Better error messages for command line errors.

CHANGELOG.md

@@ -11,11 +11,14 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 
 - Build with warnings in all build types, not only "Dev".
+- Better error messages for command line errors.
 
 ### Fixed
 
 - Make `--overwrite` and `--fsync` work in `derive_changes` command.
 - A dereference of end iterator in `derive_changes`.
+- You can not specify the special file name "-" (to read from STDIN) several
+  times for commands reading multiple files.
 
 
 ## [1.5.0] - 2017-01-18

src/cmd.hpp

@@ -132,7 +132,7 @@ class with_single_osm_input {
 
 protected:
 
-    std::string m_input_filename = "-"; // default: stdin
+    std::string m_input_filename;
     std::string m_input_format;
     osmium::io::File m_input_file;
 
@@ -160,7 +160,7 @@ class with_multiple_osm_inputs {
 
 public:
 
-    void setup_input_files(const boost::program_options::variables_map& vm, bool optional = false);
+    void setup_input_files(const boost::program_options::variables_map& vm);
 
     po::options_description add_multiple_inputs_options();
 
@@ -178,7 +178,7 @@ class with_osm_output {
 
     std::string m_generator;
     std::vector<std::string> m_output_headers;
-    std::string m_output_filename = "-"; // default: stdout
+    std::string m_output_filename;
     std::string m_output_format;
     osmium::io::File m_output_file;
     osmium::io::overwrite m_output_overwrite = osmium::io::overwrite::no;

src/command_apply_changes.cpp

@@ -85,6 +85,8 @@ bool CommandApplyChanges::setup(const std::vector<std::string>& arguments) {
 
     if (vm.count("change-filenames")) {
         m_change_filenames = vm["change-filenames"].as<std::vector<std::string>>();
+    } else {
+        throw argument_error{"Need data file and at least one change file on the command line."};
     }
 
     if (vm.count("with-history")) {

src/io.cpp

@@ -47,11 +47,19 @@ void with_single_osm_input::setup_input_file(const boost::program_options::varia
         m_input_format = vm["input-format"].as<std::string>();
     }
 
-    if ((m_input_filename == "-" || m_input_filename == "") && m_input_format.empty()) {
-        throw argument_error{"When reading from STDIN you need to use the --input-format/-F option to declare the file format."};
+    if (m_input_format.empty()) {
+        if (m_input_filename == "-") {
+            throw argument_error{"When reading from STDIN you need to use the --input-format/-F option\n"
+                                 "to specify the file format."};
+        }
+
+        if (m_input_filename == "") {
+            throw argument_error{"Missing input file. Use '-' to read from STDIN and add the --input-format/-F\n"
+                                 "option to specify the file format or specify the input file name."};
+        }
     }
 
-    m_input_file = osmium::io::File(m_input_filename, m_input_format);
+    m_input_file = osmium::io::File{m_input_filename, m_input_format};
 }
 
 po::options_description with_single_osm_input::add_single_input_options() {
@@ -70,31 +78,34 @@ void with_single_osm_input::show_single_input_arguments(osmium::util::VerboseOut
     vout << "    file format: " << m_input_format << "\n";
 }
 
-void with_multiple_osm_inputs::setup_input_files(const boost::program_options::variables_map& vm, bool optional) {
+void with_multiple_osm_inputs::setup_input_files(const boost::program_options::variables_map& vm) {
     if (vm.count("input-filenames")) {
         m_input_filenames = vm["input-filenames"].as<std::vector<std::string>>();
-    } else if (!optional) {
+    } else {
         m_input_filenames.push_back("-"); // default is stdin
     }
 
+    bool uses_stdin = false;
+    for (auto& filename : m_input_filenames) {
+        if (filename == "-") {
+            if (uses_stdin) {
+                throw argument_error{"Can read at most one file from STDIN."};
+            }
+            uses_stdin = true;
+        }
+    }
+
     if (vm.count("input-format")) {
         m_input_format = vm["input-format"].as<std::string>();
     }
 
-    if (m_input_format.empty()) {
-        bool uses_stdin = false;
-        for (auto& filename : m_input_filenames) {
-            if (filename.empty() || filename == "-") {
-                uses_stdin = true;
-            }
-        }
-        if (uses_stdin) {
-            throw argument_error{"When reading from STDIN you need to use the --input-format/-F option to declare the file format."};
-        }
+    if (uses_stdin && m_input_format.empty()) {
+        throw argument_error{"When reading from STDIN you need to use the --input-format/-F option\n"
+                             "to specify the file format. Or are you missing a file name argument?"};
     }
 
     for (const std::string& input_filename : m_input_filenames) {
-        osmium::io::File input_file(input_filename, m_input_format);
+        osmium::io::File input_file{input_filename, m_input_format};
         m_input_files.push_back(input_file);
     }
 }
@@ -146,12 +157,18 @@ void with_osm_output::init_output_file(const po::variables_map& vm) {
 }
 
 void with_osm_output::check_output_file() {
-    if ((m_output_filename == "-" || m_output_filename == "") && m_output_format.empty()) {
-        throw argument_error{"When writing to STDOUT you need to use the --output-format/-f option\n"
-                             "to declare the file format. Or did you miss the --output/-O option?"};
+    if (m_output_format.empty()) {
+        if (m_output_filename == "-") {
+            throw argument_error{"When writing to STDOUT you need to use the --output-format/-f\n"
+                                 "option to specify the file format."};
+        }
+        if (m_output_filename == "") {
+            throw argument_error{"Missing output file. Set the output file with --output/-o and/or\n"
+                                 "add the --input-format/-F option to specify the file format."};
+        }
     }
 
-    m_output_file = osmium::io::File(m_output_filename, m_output_format);
+    m_output_file = osmium::io::File{m_output_filename, m_output_format};
     m_output_file.check();
 }