I need a little help with extending _futures_ with additional context for error
reporting. I can't even get my current effort to compile without commenting out
a couple lines :-(.
Any pointers would certainly be appreciated.
# Background:
# - Test harness to check out how to extend a httpclient future to include
# additional context information (in this case the source url which could
be
# usefull in reporting failures)
import asyncdispatch, httpclient, strutils, system
type URLinfo = object
url: string
content: string
# Non-working attempt to implement the extended future
proc fetch(url: string): Future[URLinfo] {.async.} =
var fetchResult = URLinfo()
var extendedFuture = newFuture[URLinfo]
var client = newAsyncHttpClient()
fetchResult.url = url
let future = client.getContent url
# Use subordinate *simple* http future completon to trigger the
*extended* future
future.addCallback(
proc(future: Future[string]) =
fetchResult.content = future.read
echo "content: ", fetchResult.content.len
# complete(extendedFuture, fetchResult) # doesn't compile
)
discard await future
# result = extendedFuture # doesn't compile
echo "fetch finished"
proc getURLs(urls: seq[string]) : Future[seq[URLinfo]] {.async.} =
var futures: seq[Future[URLinfo]]
for url in urls:
var future = fetch url
futures.add future
result = await all futures
echo "getURLs finished"
proc main() {.async} =
const sites = @[
"https://google.com";,
"https://amazon.com";
]
discard await getURLs sites
waitFor main()
echo "main finished"
Run
