Question

I’ve got some code which downloads a list of data from numerous URLs, then calls another function, passing in each result. Something like…

def ShowUrls(self, url):
    Urls = self.Scraper.GetSubUrls(url)
    for Url in Urls:
        self.UI.addLink(
          Url[0],
          Url[1])

This works fine but there’s a long delay while self.Scraper.GetSubUrls runs, then all the UI calls are made very rapidly. This causes the UI to show “0 Urls added” for a long time, then complete.

What I’d like is to be able to pass the self.UI.addlink method in to the self.Scraper.GetSubUrls method so that it can be called as soon as each URL is retrieved. This should make the UI show the correct count as soon as each url is retrieved.

Is this possible? If so, what’s the correct syntax?

If I were in Javascript, I’d do something like….

getSubUrls(url, function(x, y) {UI.addLink(x, y)})

and then, inside getSubUrls do

SomeParamMethod(Pram1, Param2)

Is this possible? If so, what’s the correct syntax?

Answer 1

You can use lambda, but it’s usually a better idea to make a separate function and pass it.

self.Scraper.GetSubUrls(url, lambda url: self.UI.addLink(url[0], url[1]))

or

def addLink(url):
    self.UI.addLink(url[0], url[1])

self.Scraper.GetSubUrls(url, addLink)