From f14cc0bcdd2e301ef5f4c4e86be3463ef6cb5a07 Mon Sep 17 00:00:00 2001
From: Jonathan Samson <jonathan.samson@wur.nl>
Date: Wed, 11 Dec 2019 19:05:00 +0100
Subject: [PATCH] Added a style parameter to defaultGetoptFormatter.

---
 std/getopt.d | 36 +++++++++++++++++++++++++++++++++---
 1 file changed, 33 insertions(+), 3 deletions(-)

diff --git a/std/getopt.d b/std/getopt.d
index eb29e981a..fdf1095f0 100644
--- a/std/getopt.d
+++ b/std/getopt.d
@@ -1635,14 +1635,15 @@ void defaultGetoptPrinter(string text, Option[] opt)
 
 /** This function writes the passed text and `Option` into an output range
 in the manner described in the documentation of function
-`defaultGetoptPrinter`.
+`defaultGetoptPrinter`, unless the style option is used.
 
 Params:
     output = The output range used to write the help information.
     text = The text to print at the beginning of the help output.
     opt = The `Option` extracted from the `getopt` parameter.
+    style = The manner in which to display the output of each `Option.`
 */
-void defaultGetoptFormatter(Output)(Output output, string text, Option[] opt)
+void defaultGetoptFormatter(Output)(Output output, string text, Option[] opt, string style = "%*s %*s%*s%s\n")
 {
     import std.algorithm.comparison : min, max;
     import std.format : formattedWrite;
@@ -1663,7 +1664,7 @@ void defaultGetoptFormatter(Output)(Output output, string text, Option[] opt)
 
     foreach (it; opt)
     {
-        output.formattedWrite("%*s %*s%*s%s\n", ls, it.optShort, ll, it.optLong,
+        output.formattedWrite(style, ls, it.optShort, ll, it.optLong,
             hasRequired ? re.length : 1, it.required ? re : " ", it.help);
     }
 }
@@ -1864,3 +1865,32 @@ void defaultGetoptFormatter(Output)(Output output, string text, Option[] opt)
     assert(c == '-');
     assert(f == "-");
 }
+
+@system unittest
+{
+    import std.conv;
+
+    import std.array;
+    import std.string;
+    bool a;
+    auto args = ["prog", "--foo"];
+    auto t = getopt(args, "foo|f", "Help", &a);
+    string s;
+    auto app = appender!string();
+    defaultGetoptFormatter(app, "Some Text", t.options, "\t\t%*s %*s%*s\n%s\n");
+
+    string helpMsg = app.data;
+    //writeln(helpMsg);
+    assert(helpMsg.length);
+    assert(helpMsg.count("\n") == 5, to!string(helpMsg.count("\n")) ~ " "
+        ~ helpMsg);
+    assert(helpMsg.indexOf("--foo") != -1);
+    assert(helpMsg.indexOf("-f") != -1);
+    assert(helpMsg.indexOf("-h") != -1);
+    assert(helpMsg.indexOf("--help") != -1);
+    assert(helpMsg.indexOf("Help") != -1);
+
+    string wanted = "Some Text\n\t\t-f  --foo \nHelp\n\t\t-h --help \nThis help "
+        ~ "information.\n";
+    assert(wanted == helpMsg);
+}