[Tutor] Truth value testing in if, while and boolean operations

[Alan Gauld]

On 15/10/2020 16:33, Manprit Singh wrote:
> Dear sir ,
> 
> While referring to python docs , i found that under the heading "Truth
> Value testing" it is written that
> 
> empty sequences and collections: '', (), [], {}, set(), range(0) are
> considered as false .
> 
> In PEP8 docs under "programming recommendations" it is written that :
> 
> "For sequences, (strings, lists, tuples), use the fact that empty sequences
> are false:
> 
> so it is a valid practice to write like this
> 
> if sequence:        # do_this() will be executed if sequence is not empty
> 
>     do_this()

> There is nothing mentioned in PEP 8 about using the sets, dicts etc in the
> same way as given above . 

PEP 8 is a style guide not a language reference. it is not exhaustive.
However it does say "if sequence" and your quote in the first paragraph
says:

> empty sequences and collections: '', (), [], {}, set(), range(0) are
> considered as false .

ie. sequence includes strings, tuples, dicts, sets, lists, ranges...

So PEP8 includes all of the above.

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Alan G
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