FW: Re: [Jython-users] String Object id question

[D-Man <ds...@ri...>]

Ype and I discussed the syntax of assert (and raise) a bit off the
list.  I am now forwarding the discussion to the list (as requested)
in case anyone else is interested.

----- Forwarded message from D-Man <ds...@ri...> -----

From: D-Man <ds...@ri...>
Date: Wed, 28 Mar 2001 16:22:53 -0500
To: Ype Kingma <yk...@xs...>
User-Agent: Mutt/1.2.5i

On Wed, Mar 28, 2001 at 10:19:50PM +0100, Ype Kingma wrote:
| -D,
| 
| >On Wed, Mar 28, 2001 at 09:21:19PM +0100, Ype Kingma wrote:
| >|
| >| "Robert W. Bill" wrote:
| >| >
| >| > assert(test(stringtest, S[1])), "String test failed"
| >| >
| >|
| >| Also the assert code is a bit strange:
| >| 'assert' is a keyword, not a function.
| >| Leaving out one pair of brackets gives:
| >
| >Robert has already mentioned that his post was hasty and had several
| >errors in it.  The posted line is harder to read due to the lack of
| >whitespace between 'assert' and '('.  Anyways, just FYI, assert can
| 
| Sorry for that, I assumed the whole history was there...

No problem.

| >take a 2-tuple as its only "argument"
| >
| >assert ( 0 , "Hello World" )
| >
| >is equivalent to
| >
| >assert 0 , "Hello World"
| >
| >It is quite useful when the expression, or more often, the string is
| >too long.  By using parens to create a tuple the \ prior to the
| >newline is not necessary.
| 
| Useful indeed. I rechecked the (python) docs on the assert statement, but
| the tuple argument isn't mentioned there. Is there documentation
| for it somewhere?

I don't know.  I have noticed that several keywords that take 2
"arguments" (like 'raise' for example) can take a 2-tuple instead.  I
tried it with assert and it worked.  

Now that I think about it, I think it is actually caused by the
lexer/parser that expressions of the form 

<foo> , <bar>

are tuples, and also

( <foo> , <bar> )

is the same tuple.  


I just took a look at 

http://www.python.org/doc/current/ref/parenthesized.html

and the last paragraph seems most relevant.  I guess assert and raise
take a 2-tuple which can optionally have parenthesis or not.  I use
the parens when I want to break it over multiple lines without using
\, but I put a space so it doesn't look like a function call.

-D


----- End forwarded message -----