<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Hi, Rangding. This is a known issue, tracked by <a href="https://bugs.swift.org/browse/SR-1846" class="">SR-1846</a>. Essentially the compiler is not smart enough to know that you mean the existing function 'data' rather than the variable you are defining.</div><div class=""><br class=""></div><div class="">Best,</div><div class="">Jordan</div><div class=""><br class=""></div><br class=""><div><blockquote type="cite" class=""><div class="">On Oct 27, 2016, at 19:06, 张让定 via swift-users <<a href="mailto:swift-users@swift.org" class="">swift-users@swift.org</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div style="font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; line-height: 1.7; font-size: 14px; font-family: Arial;" class=""><div class=""><pre id="best-content-275191239" accuse="aContent" class="best-text mb-10" style="margin-top: 10px; margin-bottom: 10px; padding: 0px; font-family: 'Microsoft YaHei', arial, 'courier new', courier, 宋体, monospace; font-size: 16px; line-height: 29px; color: rgb(51, 51, 51); min-height: 55px;">Dear Sir/madam,</pre></div><div class=""><p style="box-sizing: border-box; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol'; margin-top: 0px !important;" class="">I have a fuction:</p><pre style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 13.3333px; margin-top: 0px; margin-bottom: 16px; line-height: 1.45; word-wrap: normal; padding: 16px; overflow: auto; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; color: rgb(51, 51, 51);" class=""><code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 13.3333px; padding: 0px; margin: 0px; background-color: transparent; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-break: normal; white-space: pre; border: 0px; display: inline; overflow: visible; line-height: inherit; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;" class="">import Foundation
public func data(with string:String?) -> Data? {
if let string = string {
return string.data(using: String.Encoding.utf8)
}
return nil
}
</code></pre><p style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';" class="">When I use it like:</p><pre style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 13.3333px; margin-top: 0px; margin-bottom: 16px; line-height: 1.45; word-wrap: normal; padding: 16px; overflow: auto; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; color: rgb(51, 51, 51);" class=""><code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 13.3333px; padding: 0px; margin: 0px; background-color: transparent; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-break: normal; white-space: pre; border: 0px; display: inline; overflow: visible; line-height: inherit; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;" class="">let data = data(with: "Hello")
</code></pre><p style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';" class="">There is a compile error: variable used within it's own initial value.</p><p style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';" class="">If write like:</p><pre style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 13.3333px; margin-top: 0px; margin-bottom: 16px; line-height: 1.45; word-wrap: normal; padding: 16px; overflow: auto; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; color: rgb(51, 51, 51);" class=""><code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 13.3333px; padding: 0px; margin: 0px; background-color: transparent; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-break: normal; white-space: pre; border: 0px; display: inline; overflow: visible; line-height: inherit; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;" class="">let stringData = data(with: "Hello")
</code></pre><p style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';" class="">Everything is OK.</p><p style="box-sizing: border-box; margin-top: 0px; margin-bottom: 16px; color: rgb(51, 51, 51); font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji', 'Segoe UI Symbol';" class="">So I wonder why not support the syntax like:</p><pre style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 13.3333px; margin-top: 0px; line-height: 1.45; word-wrap: normal; padding: 16px; overflow: auto; background-color: rgb(247, 247, 247); border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; color: rgb(51, 51, 51); margin-bottom: 0px !important;" class=""><code style="box-sizing: border-box; font-family: Consolas, 'Liberation Mono', Menlo, Courier, monospace; font-size: 13.3333px; padding: 0px; margin: 0px; background-color: transparent; border-top-left-radius: 3px; border-top-right-radius: 3px; border-bottom-right-radius: 3px; border-bottom-left-radius: 3px; word-break: normal; white-space: pre; border: 0px; display: inline; overflow: visible; line-height: inherit; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;" class="">let data = data(with: "Hello")</code></pre></div><div class=""><br class=""></div><div class=""><font color="#333333" face="Consolas, Liberation Mono, Menlo, Courier, monospace" class=""><span style="font-size: 13.3333px; white-space: pre; background-color: rgb(247, 247, 247);" class="">Yours sincerely</span></font></div><div class=""><font color="#333333" face="Consolas, Liberation Mono, Menlo, Courier, monospace" class=""><span style="font-size: 13.3333px; white-space: pre; background-color: rgb(247, 247, 247);" class="">Rangding Zhang</span></font></div></div><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><br style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><span title="neteasefooter" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class=""><div class=""> <br class="webkit-block-placeholder"></div></span><span style="font-family: Helvetica; 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