Extract with_repo_or_exit

This will run a given function in a git repo, or print an error message
and exit if the current working directory is not within a git repo.

src/bin/git-solo.rs

@@ -1,21 +1,12 @@
 use git2::Repository;
-use std::process;
 use std::fs::File;
-use git_mob::{get_main_author, gitmessage_template_file_path};
+use git_mob::{get_main_author, gitmessage_template_file_path, with_repo_or_exit};
 
 fn main() {
     let main_author = get_main_author();
     println!("{}", main_author);
 
-    match Repository::open_from_env() {
-        Ok(repo) => {
-            truncate_gitmessage_template(repo);
-        }
-        Err(_e) => {
-            eprintln!("Not in a git repository");
-            process::exit(1);
-        }
-    }
+    with_repo_or_exit(truncate_gitmessage_template);
 }
 
 fn truncate_gitmessage_template(repo: Repository) {

src/lib.rs

@@ -8,6 +8,7 @@ use std::io::BufReader;
 use std::fs::File;
 use std::error::Error;
 use std::string::String;
+use std::process;
 
 #[derive(Serialize, Deserialize, Clone, Debug)]
 pub struct Author {
@@ -58,3 +59,13 @@ fn parse_coauthors_file() -> Result<BTreeMap<String, Author>, Box<dyn Error>> {
 pub fn gitmessage_template_file_path(repo: Repository) -> std::path::PathBuf {
     repo.path().join(".gitmessage")
 }
+
+pub fn with_repo_or_exit<F: FnOnce(Repository)>(f: F) {
+    match Repository::open_from_env() {
+        Ok(repo) => f(repo),
+        Err(_e) => {
+            eprintln!("Not in a git repository");
+            process::exit(1);
+        }
+    }
+}