why brackets & commas in func calls can't be ommited? (maybe it couldbe PEP?)

Enrico 'Mc Osten' Franchi riko at despammed.com
Thu Mar 22 22:35:53 CET 2007


<bearophileHUGS at lycos.com> wrote:

> But I think in some situations Ruby allows to omit them, solving some
> of the "impossibile" problems shown in this thread. This makes Ruby a
> bit better than Python to create application-specific mini languages,
> that are quite useful in some situations.

Yes. However, Ruby parser has to resort to heuristic in many cases:

<http://www.rubycentral.com/book/language.html>

"When Ruby sees a name such as ``a'' in an expression, it needs to
determine if it is a local variable reference or a call to a method with
no parameters. To decide which is the case, Ruby uses a heuristic."

In fact it is something I don't really like about Ruby (even though I
find it useful in some cases).

This is a 'pathological example'

def a
  print "Function 'a' called\n"
  99
end


for i in 1..2
  if i == 2
    print "a=", a, "\n"
  else
    a = 1
    print "a=", a, "\n"
  end
end


But I have to say that omitting brackets in a language such as Python or
Ruby can make the code very hardly readable. The interpreter isn't the
only one who has to resort to heuristic: everytime you read a name with
no parenthesis you may have to go back and see whether it is a bound
variable, a method (so you may have to check documentation for various
modules) or an 'invalid' variable you forgot to initialize.

In fact, when I'm reading code from a project I'm not familiar with, it
can be quite hard in the first place. 

In fact most Rubyists advice to use parentheses (unless you want to
achieve a DSL like effect, or in very simple cases like

puts s

)

The third problem I found out is related to blocks ({} and do have
different precedence order). They are only syntax errors, but I find
them annoying.

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