feat: Add `clap.helpToFile`

The code for printing help became quite verbose after writegate. Writing
help to a file like stdout and stderr is very common, so this wrapper
provides a default, buffered way to report to a file.

3 files changed, 17 insertions, 12 deletions

diff --git a/README.md b/README.md
index 8db67c9..6a1435f 100644
--- a/README.md
+++ b/README.md
@@ -365,12 +365,8 @@ pub fn main() !void {
     // where `Id` has a `description` and `value` method (`Param(Help)` is one such parameter).
     // The last argument contains options as to how `help` should print those parameters. Using
     // `.{}` means the default options.
-    if (res.args.help != 0) {
-        var buf: [1024]u8 = undefined;
-        var stderr = std.fs.File.stderr().writer(&buf);
-        try clap.help(&stderr.interface, clap.Help, &params, .{});
-        return stderr.interface.flush();
-    }
+    if (res.args.help != 0)
+        return clap.helpToFile(.stderr(), clap.Help, &params, .{});
 }
 
 const clap = @import("clap");
diff --git a/clap.zig b/clap.zig
index c4dd801..4a001ce 100644
--- a/clap.zig
+++ b/clap.zig
@@ -1367,6 +1367,19 @@ pub const HelpOptions = struct {
     spacing_between_parameters: usize = 1,
 };
 
+/// Wrapper around `help`, which writes to a file in a buffered manner
+pub fn helpToFile(
+    file: std.fs.File,
+    comptime Id: type,
+    params: []const Param(Id),
+    opt: HelpOptions,
+) !void {
+    var buf: [1024]u8 = undefined;
+    var writer = file.writer(&buf);
+    try help(&writer.interface, Id, params, opt);
+    return writer.end();
+}
+
 /// Print a slice of `Param` formatted as a help string to `writer`. This function expects
 /// `Id` to have the methods `description` and `value` which are used by `help` to describe
 /// each parameter. Using `Help` as `Id` is good choice.
diff --git a/example/help.zig b/example/help.zig
index 676a56a..5c88d83 100644
--- a/example/help.zig
+++ b/example/help.zig
@@ -17,12 +17,8 @@ pub fn main() !void {
     // where `Id` has a `description` and `value` method (`Param(Help)` is one such parameter).
     // The last argument contains options as to how `help` should print those parameters. Using
     // `.{}` means the default options.
-    if (res.args.help != 0) {
-        var buf: [1024]u8 = undefined;
-        var stderr = std.fs.File.stderr().writer(&buf);
-        try clap.help(&stderr.interface, clap.Help, &params, .{});
-        return stderr.interface.flush();
-    }
+    if (res.args.help != 0)
+        return clap.helpToFile(.stderr(), clap.Help, &params, .{});
 }
 
 const clap = @import("clap");