Author: Stan Eisenstat
Subject: Re: [Cs323] << failing question
Date: Thursday, 01 Oct 2020, 12:14:12

    > Message Posted By: Unknown
    >
    > Can we fail right away if a line with << is syntactically incorrect? For
    > example, say if the parenthesis is not balanced.
    > i.e.
    > (<< HERE file
    >
    > Do we have to get the here input or can we just fail?

As I posted earlier in reference to "<<a <<b":

  Date: 27 Sep 2020 19:30:59 -0400 (Sun)
  Subject: Re: [Cs323] here doc
  ...
      
  Here are two ways to handle HERE documents:
   
  1. Read the lines when the <<HERE is encountered, in
     which case the first document will be read before the
     second <<HERE is encountered and the error is detected.
   
  2. Read the lines when the CMD struct containing the
     HERE document is added to the CMD tree, in which case
     the error is detected before the first document is
     read.
   
  Hwk2/parsley does the first, but the second is just as
  reasonable.  Thus the correct behavior (in terms of
  whether the document is or is not read) is unspecified
  and will not be tested.

Thus the behavior for "(<< HERE file" is unspecified.

Aside: bash avoids this problem by prompting for extra
lines until the parentheses balance.

--Stan-