Re: Regarding std.array.Appender

[Suliman via Digitalmars-d-learn]

On Monday, 5 March 2012 at 15:35:59 UTC, Steven Schveighoffer 
wrote:
On Wed, 29 Feb 2012 20:25:35 -0500, bearophile 
 wrote:


Do you know why std.array.Appender defines a "put" method 
instead of overloading the "~=" operator?


It should (in addition to put).  I see you have already filed 
an enhancement.


http://d.puremagic.com/issues/show_bug.cgi?id=4287

-Steve


Can I use Appender to add at end of every string my symbol?

foreach (pointsfile; pointsFiles)
{
File file = File(pointsfile, "r");
		string content = file.byLine; // I need to add "+" at at end of 
every string

}

Re: Regarding std.array.Appender

[John Colvin via Digitalmars-d-learn]

On Tuesday, 13 October 2015 at 13:21:54 UTC, Suliman wrote:
I tried to use map! but it's look like it do not work with 
string, becouse I got error: Error: no property 'map' for type 
'ByLine!(char, char)'


I suspect you don't have it imported.

import std.algorithm;

or

import std.algorithm : map;

Re: Regarding std.array.Appender

[Suliman via Digitalmars-d-learn]

On Tuesday, 13 October 2015 at 13:34:02 UTC, John Colvin wrote:

On Tuesday, 13 October 2015 at 13:21:54 UTC, Suliman wrote:
I tried to use map! but it's look like it do not work with 
string, becouse I got error: Error: no property 'map' for type 
'ByLine!(char, char)'


I suspect you don't have it imported.

import std.algorithm;

or

import std.algorithm : map;


Thanks, you are right! Can I add with map some element before and 
after string? map!(a=> a~=" +") work fine, but how to add before 
at same time?

Re: Regarding std.array.Appender

[anonymous via Digitalmars-d-learn]

On Tuesday 13 October 2015 15:47, Suliman wrote:

> something like: auto content = file.byLine.map!("start " ~ a=>a ~ 
> " end");

That's not how it works at all. Maybe stick to the examples of whatever 
resource you're learning from, for now.

Re: Regarding std.array.Appender

[Suliman via Digitalmars-d-learn]

I tried to use map! but it's look like it do not work with 
string, becouse I got error: Error: no property 'map' for type 
'ByLine!(char, char)'

Re: Regarding std.array.Appender

[anonymous via Digitalmars-d-learn]

On Tuesday 13 October 2015 15:42, Suliman wrote:

> map!(a=> a~=" +") work fine, but how to add before 
> at same time?

Use ~ instead of ~=, like so: map!(a => "+" ~ a ~ "+")

Re: Regarding std.array.Appender

[Suliman via Digitalmars-d-learn]

something like: auto content = file.byLine.map!("start " ~ a=>a ~ 
" end");

Re: Regarding std.array.Appender

[Suliman via Digitalmars-d-learn]

On Tuesday, 13 October 2015 at 13:55:07 UTC, anonymous wrote:

On Tuesday 13 October 2015 15:47, Suliman wrote:

something like: auto content = file.byLine.map!("start " ~ 
a=>a ~ " end");


That's not how it works at all. Maybe stick to the examples of 
whatever resource you're learning from, for now.


Yes, I understand that it's not work exactly like I try to use 
it, but which function can solve my problem?

Re: Regarding std.array.Appender

[Suliman via Digitalmars-d-learn]

On Tuesday, 13 October 2015 at 13:51:50 UTC, anonymous wrote:

On Tuesday 13 October 2015 15:42, Suliman wrote:

map!(a=> a~=" +") work fine, but how to add before at same 
time?


Use ~ instead of ~=, like so: map!(a => "+" ~ a ~ "+")


Thanks!

Re: Regarding std.array.Appender

[Steven Schveighoffer]

On Wed, 29 Feb 2012 20:25:35 -0500, bearophile bearophileh...@lycos.com  
wrote:


Do you know why std.array.Appender defines a put method instead of  
overloading the ~= operator?


It should (in addition to put).  I see you have already filed an  
enhancement.


http://d.puremagic.com/issues/show_bug.cgi?id=4287

-Steve

Re: Regarding std.array.Appender

[Timon Gehr]

On 03/01/2012 03:40 AM, Jonathan M Davis wrote:

On Wednesday, February 29, 2012 21:23:54 bearophile wrote:

Jonathan M Davis:

put is a function on output ranges, and Appender is an output range.


