Re: patch: to_string, to_array functions

On Wed, Jul 21, 2010 at 2:25 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
> 2010/7/21 Robert Haas <robertmhaas@gmail.com>:
>> On Wed, Jul 21, 2010 at 1:48 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
>>> 2010/7/21 Robert Haas <robertmhaas@gmail.com>:
>>>> On Wed, Jul 21, 2010 at 12:08 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
>>>>>>> I am thinking so we have to do decision about string_to_array and
>>>>>>> array_to_string deprecation first. If these function will be
>>>>>>> deprecated, then we can use a similar names (and probably we should to
>>>>>>> use a similar names) - so text_to_array or array_to_string can be
>>>>>>> acceptable. If not, then this discus is needless - then to_string and
>>>>>>> to_array have to be maximally in contrib - stringfunc is good idea -
>>>>>>> and maybe we don't need thinking about new names.
>>>>>>
>>>>>> Well, -1 from me for deprecating string_to_array and array_to_string.
>>>>>>
>>>>>> I am not in favor of the names to_string and to_array even if we put
>>>>>> them in contrib, though.  The problem with string_to_array and
>>>>>> array_to_string is that they aren't descriptive enough, and
>>>>>> to_string/to_array is even less so.
>>>>>
>>>>> I am not a English native speaker, so I have a different feeling.
>>>>> These functions do array_serialisation and array_deseralisation, but
>>>>> this names are too long. I have not idea about better names - it is
>>>>> descriptive well (for me) text->array, array->text - and these names
>>>>> shows very cleanly symmetry between functions. I have to repeat - it
>>>>> is very clean for not native speaker.
>>>>
>>>> Well, the problem is that array_to_string(), for example, tells you
>>>> that an array is being converted to a string, but not how.  And
>>>> to_string() tells you that you're getting a string, but it doesn't
>>>> tell you either what you're getting it from or how you're getting it.
>>>> We already have a function to_char() which can be used to format a
>>>> whole bunch of different types as strings; I can't see adding a new
>>>> function with almost the same name that does something completely
>>>> different.
>>>>
>>>> array_split() and array_join(), following Perl?  array_implode() and
>>>> array_explode(), along the lines suggested by Brendan?
>>>
>>> I have a problem with array_split - because there string is split. I
>>> looked on net - and languages usually uses a "split" or "join". split
>>> is method of str class in Java. So when I am following Perl, I feel
>>> better with  just only "split" and "join", but "join" is keyword :( -
>>> step back, maybe string_split X array_join ?
>>>
>>> select string_split('1,2,3,4',',');
>>> select array_join(array[1,2,3,4],',');
>>>
>>> so my preferences:
>>>
>>> 1. split, join - I checked - we are able to create "join" function
>>> 2. split, array_join - when only "join" can be a problem
>>> 3. string_split, array_join - there are not clean symmetry, but it
>>> respect wide used a semantics - string.split, array.join
>>> 4. explode, implode
>>> 5. array_explode, array_implode
>>> -- I cannot to like array_split - it is contradiction for me.
>>
>> Well, I guess I prefer my suggestion to any of those (I know... what a
>> surprise), but I think I could live with #3, #4, or #5.  It's hard for
>> me to imagine that we really want to create a function called just
>> join(), given the other meanings that JOIN already has in SQL.
>
> it hasn't any relation to SQL language - but I don't expect so some
> like this can be accepted by Tom :). So for this moment we are in
> agreement on #3, #4, #5. I think, we can wait one or two days for
> opinions of others - and than I'll fix patch. ok?

Yeah, I'd like some more votes, too.  Aside from what I suggested
(array_join/array_split), I think my favorite is your #5.

We might also want to put some work into documentating the differences
between the old and new functions clearly.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company