Re: Supply condition in function call

[Cameron Simpson]

On 27Mar2015 21:02, Manuel Graune <manuel.gra...@koeln.de> wrote:
Cameron Simpson <c...@zip.com.au> writes:
This passes the local variables inside test1() to "condition" as a
single parameter. Now, I grant that vars['i'] is a miracle of
tediousness. So consider this elaboration:

 from collections import namedtuple

 condition_test = lambda vars: vars.i + vars.j > 4

 def test1(a, b, condition):
   for i, j in zip(a,b):
     c = i + j
     vars = locals()
     varnames = list(vars.keys())
     varstupletype = namedtuple("locals", varnames)
     varstuple = varstupletype(*[ vars[k] for k in varnames ])
     if condition(varstuple):
       print("Foo")

Here, the condition_test function/lambda uses "vars.i" and "vars.j",
which i think you'll agree is easier to read and write. The price is
the construction of a "namedtuple" to hold the variable name
values. See:

 https://docs.python.org/3/library/collections.html#collections.namedtuple


This is probably getting off topic,

I think it is on topic.

but is there any relevant difference
or benefit to using namedtuple instead of something like types.SimpleNamespace?

https://docs.python.org/3/library/types.html#additional-utility-classes-and-functions

Probably not. SimpleNamespace is much easier to construct; I hadn't thought of 
it. As the doc remarks, a namedtuple is probably better for fixed records (eg 
mapping out rows of a CSV file) because it will prevent you using the wrong 
name. But for a comparison function SimpleNamespace is probably better.

Cheers,
Cameron Simpson <c...@zip.com.au>

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