
>> other languages. :)
>>
>> Your lambda does not do any work. Rather, your lambda
returns another
>> lambda, which is promptly ignored:
>
> Those are some discrete semantics. I know D pretty well and
even I
> didn't see the problem initially. Anybody else think it's
worth adding a
> warning to the compiler for this specific case?
A warning would be great but I don't see how it can cover all
cases. A special warning for std.algorithm.each might work but
this exact issue appeared on the main thread just a few minutes
ago:
http://forum.dlang.org/post/qsayoktyffczskrnm...@forum.dlang.org
alias funType = void function(int x);
funType fun = (x) => { assert(x); }; // cannot return
non-void from void function
Ali
Warning (better: disallowing altogether) about `=>` directly
followed by `{` should be enough to cover all cases. To express
that you really want a lambda returning a lambda, it can be
rewritten either as:
(x) => () { assert(x); }
or as:
(x) => ({ assert(x); })
This check can be done purely by looking at the tokens. Should we
someday introduce tuples with `{}`, the check needs to be done
after the node starting with `{` has been parsed to distinguish
between delegate and tuple literals.
Re: Setting a list of values
On 05/01/2016 12:54 PM, Xinok wrote:
> On Sunday, 1 May 2016 at 05:42:00 UTC, Ali Çehreli wrote:
>> On 04/30/2016 10:05 PM, Joel wrote:
>> > This has no effect:
>> > _bars.each!(a => { a._plots.fillColor = Color(255, 180, 0);
>> });
>>
>> This is a common issue especially for people who know lambdas from
>> other languages. :)
>>
>> Your lambda does not do any work. Rather, your lambda returns another
>> lambda, which is promptly ignored:
>
> Those are some discrete semantics. I know D pretty well and even I
> didn't see the problem initially. Anybody else think it's worth adding a
> warning to the compiler for this specific case?
A warning would be great but I don't see how it can cover all cases. A
special warning for std.algorithm.each might work but this exact issue
appeared on the main thread just a few minutes ago:
http://forum.dlang.org/post/qsayoktyffczskrnm...@forum.dlang.org
alias funType = void function(int x);
funType fun = (x) => { assert(x); }; // cannot return non-void
from void function
Ali
Re: Setting a list of values
On Sunday, 1 May 2016 at 05:42:00 UTC, Ali Çehreli wrote:
On 04/30/2016 10:05 PM, Joel wrote:
> This has no effect:
> _bars.each!(a => { a._plots.fillColor = Color(255, 180, 0);
});
This is a common issue especially for people who know lambdas
from other languages. :)
Your lambda does not do any work. Rather, your lambda returns
another lambda, which is promptly ignored:
import std.stdio;
import std.algorithm;
void main() {
auto arr = [ 1, 2 ];
arr.each!(a => { writeln(a); }); // returns lambda for
each a
}
The lambda that 'each' takes above is "given a, produce this
lambda". . To do the intended work, you need to remove the
curly braces (and the semicolon):
arr.each!(a => writeln(a));
Or, you could insert empty () to call the returned lambda but
that would completely be extra work in this case:
arr.each!(a => { writeln(a); }());
Or, remove the arrow:
arr.each!((a) { writeln(a); });
Re: Setting a list of values
On 04/30/2016 10:05 PM, Joel wrote:
> This has no effect:
> _bars.each!(a => { a._plots.fillColor = Color(255, 180, 0); });
This is a common issue especially for people who know lambdas from other
languages. :)
Your lambda does not do any work. Rather, your lambda returns another
lambda, which is promptly ignored:
import std.stdio;
import std.algorithm;
void main() {
auto arr = [ 1, 2 ];
arr.each!(a => { writeln(a); }); // returns lambda for each a
}
The lambda that 'each' takes above is "given a, produce this lambda". .
To do the intended work, you need to remove the curly braces (and the
semicolon):
arr.each!(a => writeln(a));
Or, you could insert empty () to call the returned lambda but that would
completely be extra work in this case:
arr.each!(a => { writeln(a); }());
Ali
Setting a list of values
This has no effect:
_bars.each!(a => { a._plots.fillColor = Color(255, 180, 0); });
I tried putting ..each!((ref a) =>.. with no difference
This works:
foreach(b; _bars) {
b._plots.fillColor = Color(255, 180, 0);
}
