Add concatdoc docs

README.md

@@ -74,16 +74,24 @@ fn main() {
 
 ## Formatting macros
 
-The indoc crate exports four additional macros to substitute conveniently for
+The indoc crate exports five additional macros to substitute conveniently for
 the standard library's formatting macros:
 
 - `formatdoc!($fmt, ...)` — equivalent to `format!(indoc!($fmt), ...)`
 - `printdoc!($fmt, ...)` — equivalent to `print!(indoc!($fmt), ...)`
 - `eprintdoc!($fmt, ...)` — equivalent to `eprint!(indoc!($fmt), ...)`
 - `writedoc!($dest, $fmt, ...)` — equivalent to `write!($dest, indoc!($fmt), ...)`
+- `concatdoc!(...)` — equivalent to `concat!(...)` with each string literal wrapped in `indoc!`
 
 ```rust
-use indoc::printdoc;
+use indoc::{concatdoc, printdoc};
+
+const HELP: &str = concatdoc! {"
+    Usage: ", env!("CARGO_BIN_NAME"), " [options]
+
+    Options:
+        -h, --help
+"};
 
 fn main() {
     printdoc! {"

src/lib.rs

@@ -72,16 +72,30 @@
 //!
 //! # Formatting macros
 //!
-//! The indoc crate exports four additional macros to substitute conveniently
+//! The indoc crate exports five additional macros to substitute conveniently
 //! for the standard library's formatting macros:
 //!
 //! - `formatdoc!($fmt, ...)` — equivalent to `format!(indoc!($fmt), ...)`
 //! - `printdoc!($fmt, ...)` — equivalent to `print!(indoc!($fmt), ...)`
 //! - `eprintdoc!($fmt, ...)` — equivalent to `eprint!(indoc!($fmt), ...)`
 //! - `writedoc!($dest, $fmt, ...)` — equivalent to `write!($dest, indoc!($fmt), ...)`
+//! - `concatdoc!(...)` — equivalent to `concat!(...)` with each string literal wrapped in `indoc!`
 //!
 //! ```
-//! use indoc::printdoc;
+//! # macro_rules! env {
+//! #     ($var:literal) => {
+//! #         "example"
+//! #     };
+//! # }
+//! #
+//! use indoc::{concatdoc, printdoc};
+//!
+//! const HELP: &str = concatdoc! {"
+//!     Usage: ", env!("CARGO_BIN_NAME"), " [options]
+//!
+//!     Options:
+//!         -h, --help
+//! "};
 //!
 //! fn main() {
 //!     printdoc! {"