In article <54ba39e0$0$13008$c3e8da3$54964...@news.astraweb.com>, Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote:
> Every time I think I would like to learn a new language, I quite quickly run > into some obvious feature that Python has but the newer language lacks, and > I think "bugger this for a game of soldiers" and abandon it. Wow. Another wonderful English phrase to add to my vocabulary. That's up there with Bob's your uncle :-) > Ah, wait, I forgot Ruby's brilliant "feature" that whitespace *between* > expressions is significant: > > [steve@ando ~]$ cat ~/coding/ruby/ws-example.rb > #!/usr/bin/ruby > > def a(x=4) > x+2 > end > > b = 1 > print "a + b => ", (a + b), "\n" > print "a+b => ", (a+b), "\n" > print "a+ b => ", (a+ b), "\n" > print "a +b => ", (a +b), "\n" > > [steve@ando ~]$ ruby ~/coding/ruby/ws-example.rb > a + b => 7 > a+b => 7 > a+ b => 7 > a +b => 3 > > > A shiny new penny for any non-Ruby coder who can explain that! The last time I looked at Ruby was when it was brand new. I bought the original pickaxe book and read it on a plane trip. It looked pretty cool at the time, but I never really got into it. So I think I qualify. Anyway, I'm going to guess from the above examples, that uttering a name means, "If the referent is callable, call it, if not, get its value". This is the same, for example, as django's template language. Or, kind of like Python's properties. So (a + b) means "Call a(), and add the value of b to that". I'm going to further guess that def a(x=4) means a() takes an optional argument, with a default value of 4, just like in Python. So a returns 6, i.e. 4 + 2. I'm going to further guess that (a +b) is parsed as "call a, passing +b as an argument", and the "+" is taken as a unary prefix. I want my penny. This is not the only example of significant whitespace in programming languages. Old-style C/C++ allowed either += or =+ for the increment operator. This led to parsing ambiguity for things like a=+b, where (IIRC), "a = +b" was parsed as an assignment and unary +, and "a =+ b" was parsed as an increment. Eventually, the syntax was changed to make += the only legal way to write increment. There was also the problem with nested template operators in C++, where "Foo<T1<T2>>" was mis-parsed, and you had to write it as "Foo <T1 <T2> >" (or something like that) to get it to parse right. -- https://mail.python.org/mailman/listinfo/python-list
