I am writing an iterator which calls walkDir and iterates over all of the files
in the dir creating objects from those files. I have a proc which reads the
file and creates a seq of the objects. It works fine. Amazingly so, on my
machine Nim will read one of these files and create almost 400k objects in 40ms.
I want an iterator which iterates over each of these files, serving each of its
objects one at a time.
iterator pricestream*(source: string, instrument: Instrument): Price =
## Iterator for all historic prices for the source, and instrument.
var paths: seq[string]
for file in walkDir(datapath / source / $instrument / "Prices"):
paths.add(file.path)
paths.sort(system.cmp[string])
for path in paths:
for price in pricesFromCsv(path):
yield price
# If I call like this:
var stream = pricestream("oanda", EUR_USD)
for p in stream:
...
# I get this:
# ntplayground.nim(46, 27) Error: attempting to call undeclared routine:
'pricestream'
# If I call like this:
var stream = pricestream
for p in stream("oanda", EUR_USD):
...
# I get this:
# ntplayground.nim(47, 18) Error: type mismatch: got <Price>
# but expected one of:
# iterator items[T](a: set[T]): T
# ...
Run
Any help in understanding how to write and call an iterator (this iterator)
would be greatly appreciated.
