Hello list,
Once in a while I find myself writing code that looks like this:
if <some container is empty> then
empty_stuff
else
for k,v in pairs(container) do for_stuff end
end
or
if <some numerical [a,b,step] range is empty> then
range_empty_stuff
else
for i in a,b,step do for_stuff end
end
On those occasions I find myself wishing I could write this instead, where the else clause is run whenever the for clause was not entered.
for <iteration_stuff> do
for_stuff
else
else_stuff
end
Note that the behavior I am wishing for is not what python is offering: python's else clause is run at the end of the loop whether it was
empty or not, and is skipped only if the loop is interrupted by break.
My gripe is the following: Currently the condition has to be written twice, and if for some reason the looping condition changes, I have to
maintain the if condition as well. Code duplication doubles the chance
of introducing a bug. The same remark applies to while loops.
I am aware that the language does not "need" this new syntax to express what I want to achieve. To this I can reply: the language does not need for and while loops at all either, since it has if and goto :-).
Introducing this change would not break existing Lua code, but are
there any obvious reasons that could make this feature difficult to
implement (for example syntactic ambiguities)?
Regards,
Benoit.
