Regular expressions

[rurpy at yahoo.com]

On 11/04/2015 07:24 PM, Steven D'Aprano wrote:
> On Thu, 5 Nov 2015 11:24 am, wrote:
>
>> You will find they are an indispensable tool, not just in Python
>> programming but in many aspects of computer use.
>
> You will find them a useful tool, but not indispensable by any means.
>
> Hint:
>
> - How many languages make arithmetic a built-in part of the language? Almost
> all of them. I don't know of any language that doesn't let you express
> something like "1 + 1" using built-in functions or syntax. Arithmetic is
> much closer to indispensable.

By my count there are 2377.  That's counting rpn languages where it is
1 1 +.  If you don't count them it is 2250.

> - How many languages make regular expressions a built-in part of the
> language? Almost none of them. There's Perl, obviously, and its
> predecessors sed and awk, and probably a few others, but most languages
> relegate regular expressions to a library.

Yes, like python relegates io to a library.  
Clearly useful but not indispensable, after all who *really* needs 
anything beyond print() and input().  And that stuff in math like sin()
and exp().  How many programs use that geeky trig stuff?  Definitely not 
indispensable.  In fact, now that you pointed it out to me, clearly all
that stdlib stuff is dispensable, all one really needs to write 
"real programmer" programs is just core python.  Who the hell needs "sys"!

> - How many useful programs can be written with regexes? Clearly there are
> many. Some of them would even be quite difficult without regexes. (In
> effect, you would have to invent your own pattern-matching code.)

Lucky for me then that there are regexes.

> - How many useful programs can be written without regexes? Clearly there are
> also many. Every time you write a Python program and fail to import re,
> you've written one.

By golly, you're right.  Not every program I write uses regexes.
Who would have thought?!  However, you failed to establish that 
the programs I write without re are useful.

> Can you call yourself a well-rounded programmer without at least a basic
> understanding of some regex library? Well, probably not. But that's part of
> the problem with regexes. They have, to some degree, driven out potentially
> better -- or at least differently bad -- pattern matching solutions, such
> as (E)BNF grammars, SNOBOL pattern matching, or lowly globbing patterns. Or
> even alternative idioms, like Hypercard's "chunking" idioms.

Hmm, very good point.  I wonder why all those "potentially better" 
solutions have not been more widely adopted?  A conspiracy by a 
secret regex cabal? 

> When all you have is a hammer, everything looks like a nail.

Lucky for us then, that we have more than just hammers!

Sorry for the flippant response (well, not really) but I find your 
arguments pedantic beyond the point of absurdity.  For me, regular 
expressions are indispensable in that if they were not available in 
Python I would not use Python.  The same is true of a number of other 
stdlib modules.  I don't give a rat's ass whether they are in a 
"library" that has to be explicitly requested with import or a 
"library" that is automatically loaded at startup.