Also, given that it doesn't define ~ (and it wouldn't really make sense
for it to), it would be very weird IMHO to define ~=.


I don't understand why that's weird.
In Java you can't overload an append operator, so using a method is right.
But for me it's weird that Appender doesn't use the D operator to _append_.
I sometimes use add instead of put by mistake, forgetting the right
method name, because I find it quite unnatural. If Appender needs a put,
then I suggest to give it both put method and ~= operator.


Would you define += without defining +? Or *= without defining *? It strikes me
as a misuse of operator overloading if you have an opOpAssign without its
corresponding opBinary.

- Jonathan M Davis


It is not the same thing. a=a~b has different semantics from a~=b;

Re: Regarding std.array.Appender

[Sönke Ludwig]

Am 01.03.2012 03:40, schrieb Jonathan M Davis:

On Wednesday, February 29, 2012 21:23:54 bearophile wrote:

Jonathan M Davis:

put is a function on output ranges, and Appender is an output range.


Also, given that it doesn't define ~ (and it wouldn't really make sense
for it to), it would be very weird IMHO to define ~=.


I don't understand why that's weird.
In Java you can't overload an append operator, so using a method is right.
But for me it's weird that Appender doesn't use the D operator to _append_.
I sometimes use add instead of put by mistake, forgetting the right
method name, because I find it quite unnatural. If Appender needs a put,
then I suggest to give it both put method and ~= operator.


Would you define += without defining +? Or *= without defining *? It strikes me
as a misuse of operator overloading if you have an opOpAssign without its
corresponding opBinary.

- Jonathan M Davis


Consider matrix * vector and matrix *= vector for an opposite example.

Regarding std.array.Appender

[bearophile]

Do you know why std.array.Appender defines a put method instead of 
overloading the ~= operator?

Bye and thank you,
bearophile

Re: Regarding std.array.Appender

[Jonathan M Davis]

On Wednesday, February 29, 2012 20:25:35 bearophile wrote:
 Do you know why std.array.Appender defines a put method instead of
 overloading the ~= operator?

put is a function on output ranges, and Appender is an output range.

- Jonathan M Davis

Re: Regarding std.array.Appender

[Andrej Mitrovic]

Luckily you can always use alias this and overload opCatAssign. 'alias
this' is a great tool for customizing APIs. :)

Re: Regarding std.array.Appender

[Jonathan M Davis]

On Wednesday, February 29, 2012 20:53:04 Jonathan M Davis wrote:
 On Wednesday, February 29, 2012 20:25:35 bearophile wrote:
  Do you know why std.array.Appender defines a put method instead of
  overloading the ~= operator?
 
 put is a function on output ranges, and Appender is an output range.

Also, given that it doesn't define ~ (and it wouldn't really make sense for it 
to), it would be very weird IMHO to define ~=.

- Jonathan M Davis

Re: Regarding std.array.Appender

[bearophile]

Jonathan M Davis:

  put is a function on output ranges, and Appender is an output range.
 
 Also, given that it doesn't define ~ (and it wouldn't really make sense for 
 it 
 to), it would be very weird IMHO to define ~=.

I don't understand why that's weird.
In Java you can't overload an append operator, so using a method is right. But 
for me it's weird that Appender doesn't use the D operator to _append_. I 
sometimes use add instead of put by mistake, forgetting the right method 
name, because I find it quite unnatural. If Appender needs a put, then I 
suggest to give it both put method and ~= operator.

Bye,
bearophile

Re: Regarding std.array.Appender

[Adam D. Ruppe]

On Thursday, 1 March 2012 at 02:23:55 UTC, bearophile wrote:
But for me it's weird that Appender doesn't use the D operator 
to _append_.  [...] I suggest to give it both put method and 
~= operator.


I agree entirely.


Another annoyance is if you have a function that works on
regular arrays, you probably used ~=.

But you decide to switch to Appender to try for a speed boost.

Now you have to change all the usage too, since the interfaces
are incompatible!

Re: Regarding std.array.Appender

[Jonathan M Davis]

On Wednesday, February 29, 2012 21:23:54 bearophile wrote:
 Jonathan M Davis:
   put is a function on output ranges, and Appender is an output range.
  
  Also, given that it doesn't define ~ (and it wouldn't really make sense
  for it to), it would be very weird IMHO to define ~=.
 
