Use fmt::format for string formatting where it improves clarity.

src/files.cpp

@@ -19,6 +19,8 @@
 #include "json.hpp"
 #include "types.hpp"
 
+#include <fmt/format.h>
+
 #include <algorithm>
 #include <cstdint>
 #include <cstdlib>
@@ -32,6 +34,7 @@
 namespace FediBlock::files
 {
 
+using fmt::format;
 using std::getenv;
 using std::ifstream;
 using std::ofstream;
@@ -70,7 +73,7 @@ void remove_tmpdir()
 
 fs::path get_xdg_dir(const string &identifier)
 {
-    const string xdg_variable{("XDG_" + identifier) += "_HOME"};
+    const string xdg_variable{format("XDG_{:s}_HOME", identifier)};
     char *env{getenv(xdg_variable.c_str())};
     if (env != nullptr)
     {
@@ -133,11 +136,12 @@ fs::path get_cachedir()
 
 string get_access_token()
 {
-    ifstream file(get_datadir() / "gitea_access_token");
+    const fs::path access_token_path{get_datadir() / "gitea_access_token"};
+    ifstream file(access_token_path);
     if (!file.good())
     {
-        throw runtime_error{"Could not read access token: "
-                            + (get_datadir() / "gitea_access_token").string()};
+        throw runtime_error{format("Could not read access token: {:s}",
+                                   access_token_path.string())};
     }
     stringstream ss;
     ss << file.rdbuf();
@@ -199,7 +203,7 @@ vector<entry_type> read_json_files(const bool cache)
 fs::path get_lockfile()
 {
 #if defined(__linux__)
-    fs::path path{"/run/user/" + to_string(getuid())}; // pam_systemd
+    fs::path path{format("/run/user/{:d}", getuid())}; // pam_systemd
     if (!fs::exists(path))
     {
         path = "/run/lock"; // Linux
@@ -236,8 +240,8 @@ bool create_lockfile()
     }
     catch (const std::ofstream::failure &e)
     {
-        const auto msg{string("Could not write lockfile: ") += e.what()};
-        throw std::runtime_error{msg.c_str()};
+        throw std::runtime_error{
+            format("Could not write lockfile: {:s}", e.what())};
     }
 
     return true;

src/generators/rss.cpp

@@ -20,6 +20,8 @@
 #include "git.hpp"
 #include "time.hpp"
 
+#include <fmt/format.h>
+
 #include <algorithm>
 #include <chrono>
 #include <cstdint>
@@ -35,6 +37,7 @@
 namespace FediBlock::rss
 {
 
+using fmt::format;
 using std::find;
 using std::getenv;
 using std::none_of;
@@ -149,11 +152,11 @@ void write_rss(ostream &out, const vector<entry_type> &entries,
                    "FediBlock: " + entry.report_time + " " + entry.instance);
         write_line(out, 6, "pubDate",
                    time::to_string(entry.report_time, rss_time_format));
-        write_line(out, 6, "link", baseurl + '#' += entry.instance);
+        write_line(out, 6, "link",
+                   format("{:s}#{:s}", baseurl, entry.instance));
 
-        string item_description{"<p>" + cgi::text2html(entry.description)
-                                + "</p>"};
-        item_description += "<p><strong>Tags:</strong> ";
+        string item_description{format("<p>{:s}</p><p><strong>Tags:</strong> ",
+                                       cgi::text2html(entry.description))};
         for (const auto &tag : entry.tags)
         {
             if (tag != *entry.tags.begin())
@@ -162,25 +165,23 @@ void write_rss(ostream &out, const vector<entry_type> &entries,
             }
             item_description += tag;
         }
-        item_description += "</p>";
-        item_description += "<strong>Receipts:</strong><ul>";
+        item_description += "</p><strong>Receipts:</strong><ul>";
         for (const auto &receipt : entry.receipts)
         {
-            ((((item_description += "<li><a href=\"") += receipt) += "\">") +=
-             receipt) += "</a></li>";
+            item_description +=
+                format("<li><a href=\"{0:s}\">{0:s}</a></li>", receipt);
         }
         item_description += "</ul>";
         if (!entry.screenshot_filepath.empty())
         {
             item_description += "<p><strong>Screenshot:</strong><br>";
-            ((item_description += "<a href=\"") += baseurl) +=
-                entry.screenshot_filepath;
-            item_description += "\"><img src=\"";
-            (item_description += baseurl) += entry.screenshot_filepath;
-            (item_description += R"(" height="200"></a></p>)") += '\n';
+            item_description +=
+                format("<a href=\"{0:s}{1:s}\"><img "
+                       "src=\"{0:s}{1:s}\" height=\"200\"></a></p>\n",
+                       baseurl, entry.screenshot_filepath);
         }
         write_line(out, 6, "description",
-                   "<![CDATA[" + item_description + "]]>");
+                   format("<![CDATA[{:s}]]>", item_description));
 
         out << "    </item>\n";
     }

src/git.cpp

@@ -21,6 +21,7 @@
 #include "gitea.hpp"
 #include "json.hpp"
 
