From: "Michael W. Ryder" <_mwryder@...>
Date: 2007-04-24T02:40:09+09:00
Subject: Re: Question regarding design of the String Class

Rick DeNatale wrote:
> On 4/22/07, Daniel Martin <martin@snowplow.org> wrote:
>> "Michael W. Ryder" <_mwryder@worldnet.att.net> writes:
>>
>> > Was there a reason the string class was implemented with str[i]
>> > returning the code of position i in str?  The reason I ask this is
>> > that in other languages str[i] returns the string starting at position
>> > i. For example C uses t = strcpy(str[i]) and Business Basic uses
>> > S$=T$(I) to copy a string from position i.
>>
>> I can't comment on what "Business Basic" uses, but your C code is
>> completely wrong.  In C, str[i] returns a char which, since C has
>> "char" as one of its integral types, is equivalent to returning the
>> character code.
> 
> Daniel,  your points are well taken, but if the rusty old neurons in
> my brain which contain knowledge of C aren't mistaken, str[i] isn't a
> function, and therefore doesn't 'return' anything.
> 
> C doesn't really have a string type.  A string literal is really an
> array of chars, although in almost all cases (i.e. either than when
> it's used in a string initializer, or as the argument to sizeof), it's
> interpreted as a pointer to the first character, due to the
> relationship between arrays and pointers in C.
> 
> So if str is declared either as:
> 
>   char str[];
> or
>   char *str;
> 
> the expression str[i] is equivalent to *((str) + (i)), it's really a
> pointer to a char, which because of the relationship between arrays
> and pointers in c, can  be interpreted as an array of chars.
> 
> And in Ruby the whole notion of pointers is meaningless.
> 
> The point here, of course, is that when learning Ruby, or any other
> language, one needs to be aware that things one knows from other
> languages often don't carry over without conceptual modification, if
> at all.
> 
> If all languages did everything exactly the same way, there'd be no
> need for so many of them.
> 
> To sum it up, let Ruby be Ruby, don't expect it to be Java, C++,
> Visual Basic, or anything else.
> 

I guess my point was that str[i] behaves totally different from all the 
other implementations of [].  All of the others return a string.  This 
seems to be an inconsistency.  If there is a valid reason for it I have 
no problem, it just makes it harder to transfer over 25 years of 
experience to a new language.
In Business Basic or C if I want the numeric value of a character in a 
string I specify that.  Likewise if I want to copy a string from an 
arbitrary position I don't have to specify an ending character like 
Ruby.  I just find s = t[i, -1] to be much harder to understand in a 
quick read then s = t[i].  Others may not have this problem.