Maarten, 25.08.2011 09:52:
On Aug 25, 9:13 am, Steven D'Aprano wrote:
One design principle often mentioned here (with a certain degree of
disagreement[1]) is the idea that as a general rule, you shouldn't write
functions that take a bool argument to switch between two slightly
different behaviours.
This is a principle often championed by the BDFL, Guido van Rossum.
Here's a Javascript-centric article which discusses the same idea, and gives
it a name: the Boolean Trap.
http://ariya.ofilabs.com/2011/08/hall-of-api-shame-boolean-trap.html
No doubt there are counter arguments as well. The most obvious to me is if
the flag=True and flag=False functions share a lot of code, it is poor
practice to implement them as two functions with two copies of almost
identical code.
A simple one: C and C-like languages only have arguments, not keyword-
parameters. That alone makes a world of difference.
Right. It's totally unreadable to find this in the code:
data1.merge_with(data2, true);
Requires you to either a) know the underlying signature by heart, or b)
look it up before understanding the code.
It's a lot harder to argue against this:
data1.merge_with(data2, overwrite_duplicates=True)
Stefan
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