[TCLCORE] Re: TIP #252: Add new 'string' command options

[Twylite <tw...@cr...>]

'subst' is related to the Tcl interpreter, and can do things one would 
not expect of a generic string processing function (variable and command 
substitution).  I believe that makes it special enough to remain its own 
command.
'scan' seems to be appropriate for inclusion in 'string' (it operates on 
a string, and this structure would be consistent with the 'binary' 
command).  On the other hand, 'format' does not (strictly speaking) take 
a string as an argument an operate on it.
As for 'split' and 'join'; well, Brian's placement of them sees 
logically correct: 'split' acts on a string and must therefore be part 
of 'string'; while 'join' acts on a list and should be part of 'list'.  
But I have to admit that 'string' isn't the most obvious place to look 
for a 'split' command.

In fact all of these commands ('format', 'scan', 'split' and 'join', 
even 'subst') as well as 'regexp' and 'regsub' are about parsing or 
combining more than they are about string or list manipulation.  It 
would seem to me that they don't belong in 'string' or 'list', but could 
belong to some other ensemble if we could find an appropriate name for 
it.  At the same time, it seems like a good plan to get them out of the 
global namespace (other than 'subst'), even if they have to become part 
of 'string' and 'list'.

While we're talking about 'string' command options, can I propose two 
new ones:

'string insert string /index/ /string2/' : inserts string2 at position 
index in string.  I believe this is required as 'string replace' must 
remove at least one character, leading to nasty workarounds to insert 
without deleting.

'string endswith /string1/ /string2/' : there is no need for a 
'startswith' because you can use [string first s1 s2] == 0, but to check 
if a string ends with a particular substring currently requires the use 
of [string length] and [string first] (or last), again causing 
non-obvious code.  Returns 1 (true) or 0 (false).

Twylite