Better way to remove all occurrence of matches on a String

Hi Rubyists !

I remember many times I searched for a better way to “remove all
occurrence of matches on a String”.

I usually do:
str.gsub! /\bword\b/, ‘’

I remembered the String#[]= from tryruby.org, but that only replace
the first occurrence.
String#delete “Uses the same rules for building the set of characters
as String#count”, and does not work with Regexp.
String#tr follow the same rules, and would need a second ‘’ parameter.

What feels a bit “awkward” to me in the first approach is to specify I
want no replacement (so nothing, so I should not have to specify it).

I think for a default second parameter to (g)sub(!) (without block),
but this case is supposed to return an Enumerator (is it sometimes
useful?).
Also the “sub” part of the name clearly indicate it is substituting
sth for a new thing (the new thing should not be empty).

I would then go for #delete, adding a special case for RegExp
arguments, but that is not consistent with current behavior with a
String.
However, String#delete seems very rarely used, and could get some
interest back. (and “str”.delete(/\bword\b/) do feel right to me)

What do you think ?

Benoit D.

What feels a bit “awkward” to me in the first approach is to specify I
want no replacement (so nothing, so I should not have to specify it).

If you really want to avoid a second parameter, you could try
something like this.
But, I would not actually say it is better.
Anyway…

str = “foo bar foo bar foo”
p str.split(/\bbar\b/)*""

Harry

On Sat, Oct 9, 2010 at 9:09 AM, Benoit D. [email protected]
wrote:

String#delete "Uses the same rules for building the set of characters
sth for a new thing (the new thing should not be empty).

I think gsub with an empty string is ugly too, but I am pretty confident
there is not a better way.

You need to be careful, though, delete and tr don’t work the way you
think
they work. They are based on characters not words. They don’t work with
regex because they consider the input string to be a set of characters,
and
that doesn’t make sense with regex.

“abcde”.delete(“bd”) # => “ace”
“abcde”.tr(“bd”,“12”) # => “a1c2e”

On 9 October 2010 19:30, Harry K. [email protected] wrote:

str = “foo bar foo bar foo”
p str.split(/\bbar\b/)*""

Harry

Nice one, but I guess the extra parameter is not too bad compared to
this :slight_smile:

On 10 October 2010 03:39, Josh C. [email protected] wrote:

I think gsub with an empty string is ugly too, but I am pretty confident
there is not a better way.

So I am not the only to think that :slight_smile:

You need to be careful, though, delete and tr don’t work the way you think
they work. They are based on characters not words. They don’t work with
regex because they consider the input string to be a set of characters, and
that doesn’t make sense with regex.

“abcde”.delete(“bd”) # => “ace”
“abcde”.tr(“bd”,“12”) # => “a1c2e”

Yes, I know, I proposed to add some functionality to #delete.

I would then go for #delete, adding a special case for RegExp
arguments, but that is not consistent with current behavior with a String.

That is indeed a consistence issue.
However, the semantic of “delete” (in general) seems right to me to
delete/remove a part of a String (and I think is makes even more sense
than the current implementation which does tr(str,’’)).

On 10 October 2010 12:20, Robert K. [email protected]
wrote:

Don’t waste too much thought on this. After all the second parameter makes
it clear what’s happening here. My 0.02 EUR.

Cheers

   robert

Sure, it is already quite good now and it makes sense.

… But it can be better :slight_smile:

On 09.10.2010 16:09, Benoit D. wrote:

String#delete "Uses the same rules for building the set of characters
sth for a new thing (the new thing should not be empty).

I would then go for #delete, adding a special case for RegExp
arguments, but that is not consistent with current behavior with a
String.
However, String#delete seems very rarely used, and could get some
interest back. (and “str”.delete(/\bword\b/) do feel right to me)

What do you think ?

Don’t waste too much thought on this. After all the second parameter
makes it clear what’s happening here. My 0.02 EUR.

Cheers

robert

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