Re: Proposal for adding symbols within Python

On Tue, 15 Nov 2005 01:57:53 -0800, Ben Sizer wrote:

>> I don't think I even understand what the objection is. What is
>> needed is a code fragment that shows how the use of strings is
>> untenable.
>
> myObject.value = 'value1'
>
> #... 100 lines of code elided...
>
> if myObject.value = 'Value1':
> do_right_thing()
> else:
> do_wrong_thing()
>
>
> I don't actually think string use is 'untenable', but it is definitely
> more error-prone. With some sort of named object on the right hand side
> you will at least get a helpful NameError.

It is moments like this that I'm not too proud to admit I learnt some good
techniques from Pascal:

# define some pseudo-constants
RIGHT_THING = 'value1'
WRONG_THING = 'some other value'
INCHES_TO_FEET = 12
CM_TO_METRES = 100

# ...

myObject.value = RIGHT_THING

#... 100 lines of code elided...

if myObject.value = RIGHT_THING:
do_right_thing()
else:
do_wrong_thing()


It isn't always appropriate or necessary to define "constants" (and I
sometimes wish that Python would enforce assign-once names), but they can
help avoid some silly mistakes.



--
Steven.

.

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