220 7652 <CAFk2RUZYvC8_vtSbQfTMUs64yego-ZgGK1qcD1tZJT9g4OOVDg@mail.gmail.com> article
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From: Ville Voutilainen <ville.voutilainen@gmail.com>
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Subject: Re: Re: Could we remove the size() method in the std::list<T>?
Date: Sat, 9 Nov 2013 20:00:42 +0200
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On 9 November 2013 18:33, <euloanty@live.com> wrote:

> 1.It makes most of the operations of std::list slower;
>

Well, "most" is debatable, and it makes many programs using std::list
faster,
in fact much faster.


> 2.std::forward_list don't have this method. This makes people
> very confused.
>

forward_list doesn't have it because it doesn't have the same complexity
guarantee for forward_list. Now that it's O(1) for std::list, containers
that
do have it have the same complexity guarantee for it.


> 3.the method splice() becomes much slower.
>

Yes, and the programs mentioned in my response to (1) become much faster.

4.We know our library couldn't make people very confused. That was why we
> didn't define the operator[] in the std::list<>;
>

I don't see why std::list::size makes anyone confused.


> 5.The function of this method can be easily implied by programmers
> themselves. We know this function had been defined clearly in cpp11, but in
> the cpp98, its time-complexity is not defined clearly. For this reason, in
> the past we almost didn't use it. So  I think this change won't make so
> many codes invalid.
>
>
>
>
I don't see how a programmer can easily implement size(). Furthermore,
changing a function's
complexity from linear to constant breaks much fewer programs than removing
a function
completely.

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<div dir=3D"ltr"><br><div class=3D"gmail_extra"><br><br><div class=3D"gmail=
_quote">On 9 November 2013 18:33,  <span dir=3D"ltr">&lt;<a href=3D"mailto:=
euloanty@live.com" target=3D"_blank">euloanty@live.com</a>&gt;</span> wrote=
:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-le=
ft:1px #ccc solid;padding-left:1ex">
<div dir=3D"ltr"><div>1.It makes most of the operations of=A0std::list slow=
er;</div></div></blockquote><div><br></div><div>Well, &quot;most&quot; is d=
ebatable, and it makes many programs using std::list faster,<br>in fact muc=
h faster.<br>
=A0<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;b=
order-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr"><div>2.std::fo=
rward_list don&#39;t have this method. This makes people very=A0confused.</=
div></div>
</blockquote><div><br></div><div>forward_list doesn&#39;t have it because i=
t doesn&#39;t have the same complexity<br></div><div>guarantee for forward_=
list. Now that it&#39;s O(1) for std::list, containers that<br>do have it h=
ave the same complexity guarantee for it.<br>
=A0<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;b=
order-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr"><div>3.the met=
hod=A0splice() becomes much slower.</div></div></blockquote><div><br></div>=
<div>Yes, and the programs mentioned in my response to (1) become much fast=
er.<br>
<br></div><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bord=
er-left:1px #ccc solid;padding-left:1ex"><div dir=3D"ltr"><div>4.We know ou=
r library couldn&#39;t make people very confused. That was=A0why we didn&#3=
9;t define the operator[] in the std::list&lt;&gt;;</div>
</div></blockquote><div><br></div><div>I don&#39;t see why std::list::size =
makes anyone confused.<br>=A0<br></div><blockquote class=3D"gmail_quote" st=
yle=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div =
dir=3D"ltr">
<div>5.The function of this method can=A0be easily implied by programmers t=
hemselves. We know this function had been defined clearly=A0in cpp11,=A0but=
 in the cpp98, its time-complexity is not defined clearly. For this reason,=
=A0in the past we=A0almost didn&#39;t=A0use it. So =A0I think this change w=
on&#39;t make so many codes invalid.<br>
</div></div><div class=3D"HOEnZb"><div class=3D"h5">

<p></p>

<br><br></div></div></blockquote><div><br></div><div>I don&#39;t see how a =
programmer can easily implement size(). Furthermore, changing a function&#3=
9;s<br>complexity from linear to constant breaks much fewer programs than r=
emoving a function<br>
completely. <br></div></div><br></div></div>

<p></p>

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