Closed
Description
openedon Apr 21, 2016
I was confused as to why my custom iterator, was failing to collect
Consider the MWE:
type Foo
values::Vector{}
end
function Base.start(f::Foo)
return 1
end
function Base.next(f::Foo, state)
f.values[state], state+1
end
function Base.done(f::Foo, state)
state>length(f.values)
end
Running with a for loop works fine:
for f in Foo([1,2,3])
print(f)
end
> 123
Collecting Breaks:
collect(Foo([1,2,3]))
>LoadError: MethodError: no method matching length(::Foo)
while loading In[26], in expression starting on line 1
This is true -- there is not method to find the length of a ::Foo
So why is it being ask?
Because
Base.iteratorsize(Foo([1,2,3]))
>Base.HasLength()
It thinks it has a length.
I think it is coming from:
Line 35 in c603a79
The workaround is to add to my definition
Base.iteratorsize(::Foo) = Base.SizeUnknown()
But I feel like this should be being inferred, by the face that neither size(::Foo) or Length(::Foo) are defined?
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