"no variable or argument declarations are necessary."

Will McGugan news at NOwillmcguganSPAM.com
Sun Oct 2 23:08:04 CEST 2005


James A. Donald wrote:
> I am contemplating getting into Python, which is used by engineers I
> admire - google and Bram Cohen, but was horrified to read
> 
> "no variable or argument declarations are necessary."
> 
> Surely that means that if I misspell a variable name, my program will
> mysteriously fail to work with no error message.
> 
> If you don't declare variables, you can inadvertently re-use an
> variable used in an enclosing context when you don't intend to, or
> inadvertently reference a new variable (a typo) when you intended to
> reference an existing variable.
> 
> What can one do to swiftly detect this type of bug?

A variable has to be assigned to before it is used, otherwise a 
NameError exception is thrown..

 >>> a + 1
Traceback (most recent call last):
   File "<interactive input>", line 1, in ?
NameError: name 'a' is not defined
 >>> a = 1
 >>> a + 1
2

Typos in variable names are easily discovered unless the typo happens to 
exist in the current context.

Will McGugan
-- 
http://www.willmcgugan.com
"".join({'*':'@','^':'.'}.get(c,0) or chr(97+(ord(c)-84)%26) for c in 
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