Discovered build constraints today! Life just became easymode for cross-platform specific stuff.

<p>So I&#39;ve been plugging away at code that I intend to transpile to javascript for a user interface piece with gopherjs. The biggest issue I was running into is part of my APIs were not going to be compatible in gopherjs. As a result, I assumed I was going to have to make a massive make file to handle what to compile and when. </p> <p>Well, it turns out GoLang has my back! I was stoked to find out about build constraints and they don&#39;t seem to be talked about much. It seems that if we ever wanted desktop UI&#39;s to exists, these things would be our saving grace. </p> <p><a href="https://golang.org/pkg/go/build/#hdr-Build_Constraints">https://golang.org/pkg/go/build/#hdr-Build_Constraints</a></p> <hr/>**评论：**<br/><br/>danredux: <pre><p>I love build constraints.</p> <p>I have a very weird use case. 98% of my code is in a public repo, but there is a private repo containing the final 2%. The public repo has stubs which the private repo overwrites.</p> <p>Simple solution? Import the private repo as a package. However, that means the public package is not build-able, because it&#39;s missing an import.</p> <p>Build constraints saved me, by hiding the import in a build-constrained file, I have to pass in a specific tag to have the import be included. Others can &#34;go get&#34; with no weird trickery but I can pass in a build tag and have my private overrides applied.</p></pre>titpetric: <pre><p>Ugh, the documentation here for this sucks. I had to dig through at least two github issues about it before figuring out how you do this. So, I suspect:</p> <pre><code>// +build !private something here... </code></pre> <p>and then run <code>go build -tags private</code> that would &#34;include&#34; your 2% package. How do you modify public repo stubs? Globals? init()? A more concrete example would be interesting.</p></pre>igknighted: <pre><p>Important to note, <code>-tags private</code> must be before any file names. Go is kinda specific when doing this.</p></pre>Xanarion: <pre><p>Do you have an example code how that is done?</p></pre>igknighted: <pre><p>Probably separate files that import that 2nd private repo. In addition to the <code>go build -tags private</code> flag that <a href="/u/titpetric" rel="nofollow">/u/titpetric</a> mentioned. </p> <p>It can work like this: <a href="https://gist.github.com/protosam/a8900dde24c6fe3ecc1056749131471a" rel="nofollow">https://gist.github.com/protosam/a8900dde24c6fe3ecc1056749131471a</a></p></pre>Xanarion: <pre><p>Thanks, I get the idea now :) </p></pre>