• Gary Willoughby (7/7) Jul 16 2013 What is the correct way to test for an empty string?
• Adam D. Ruppe (3/3) Jul 16 2013 I just use
• bearophile (7/14) Jul 16 2013 The right, safe and readable way is to use std.array.empty:
• Gary Willoughby (2/4) Jul 16 2013 OMG, of course. Thanks!
• Rob T (4/10) Jul 17 2013 What was the rational for empty not being built in?
• Jesse Phillips (5/8) Jul 17 2013 empty() was added to provide a range interface to arrays.
• H. S. Teoh (17/33) Jul 17 2013 [...]

"Gary Willoughby" <dev nomad.so> writes:

What is the correct way to test for an empty string?

I've used

if (string == "")

and

if (string is null)

and both (O_o) in some places, it's starting to do my head in. 
What is the correct way?

"Adam D. Ruppe" <destructionator gmail.com> writes:

I just use

if(string.length == 0) {}

which covers both cases and is pretty intuitive too.

"bearophile" <bearophileHUGS lycos.com> writes:

Gary Willoughby:

 What is the correct way to test for an empty string?

 I've used

 if (string == "")

 and

 if (string is null)

 and both (O_o) in some places, it's starting to do my head in. 
 What is the correct way?

The right, safe and readable way is to use std.array.empty:

if (myString.empty)

If you don't want to import functions, then test for the length:

if (string.length == 0)

Bye,
bearophile

"Gary Willoughby" <dev nomad.so> writes:

On Tuesday, 16 July 2013 at 19:33:13 UTC, bearophile wrote:
 The right, safe and readable way is to use std.array.empty:

 if (myString.empty)

OMG, of course. Thanks!

"Rob T" <alanb ucora.com> writes:

On Tuesday, 16 July 2013 at 19:33:13 UTC, bearophile wrote:
 The right, safe and readable way is to use std.array.empty:

 if (myString.empty)

 If you don't want to import functions, then test for the length:

 if (string.length == 0)

 Bye,
 bearophile

What was the rational for empty not being built in?

Is there a performance penalty using "empty"?

--rt

"Jesse Phillips" <Jesse.K.Phillips+D gmail.com> writes:

On Wednesday, 17 July 2013 at 19:18:29 UTC, Rob T wrote:
 What was the rational for empty not being built in?

 Is there a performance penalty using "empty"?

 --rt

empty() was added to provide a range interface to arrays. 
Probably wasn't built in since you have to handle all array 
types. The concept of ranges make this clear, and since it didn't 
need to be built in to make it a range, it wasn't.

"H. S. Teoh" <hsteoh quickfur.ath.cx> writes:

On Wed, Jul 17, 2013 at 09:18:27PM +0200, Rob T wrote:
 On Tuesday, 16 July 2013 at 19:33:13 UTC, bearophile wrote:
The right, safe and readable way is to use std.array.empty:

if (myString.empty)

If you don't want to import functions, then test for the length:

if (string.length == 0)

Bye,
bearophile

 
 What was the rational for empty not being built in?
 
 Is there a performance penalty using "empty"?

[...]

AFAICT the reason is mainly historical. The whole deal with ranges was
introduced rather late into the language, whereas array.length has
always been there as a built-in feature. So .empty was layered on top of
the language primitives after the fact, that's why it's in std.array
instead of being built-in to the language.

In a sense, it's a good thing to have only .length built-in; it
simplifies the core language and the compiler, and allows more
compile-time flexibility. OTOH, though, it might be a good idea to move
parts of std.array into druntime's object.di so that things like .empty
are available by default, rather than hiding in an obscure corner of
Phobos. If ranges are such a big deal in D, as Walter seems to be
pushing for, it makes sense to provide it by default in object.di.


T

-- 
Кто везде - тот нигде.