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copied!<p>(Note: This should all hopefully work, but I cannot test it at this time. Please give it your own sanity check.)</p> <p>You could write</p> <pre><code>(defn download-web-page "Downloads the webpage at the given url and returns its contents." ([^String url] (download-web-page url nil nil)) ([^String url ^String user ^String password] (with-open [client (doto (WebClient.) (-> (.set_Credentials (NetworkCredential. user password "")) (->> (when user))))] (.DownloadString client url)))) </code></pre> <p>That seems pretty convoluted to me, though. Another approach:</p> <pre><code>(defn download-web-page "Downloads the webpage at the given url and returns its contents." ([^String url] (download-web-page url nil nil)) ([^String url ^String user ^String password] (with-open [client (let [c (WebClient.)] (when user (.set_Credentials (NetworkCredential. user password ""))) c)] (.DownloadString client url)))) </code></pre> <p>The convoluted <code>-></code> / <code>->></code> pattern from the first version could be abstracted away with a macro:</p> <pre><code>(defmacro doto-guard [guard action] `(-> ~action ~guard)) </code></pre> <p>Then you could write</p> <pre><code>(doto (WebClient.) (doto-guard (when user) (.setCredentials ...))) </code></pre> <p>This has the nice property that you could use it multiple times in a single <code>doto</code> form while mixing in regular <code>doto</code> clauses. Well, it's nice if this sort of thing comes up more often in your code, anyway. Otherwise the <code>let</code>-based version should do fine.</p> <p>(If that pattern comes up <em>really</em> often for you, the macro could be made more flexible... It's also tempting to make it slightly <em>less</em> flexible, but prettier, say by replacing <code>~guard</code> with <code>(when ~guard)</code>, so that at point of use one would write <code>(doto-guard user (.setCredentials ...))</code>. Any deep reason to choose a particular version would have to come from a broader context, however.)</p> <p>The split into two function bodies is just a matter of style -- I prefer not to write the <code>nil nil</code> when no credentials are actually provided.</p>

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