 I don't understand why that's weird.
 In Java you can't overload an append operator, so using a method is right.
 But for me it's weird that Appender doesn't use the D operator to _append_.
 I sometimes use add instead of put by mistake, forgetting the right
 method name, because I find it quite unnatural. If Appender needs a put,
 then I suggest to give it both put method and ~= operator.

Would you define += without defining +? Or *= without defining *? It strikes me 
as a misuse of operator overloading if you have an opOpAssign without its 
corresponding opBinary.

- Jonathan M Davis

Re: Regarding std.array.Appender

[Jonathan M Davis]

On Thursday, March 01, 2012 03:29:06 Adam D. Ruppe wrote:
 On Thursday, 1 March 2012 at 02:23:55 UTC, bearophile wrote:
  But for me it's weird that Appender doesn't use the D operator
  to _append_.  [...] I suggest to give it both put method and
  ~= operator.
 
 I agree entirely.
 
 
 Another annoyance is if you have a function that works on
 regular arrays, you probably used ~=.
 
 But you decide to switch to Appender to try for a speed boost.
 
 Now you have to change all the usage too, since the interfaces
 are incompatible!

True, but it can't do all of the other operations that array can do either. 
It's an output range, not an array. And odds are that it's going to be 
refactored such that it doesn't even contain an array internally anymore, 
beacause that's an inefficient way to implement appending. Someone (Robert 
Jacques IIRC, but I'd have to check) has already created such an 
implementation, and there's a decent chance that it's going to make it into 
Phobos.

So, I'm not sure that treating Appender as an array is really a good idea in 
the first place. If you want the truly generic approach, then treat is an 
output range.

- Jonathan M Davis

Re: Regarding std.array.Appender

[Adam D. Ruppe]

On Thursday, 1 March 2012 at 02:44:35 UTC, Jonathan M Davis wrote:
True, but it can't do all of the other operations that array 
can do either.


Yeah, but the one operation it replaces, ~=, can be done
on an array.

If you're trying to convert array code to Appender for
speed, most likely you're going to be replacing a
bunch of ~= calls.

It's ok if the other op don't compile, but this one
really should. Appender, regardless of the internal
representation vs array is a speed optimization;
an implementation detail.


It's an output range, not an array.


It's also an Appender, though. I think it is a little
silly to have an Appender to which you can't /append/.

(put is great too, don't get me wrong, but so is ~=).

Re: Regarding std.array.Appender

[James Miller]

On 1 March 2012 15:49, Adam D. Ruppe destructiona...@gmail.com wrote:
 On Thursday, 1 March 2012 at 02:44:35 UTC, Jonathan M Davis wrote:

 True, but it can't do all of the other operations that array can do
 either.


 Yeah, but the one operation it replaces, ~=, can be done
 on an array.

 If you're trying to convert array code to Appender for
 speed, most likely you're going to be replacing a
 bunch of ~= calls.

 It's ok if the other op don't compile, but this one
 really should. Appender, regardless of the internal
 representation vs array is a speed optimization;
 an implementation detail.


 It's an output range, not an array.


 It's also an Appender, though. I think it is a little
 silly to have an Appender to which you can't /append/.

 (put is great too, don't get me wrong, but so is ~=).

I can see both sides, but I'm on Adam's side here. While all the other
opOpAssign functions are defined in terms of their opBinary equivalent
(e.g, += is 'add and assign'), ~= is essentially an operator in its
own right, specifically an append (as opposed to '~' which is
concatenate). Having both ~= and .put() would be fine, and would make
switching from arrays to Appenders much easier.

I understand that Appenders aren't arrays, and should not be used as
such, but you /can/ use an array as an Appender. At some point, you
have to concede design purity to convenience, otherwise you have a
language that is actively hostile to changing designs. *In best
nagging wife voice* You should have used an Appender from the
start. Now you have to go change all that code. Its your own fault
really

--
James Miller

Re: Regarding std.array.Appender

[Ali Çehreli]

On 02/29/2012 08:28 PM, James Miller wrote:

 I understand that Appenders aren't arrays, and should not be used as
 such, but you /can/ use an array as an Appender.

Yes you can but whatever you put() into the array is immediately 
popFront()'ed from the array. ;) You must use a temporary surrogate slice:


import std.stdio;
import std.range;

void main()
{
int[] array = [ 1, 2, 3 ];
int[] slice = array;

put(slice, 100);  // -- slice shrinks! :)
}

slice.length is 2 and array.length is 3.

 At some point, you
 have to concede design purity to convenience, otherwise you have a
 language that is actively hostile to changing designs.

Agreed.

Ali