String starts? and ends? methods

George · September 27, 2006, 1:20pm

This comes up every now and again, and lots of frameworks implement
their own versions. I’m thinking
of submitting an RCR for something functionally equivalent to the
following to be incorporated into
the base library:

class String
def starts?(aString)
index(aString) == 0
end

def ends?(aString)
rindex(aString) == length - aString.length
end
end

Of course, the real implementation would have much better performance.
The advantage of including
something like this is that these common functions can be made both
high-performance and readable.

Comments?

George · September 27, 2006, 1:38pm

“G” == George [email protected] writes:

G> class String
G> def starts?(aString)
G> def ends?(aString)

1.9 has String#startwith?, String#endwith?

Guy Decoux

George · September 27, 2006, 1:44pm

Hi –

On Wed, 27 Sep 2006, ts wrote:

“G” == George [email protected] writes:

G> class String
G> def starts?(aString)
G> def ends?(aString)

1.9 has String#startwith?, String#endwith?

No underscores between words?

David

George · September 27, 2006, 1:50pm

“d” == dblack [email protected] writes:

d> No underscores between words?

moulon% grep ith? string.c

str.startwith?([prefix]+)   => true or false

```
str.endwith?([suffix]+)   => true or false
```
rb_define_method(rb_cString, “startwith?”, rb_str_startwith, -1);
rb_define_method(rb_cString, “endwith?”, rb_str_endwith, -1);
moulon%

Guy Decoux

George · September 27, 2006, 1:46pm

ts wrote:

G> class String
G> def starts?(aString)
G> def ends?(aString)

1.9 has String#startwith?, String#endwith?

Where is this documented? I can’t find it anywhere.

George · September 27, 2006, 1:54pm

Hi –

On Wed, 27 Sep 2006, ts wrote:

“d” == dblack [email protected] writes:

d> No underscores between words?

moulon% grep ith? string.c
str.startwith?([prefix]+)   => true or false
str.endwith?([suffix]+)   => true or false
rb_define_method(rb_cString, “startwith?”, rb_str_startwith, -1);
rb_define_method(rb_cString, “endwith?”, rb_str_endwith, -1);
moulon%

It’s not that I didn’t believe you It just seems a bit unusual,
in terms of the general Ruby practice.

David

George · September 27, 2006, 2:20pm

Makes sense. It was just honoring the origin (this case Python).
Since they are young (I just added it last week), it is fairly easy to
change the names. Any opinion?
                                                    matz.

+1 for changing to start_with? end_with?

Consistency in naming is a big plus for ruby (and minus for PHP).

Regards,
Rimantas

George · September 27, 2006, 2:16pm

Hi,

In message “Re: String starts? and ends? methods”
on Wed, 27 Sep 2006 20:53:54 +0900, [email protected] writes:

|It’s not that I didn’t believe you It just seems a bit unusual,
|in terms of the general Ruby practice.

Makes sense. It was just honoring the origin (this case Python).
Since they are young (I just added it last week), it is fairly easy to
change the names. Any opinion?

						matz.

George · September 27, 2006, 2:24pm

Yukihiro M. wrote:

Makes sense. It was just honoring the origin (this case Python).
Since they are young (I just added it last week), it is fairly easy to
change the names. Any opinion?

My vote is also for naming them start_with? and end_with? because of
consistency and better looks :).

Robin

George · September 27, 2006, 2:30pm

Hi –

On Wed, 27 Sep 2006, Yukihiro M. wrote:

change the names. Any opinion?
Yes: add the underscores. Otherwise we’ll have those exceptions “for
historical reasons” – in this case the history of Python!

David

George · September 27, 2006, 2:58pm

Hi,

In message “Re: String starts? and ends? methods”
on Wed, 27 Sep 2006 21:29:09 +0900, [email protected] writes:

|> Makes sense. It was just honoring the origin (this case Python).
|> Since they are young (I just added it last week), it is fairly easy to
|> change the names. Any opinion?
|
|Yes: add the underscores. Otherwise we’ll have those exceptions “for
|historical reasons” – in this case the history of Python!

OK, done.

						matz.

George · September 27, 2006, 3:16pm

Rimantas L. wrote:

Makes sense. It was just honoring the origin (this case Python).
Since they are young (I just added it last week), it is fairly easy to
change the names. Any opinion?
                                                    matz.
+1 for changing to start_with? end_with?

1 for me as well

Vince

George · September 27, 2006, 3:00pm

On Sep 27, 2006, at 7:19 AM, Rimantas L. wrote:

Makes sense. It was just honoring the origin (this case Python).
Since they are young (I just added it last week), it is fairly
easy to
change the names. Any opinion?
                                                    matz.
+1 for changing to start_with? end_with?

I agree completely.

James Edward G. II

George · September 27, 2006, 3:32pm

Yukihiro M. wrote:

Makes sense. It was just honoring the origin (this case Python).
Since they are young (I just added it last week), it is fairly easy to
change the names. Any opinion?
My English-fu has me prefer starts_with? to start_with?, but general
Ruby convention seems to be not to conjugate the verbs, so I’ll just
vote what everybody else is voting.

George · September 27, 2006, 3:38pm

Dirk M. wrote:

to be honest, i don’t really think this is that useful.
what wrong with

string=~/^start/
string=~/end$/

this seems to be self-explanatory enough.

For the Regexp-friendly users… In my opinion, a part of Ruby’s
coolness is that you have quite a lot of ways to say similar things,
which leaves you to chose the most readable for the code at hand (and
for your own eyes).

I don’t expect having another method for String will cause a huge
performance drop ;-)… And I definitely think some code will look
easier to read with that.

Cheers !

Vince

George · September 27, 2006, 3:26pm

to be honest, i don’t really think this is that useful.
what wrong with

string=~/^start/
string=~/end$/

this seems to be self-explanatory enough.
greeting, Dirk.

George · September 27, 2006, 3:42pm

Hi –

On Wed, 27 Sep 2006, Devin M. wrote:

Yukihiro M. wrote:

Makes sense. It was just honoring the origin (this case Python).
Since they are young (I just added it last week), it is fairly easy to
change the names. Any opinion?
My English-fu has me prefer starts_with? to start_with?, but general Ruby
convention seems to be not to conjugate the verbs, so I’ll just vote what
everybody else is voting.

It’s a little inconsistent:

obj.respond_to? # second person
obj.is_a? # third person

But I think second person is the most common. Or maybe are_a? just
sounded too weird

David

George · September 27, 2006, 4:01pm

Hi,

In message “Re: String starts? and ends? methods”
on Wed, 27 Sep 2006 22:40:29 +0900, [email protected] writes:

Right. “is-a” is a too common phrase among object-oriented
programming. I wasn’t brave enough to rename it “be_a” or something
like it.

						matz.

George · September 27, 2006, 4:07pm

Yukihiro M. wrote:

|But I think second person is the most common. Or maybe are_a? just
|sounded too weird

Right. “is-a” is a too common phrase among object-oriented
programming. I wasn’t brave enough to rename it “be_a” or something
like it.
  					matz.

(a newbie speaking)

but what about puralization?

we gonna have “string”.respond_to?() but “string”.starts_with?()

further: could there be need for starts_with!() and ends_with!() ? or
is it bollox?

George · September 27, 2006, 4:11pm

On Wed, Sep 27, 2006 at 10:25:44PM +0900, Dirk M. wrote:

to be honest, i don’t really think this is that useful.
what wrong with

string=~/^start/
string=~/end$/

That’s almost right.
You want /\Astart/ and /end\z/