+#include <fmt/format.h>
 #include <git2.h>
 
 #include <chrono>
@@ -46,6 +47,7 @@
 namespace FediBlock::git
 {
 
+using fmt::format;
 using std::ofstream;
 using std::runtime_error;
 using std::string;
@@ -57,9 +59,8 @@ using std::this_thread::sleep_for;
 using namespace std::chrono_literals;
 
 git_repository *_repo{nullptr};
-const string _clone_url{
-    (((((string{"git@"} += config::forge_domain) += ":") +=
-       config::forge_org) += "/") += config::forge_repo_data) += ".git"};
+const string _clone_url{format("git@{:s}:{:s}/{:s}.git", config::forge_domain,
+                               config::forge_org, config::forge_repo_data)};
 fs::path _repo_dir{};
 
 void init(const bool cache)
@@ -145,7 +146,8 @@ void commit(const entry_type &entry)
     ofstream file(basename + ".json");
     if (!file.good())
     {
-        throw runtime_error{"Could not create file: " + basename + ".json"};
+        throw runtime_error{
+            format("Could not create file: {:s}.json", basename)};
     }
     file << json::to_json(entry);
     file.close();

src/gitea.cpp

@@ -22,6 +22,7 @@
 #include "types.hpp"
 
 #include <curl/curl.h>
+#include <fmt/format.h>
 #include <nlohmann/json.hpp>
 
 #include <stdexcept>
@@ -31,6 +32,7 @@
 namespace FediBlock::gitea
 {
 
+using fmt::format;
 using std::runtime_error;
 using std::string;
 using std::string_view;
@@ -91,7 +93,7 @@ string api_request(const http_method method, const string_view path,
                    const string_view body)
 {
     CURLcode code{};
-    string url{(string("https://") += config::forge_domain) += path};
+    string url{format("https://{:s}{:s}", config::forge_domain, path)};
     _curl_buffer_body.clear();
 
     switch (method)
@@ -122,13 +124,13 @@ string api_request(const http_method method, const string_view path,
     code = curl_easy_setopt(_connection, CURLOPT_URL, url.c_str());
     if (code != CURLE_OK)
     {
-        throw runtime_error{"Couldn't set URL: " + to_string(code)};
+        throw runtime_error{format("Couldn't set URL: {:d}", code)};
     }
 
     code = curl_easy_perform(_connection);
     if (code != CURLE_OK)
     {
-        throw runtime_error{"libcurl error: " + to_string(code)};
+        throw runtime_error{format("libcurl error: {:d}", code)};
     }
 
     long http_status{0}; // NOLINT(google-runtime-int)
@@ -136,7 +138,7 @@ string api_request(const http_method method, const string_view path,
     curl_easy_getinfo(_connection, CURLINFO_RESPONSE_CODE, &http_status);
     if (http_status < 200 || http_status >= 300)
     {
-        throw runtime_error{"HTTP error: " + to_string(http_status)};
+        throw runtime_error{format("HTTP error: {:d}", http_status)};
     }
 
     return _curl_buffer_body;
@@ -145,8 +147,8 @@ string api_request(const http_method method, const string_view path,
 void pull_request(const string_view branch, const entry_type &entry)
 {
     api_request(http_method::POST,
-                (((string("/api/v1/repos/") += config::forge_org) += "/") +=
-                 config::forge_repo_data) += "/pulls",
+                format("/api/v1/repos/{:s}/{:s}/pulls", config::forge_org,
+                       config::forge_repo_data),
                 json::pull_request_body(branch, entry));
     ++_last_pr_number;
 }
@@ -155,11 +157,11 @@ uint64_t get_last_pr_number()
 {
     if (_last_pr_number == 0)
     {
-        const auto answer{api_request(
-            http_method::GET,
-            (((string("/api/v1/repos/") += config::forge_org) += "/") +=
-             config::forge_repo_data) += "/pulls",
-            "?sort=newest&limit=1")};
+        const auto answer{
+            api_request(http_method::GET,
+                        format("/api/v1/repos/{:s}/{:s}/pulls",
+                               config::forge_org, config::forge_repo_data),
+                        "?sort=newest&limit=1")};
         if (answer == "[]")
         {
             return 0;

src/time.cpp

@@ -54,8 +54,7 @@ string to_string(const string_view timestring, const string_view format)
     std::tm tm{};
     tm.tm_isdst = -1; // Detect daylight saving time.
     stringstream ss(timestring.data());
-    ss >> get_time(&tm,
-                   "%Y-%m-%dT%T"); // Assume time is UTC (%F doesn't work).
+    ss >> get_time(&tm, "%Y-%m-%dT%T"); // Assume time is UTC (%F doesn't work).
 
     return to_string(system_clock::from_time_t(timegm(&tm)), format);
 }