[Python-Dev] PEP 8 modernisation (original) (raw)

Terry Reedy tjreedy at udel.edu
Thu Aug 1 22:56:55 CEST 2013

On 8/1/2013 11:35 AM, Alexander Belopolsky wrote:

Here is one use-case where .. = lambda .. cannot be replaced with def ..

op['add'] = lambda x,y: x+y op['mul'] = lambda x, y: x*y

Yes, you are binding the functions to named slots, not to names, so not covered by the PEP. Once might still want to replace the expressions themselves, at the cost of more typing, for the advantage of better representations.

op = { 'add': lambda x,y: x*y, 'mul': lambda x, y: x+y} print(op) # no apparent problem

{'add': <function at 0x000000000227F730>,

'mul': <function at 0x00000000033867B8>}

def add(x, y): return x + y def mul(x, y): return x * y

These can be unittested individually

op = {'add': mul, 'mul': add} # mistake easily seen in original code print(op)

{'add': <function mul at 0x0000000003440950>,

'mul': <function add at 0x00000000034408C8>}

problem apparent to user who import this object and prints it when

code fails

If op has 20 such functions, names become even more of an advantage

-- Terry Jan Reedy

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